ChuckD

I decided to do some real work to the car today and start into the coolant leak issue I found after I drove it back from storage. I found coolant pooled down in the valley when I first began to inspect the engine. Turns out there is NO THERMOSTAT! This might also account for why coolant leaked through that o-ring at the housing. Why would anyone fail to install a thermostat? Bolts torqued approximately correctly and I don't see any evidence of any other shoddy work around the car. Is there something the previous owner needed to remedy? Is there anything they were trying to fix by leaving it out? Any thoughts on this would be helpful. If it wasn't for oil also in the valley, I'd be tempted to put the new one and and button it back up.

Speedtoys

"Cars run cooler and better with no thermostat"

Ricer rule #6.

Ducman82

that is crazy! maybe they took it out due to other heat issues? clogged radiator?

ChuckD

The nice thing about this car is that the radiator isn't leaking at all. I don't see any issues with it.

rbrtmchl

I thought the 928 was the exact opposite. Wouldn't running without a thermostat make the car overheat?

Speedtoys

Your radiator likely will never leak if it never sees pressure.

Ive driven for a week with a lower rad hose with a gash in it...only leaked with pressure. Removed the cap, didnt leak while I waited for a new hose. Drove everyday.

SeanR

That, um, interesting.

Had a 924 that the owner rebuilt the engine and it kept over heating. When I took the huge rad hose off, there was not thermostat. Put one in and the over heating stopped.

ammonman

Be sure to replace the front seal with the stat. It goes on AFTER the stat goes into the housing.

Mike

Mrmerlin

make sure to install the rear thermostat seal as well ,
since the one in the housing is missing you dont have to remove the old rear seal.

Also since things are apart install a new heater control valve and short hose and a new coolant bottle cap.
I suggest to use Dow Corning 111 on the new Thermostat front O ring, this will keep it soft

so parts to order
Thermostat
Thermostat O ring
Rear thermostat seal
heater control valve
short hose
coolant bottle cap
And if the coolant bottle you have is tan or brown or is cracked a new coolant bottle

ammonman

I didn't think the 78-82 cars had the rear seal.

Mike

James Bailey

That hole behind the thermostat lets the coolant loop and stay in the engine to warmup more quickly....when warm the thermostat opens to let coolant flow into the radiator..when fully open the round flat disc on the back of the thermostat close off that hole(thus the seal on later cars) and directs all coolant to the radiator...
And yes running without a thermostat will cause overheating if the radiator resistance to flow is too high as the coolant just loops in the engine...

ChuckD

I ordered parts from Roger and told him to send me everything I needed for the removal of water bridge. I was thinking the ports at heads might be the culprit so I wanted to remove the whole thing. I did not get the smaller diameter seal that I see in posts for later cars. So...I don't think I need the rear seal.

Hilton

A local '83 "Euro" didn't have the rear seal either.

James Bailey

Correct, no seal on the early cars...But Porsche decided that a better seal was needed to better direct more water/coolant into the radiator so added it.

PorKen

BTW, get an OEM t-stat.

I don't think the ones which 'fit', but have a smaller seal disc, seal as well as the big disc. (Ahem.)


Also, when I replaced one of the small ones while replacing a bad water pump, I noted that the bypass spring pressure was noticeably higher on the smaller disc type. (This may be amplified by the smaller surface area?)

I believe the bypass spring keeps the water pump from cavitating at high rpm, and/or limits the coolant pressure in the block?

It might be a cause for water pump impellers to become loose?

The new Chinese water pump I replaced had a loose impeller, which happened the first time the car was opened up on the track.