John’s Mk4 Build Thread

[John Ibele]

Hey pal, not to give you anything else to fiddle with but I have the exact same setup for my heater. I have my cockpit vents in the same location. Here is the issue, when it's cold the heater works fantastic. I really like it. But when it's hot and I have it off REALLY hot engine air moves through the blower fan and puts hot air on your lap when in motion. It was 85 this weekend (ducks behind a desk) and I finally figured out what was happening.

There are 2 possible solutions. One is cover the inlet to the blower fan. This is fine, although it requires finding something that already fits or fabricating something. I don't like the idea of needing to go into the engine bay and removing something in order to use my heater. 2nd option is to replace the louvers with something that closes. This is what I am doing I have ordered these and should have them this week. I can't promise this will work but I bet it will. These were the only closing louvers I could find that were the same size and shape. I am assuming I can remove the old ones and replace them in the same plastic holder. I will let you know.

https://www.oldairproducts.com/produ...er-2-duct-hose


Either way this may be something you want to get in front of before paint if possible. I plan to do a general post after I finish to update the community but wanted to give you a heads up.

Hey Jesse, thanks for looking out for me ... good news or bad, it's always best to deal with the reality in front of you! I'll think on that and look for your broader note.

Edit: did a brief search, and I think something like this is what's needed. You'd cut into both hoses, not just the one. In closed position, the coolant would cycle right back to the pump, and the heater would have its own loop (of non-moving coolant). In open position, you have the heater included in the loop, with a bit of a jog through the bypass valve for each hose. Make sure to get the pull to open version, not pull to close.

Old Air Products 25-1018 - Heater Valve

Further edit: not Jesse's problem, exactly. His valve seems to work fine in closing off the heater core. The problem is that forward movement of the car pushes hot engine bay air through the blower and through the vents. I can't think of a better solution than closeable louvers like he mentioned. I will drive in gelcoat this summer, and will leave what I have in place to see what I experience.