Engine getting hot

[massive]

Had to drive across London today with the heater on full to try and keep the temperature down on my 944. Got stuck in some traffic when I first noticed that the temperature gauge didn't stop at half way on the dial like it usually does. Have checked coolant levels and they are fine, also the radiator fan kicks in when it should. I'm guessing it's likely to be the thermostat or the water pump not circulating the coolant efficiently.

Any ideas?

[John_AZ]

You mentioned the coolant level looked OK.

Have you noticed any small loss of coolant in the reservoir?
When you check the spark plugs, does one look like it was steam cleaned?

Before you drain the coolant and check the thermostat, "burp" the coolant system to make sure you do not have an air pocket. Lift the front up on jack stands.
Open the coolant air relief bolt, wrap a rag around the part to catch overflow and squeeze the top hose gently.

Sometimes the radiator fan switch contacts get fouled and not make contact correctly or soon enough. Replace the switch with the same temp as the old one. (3 temps available)

Make sure the contacts on the coolant temp sensor are clean.

Bad grounds can cause overheating. Clean the battery posts and the large negative cable connection on top of the bell housing. Cover the TDC hole with tape.

Clean the front of the radiator. Spray with a strong cleaner and rinse from the engine side to push the dirt out and not further in the radiator fins.

Just a few ideas.
GL
John

[massive]

Originally Posted by John_AZ

You mentioned the coolant level looked OK.

Have you noticed any small loss of coolant in the reservoir?

No loss of coolant, sitting spot on the max mark

When you check the spark plugs, does one look like it was steam cleaned?

Plugs all look the same with nice tan colour.

Before you drain the coolant and check the thermostat, "burp" the coolant system to make sure you do not have an air pocket. Lift the front up on jack stands.
Open the coolant air relief bolt, wrap a rag around the part to catch overflow and squeeze the top hose gently.

Tried this yesterday and the hose was quite firm directly after driving the car and it did produce a 'burp' into the expansion tank. However today the hose was soft and no 'burp' was produced when I squeezed it, though this was after the car had been sitting for an hour or so.

Sometimes the radiator fan switch contacts get fouled and not make contact correctly or soon enough. Replace the switch with the same temp as the old one. (3 temps available)

Make sure the contacts on the coolant temp sensor are clean.

Bad grounds can cause overheating. Clean the battery posts and the large negative cable connection on top of the bell housing. Cover the TDC hole with tape.

Not tried these yet, interestingly why does the TDC hole need to be covered with tape?

Clean the front of the radiator. Spray with a strong cleaner and rinse from the engine side to push the dirt out and not further in the radiator fins.

Just a few ideas.
GL
John

Not tried this yet either.

[John_AZ]

Originally Posted by massive

Not tried these yet, interestingly why does the TDC hole need to be covered with tape? .

If you remove the negative end on the bell housing, the nut/washer is removed.

If you are shakey and drop the nut/washer in the TDC hole, the usual outcome results in removing the entire clutch to get the nut out of the bell housing.

Anything that drops in this hole will hide in a crack.

John

[massive]

Originally Posted by John_AZ

If you remove the negative end on the bell housing, the nut/washer is removed.

If you are shakey and drop the nut/washer in the TDC hole, the usual outcome results in removing the entire clutch to get the nut out of the bell housing.

Anything that drops in this hole will hide in a crack.

John

Cheers thanks for the tip.

[malidoco]

I have been working on a similar problem as well. the temp gauge would climb just to lower level of the red. I did everything that you are doing only to find out my car was not overheating. When you gauge goes into or close to the red check the temp with a temp gun. When my gauge was at half and almost to the red the temp was the same 175-180 degrees F. Just saying make sure you have a problem before wasting your resources.

[massive]

Have replaced the thermostat with a brand new one from Porsche, here's a video of the old one being tested. What does everyone think?

[smokin_944]

The thermostat in the video was definitely not properly functional. However, malidoco has a point with gauge accuracy. Checking the temp with a temp gun is a good idea. Early cars are notorious for having flaky gauges (usually due to grounding problems) which often lead the owners to think something is wrong when there isn't.

[Rasta Monsta]

You may want to have your rad flow tested (also be advised that some find this suggestion ridiculous). Also, +1 on the early gauges. Shooting the head with a temp gun is a good idea.

[massive]

Finally got around to writing this one up.

Here's the procedure for thermostat removal, testing and replacement

[BryO]

When he talks about the hose being tight, would that not be a combustion gases leaking in to the cooling system?

[porschetub]

Originally Posted by BryO

When he talks about the hose being tight, would that not be a combustion gases leaking in to the cooling system?

Good point BryO ,system pressure will swell the hose to a point but if the hose is in good condition it shouldn't be really hard,do you have even heat over your radiator when the car is up to temp?.
You haven't stated what effect the new thermostat has had,is it now sorted?

[CatsEyes]

Not wanting to digress here, but 'normal' on my gauge is in practice a bit below half-way. Is that unusual? Or was Massive's already runnning a bit warm? (I'm in southern Australia, BTW, so the average ambient air temperature should be a lot higher than London!)

I have found that even a very small air-pocket after a coolant drain or change (see John AZ's suggestion) can produce striking irregularities in my average engine temperature as displayed on the gauge. I'd be inclined to check that again.

[mytrplseven]

My '87 NA usually sits on about 1/3 the way up and in traffic where I'm not getting much "ram" airflow over the radiator it goes up a bit. My temp fans will come on after engine is shut down when it's got some residual temperature and shut off when it's happy with itself. That, according to my manual is proper and my ambient temps here are around 30 degrees celcius/ low 80's F for us colonists.

[massive]

Originally Posted by CatsEyes

Not wanting to digress here, but 'normal' on my gauge is in practice a bit below half-way. Is that unusual? Or was Massive's already runnning a bit warm? (I'm in southern Australia, BTW, so the average ambient air temperature should be a lot higher than London!)

Yep, sorry I wasn't being specific enough mine always used to sit below half-way whilst driving around, it's not until I stop that the temp had started to creep up.

[massive]

Originally Posted by mytrplseven

My temp fans will come on after engine is shut down when it's got some residual temperature and shut off when it's happy with itself. That, according to my manual is proper and my ambient temps here are around 30 degrees celcius/ low 80's F for us colonists.

Sounds exactly right to me, same here.

[porschetub]

Originally Posted by CatsEyes

Not wanting to digress here, but 'normal' on my gauge is in practice a bit below half-way. Is that unusual? Or was Massive's already runnning a bit warm? (I'm in southern Australia, BTW, so the average ambient air temperature should be a lot higher than London!)

I have found that even a very small air-pocket after a coolant drain or change (see John AZ's suggestion) can produce striking irregularities in my average engine temperature as displayed on the gauge. I'd be inclined to check that again.

So true,i've lived in Australia any cooling is working hard in those conditions,but London in the middle of winter?,they ARE A ***** TO BLEED,no question there????

[CatsEyes]

Hey Massive,

Just following this one up, since it's bound to hit amost of us sooner or later (and especially down this way).

So all's good now? It was the thermostat after all?

Happy New Year's driving...

[massive]

Seems to be all OK at the moment, temp needle sits between quarter and half distance on the gauge once the car is up to temperature and moving. Then sits just below half-way in when waiting in short traffic queues, might go just above half-way when sitting for longer periods. It's winter here in the UK at the moment so haven't been able to test under the same conditions as when the old thermostat was in back in the extended summer we had. But current signs appear promising.

[CatsEyes]

Good news!

Good luck.

I'm just about to take my car down the coast here for family holidays. Much warmer than where wel ive.

I guess I'll find out soon enough if I bled her properly!