Toyota supra mk3 part # 8601-8808

[supraheelfan]

http://www.cygnusx1.net/Supra/Librar...spx?F=8717&P=1

what would happen if I bypass this vacuum hose? It was making my car overheat. Why would it make the car overheat, and is it better to just bypass the valve/vacuum thing or to replace it. I cannot seem to find a name for the part either. The hoses go into the top of the head and into the heater core and I figured i wouldn't have any heat but the heat works fine. I have had it bypassed for a few days now and no overheating or problems with the car since, so I don't even won't to bother with another if I don't have to. SO ANY INFO on this stupid mysterious part would be grateful, thank you.

[btwilson86]

Are you talking about your heater control valve? The part with a vacuum line and 2 coolant lines running to it? If so, that shouldn't cause the car to overheat, but bypassing it could help lower coolant temps because now coolant can travel freely through your heater core which is essentially a second, smaller radiator.

With it bypasses you should still have a working heater, although IIRC you won't be able to completely stop hot air moving through your vents.

Also, the part number you listed is actually the date range for that diagram, Jan 86-Aug 88 (8601-8808), the part number for the piece I think your talking about is 87240-14140

[supraheelfan]

Yes that is the valve/part I am talking about, and ever since I bypassed the valve the car has not overheated since. So, IDK why but it worked. It was leaking out of the valve even though it was opening and closing and now it doesn't overheat at all.

[supraheelfan]

Anybody out there know of any other cars that would use the same valve that the goes on the supra? The part the link takes you to.
Oh yea, I have a parts car supra and put the valve from that on it and it busted that one too!? Any suggestions to why my engine keeps busting these valves? Or where I can get another one?

[btwilson86]

I'm interested to know if any other cars use this valve or a compatible one too, as the one on my car no longer opens...

[supraheelfan]

Your valve doesn't open? That should cause the hoses to build up pressure and start to leak coolant and overheat the car?! that is crazy, b/c that's exactly what happen to mine (as far as I know) anyway. Coolant would come out the top and sometimes the bottom hose.

[btwilson86]

Not exactly; my valve doesn't open, so coolant doesn't go through the heater core and I have no heater. My car does not have any overheating problems or leaks.

As I said earlier, the system is designed to work just fine with the valve closed. In a properly functioning cooling system a closed or clogged heater control valve will not cause an overheating issue. This is because the coolant does not have to travel through the valve to circulate throughout the engine, it has a path to bypass it. When you're climate control is set to the coldest temperature, that valve is supposed to be closed. If closing the valve increased pressure and caused leaks, then every Supra would overheat with the AC on.

Hopefully replacing the valve on your car fixes your problem.

[supraheelfan]

Well do you have any idea on why there was too much pressure on the two coolant hoses that pass through the valve that made it leak?

[btwilson86]

My guess is possibly some sort of blockage, maybe in the pipe that runs down the exhaust side of the engine, that's forcing the coolant to have to run through the core

[supraheelfan]

I don't know if this is right or not but, I don't think the coolant was even making it to the heater core b/c it was building up pressure on both hoses and leaking out of both of them (one hose at a time mind you). The valve thing would work for a while then it would come out the bottom hose, I would fix it, then it would start coming out the top or other hose on top?!.....