s14kev

Noticed the 951 running at the 3rd white line on the temp gauge after the turbo install. I ended up replacing the gauge temp sender, fan thermoswitch, thermostat (77 degrees C/160 degrees F). All cooling system hoses are brand new and cooling system was pressure bled of air. I also cleaned the grounds on the back of the gauge cluster (they appeared very clean), replaced the battery to bellhousing and firewall ground cables again and installed a supplementary ground.

Temp gauge after all this reads between the 2nd and 3rd white line while driving and will drift to the 3rd white line while idling for a period.

I also tested calibration of the temp gauge via the procedure on Clark's garage. Interestingly when the potentiometer is set for 80 degrees C the needle on the gauge is more at 90 degrees (between 2nd and 3rd white lines). I am hoping my gauge calibration is just off so I used an IR temp gun on the coolant neck (the one with the bleed screw on it). It consistently reads 90 degrees C (194 degrees F). It this consistent with what everyone else is getting? Anyone with an IR temp gun that can measure the coolant neck temp on theirs?

The only cooling system component that hasn't been replaced is the radiator.

thirdgenbird

I would expect a car that is not moving to read 90 degrees. My temp gun shows about the same on a normal summer day.

s14kev

Thanks! Anyone else got a temp gun and can take measurements?

I found another post that suggested things should be a little cooler. Like 175 degrees F at the coolant neck.

https://rennlist.com/forums/5054805-post41.html

Just want to make sure that I don't need to swap out the radiator also.

thirdgenbird

the stock thermostat would still be closed @ 175 degrees

John_AZ

Suggestions:

What temp theremofan switch did you use? Lo 87c-92c or Hi 92c-102c?

Clean the front of the condensor and radiator with straight Simple Green. Let soak and flush from the engine/fan side.

Are your temps HI with the AC on as well?

Did you put the correct thermostat in the WP? There are 2 possibilities. The updated turbo waterpumps were built "early" and "late".

Clarks forum explains:
http://www.clarks-garage.com/phpBB2/...c1142c5e52dc39

http://www.clarks-garage.com/shop-manual/cool-08.htm

Backflush the radiator.

Do a compression and leak down test to make sure it is not a faulty head gasket.
http://www.dietersmotorsports.com/Co...akdowntest.htm

Then replace the radiator.

John

thirdgenbird

are you stating 90 degrees is too hot?

John_AZ

I match the thermostat to the auxiliary fan switch.

Stock auxiliary fan switch is 85C (87C-92C)

The OP is using a 77C thermostat. The auxiliary fan switch should be a 75C (77C-82C) if matched.

Using a lower thermostat or/and fan switch may not be good for engine performance or emissions due to not reaching or maintaining optimum engine temp. I use both lower thermostat and fan switch in AZ with constant HI outside temps with no problem.

John

s14kev

Thermofan switch is 85C whereas thermostat is 77C. I know most match high thermofan/high thermostat or low thermofan/low thermostat but figure this is OK (What wouldn't work obviously is low temp thermofan switch with high temp thermostat). I would rather have the thermostat open earlier but don't like the idea of the fans running constantly as often happens with a low thermofan switch.

Externally the radiator has been clean. I used a small pick to pick out all the debris from the condenser fins also.

Waterpump and thermostat are late style.

Temps are the same with A/C on also.

Compression and leakdown tests indicate all is healthy.

I believe it is the gauge cluster temperature gauge that is inaccurate. I just want to confirm that a coolant neck temp of 90 degrees C taken with an IR gun is not abnormally hot. Anyone have good leads on a VDO service place to check and calibrate the temp gauge? I'm in Nashville and can't find someone locally.

s14kev

Yep, that is the question! Is an coolant outflow temp of 90 degrees C as measured at the aluminum coolant neck with an IR temp gun considered too hot. This is with me driving when the outside ambient temp today is around 25 degrees C (77 degrees F).

John_AZ

Here is a calibration "test" from FRWilk:
http://www.the944.com/watertemp.htm

Another test method is to remove the temp sensors from the top of the engine, put in a pan of hot water, temperature determined by digital meat thermometer and watch the dash guage if it relates to the FRWilk numbers.

No calibration but just confirms temps.

John

SirLapsalot

I thought 195 F was normal operating temperature and 90 C is 194 F .....