FIA-F1

I have a 91 S2 Cab with 80K miles. After about 15 minutes, the temp starts rising slowly and maxes out (I stay close to home obviously). I have no leaks, the system has been flushed. It only has about 5K miles since the timing belt and water pump has been replaced BUT 8 years have passed. It needs to be done again. Some have said that a symptom that a water pump is going bad is overheating. I'm hoping not to be faced with the timing belt job right away but know its coming. What other fixes can I try buy some more time? I understand the thermostat replacement is one possible resolution. I also heard the temperature switch could be bad (located under the upper radiator hose). I would appreciate someone who knows about this commenting.

veleno

Do you see the fans (both, behind radiator) turning on when it's getting hot? If they're not turning on then maybe the motors died.

BikePilot

15 minutes of what? Idling, freeway driving, stop and go? If it gets hot while underway at a decent clip then it's not fans and could be stuck t-stat, wp, low coolant level (or not bleed properly), etc. If at slow speed or idling it could be any of those or simply fans not running. Fans not running is most often caused by a faulty thermo-switch and can also be caused by a faulty fan resistor, motor, wiring, etc.

FIA-F1

Thank you both for your help. Good idea to check the fan, I could not wait to do that and just did. I let the temp get up with the AC switches on but unfortunately for our purpose the fans were both running. So scratch the fans as a cause. Also, logic would seem to eliminate the water pump going bad (of course, anything can go bad at any time). I can see the timing belt with associated plastic parts getting brittle over several years even with only 1000 miles put on them but it seems the water pump would not be similarly vulnerable...8 years and 1000 miles of wear should not cause the water pump to go bad so I'm eliminating a bad water pump as a cause. So that leaves a temp switch or a thermostat. The temp seems an easy next step since I have a 29mm deep well socket but if that only turns the fan off and on, I don't see the benefit. Not sure what that switch costs at the Porsche dealer. Also need to youtube how to switch out a themostat. If that doesn't catch it, I don't know where to turn! To answer your question BikePilot, 15 minutes of around town driving and the needle moves up steadily within a few minutes and just keeps going up. As mentioned, I flushed the radiator and the fluid is as new with no signs of clogging or residue. Any other ideas?

BikePilot

So it gets hot even with the AC switched on and the fan running? All the thermo switch does it turn on the fan (if not already on from the AC), so if it gets too hot with the fan on then the thermo switch probably isn't the problem. If you aren't sure if the thermo switch is turning the fan on you could let the car get up to temp with the AC off and see if the fans come on. Of course take care not to let it overheat and cause damage.

I think a thermo switch would cost around $15. They are widely available. Paragon, etc. stock them.

Also, to make things more complicated, I think that car will have high and low speed fan operation. I suppose it's possible that the fans are only working in low speed and that that's not quite enough to do the job. I think it uses resistors and actually two thermo switches to get the high-low speed functionality. Assuming it's not super hot where you are I would think that even low speed would be enough to keep it cool for 15 min of around town driving.

FIA-F1

Ok, I'll check the relays, etc to make sure they are working. Just eyeballing the fan speed, I would say they were turning at the fast speed, I couldn't picture them turning faster. I think I'll focus on the thermostat. That doesn't seem like too bad a challenge. I read anouther forum where a few swear an OEM thermostat is a must even if it's not the lower 165 degree temp.

Grandpa#3

Hello, 8 years on the Cam and Balance Belts is asking for SNAPPED BELTS and an expensive head job. I would not even start your car if it was mine with those old belts. The Belts are cheap to change out compared to bent valves and a head job. We normally only allow 3 years or 30K miles, which ever comes first, to change out the belts. When were the Cam Tensioner Pads / Chain Inspected for wear? The High Temperature is more likely the Thermostat. A cheap pair of Snap Ring Pliers will break trying to remove the snap ring. Use the link below for checking Trouble Shooting the Temperture problem under Engine and the second one for Cam Tensioner Pad change.

http://www.clarks-garage.com/shop-ma...ure-index4.htm

http://www.944online.com/cgi-bin/for...num=1294429355

Cheers,
Larry

FIA-F1

Larry, I appreciate the advice, I'm sure there's a lot of wisdom in the experience behind those words. Realistically though, assuming a belt and water pump replacement job runs a couple of thousand, give or take, by a reputable service company, how many 944 owners are willing to put that into their cars every 3 years on top of other expected maintenance costs? Maybe $2K is above market price for that job...I should start another thread "how much should we pay for a timing belt/water pump replacement job?"

1933beer

why not do the tb and wp job yourself? it won't cost that much. I think part of the problem is you are not driving the car. Youat least change the timing belt. You could remove the thermostat and see if that is the issue. with the car just sitting it could just be stuck. question since you have not driven the car much perhaps it had the problem before sveral people have a problem with the radiators getting plugged at the bottom so the fluid will not flow right.

getting out the snap ring is difficult as Larry said a cheap pair of plyiers will not work. i bought a 45 degree needle nose pliers and ground the tips down to fit in the holes of the snap ring and they work great.

mikey_audiogeek

What he said.

Cheers,
Mike

Grandpa#3

Hi, You can take a look at a video on how to change a Water Pump and all belts. It comes in 3 parts and all you have to do is type in (Youtube Porsche 944 Water Pump Change) and it will take you to the first part. Ah heck, here it is. The Water Pump is changed out about every other belt change or 60K miles. I know the Air Box is a PITA to remove on a S2 but the Owner Manual should show how. You can also find out on Youtube. The only Cam/Balance Belts we use are made by Gates or Dayco. Getting a little dirt and grime on your hands make you appreciate your Porsche more after working on her yourself. Another place we all use is Clark's Garage.com for maintenance help.

http://www.clarks-garage.com/shop-ma...ure-index4.htm


Cheers,
Larry

william_b_noble

ok, for what it's worth, I have an 85.5 NA that I bought new. It has over 250K miles on it. I have changed the clutch once (at about 140K miles) and the water pump once (at about 90K miles). the water pump is not leaking. If you are worried about the belts, the usual pattern is for th ebalance shaft belts to fail first because the balance shaft goes twice the crank speed - personally I change them based on miles but when your odometer gear fails, you can avoid panic by noticing when you get increased vibration from a failed balance shaft belt and then PROMPTLY changing the belts and rollers.

FIA-F1

Alright, I'm leaning towards doing the belts and waterpump myself. I've seen a couple of videos and there certaily are a lot of steps. I'm not intimidated by the work, I think its more the period afterwards when I'm driving down the interstate wondering if I tightened some a bit too much or too little, or if I left off a critical step. I'll take all the links, urls and anything else out there that I can read or reference. I like to do a lot of research and studying before i take on soething like this. Thanks guys, thios is when I'm most grateful for a forum like Rennlist.

rufrob

I found the S2 cooling system is particularly difficult to bleed. The timing belt and water-pump are not hard to do. First time will be exciting and a bit frustrate. Go slow and enjoy it. Get the flywheel lock.
I can do it now in about 5 hours. less if I skip lunch.