Tach

So I posted some info on the 924/944 area but wanted to try here

I have a 88 944 na that has been running hot (will keep climbing the gauge) I have been bleeding system over the last week or so -had on ramps got a coolant pressure tester filled bled pressurized re bled started and over again and again haha -
So I finally got interior fans to blow hot air but I noticed after about 10 mins of idling the eng temp starts to climb and interior blower temp starts to fall (usually I notice the air temp inside drop and than the engine start to rise)
the radiator fans don’t seem to be kicking on unless I click on ac.
So my guesses are - still a bubble in system, bad thermostat and maybe bad temp switch for radiator fans? (I did compression test and looked good)
I saw a write up on jumping wires at the radiator switch so I’ll try to give that a shot tonight.
My hopes were to be able to drive it a couple more weekends before winter :/ but obviously don’t want to push it. I just received my timing belts, acc belts, thermostat and water pump so that’ll be my next steps to her.
Just replaced clutch pedal system and bled with good luck so far there
Do you guys think it sounds like thermostat issue? It’s kinda where I’m leaning
Thanks!

Jfrahm

Could be a spun water pump impeller. I have had that problem on an S2.

Thermostat should not cause a lack of cabin heat, that means air or lack of coolant or lack of coolant flow. It can be an indication of a blown head gasket as that will push gases into the cooling system and an air bubble in the heater core.

ElRicardo

A new thermostat switch is always a good idea-relatively cheap and easy to install. If you move quick you don't have to lose a lot of coolant, but you will need to bleed again. The other possibility, more expensive, is a new fan relay for your fuse box. If you can get your hands on a loaner and plug it in this will tell you pretty quick. Also cheap and easy is putting in a new coolant temperature sender- the one with two simple spade fitting, on top of the engine near front (right behind the gooseneck-hint- its not the one with a blue connector). This helps reduce the possibility of "maybe its just the gauge". From there, as the previous poster said, it could be a spun impeller and other darker, more nefarious, less easy to cure possibilities. But I really think your smoking gun of the fans not switching on at all unless you press the A/C button tells you it is an electronic issue.

curtisr

Does the needle eventually stop or, as you've indicated, does it climb until it's pegged at the right?
Perhaps the best friend that a Porsche 944/924s has ever had -- Clark Fletcher and his website -- can help you out. Here you can find his help for cooling systems here.

Tach

Thank you for the reply's!
I agree I think changing the switch is a good idea anyways and that’s what I was guessing with thermostat kept going back in my head to the last owner changed it and seemed like a bit of a tool sooo I was worried about the gasket or clip not installed correctly
with how the gauge moves (and yes I think it’ll just keep climbing I didnt want to push it too far)...and cabin temp dropping I am leaning towards water pump just not moving coolant around or air still in heater core. I’m not sure what else to do to get air out I’ll try lifting front higher although I’ve also heard that doesn’t help so I don’t know....
mechanic friend said vw/Porsche uses quite small openings in heater cores that like to clog and he was thinking that or air in core said can pull core fill and re install but that sounds like a nightmare

Jfrahm

It's not hard to get all the air out of the system, even the typical shop manual procedure works fine but it's a bit messy. Obviously you want the heat on full blast when you bleed the air out. The idea of pulling and then filling the heater core is goofy.
Usually when someone is bleeding the system over and over again they have a different problem, not a problem with how they are bleeding the coolant.

If indeed the heater core warms up and then cools off I do not think air is the problem, unless it's new air caused by combustion gases leaking past the head gasket. It might be a slipping water pump impeller (once warmed up). These are kinda strange as they will often move some water at idle but you overheat when driving.

curtisr

As frightening as it seems, you can expect to see this: