Coolant Boost Pumps

[Bob_n_Cincy]

Red race car engine number one: Blown head gasket due to pushing the limit of boost on a 175k mile engine. If you watch the video where that car blows coolant out of the rad cap the temp is just barely over 200 degrees, not enough to boil over but it blows the cap due to compression leaking past the gasket into the cooling system.

Jim,
When this red car blew its head gasket, I see 2 numbers on the video that are out of wack.

The boost pressure was above 40 psi. I read somewhere that the vacuum hose going to the wastegate got melted and caused this. Is this correct?

The other number was the "air intake temperature" above 200 degrees.
The stock sensor is right after the air filter so I know it wasn't located there.
Was the AIT sensor located before or after the intercooler?
Thanks,
Bob

PS. Thanks for explaining that the thermostat was gutted. That explains why the motor was slow setting up to temperature.

[metalmaker12]

I'm not too concerned with the cooling system. I was worried about the other things (TMIC, Dry Sump). I'll know in less than 2 weeks when I test the 818R on the track. It's sad when my buddies and I are already joking about blowing a motor. So hopefully, none of that will happen and I will have good things to report after some hard driving.

I would take it easy and really watch the iats. That is the motor killer. The cooling system seem good to me, maybe even to efficient. You should be fine, and actually I want your motor to last and last, cause we need success at this point.

[Jim Schenck]

Jim,
When this red car blew its head gasket, I see 2 numbers on the video that are out of wack.

The boost pressure was above 40 psi. I read somewhere that the vacuum hose going to the wastegate got melted and caused this. Is this correct?

The other number was the "air intake temperature" above 200 degrees.


The stock sensor is right after the air filter so I know it wasn't located there.
Was the AIT sensor located before or after the intercooler?
Thanks,
Bob

PS. Thanks for explaining that the thermostat was gutted. That explains why the motor was slow setting up to temperature.

Bob,

The blown head gasket occured in the first engine, a 175K mile donor 2.5 out of a Legacy GT we were running at 23 lbs of boost. This is not the same engine we had the overboost issue with. I think a lot of concern has been generated because of this failure but the results really were not unexpected, we hoped to make it one hot lap to get a time in but we ended up making it 2/3 of a lap 3 times. As to why the heck we would go the track with such a ticking time bomb, thats a long story, but one that I can't spill the beans on yet and ruin what is coming but an explanation is on its way. I do promise though it was not our original plan or even our backup plan and not also just sheer ignorance!

The second engine was the one that had the small fire and overboost. After dissasembly I don't honestly know what order those things occured in, however I am sure that one of them led to the other. The crazy high IATs on that engine on that hot lap were for sure a problem, something that had not shown up on the dyno. We added a reservoir to the system between the dyno and the track which maybe was the cause of the problem (I always look at the most recent change first and this was really the only change between the dyno and the track.) We tested the system with the tank for flow at the shop and it was working but during the run the speed at which the IATs cllimbed and the volume of fluid in the system makes me think the fluid just simply wasn't circulating enough. The tank was hot after the run so there was at least some circulation.

The IAT sensor is in the tube between the cooler and the throttle body, so those are post cooler temps. We were seeing 130s on the dyno, which is why we added the tank, plus we were considering running ice just because of the time trial nature of the event. We also thought that the stationary dyno pulls were not allowing the heat exchanger to work to its full potential and we would have better cooling once the car was at speed.

Without the thermostat the engine never got above 180 degrees during a whole day of running on the dyno, it wasn't just slow to warm up, it stayed at those temps under full load and not great airflow.

[Mechie3]

Jim,
What size heat exchanger were you using? I recall seeing photo of one about half the width of the radiator, but don't know what car it was on. I also remember seeing a very large AWIC core on one of the cars. Was this with a stock turbo?

Thanks.

[ssssly]

As far as the previous logging discussion. Get a tractrix cable and an old laptop.

Can log every single sensor in the engine. More data than you can shake a stick at.

From everything I have seen however, the coolant system isn't much of a problem. With the corrugated pipes, just bleed the system thoroughly to avoid air bubbles in the ridges.

I would suggest parking the car on a slight hill, bum up, to get the filler tank good and above the radiator. Open the filler tank and jam a tall skinny funnel in it and fill until the entire system and the funnel is half way filled. Start the car and rev it slowly.

If you get a good rite you will see the fluid in the funnel sucking into the engine and then spitting all the bubbles out as it fills again.

If you have big enough air pockets it will suck the funnel dry. Just fill it up again.

(Note: Wait until the fluid cools before pulling the funnel out. And its going to make a bit of a mess. So you might want to throw some rags or nasty towels under the tank.)

Air bubbles can cause cavitation in both the impeller and the tubing causing premature pump failure.

The far bigger concern of mine is the IATs. High IATs will blow a boxer very quickly.

I strongly suggest everyone tune their engine to pull timing if IATs are over 120 and to go into full limp over 150 or 160 (depending how brave you are).

Hopefully I will get my 3d printer and scanner soon so I can start working on the air diverter vents. Car definitely needs more air to the TMIC if running more than a td04.


metalmaker12: I wouldn't suggest going straight MBC unless it is going to be a dedicated track car. Twinscrolls are particularly prone to PTFB issues with MBCs. The last thing you want is full boost at low RPM going up a slight hill in a high gear. There is no way to tune for it and things will pop. Quickly.

I would suggest a hybrid EBC/MBC setup. Works quite well when set up properly with one way check valves.

[Bob_n_Cincy]

As far as the previous logging discussion. Get a tractrix cable and an old laptop.
Can log every single sensor in the engine. More data than you can shake a stick at.
I strongly suggest everyone tune their engine to pull timing if IATs are over 120 and to go into full limp over 150 or 160

Hi ssssly,
I am running a stock 04 FXT engine. My IAT sensor is before the turbo so it doesn't get hot.
I can add in another IAT sensor but I have no way to log it.
What does it take tuning wise to change my IAT to post turbo?
Bob

PS: I had to look up all the acronyms you used in your comments to Metal.

[Bob_n_Cincy]

Thanks Jim for your response in post 43 above, that clears some things up for me.
I am going to work on my AWIC System.
Bob

[Scargo]

Per Jim: "As to why the heck we would go the track with such a ticking time bomb, thats a long story, but one that I can't spill the beans on yet and ruin what is coming but an explanation is on its way."
The saga continues. What can they be up to?

[Jaime]

I can add in another IAT sensor but I have no way to log it.

Sponaugle's recommendation was to wire the second IAT sensor to the TGV sensor, that way you can log it with ROMRaider.

[Bob_n_Cincy]

Sponaugle's recommendation was to wire the second IAT sensor to the TGV sensor, that way you can log it with ROMRaider.

Thanks Jamie,
Right now I am still using my TGV. I did look a my schematics and found the only analog sensor I'm not using is the fuel tank pressure sensor. So maybe I can use that one.
Bob

[Mechie3]

re: datalogging, I wanted more data that just what the ECU spits out. Post turbo temps, post IC temps, water temp at radiator (vs water temp at engine as well). It's good to have the ECU data, but it doesn't always tell you the full story (such as, how efficient is a certain system).

[metalmaker12]

As far as the previous logging discussion. Get a tractrix cable and an old laptop.

Can log every single sensor in the engine. More data than you can shake a stick at.

From everything I have seen however, the coolant system isn't much of a problem. With the corrugated pipes, just bleed the system thoroughly to avoid air bubbles in the ridges.

I would suggest parking the car on a slight hill, bum up, to get the filler tank good and above the radiator. Open the filler tank and jam a tall skinny funnel in it and fill until the entire system and the funnel is half way filled. Start the car and rev it slowly.

If you get a good rite you will see the fluid in the funnel sucking into the engine and then spitting all the bubbles out as it fills again.

If you have big enough air pockets it will suck the funnel dry. Just fill it up again.

(Note: Wait until the fluid cools before pulling the funnel out. And its going to make a bit of a mess. So you might want to throw some rags or nasty towels under the tank.)

Air bubbles can cause cavitation in both the impeller and the tubing causing premature pump failure.

The far bigger concern of mine is the IATs. High IATs will blow a boxer very quickly.

I strongly suggest everyone tune their engine to pull timing if IATs are over 120 and to go into full limp over 150 or 160 (depending how brave you are).

Hopefully I will get my 3d printer and scanner soon so I can start working on the air diverter vents. Car definitely needs more air to the TMIC if running more than a td04.


metalmaker12: I wouldn't suggest going straight MBC unless it is going to be a dedicated track car. Twinscrolls are particularly prone to PTFB issues with MBCs. The last thing you want is full boost at low RPM going up a slight hill in a high gear. There is no way to tune for it and things will pop. Quickly.

I would suggest a hybrid EBC/MBC setup. Works quite well when set up properly with one way check valves.

Thanks for your input but I have used, mbc,ebc, hybrids with success and reliability on twin scrolls and non. You just gotta know how to tune it correctly for each one. I have never had an issue with mbc and all my subarus have had them. I am also not going to run as high a boost as I would normally so peak boost of 16 all the time is not a concern. It's all in how you skin it and like your boost. I like the boost there all the time, it does not have to be really high, just there. I like 25% throttle and full boost on the ej207 running avcs with a 1.5 dom. I can run lower peak boost and feel power sooner and for longer. You just have to complete the map correctly. I think I can get away with 14 psi- 16psi on this setup with the avcs and timing set just right to be plenty of power. The dyno will tell the story. If it feels like too much response than I will hybrid, but I always start off with what I like most first. I feel from my years of owning and playing with these cars that a mbc can be as reliable/safe as any setup, and the most responsive.
Keep in the loop, my car is about a week away from first starting (for second time). And I did not over boost first time and it was the Sti oem soleniod lol
I just have to set up awic and run coolant with My vacum filler.

[ssssly]

For an EJ207 with that size turbo I generally put an 11lb spring in the wastegate and run on spring pressure bellow 50% throttle. Below 11psi, even on pump gas, you can still run pretty aggressive timings below 3k. Allows the turbo to stay nice and spooled up down low with the a good failsafe against ptfb related engine failures on the road.

I then run 75% wgdc at 60% throttle, 100% wgdc above 70% throttle with the MBC setting max boost. I set my boost tables 25% higher than whatever the MBC is set for. And a one way check valve before and after the MBC. So if either the MBC of EBC fails it failsafes to the other. Then on the load table I always run a row above whatever the max load is, at full target boost, and run it rich as hell.

So if it ever overboosts there is plenty of cooling fuel to keep the detonation down.

I'm also running 24 PSI though. So if I have full boost at 4k and low load, is a way bigger deal than you. The ecu can probably get close to pulling enough timing for 5 psi of overboost at low load. Can't come close at 13 psi of overboost. Tuning for 16psi at low load will create a weird revers hump in your timing map though. Haven't tried it, but I wouldn't necessarily suggest it. Could do weird things in shifts and when lifting off throttle going up or down hill. But again, never tried it so it could work great.

I also tune everything to 85% though. If I can't get the power I want out of 85% of current setup, I change the setup. I don't mind blowing stuff up at a track, but I prefer not to. And I definitely don't like blowing things up driving around town.

I have found running like this makes the car feel way more like a turbo charged 6 than 4. The power build linearly with how much throttle you apply. As opposed to mashing the throttle and waiting for the turbo to spool. Unless you mash it off the line. But with a twin scroll turbo and aggressive AVCS and cams, you are only waiting 3k RPM for spool.

Looking forward to seeing you up and running again. Particularly interested in how you get the power to the ground. As a guideline to how far I am going to need to go with suspension and body mods for humongous rear tires.

[Scargo]

ssssly, you said "For an EJ207 with that size turbo". I can't find what you're referring to, though perhaps it is irrelevant to my comment/question. I'm trying to pick a turbo and am worried about excessive wastegating when trying to stay at a 8:1 P/W ration for ST-2. You bring up some interesting ideas.
Could you and others comment on this issue in my thread, Discuss Subaru EJ Motor Builds For Road Racing, where I think it is more appropriate?

[metalmaker12]

For an EJ207 with that size turbo I generally put an 11lb spring in the wastegate and run on spring pressure bellow 50% throttle. Below 11psi, even on pump gas, you can still run pretty aggressive timings below 3k. Allows the turbo to stay nice and spooled up down low with the a good failsafe against ptfb related engine failures on the road.

I then run 75% wgdc at 60% throttle, 100% wgdc above 70% throttle with the MBC setting max boost. I set my boost tables 25% higher than whatever the MBC is set for. And a one way check valve before and after the MBC. So if either the MBC of EBC fails it failsafes to the other. Then on the load table I always run a row above whatever the max load is, at full target boost, and run it rich as hell.

So if it ever overboosts there is plenty of cooling fuel to keep the detonation down.

I'm also running 24 PSI though. So if I have full boost at 4k and low load, is a way bigger deal than you. The ecu can probably get close to pulling enough timing for 5 psi of overboost at low load. Can't come close at 13 psi of overboost. Tuning for 16psi at low load will create a weird revers hump in your timing map though. Haven't tried it, but I wouldn't necessarily suggest it. Could do weird things in shifts and when lifting off throttle going up or down hill. But again, never tried it so it could work great.

I also tune everything to 85% though. If I can't get the power I want out of 85% of current setup, I change the setup. I don't mind blowing stuff up at a track, but I prefer not to. And I definitely don't like blowing things up driving around town.

I have found running like this makes the car feel way more like a turbo charged 6 than 4. The power build linearly with how much throttle you apply. As opposed to mashing the throttle and waiting for the turbo to spool. Unless you mash it off the line. But with a twin scroll turbo and aggressive AVCS and cams, you are only waiting 3k RPM for spool.

Looking forward to seeing you up and running again. Particularly interested in how you get the power to the ground. As a guideline to how far I am going to need to go with suspension and body mods for humongous rear tires.

This is pretty much how were going to do it except much less boost, I only want 275-300whp, but am going to try to get the setup to have minimal lag. I also run it rich as hell lol. I am interested in how it will shift off and on boost etc, but I feel we will get it where I want it with some road and dyno tuning. Typically I run 21-26 psi with this setup and make 400-420whp, but the 818 does not need it and I want to try to keep it together.

[ssssly]

Scargo. Referring to a twinscroll Dom 1.5x.

Tuned to around 16 psI it should have no lag if you have at least a 10lb spring in the wastegate. Would think you will have issues keeping no lag and below 350ft lb of torque under 5k. It's gonna want to make more like 360. You're probably gonna have to pull a ton of timing. Or you will have to use more like a 7 lb spring to bleed of boost earlier, which will make it feel laggier down low. Still plenty of juice for this car though.

[iblackwe]

Hi all,

Bringing a thread back up again. I just had a very expensive dyno experience as my car overheated on the dyno and the techs couldn't remove the air lock. I was told that a coolant boost pump would likely be necessary however, after reading all of this I believe the stock mechanical pump is fine and that the system just needs to be burped very correctly. I have done waynes mod prior to the dyno and filled the system myself prior to them trying to purge it as well.

I am looking to see if anyone has come up with a definitive answer as to whether the 818 needs a boost pump or not. As well, does anyone else have a trick to bleed the system of air entirely. I think what I found is that I had a air lock in the cool return line of the radiator going over the steering rack and down alongside of the car.

Please let me know what you guys think, I honestly can't imagine another botched dyno run haha.

[Bob_n_Cincy]

Hi all,

Bringing a thread back up again. I just had a very expensive dyno experience as my car overheated on the dyno and the techs couldn't remove the air lock. I was told that a coolant boost pump would likely be necessary however, after reading all of this I believe the stock mechanical pump is fine and that the system just needs to be burped very correctly. I have done waynes mod prior to the dyno and filled the system myself prior to them trying to purge it as well.

I am looking to see if anyone has come up with a definitive answer as to whether the 818 needs a boost pump or not. As well, does anyone else have a trick to bleed the system of air entirely. I think what I found is that I had a air lock in the cool return line of the radiator going over the steering rack and down alongside of the car.

Please let me know what you guys think, I honestly can't imagine another botched dyno run haha.

Hi Iblackwe,
I have put many hours into the 818 cooling system.
The setup I have now has been drain and refilled at least a 1/2 dozen times with no airlock or other issues.
No special bleeding procedures. Fill system, heat cycle it once, refill and your done.

The number one rule: every high spot in the system must automatically bleed back to the expansion tank.
I have 2 paths.
First I did modification very equivalent to Wayne's Mod. I put an 1/8" pill in that hose to let air flow freely and it would restrict water flow.

Secondly, I add a bleed hose from the top of the radiator back to the expansion tank. (my radiator has a sealed cap.) I raised my expansion tank up into the hump to make it more effective.

The number 2 rule.
Run every hose (bleed or main) with no rises that will trap air.

The number 3 rule.
Run smooth line (tubing or rubber). The pressure out of the water pump has multiple paths it can take. You need to make it run easily to and from the radiator.


Picture of bleed pressure testing:

testing.jpg

Picture of engine bleed hose.
waynes.jpg

With all that said, A boost pump would help.
I don't know what would happen to a boost pump when the thermostat was closed and nothing is flowing.

Bob

[JeffS]

I accomplished the same thing as Wayne's engine mod using one of these drain fittings....

DSC_0318.jpg

DSC_0317.jpg


For the steering rack bump I welded a bleeder bung at the highest point on the bend...

DSC_0316.jpg

I can't tell you yet how well it's going to work though... a few more months to go-carting.

Jeff

[UnhipPopano]

Two things. First, the proper term to use "The number one rule: every high spot in the system must automatically bleed back to the expansion tank." is Vent. All high-point vents can be connected together in the front of the car and then routed to the expansion tank or some other high point vent tank. Note that vent lines can be routed higher than the point that they are venting. Air will find its way to these high points and then be drawn to the vent tank. The second thing is to ask if anyone has added any testing for flow rate of the coolant through the engine. The purpose of the closed impeller cooling pumps are to ensure enough flow by generating a higher head pressure.

If the flow rate is not high enough, then the surface temperatures of the cylinders will be higher. This would possibly cause failure down the road.

[flynntuna]

I was under the impression that flow rate is critical to engine cooling. To fast and the heat doesn't have time to transfer to the radiator fins, to slow and there's to much heat at the heads.

[Wayne Presley]

There is no such thing as too fast. The fast flow prevents localized boiling. The faster flow also cause turbulence in the radiator tubes breaking up the boundry layer which helps in transferring heat to the fins/air.

[STiPWRD]

I was under the impression that flow rate is critical to engine cooling. To fast and the heat doesn't have time to transfer to the radiator fins, to slow and there's to much heat at the heads.

There's no such thing as the flow rate being too fast that heat transfer won't occur. However, if it's too slow, yes the heads will be hotter.

Imagine a table fan blowing on your face, it's not actually removing any heat from the air (like an AC system would), it's simply creating some air flow, which improves convection - so you feel cooler. If the fan velocity increases, you're not going to suddenly feel hot because heat transfer stops. The convection will asymptote to some limit for forced air. In fact, as the flow increases, it will transfer from laminar to turbulent and heat transfer improves drastically with turbulent flow.

Edit: Wayne beat me to it

[Wayne Presley]

At least we both paid attention in thermodynamics class

[iblackwe]

Hi Iblackwe,
I have put many hours into the 818 cooling system.
The setup I have now has been drain and refilled at least a 1/2 dozen times with no airlock or other issues.
No special bleeding procedures. Fill system, heat cycle it once, refill and your done.

The number one rule: every high spot in the system must automatically bleed back to the expansion tank.
I have 2 paths.
First I did modification very equivalent to Wayne's Mod. I put an 1/8" pill in that hose to let air flow freely and it would restrict water flow.

Secondly, I add a bleed hose from the top of the radiator back to the expansion tank. (my radiator has a sealed cap.) I raised my expansion tank up into the hump to make it more effective.

The number 2 rule.
Run every hose (bleed or main) with no rises that will trap air.

The number 3 rule.
Run smooth line (tubing or rubber). The pressure out of the water pump has multiple paths it can take. You need to make it run easily to and from the radiator.


Picture of bleed pressure testing:

testing.jpg

Picture of engine bleed hose.
waynes.jpg

With all that said, A boost pump would help.
I don't know what would happen to a boost pump when the thermostat was closed and nothing is flowing.

Bob

Hi Bob thanks for the advice, I will definitely try and remove the high point going over the steering rack. I like jeffs idea in putting a bleed point right overtop of that section and I think I can utilize that drain fitting to do so as I am still using the corrugated tubing and can cut and splice that into the line.

Would i potentially be able to plumb that bleeder vent back into the vent line coming from the top of the front radiator that runs all the way to the back of the car into the expansion tank on top of the manifold? As of right now I have waynes coolant mod coming from the cross over pipe tee'd into the vent line from the front of the radiator and then they both plum into the vent line of the tank on the manifold... I am sure plumbing in a third line from the front of the car wouldn't be an issue. I could also put 1/8" restrictors into each line as I think that is a great idea.

I currently have the expansion tank barb on the front radiator sealed and so I am assuming I should be using a sealed (no vent) radiator cap as well. What pressure rating should I be using for the rear coolant expansion tank (on the manifold) as well?

Thanks everyone.

[flynntuna]

Thanks for the explanation. It inspired me to do further research.

http://iosrjournals.org/iosr-jmce/pa...volume2/13.pdf

http://www.maplesoft.com/application...6403&view=html

[Wayne Presley]

I run a 1.3 bar front cap and a 1.1 bar expansion tank on the motor

[Bob_n_Cincy]

I currently have the expansion tank barb on the front radiator sealed and so I am assuming I should be using a sealed (no vent) radiator cap as well. What pressure rating should I be using for the rear coolant expansion tank (on the manifold) as well?

Thanks everyone.

I think a large air pocket in the radiator is most likely your biggest problem.
Use Wayne's suggestions on the radiator caps.
I would run a 5/16 hose from the radiator bleed port to the expansion tank. I did not put a pill in that line from the radiator. That is the most important place that needs bleeding.

[DodgyTim]

I used one of these temperature sensor fittings in the high point of the coolant line at the steering rack.
Its an easy way of getting a bleed port, and only cost about $5
p[1].jpg

[UnhipPopano]

The bad part of this Test Report "Thanks for the explanation. It inspired me to do further research. - http://iosrjournals.org/iosr-jmce/pa...volume2/13.pdf" is that it was only testing the Radiator and did not take into account the combined effect on both the Radiator and Engine. As the flow goes up, more energy is removed by the coolant at the engine, and then released by the Radiator. At the same time, energy is being used by the pump to pump the coolant and this reduces the available engine power.

As far as "tank barb on the front radiator sealed ....I think a large air pocket in the radiator is most likely your biggest problem." this is self evident. If the Radiator is in effect not full, then it can not remove as much heat. A Radiator that the coolant is only covering half the cooling fin area will only remove 50% of the heat, assuming no increase in inlet temperature.

[iblackwe]

I think I may have mis led everyone on the front radiator. I have a mishimoto front radiator and the passengers side of it has a barb fitting which I believe is the vent line. So I have that line running to the back of the car to the small coolant tank on the top of the manifold. The barb coming from the radiator cap has been removed and plugged with a set screw as I didn't leave the overflow coolant tank up front, I mounted it in the back and plugged it into the small manifold coolant tank. If I need to put that barb back in under the radiator cap I will definitely do so but my initial impression was that it wasn't necessary.

Thanks

[Wayne Presley]

Front capped is fine

[flynntuna]

Found this on line...http://www.mgf.ultimatemg.com/group2/coolant/ewp.htm
Is this a reasonable approach?

[Wayne Presley]

Found this on line...http://www.mgf.ultimatemg.com/group2/coolant/ewp.htm
Is this a reasonable approach?

I think you are addressing a problem that isn't there in the first place. I've had 2 818's on the track and 8 on my dyno without any cooling issues

[Bob_n_Cincy]

I think I may have mis led everyone on the front radiator. I have a mishimoto front radiator and the passengers side of it has a barb fitting which I believe is the vent line. So I have that line running to the back of the car to the small coolant tank on the top of the manifold. The barb coming from the radiator cap has been removed and plugged with a set screw as I didn't leave the overflow coolant tank up front, I mounted it in the back and plugged it into the small manifold coolant tank. If I need to put that barb back in under the radiator cap I will definitely do so but my initial impression was that it wasn't necessary. Thanks

Sounds like your set up on the front radiator is good.
When the engine is running (water pump spinning). You should get a flow of coolant in each of the bleed(vent)lines to the expansion (degas) tank on top of the intake manifold. Heat cycling your engine should push any air and excess coolant out of the expansion (degas) tank into the overflow bottle. Each time the engine cools, the expansion (degas) tank will suck coolant only from the overflow bottle.
Bob

[JeromeS13]

https://www.amazon.com/Lisle-24680-S.../dp/B00A6AS6LY

Everyone that has a turbo Subaru should have one of these...

[Mechie3]

Bob, how did you run the vent line from the radiator to the rear degas tank without it dipping and causing low spots?

[Bob_n_Cincy]

Bob, how did you run the vent line from the radiator to the rear degas tank without it dipping and causing low spots?

Hi Craig,
It runs parallel to my right side radiator hose.
When the thermostat is closed.
With a 1/8" pill in Wayne's hose.
The water pump develops enough pressure to push water toward the radiator in the 1.25 line and return air and coolant back through the 5/16 bleed hose attached to the expansion tank. I "T" wayne's hose and the radiator bleed very close to the expansion tank.

Here is the post where I was doing pressure/flow testing.
http://thefactoryfiveforum.com/showt...l=1#post228056

Bob

[Bob_n_Cincy]

To avoid humps on the coolant lines, I didn't go over the steering rack, I went under the front LCA.
pipe.jpg
I moved the fittings in the radiator from the back to the sides to make attaching easier.
Bob