flat12boxer

Hi Guys,

My car overheated in traffic yesterday. It has never overheated in the 9 years I have owned it. I lost a good amount of coolant.

As I was driving to the post office (cruising at about 20 mph) the main "!" light came on and I'm saying why?!?! As I look at the gauge cluster, instinctively thinking, brake pad sensor, oil level, etc. I look at the temp gauge and it is pegged all the way at the top with the additional red temp gauge "!" light lit up red.

I was not in a safe neighborhood and had to turn the car around to pull over a block up. I would have shut it off right there but like I said it was not a safe location.

The coolant started to leak and hit the hot engine causing white smoke. I shut the car down immediately and we pushed it to the side of the road. AAA happened to be right there so I got a quick tow.

Things were too hot and we couldn't get to diagnose until today. I ran the garden hose into the overflow tank to find the leak and it is coming from the area behind the engine (on the firewall area?) that looks like a thermostat. What is that part?

With the water from the garden hose pumping through, the car still started and ran fine. I don't know why I overheated or what part failed. Can anyone help or offer advice?

Fara

Sounds like the heater valve failed.
I believe there is a cheap substitute part from a different model car that fits.

flat12boxer

Is that what it is? To the above left of the oil cap, under all the wires and plug connections. Why would that fail? From overheating, or would something else have failed that in turn made it fail?

Also, mine is definitely metal, looks like a thermostat when still in place. I was confused because all I see is black plastic looking HCVs in pictures online.

Fara

Ah, I may have misinterpreted which component you were referring to

is it this one?

flat12boxer

I can't tell from your picture. The best thing I can tell you is I have the late model car, not early like yours. I have the bracket that holds the two sensor plugs and the part is below/behind those.

I can see the part that failed - the coolant shoots out in little streams around it. I can see the part when looking at the car from either side or the front of the engine bay, but the best angle to see it is looking at the firewall area standing on the left side (drivers side here in the us) of the car. I took a picture during daylight but the camera did not have enough light to get everything even though the picture came out clear.

Fara

https://rennlist.com/forums/6810929-post12.html

Does it look like either of those parts?

flat12boxer

More like the metal one but not exactly...I will try to get a better description or picture tomorrow. It's been dark for a few hours here now.

I know those are the 2 HCVs you pictured but what I saw leaking basically looks like an automobile thermostat sitting in its housing. I didn't remember seeing any hoses going to it.

mel_t_vin

Was your leaking part free-standing or attached to the engine?

Not sure about the 2.7, but the 2.5 8v cars have a coolant temp-controlled vacuum valve, 058.131.851.A, fitted to a neck at the rear of the head, drivers side. The valve has two 3mm vac hose connections and is part of the charcoal canister/vapor emissions systems.

flat12boxer

Ok I got clearer pics taken and it looks like it is the late model plastic heater control valve. It was either some sort of snap ring or the reflection/glare from the coolant on the round edges that made me think otherwise.

I have a picture I can email to either of you to confirm. PM me your email address if you'd like to see it.

I am looking at the 928 motor sports all metal unit now and also the autozone style replacement. I may just not want to go with another plastic one.

When I bought the car 9 years ago, I never had constant hot air, but with no blower on I would feel the hotness overall if it was a hot day. I check the clips and metal brackets under the dash yearly and they are fine. I have also been chasing a ghost coolant leak for at least two years. Not enough to even see drops on the ground, only dropped the overflow to the min mark. So once every week or two, I had to fill the overflow from min to max.

Do you think this basically failed very very slowly over time? I had a small leak from the WP gasket on a cold day last year when putting the car back in storage, but that has gone away. The car ran with water pumping through the hose, so I am hoping I replace this and the car won't overheat again. It had never overheated at all in 9 years even on the hottest days.

Up until this blew, I was driving the car 10 miles or less total, every other day, in 25-30 mph traffic. Right now I am really just hoping nothing more serious made it overheat or fail.

I have some minor work like from sway bushings, then things like a PS pump rebuild and my belt/rollers service that will be coming up...and on top of that my wipers stopped working. Hope it is the switch or relay and not the damn motor. Tires are on the list as well bit really want to do those at the beginning of next spring so brand new tires aren't sitting all winter. A lot of things are kind of coming to a head, and the ethanol is destroying my fuel lines and pump on top of everything else. I have already replaced 2 or 3 fuel lines...

Fara

If it's just the heater valve, it's unlikely there is another cause of the issue.
The heater valves are made out of 1980's technology plastics (2nd generation) and degrade over time.
Unfortunately, this means that your heater valve probably just finally reached it's limit and split.

Some have had great results with the metallic replacement part (From Audi) but at the same time, the plastic OEM part also seems to last quite a while before giving out.

with regards to the fix: Most likely, you can fit a new valve and you'll be good to go.
Hopefully you haven't done any damage to the rest of the engine, but I'd personally just put in a new valve, fill it up, bleed it and call it good unless you show other symptoms after that.

konakat

Biggest worry would be your head gasket, so you could always do a compression test if you really want to be thorough, but I would just replace the valve then cross my fingers.