sillbeer

Ok, like the topic states: About a month ago, I was driving the P-car to work and for the first time, while driving on the freeway, the needle hit the yellow "hot zone" on the temp gauge. So, I turned the the heat to full blast and limped it the 10 minutes to work. This is with the A/C off, and 70mph. temperature couldnt have been more than 85-90 ambient. So, I order a new thermostat, and I change the coolant. I also upgraded to the 951 rad fans. I went like 70 water and 30 coolant. I've bled the system a couple of times now. The most recent 2 times, I opened the bleeder bolt with the car hot and got no air and all coolant. The problem is, now the needle sits at the 3rd bar, and if im sitting, it will climb halfway between the 3rd bar and the hot zone. then it will creep back down again when im moving. But, the needle stays at the 3rd bar while driving. Fans run constant. Is this normal for early 944s? this is the 1st summer I've had it, and when I got it in december, it was rare for the needle to hit the 2nd bar on the gauge. On a side note, I had to put the 951 fans into the early fan shroud. I read it was bolt up but maybe that was for the 85.5+ thanks!

Neil

PeteL

Bleed the crap out of the coolant. Get the front of the car up high, on ramps, and be sure the heater is on. I am battling the same thing, but after a good, long bleeding session, I think I have it under control.

M758

Well,
Also pressure test the system. Make sure you have no leaks as this will cause problems too.

If that still does not work you may need to put in a new radiator and water pump.

It is hot out here and old radiators simply don't cool as well as new ones. The car should run to the 3rd line, but not beyond.

KuHL 951

I'm not sure about your bolt up problems. The 86 Turbo fans w/ shroud was a drop in on my 83. As others have said bleed it all you can with the heater on. What I find unusual though is the temp climbing like that while on the highway. Usually that means either the radiator is semi-plugged or your water pump isn't up to snuff. When you did all the cooling work did you chemically flush it and use the same type of coolant as before? On my 83 I'm able to run the air while in traffic and it only climbs to the third mark before the fan kicks in on high, it never gets into the yellow at all. This was just yesterday on a 105 deg. day. I hope you find it, Phoenix is no place to overheat.

fmalgapo

Same issues with my car, both fans are running - i use my AC **** as the high speed fan switch since the A/C isnt kicking in anyway, and it'll still get 1/2 way between 3rd notch and yellow hot zone while idling EVEN with the hood open!!

Jeremy Himsel

Assuming you have an original radiator, at 23 years old it’s probably due for a replacement. That being said, I do have a couple of tips on bleeding that seem to work well. Drive the car like you normally do and once it’s up to temp, shut it off and let it sit for a few minutes (the coolant pressure will rise a bit). After five minutes or so slightly open the bleeder valve and you will purge out all of the air in the system that has risen to the highest point and the build up of pressure will force it out. When you do it with the car running you really have to rev the throttle to get the coolant to start to flow out the bleeder. Are the 951 fans turning on? You could swing by my house with Destin and I could take a look at it for you if you want. My 84 NA with updated fans runs cool when it’s 110 out with the AC on. We should have a couple of good 951 radiators soon if you can hold out a bit.

sillbeer

thanks for the replies everyone! It looks like the radiator has been replaced before, becuase its cleaner than the rest of the car hehehehe. I cant be sure though. The waterpump is the updated one, so it has been replaced at least once. One thing I noticed was, that there was alot of "scale" on the inside of the radiator hoses, and inside the upper coolant neck on the engine. Could this all be building up inside preventing the efficient heat transfer? When I crack the bleeder open with the engine running, I get instant coolant. no air. Both fans are running constant..The a/c currently doesnt work so I use the Ac switch as a fan switch...the fans dont come on until slightly after the 3rd mark, but after that they stay on....

Luis de Prat

Sillbeer, my suggestion is to spend $50 on a brand new cooling fan relay (doubles as A/C relay) and see what happens.

BTW, how do you SURVIVE in AZ this time of year without A/C???

Gawd that would've been my benchmark setup during the 6 years I had an 83 as a daily driver in the Caribbean!

photoguy

I had that problem on my '86. I repeatedly flushed/cleaned the system, replaced with varying mixtures and bled the thing forever but it always seemed to end up at the third bar after an hour or so of driving.

Finally I replaced the hoses and radiator - problem solved.

Good luck with it.

Crunky

The only time my 944 has gotten hot was in a traffic back up on the 51 N bound, it didn't quite make it to the solid yellow, was a little higher up than the third bar, and my oil pressure started to fall a little. I do a lot of highway driving, and it usually doesn't get above the 2nd bar, infact it normally sites just above the first bar, is this normal? and does anyone know what degree in F the marks on the temp guage are? I was also going to flush my radiator, I peeked in the expansion tank, nice and rusty , was wondering if I need to use any special type of antifreeze, or is the ethylene glycol(green stuff) ok? I was also told that using CLR as radiator flush works great, but I'd be scared of it attacking any solder joints in the radiator. Anyone here ever used CLR for this purpose before?

Mike C.

It sounds like a good flushing wouldn't be a bad idea for your cooling system. Some radiator repair shops can flow test the rad to see if it's passing enough water (not in the car). My guess is a partially clogged radiator. If you do replace it, I would suggest also replacing the coolant temp fan switch (screws into the radiator just below the upper rad hose connection). Mine was running hot in traffic and this turned out to be the problem. A trick I use for bleeding is to open the bleeder screw a couple of turns before adding the new coolant/water. After it's filled up to near brimming on the reservoir tank I do a little mouth-to-mouth on the tank opening to pressurize the coolant and force it to flow out of the bleeder port (it doesn't take much). Then close the bleeder. This seems to greatly minimize and additional bleeding.

Jeremy Himsel

Do not use it on aluminum. Very bad things will happen. It's fine on a non aluminum radiator and in a cast iron block.

89AZ944

Check your expansion tank for hairline cracks. Mine has run much better since the tank has been replaced.

KuHL 951

Good advice, CLR will break the passivatiing film that prevents aluminum from corroding. If the concentration is too strong or left in too long it will actually promote self consumption of aluminum and cause severe pitting. The solder joints aren't as effected but it will appear that way because a selective localized attack will take place on the aluminum at the joint. Please avoid this product unless you are a driving old American iron. There are much better flushes for aluminum engines with a more neutral pH.

sillbeer

thanks for all the help guys! I might try an experiment. Ill open the bleeder when cold, see if i can get anymore air out, then ill just turn the fans on (using the A/C switch) and then see if I can keep it from ever getting that hot in the 1st place. Luis, I survive by daily driving the honda with ice cold A/c =)