F451

Ahh, I see, said the blind carpenter as he picked up his hammer and saw.

I thought maybe it meant North American model. Thanks for the clarification.

silverBean

N/A= Natural or normal aspiration. I've heard it both ways.

Charlotte944

Let's not forget that loose/dirty ground points and/or battery connections can make the car appear to be running hot. Try cleaning the electrical connections to the starter and alternator, clean the battery cables and where the negative cable is bolted to the firewill, clean the ground points on each frame rail behind and below the headlignts, check the ground strap that runs from the centerline of the firewall to the engine block, clean the ground point in the rear cargo area under the carpet on the driver side between the tail light assembly and the license plate.

rudidelange

An early model should not overheat on a freeway, even under load. A thermostat, blocked radiator / hoses or the switch in the radiator that controls the fan. There is so much wind that travels through the radiator at high speed that a vehicle does not need a fan under normal condition on a freeway.
Another cause could be that the fins of the aircon radiator or h2o radiator is clogged with insects or are damaged, preventing air from circulating through the radiators. Buy the Haney manual - it helps a lot.
All the best with the new toy.

F451

Ok guys, finally got a chance to do some troubleshooting on the 944 intermittant overheating issue. My first time working on the car.

Some interesting things that I found. Turns out, beside a new waterpump and thermal switch, the car has a new radiator. Yeah! I thought the previous owner mentioned that, but then when I was reviewing the reciepts, I didn't see that, so that was a nice bonus.

And the the car is in fact leaking coolant, check out all the green drips and wet surfaces.



It's leaking from the lower rad hose by the water pump.



I think the hose leak is the source of the drips in the upper pic. It also had a very slow leak from the thermal heat switch which was pretty loose, surprised me that it wasn't leaking more it was so loose.

So I tightened up every hose clamp on every hose in the cooling system that I could find and get to, as well as the thermal switch. Some of the clamps weren't that tight, again, surprised me.

To get to the thermal switch I removed the fan assembly, and while I had it off I checked the continuity of the thermal switch while it was cold and it checked out (no current being passed).

Then I checked the functionality of both fans by running jumper leads straight off the batt, and the fans were functioning fine.

I also checked the expansion tank cap and made sure the cap was sealing properly and it was clean at the filler neck. That all checked out.

After drying everything off and snugging everthing up, I started up the car and warmed it up (with the fan assb off). Checked for continuity on the thermal switch, and got current when the temp gauge was between 3/4 and the overheating range. Kind of surprised me, I would have thought it would have switched on earlier. Anyway, it seemed to be working fine.

Then I put the fan assembly back on, ran the car, and waited for it to heat up. Sure enough, the fans came on when the needle was between 3/4 and the overheating range, just like my test previously indicated. So those components seemed to check out.

And the whole time I was keeping an eye out for leaks from the lower rad hose and the thermal switch, but didn't spot any, so I'm confident I've nipped those in the bud.

Lastly, after the car cooled down a bit, I pulled the plugs to take a look at them to see if they have the coolant pressure washer treatment (indicating a head gasket leak), and they look pretty good. They are all consistent in color, a nice light brown/tan, so I don't think the head gasket is leaking.





I also checked the system for air by pulling the purge plug, but it didn't pass any bubbles so I think its ok, but I did not completely drain the coolant. Once I found the leaks I figured I would snug those up and see how it goes.

I also did not pull the thermostat, but that is also relatively new, so I'm hoping its ok.

And I unfortunately did not get a chance to run the car at the high speeds and up the big hill on the highway where it almost overheated that one night (I'm watching the kids). So, I'm not sure I've cured the problem, but I hope so.

Tomorrow I will run it up that same big hill on the highway and report back.

I want to thank everyone that offered tips and suggestions. This is great. I had a solid plan of attack when I went out into the garage, and it really paid off. I feel like I accomplished a lot. And if I haven't fixed it, I have a few more things to check (thermostat, drain and refill coolant, pressure test, etc).

Thanks again guys!

Ed

F451

Hey,

Saw this outlet coming off the water pump without a hose attached to it, and was wondering if this is normal. Its not leaking or anything, so I'm figuring its something to do with a different model, maybe a turbo model or something? Maybe they use the same water pump for the different models and this one has the unused outlet blocked off from the inside?



Thanks,

Ed

Keithr726

My car was leaking only when it would heat up. So I check all of the hoses. I removed the air box to find that the upper radiator hose rubbed against the sharp part of the radiator a made a tiny hole and when it would heat up the hole would expand at leak all over the garage.

SoCal Driver

Turbo fitting.

If you see a leak coming from the temp switch side of the radiator around where the upper radiator hose connects besides the large hose it could be a crack in the plastic side or a cracked fitting for the small hose that connects with the over flow tank. The plastic nipple does crack. A new radiator can have the threads for the temp switch strip out too. These are not pipe threads. They are straight cut and the temp switch and hose fitting use fiber washers to seal against the radiator.

Hoses leak because they take a set with the original water pump and can't with the torn up flanges on the rebuilts. I find the lower radiator hose usually has to be replaced when using a rebuilt water pump.

__________________
83 944 = It's NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts
and/or cam chain and tensioner?

The 83

barelyrunshalfthetime

yea u nailed it, that is a new style waterpump that was used on later cars, and on the early cars, that hose isnt used needed, so they blocked it off with that plastic plate for use on the early cars.

F451

Very cool! Thanks!

yellowline

Seconded. After cleaning grounds on both ends (behind gauges and under the hood), my gauge reads 1 mark lower at all times.

We need to make a 944 Ten Commandments and sticky it. "Clean thy grounds" should be one.

F451

Thanks for the reminder. I will do this next weekend.

F451

Update: I've been driving the car all this week since doing the troubleshooting, including running up the long hill on the highway and the car is doing much better. Yeah!

Going up the big hill (a couple of times now), the temp gauge did climb, from 1/2 to the 3/4 mark, but it did not go up near the "danger zone" on the right of the gauge the way it did before I did the troubleshooting. When it was heating up that one time, I also slowed down quite a bit, and turned on the heat full to bleed off some heat. All this week I haven't had to do that up the hill, so definite progress.

Coolant level has been constant, and no drips from the hose or the temp switch either. No drips or leaks at all that I can see now.

The gauge is still moving around between 1/2 and 3/4, and I'd really like it to be more steady.

Next thing is to clean up all the grounds. I'm curious to see if this will affect the gauge at all. And it sounds like a no brainer task anyway.

I will also change out the coolant and may replace the rad hoses as they seemed a bit soft to me.

I'll report back after I change the coolant and clean up the grounds.

Charlotte944

You are on the right track.

FYI: The cooling system is designed to maintain the coolant temperature within a farily wide RANGE of temperatures, unlike more contemporary systems that are designed to operate within a much more narrow range.

For example, when you come to a stop at a light, the temperature is supposed to climb to the point where the fans come on, and then the temp should start to start to drop. If you sit with the engine at idle, the cooling fans will cycle on and off in concert with the temperature's rise and fall. 'Tis normal for the early cars.

Here is a much better test than your hill climb:

Get on an interstate and settle into a curise just below the limit.
Note the temp gage reading.
Down shift to 4th and accelerate as though you are passing slower traffic.
When you shift back into 5th, note the temp gage reading.

If the temp spiked during this test you may have a leaking head gasket. If the temp stayed fairly constant, then you are OK. Just keep a VERY close eye on your coolant levels. Remember, the proper level is between the Max and Min marks on the expansion tank when the engine is HOT. HINT: A strip of black electrical tape on the tank makes an easy reference point.

FYI: Based on the pictures of your plugs, I doubt you have a head gasket leak. I suspect the temperature spike you were seeing was caused by the pressure drop from all of those leaking hose clamps. Also, ditch those plugs and get "regular" single electrode plugs. Those Platinum Plus 4's just don't work well in these cars. Either install the Bosch recommended plug (WRDC8?) or the equivelant NGK plug.

F451

Good to know.

More good feedback, that's what I'm thinking/hoping.

Will do. My 944 has a few questionable mods IMO, including a noisy exhaust with some ridiculose giant dual exhaust tips.

Thanks for the feedback!