MK IV - first start - we have take off - but 2 questions - water temp, light switch

[tmmski]

Hi
Well started the new year with a roar, was able to turn over and successfully start my MK IV roadster today. A couple things I need to work out.

minor thing
1 - I haven't figured out how to get the knob for the light switch to stay in. I"m going to crack open the manual and search the forum, but right now, I had it so I pushed the road in to the switch and I heard a click, when I went to pull the knob out, it pulled right out. It didn't clip into place

more concerning
2 - my autometer water temp gauge went to 250 degrees within about 3 minutes, the lower radiator hose was warm to the touch, but not dangerously hot. The upper hose was cool to the touch. I put in a 50-50 mix of coolant, about 4 gallons.

- Where should I look? Could air trapped in the coolant system be causing that? I have an autometer oil temp gauge (I didn't install) that has a temp sensor could I swap them out to see if it is the sending unit?

- I started it 4 times and ran it for about 5 minutes each time about 30 minutes apart, the last time I ran it the radiator fan motor did kick on and ran for a few minutes, then I shut the motor off.

I'm going to let it set for a little while, while I connect my laptop to the XFI control unit, and see if I can figure out what that is sensing at it's water temp sensor.

Is there something else I should check. I can post some pictures of the upper hose connection.

Also wanted to say thanks to BB767, and Papa for helping with the wiring, I wouldn't have been able to get this far with out sorting out those questions.

I need to figure out how to get the video of the start uploaded, I'll get it posted soon.

Happy new year.

Tim

[BB767]

Hi Tim, thanks for the kudos, glad I could contribute. My water temp did much the same as yours. May be a dumb question, but have you rechecked the coolant level? After first start mine needed over a gallon more coolant! After that the temp was more normal.

[cgundermann]

Suspect the same, if it hasn’t been through several heat cycles and adequately “burped” and filled - could show you a false high reading because of air pockets...

Chris

[Itchief]

If the fluid level is still full I would check the thermostat make sure it is installed properly, place it in hot water to verify that it opens

You could also run it without the thermostat to check and see if the water pump is working properly m

Rick

[Papa]

Tim,

Congrats! It definitely feels good to hear the engine come to life. Can't help on the light switch, as it should just push in and require you to press the release button on the switch to get it back out. On the coolant, I had the exact same thing happen. I bought one of these to help get the system purged of air without making a mess:

https://www.amazon.com/Lisle-24610-S...ll+free+funnel

It worked like a champ and my temps stabilized at 180 degrees +/- ~3 degrees. I also found that once I got coolant to completely circulate through the engine, it needs to be flushed and refilled. Are you sure your gauge temp is accurate? The fan should come on with water temp at ~180 degrees. If the gauge is reading 250, I'd suspect the gauge or sending unit.

Dave

[tmmski]

thanks for the tips guys, I've borrowed a Lisle 24610 Spill-Free Funnel. I'll give that a shot tomorrow. I'll let you know how it goes. I"m sitting in the garage and can still smell the fumes from the first start, it brings a smile to my face. What a pretty sound the motor made.... I guess I better go inside, maybe it's lack of oxygen. Appreciate the help.

Tim

[KDubU]

Congrats! Looks like others more knowledgeable than me have answered your questions.

[CraigS]

You can do the Lisle thing and that will help. But, assuming you have the common T-filler w/ a hose over to a reservoir tank, from then on, do all filling at that tank. Do not remove the pressure cap again. As the engine cools and sucks coolant back out of the tank, assure it doesn't empty. Look to get to where the tank is 1/4 full cold and 3/4 to full hot. If you have the standard FFR tank, be aware that sometimes it has a marginal capacity. For some reason it works fine for some people while others find they need more capacity.

[scottiec]

I went through a similar experience with the light switch/knob. Basically, you need to take it apart because there is a detent that the rod gets held in by, you can see the button with spring that controls it from the outside. It was extremely difficult to get the rod lined up with all the holes and get it to click in to the detent. I had FF send me a new one.

[FFinisher]

I have found if you put some tension on it like you were trying to bend the two ends toward the middle with the connectors facing up the knob stays in.


I know you are thinking I should just get a new one.......... But the new one will likely be the same.

[tmmski]

Hi,
Well, it's never what you think it is..... We used the Lisle thing and it definitely got the air out. But still ran upto 250. we were going to test the sensor in boiling water like ItChief suggested. Well while we were waiting for it to cool down I thought I'd look at the gauge and how I wired it up. What's Homer say "D'oh!" I left the ground off. Hooked it back up and fired up the motor and the temp gauge matched the XFI temp. We are moving on. thanks for the tips guys. I'm working on gettting the dash completely installed and getting the seatbelts and seats in. I hope to be gokarting by tomorrow. I looked at the light switch and used a little bit of pressure and got it to click in and stay. I'm going to keep an eye on it and see how the lights controller behaves.

thanks for the pointers. hope everybody is having a nice week. - I sure like the tag line 'built not bought' By building I"m sure learning lots.

Tim

[CraigS]

Sure is nice when it turns out to be a simple fix isn't it? Congrats!