GaryK

With our first really warm weather, my '89 is running hotter than I think it should - at the second mark in the gauge and even a bit above in traffic. The head gasket, waterpump, etc have been replaced recently. I was thinking of fitting a cooler thermostat - 180 or even 160 - and possibly replacing the radiator fan thermoswitch.
The thermostat for the '89 appears to be different than the earlier models, but the same as the 968.

I've read the thermostat is difficult to replace, but on my car it appears simple if it is located where the upper radiator pipe/hose attaches to the block. Is this correct?
Also, where are the fan thermoswitch and the coolant bleeder valve? I assume the switch will be visible from beneath the car, but I don't see a bleeder valve anywhere.

Thanks,
Gary

Russ Murphy

I don't know specifically about an '89 but all the rest of the 951's have the thermostat located on the front of the water pump, so if the pump was replaced recently, the thermostat is probably new also. I got my car from out west where sand is the preferred method of dealing with ice and snow and my car ran hot until I removed the radiator and blasted out about two pounds of sand and tiny gravel from the cooling fins ( not to mention the pine needles and leaves and feathers clotted on the front).

951Racer

The fan thermo switch is on the driver side of the radiator just below the upper radiator hose. It is difficult to remove unless you have the correct thin deep socket. The bleed valve is just above the coolant intake pipe in the head. Look at your IC "in" pipe which had a small schematic on it.

Danno

Hmmm, a thermostat only manages the low-end of the operating range of temperatures. Once you reach warmed-up temperatures around 210 degrees, it doesn't matter what temperature setting your thermostat is, it's fully open anyway. A 170-degree thermostat will flow the exact same amount of water as a 185-degree thermostat. It will just take your car longer to warm up, but the high temperatures will still be the same.

Most likely it's something else. Like perhaps a clogged thermostat would restrict flow. Or a thermoswitch is out that should be activating your cooling fans. Or even some clogged water-passages inside your radiator. I'd check these before the replacing thermostat (a cruel joke of a procedure).

sm

Gary,

Was your cooling system properly bled? As mentioned, the bleed screw is right behind (when looking from the front of car) the intercooler pipe coming out of the turbo. It's near the part of the IC pipe that is parallel to the front of the car. It faces the passenger side of the car. Requires a 12mm wrench. Give it a shot as it won't cost you anything...

GaryK

Thanks to all the responses, I've located the fan thermoswitch and the bleeder plug. And now I know the thermostat is in the water pump and a pita to replace. And yes, my invoice for the timing belt job shows a new thermostat.

A simple test I was told to check the thermoswitch was to switch on the A/C and see if both fans start running, which they do. I've got a spare switch and could replace it anyway, but it looks like a (minor) pita.

As far as bleeding the cooling system, I assume this is done with the engine/coolant cold? Simply loosen and then retighten the bleeder?

Is it normal on a warm day for the temp gauge to read at the second mark in stop-and-go traffic or when pushed hard?

Thanks,
Gary

sm

Gary,

Bleed the cooling system with the car warm/hot.
Check this procedure out:

<a href="http://www.tech-session.com/Paragon/Tech/944_coolant_flush.htm" target="_blank">http://www.tech-session.com/Paragon/Tech/944_coolant_flush.htm</a>

adrial

Anyone care to explain proper fan operation? (Is it different on a 89 vs. other years??)

I just want to make sure my car is running the fans properly...it gets up to the 3rd bar on a hot day while not moving, but never gets above it.

TIA

--Adrial

Jeremy Himsel

I experienced the same problem here in phoenix on my 951. In the summer (120 degrees) with the A/C on it was hitting the second mark and would go above it during acceleration. My solution, a 180 degree thermostat, one bottle of Redline Wetter Watter, 15% antifreeze and distilled water. It worked like a champ. It's amazing how well the Wetter Water works. The advertised 30 degree temperature drop is not that optimistic and is pretty close. This probably isn't a good mixture to run in the winter if you experience freezing temps or want heat in the winter. Good luck.

GaryK

Well, I replaced the fan thermoswitch with a lower temp one - stock is 92/102C, the new one is 85/94C. Also bled the cooling system with the car warm per the instructions in the Paragon tech article.

Haven't driven in stop/go traffic or the track yet, but on my favorite test road pushing the car hard in 90deg weather, the temp didn't get over the 2nd mark. Previously, it was getting between the 2nd mark and the red zone.

My shop recommended replacing the radiator and using the Pentosin blue coolant for further improvements.

I though more about the thermostat, and believe Danno is correct - it will impact warm-up and cold weather operation, but not hot running. Besides it seems like a real pita to replace and mine was done recently with the timing belt job. Anyone know what the stock thermostat temp is?

I've tried Water Wetter before and found it works best with low concentrations of antifreeze in the coolant mix. With the normal 50/50 mix of water/antifreeze, the Water Wetter has little effect.

btw, the p/n on the the lower temp "auxiliary fan switch" is a Wahler 321 959 481. It's cheap and not that difficult to replace with a deep 12pt 1 1/8" socket.

Gary

adrial

[quote]Originally posted by GaryK:
<strong>Well, I replaced the fan thermoswitch with a lower temp one - stock is 92/102C, the new one is 85/94C. Also bled the cooling system with the car warm per the instructions in the Paragon tech article.

</strong><hr></blockquote>

The factory service manuals indicate that the stock one is a 87/92 for N/A's...and doesn't list it for the turbo's. (Meaning that it is only mentioned in the regular service manuials, nothing in the turbo supplement)

It says "Connect testing buzzter on flat male plugs of switch. Place switch in warm water bath. Buzz must sound off at temperature of about 92 degrees C and stop buzzing when temperature drops to approx. 87 degrees C."

Thoughts? Is the thermoswitch different for turbo's vs. N/A's?

(Anybody know the sequence of events for the fans when the car runs hot? What is the most powerful state of the fans and when should I be seeing it?)

thanks,
Adrial

GaryK

The switch I pulled off my car, which appears original (but who knows?), is marked
951 606 481 00
1. 92deg
2. 102deg

Gary

tazman

[quote]Originally posted by adrial:
<strong>Anyone care to explain proper fan operation? (Is it different on a 89 vs. other years??)

I just want to make sure my car is running the fans properly...it gets up to the 3rd bar on a hot day while not moving, but never gets above it.

TIA

--Adrial</strong><hr></blockquote>

My car will get up to the third mark also then the second fan kicks on and runs untill it goes down to the second mark and turns off.

Bii

Temperature readings will vary between cars due to the use of different temp fan switches and thermostats. Also there are many possibilities with abnormal engine temperatures on these cars. I've seen corroded and loose male terminal connectors on engine cooling fans and fan switch. Incorrectly installed thermostats and no thermostats. New fan relays which were defective. Corroded fuse/relay panels due to water entry caused by blocked drains. How about a very slow head gasket leak trapping air into cooling system which is barely noticeable.

GaryK

Mine was actually running above the third and last mark before the red zone. Now with the fans coming on earlier, it's running at the third mark when pushed hard.

Any higher and I'm going to seriously considering replacing the radiator.
First, I think I'll check the oil and water temps with my pyrometer to get some real numbers.

Gary