Last Lemming

Here is the problem, I have changed the thermostat, I've changed the water pump, changed the radiator in the car and while driving the temperature is fine. The temperature stays at the midway between the two white marks. However when I come to a stop the temperature slowly starts to rise and get all the way up to the second white mark. In about 5 -10 minutes it stays at the second white mark even though the high fans kick on. The temperature does not drop. But if I give it some gas while sitting at idle the temperature does drop below the second white mark. As soon as I stop giving it gas and let it drop back down the idle speed the temperature starts to to creep back up into the second white mark. It's like there's not enough fluid passing through radiator while it's at idle.

What could this be? Could it be the thermostat is not opening up all the way or could it be that something is slipping on the pulley for the water. I don't think it's the belt slipping on the water pump since I double-checked that for tightness before the button everything up.

The engine has a new head gasket and there is no oil in the water.

While the thermostat is new I have I did not check it prior to installing it, could it be that it is just not opening enough to let enough water through until the engine is revved?

Also the oil filter heatshield is not installed on this car. I am not sure that would do anything at idle.

Also both high and low fans work and come on at the right time

odonnell

The factory-spec fan switch doesn't kick on until 2/3 up the gauge, so this sounds normal.
I recommend the lower-temp switch, my car never goes above 50% and is usually rock solid at the first white line.

Of course, I'm assuming you've eliminated any room for error in the expansion cap tank, and you've eliminated any air pockets in the coolant.

Last Lemming

Every time I cracked the bleed screw I only get fluid no air escaping. The cap seems fine but I do not know how you would check it.

The thing is the fan doesn't seem to drop the temperature once it kicks on.
What I mean is even though the high fan is running a temperature still seems to creep up ever so slightly. That is of course until like there were a few revs at it.

odonnell

Is the front of the car jacked up when you check? (or the system is pressurized?)

Last Lemming

The car is fully warmed up. I don't have it up in the front every time I check and I do. It check it while the car is running, but right after I shut it off

use2windsurf

I have the same issue with my 87 944 NA. Never runs hot, but does just as you described .

1987 Red 944 N/A *** NOTE- I probably posted from my iPad, please excuse any typos, bad punctuation or odd grammar, if it is unreadable, it probably was posted from my iPhone.

Last Lemming

My gut instinct is that the bleeding of the system isn't the issue. I also pressure bled the system as well and got a constant stream of coolant as well.

Assuming it's not a bleeding issue what else can be causing this. I don't think the new pump is the issue either but I'm not sure how to test it on the car. It is the updated pump btw.

use2windsurf

I just replaced the DME temp sensor but did not replace the temp sensor that drives the gauge. I doubt that would be it. Mine reads right in the middle at speed right around where it is in the pic, always stays in the middle of the green. At idle when the temp does increase, it creeps up to the line between the green and yellow, probably over a minute or so, sits there for 15-30 secs, the drifts back down in the normal range. since it never gets far into the yellow section, and only stays there briefly, i have never looked into it until I saw your post. I will replace the gauge sensor next weekend and see if that has an effect.



1987 Red 944 N/A *** NOTE- I probably posted from my iPad, please excuse any typos, bad punctuation or odd grammar, if it is unreadable, it probably was posted from my iPhone.

odonnell

You can check the sensor: http://www.clarks-garage.com/shop-ma...19.htm#coolant

I would replace the expansion tank cap just because. Sometimes the seal rots, and you lose pressure. FWIW I had similar issues and was sure it was WP related (high revs cooled it down) or a blocked radiator.

You guessed it... the $#%& cap had developed a crack!

Attachment 1363546

Last Lemming

I'll certainly check my cap but when I take it off I here the pressure release. That's why I doubt it's my cap.

odonnell

My cap did the same thing, I was weirded out when I found the crack (and my problems stopped)

Last Lemming

Okay checked my cap. No crack.

Ky944TurboNewbie

I had this issue on my car. Would creep up at idle, but when the rpm's increased, the temp went immediately down. In my case, I had a leak that allowed fluid to escape and caused air to enter the system. My bet is you need to bleed the system again. I don't ever see my temp over the first line on the gauge when it is running properly. Pressure test the system and see if it can hold pressure for an extended period. Can it hold 10 lbs for 10 minutes?

Velozipedia

Hi,
bringing up an old thread hence I have the same problem with a new rebuilt 3L turbo. I am running it with Peep's VEMS kit. Everything is new, from the sensors, water pump, hoses, thermostat, radiator and sure the 150 kPa expansion tank cap. Has there been a solution to this issue with the crawling coolant temp at idle?

Thanks and regards from Germany!

Ollum

Dan Martinic

I had this issue twice. First time, it was the tiny connection at the radiator top (it's a 951 so not sure if you have it). Second time it went away after a lengthy bleeding. Very, very lengthy.