Cameron Bishop

My NA 1984 944 pours out coolant whenever it is shut off. The cooling system holds pressure well to atleast 10PSI. The coolant reservoir cap is brand new "OEM PORSCHE" off of pelican parts. The coolant has been bled multiple times carefully with both the bleeding precedures listed on Clarks-Garage to my best ablility. A cold, dry pressure test read out 140PSI on all 4 cylinders nearly exactly. The engine seems to run well. I have seen no evidence of mixing of oil and coolant in either. None of the spark plugs new or old appear "Steam Cleaned" and they were replaced a 2 weeks ago. the car seems to run , start and drive great right now. the coolant gauge reads close to the fist tick when moving, and creeps to the middle tick when idleing, the gauge may be reading quite low according to a basic laser thermometer on radiator hoses and some reading on what they gauge should show. I have not seen any white smoke on startup.The thermostat works at a certain temperature for sure, but I do not know what exactly. to ask any questions about other symptoms and ill tell you or test it if I dont know.





This should be most of what you need to make your own judgements; but here is some extra context for to put all my cards on the table.




Context:

So, I replaced the clutch with my brother on my 1984 NA Porsche 944 and it went overall well. the clutch grabs great, makes little noise, and overall has had no issues in the sort time had driving, The car seems to have come up with some other issues that may be new from driving, from something that occured during the clutch job, or from before my period of ownership ( ~3 months) . The main issue is its coolant. It seems to pour it out immediately when the car stops and is turned off. I do not think this was an issue for the first few days after repairing the clutch, but it is possible I just did not notice. The issue seemed to suddenly appear one day, after taking it for a short drive, the car was parked in my neighbors driveway for maybe a couple minutes and it poured out a lot of coolant, probably half a gallon. This was quite alarming, because the car seemed to run great before the clutch job, and little was touched to do with the engine. We did though, drain the coolant for one reason or another, my brother may have misread the directions or something but for whatever reason the coolant came out of the car. we filled the car using the gravity fed method; bled the coolant to the T multiple times off of the instruction on Clarks-garage. The car seemed to run below the second hash on the coolant temp gauge and gave no problem until it came pouring out maybe 2 to 3 days after. we assumed that we must have failed to properly bleed the coolant and bought a coolant pressure tester to hopefully properly bleed the coolant. We once again bled the coolant via clarks page as exact as possible once again, before, and after idling the car to temp. We were fairly sure it was properly bled from the best of our knowledge. Once again though, after driving the car, it promptly poured out the coolant all over the driveway. I went down the list of fixes once again from cheapest to most expensive, and bought a radiator cap; after installing it once again poured out the coolant after a test drive. fearing head gasket failure, me and my father ran a compression test and it overall seemed pretty good with all 4 cylinders giving the same compression within 1-2psi. we read some more and tried to find any possible leaks in the coolant system, and pressurized the system with the pressure tester and we did things like tighten some hose clamps, and install an O-ring on a slightly leaky drain plug. We got the system without leaks at 10PSI, as as high as I was willing to go, because of a warning on Clarks. We once again took the car out and it seemed to be ok, until the car was left idling and started leaking some coolant. We were maybe 2 blocks from home, and although alarmed by it leaking coolant while running for the first time, decided to drive it home, and it proceeded to pour out all the coolant in the driveway once again. It really seemed to be quite hot, and the coolant was probably boiling and really coming out, mostly from the overflow at the top of the coolant reservoir but if it really does have a head-gasket issue it could have been exhaust gas. decided to give it a break and finally ask the forums I have been reading for help personally. That is where I am currently with the car. I have little idea of what is wrong with the car, and and also unwilling to replace the head-gasket right yet, without being sure it is the issue.

even more context if needed:



Me and my brother recently replaced the clutch on my new to me 1984 Porsche 944. It went relatively easily without breaking anything, and only some minor setbacks that only really costed lots of time. The car seemed great, and completely rust free everywhere. overall seemed to be in great working order other than a shot clutch.seemed to run great before any repairs were done, during the time before it came apart. Recently, after the clutch was replaced it has had some major and quite confusing issues. It started with the car not starting, but that was fairly easily diagnosed, I just assumed it was the speed and reference sensors due to them being one of the few pieces removed to get the clutch off, and the disintegration of their connectors. I bought both of these from Bosch and the car started first time. The only other thing that *may have been damaged is the heater valve, which had some minor warping in the outer plastic from smacking around when we tried to get the *clutch bellhousing? off. The cars only other non cosmetic issue is it idles somewhat weird and fluctuates. when the idle speed screw is adjusted it seems to fix the idle when it gets to the idle that is spec according to clarks garage, but it will not start when set at this idle speed. as well as that issue, if the idle is set two low, it seems the computer would shut of the injectors when the throttle is let off, but would struggle to catch again when it would turn them on again to idle to a pretty extreme degree of getting very close to stalling

complete backstory if anyone really wants to know:



So, I am fairly young, and decided to purchase a NA 1984 944 mostly as a fun car, and something to work on and improve. I kinda thought I knew what I was getting into. So, a while back, I checked out the car, and though it looked great for such a old car, and seemed to have a few minor issues. I came back after a while, and brought my father who was much more apt at driving stick, prepared to either purchase the car or walk away. I tried to do as much research as possible, but I missed a lot of the important things and focused on very general things. I ended up purchasing the car after my father came back from the test drive saying it seemed good. It had a obviously quite aged and not in great condition interior, but otherwise seemed great. From the for sale posting it seemed like many of the issues that would crop up were preemptively prepared, slave cylinder, brand new tires, a timing belt and water pump change nearly 1000 miles ago, new pulleys, etc. The only issue that seemed important was something that we thought was minor drive train lash, mostly because the previous owner said they were told it was probably a worn out component in the differential. I probably should have at-least thoroughly researched this issue, but it is quite hard to diagnose or pinpoint, but I should have known it was probably serious and at least talked him down. we got the car home, drove it for maybe 2 days and while it was in the garage decided to google, and try to diagnose its issues to make sure they weren't serious enough to hurt the car. I found little info on drive train lash being because of a differential part wearing out, and by observing through the holes in the transaxle, saw that the differential seemed to be moving the torque tube 1:1 without clunkage. This and some well written posts made me come to believe that the car had a OEM or OEM spec clutch where the rubber must be shot. from there I decided to purchase the parts and fix the car.




Thanks, Cameron.

harveyf

Thanks for taking the time to give complete details. Sounds like you're really in to it. Good!

In general, the white plastic tank on the drivers side of the engine compartment is designed to allow for the expansion of the coolant volume as it gets hot. So if you were to fill the coolant right to the top of the tank and then drive around, you would loose some coolant. Eventually, as you blew out coolant, it would come down to a working level. The Porsche recommended working level for the coolant is between the max and min marks on the tank. So if you are having an OMG moment and realize that you have been overfilling your tank, then there's your problem.

BTW, the plastic on all those tanks gets' cloudy and it can be hard to see exactly how much coolant is actually in there. You can't directly see the level through the cap opening because of how the tank slopes. Assuming your coolant has a color from the antifreeze, I find it helps to rock the car a little and look for the coolant as it sloshes up and down. I personally think buying a new tank should be on everyones list simply since they are so hard to see through.

If you haven't been overfilling your tank, the problem gets more interesting. You have checked the various systems (coolant at 10 psi, cylinders at 140 psi) which are reasonable numbers. The coolant system operates at a pressure between 0 and 10 psi. If your cap is defective, I would think you would blow coolant while driving. There is a phenomena known as "heat soak" where the whole engine gets extra hot right after you shut it down. The stock setup on the these cars will run one fan on a low setting after you shut off the car, if it is really hot. This arrangement many times is hacked and doesn't work properly. Clarks discusses the fans in more detail. Also make sure both fans are running when you come back from a drive and haven't yet shut the car down.

I would suggest you carefully drive the car and see if the coolant stops coming out and the temperature gauge remains in a reasonable range. It may be that you haven't found the right level for the coolant in your expansion tank.

Where to you live?

Harvey

Here's some background info for you.

https://newhillgarage.com/2018/02/04...tem-explained/

Cameron Bishop

Thanks for the quick response. I am fairly certain that the tank has not been overfilled at-least one of the times I have driven the car. I have been careful to put the level very close to the min mark almost all the times it has been filled using your method and sometimes putting a flashlight up to the tank. I also once drove the car after it had poured out the coolant after only filling it with maybe an extra 2 quarts just to get it home a couple blocks and it still dumped a lot of coolant upon stopping the car.. I am honestly not sure about both fans running when the car is at temp and brought home. The drivers side fan does for sure run when the car reaches its temp, and when the AC is put on the passenger and drivers side fans go on. The drivers side fan stays without fail when the car is shut down. The temp gauge does seem to show reasonable temperatures when driving, and generally rides close the the first tic mark, until it stops moving, and it creeps up closer to the middle. I have come to possibly believe that this is maybe reading colder than it is because if the coolant really is boiling because it never has really gone above the second tic mark which should be cold enough to not be boiling. maybe three minutes after it was "boiling" it was around 180F according to a handheld laser thermometer on the outside of the radiator hoses. It isn't super hot where I am in western PA, and I haven't been turning on the AC except in the garage to test the fan and then switching it off. I really am unsure at if it really is heating up to unreasonable temps because it seems to run cool enough according to the gauge.





Thanks for all the help.

Jfrahm

If your pressure cap fails it'll blow out coolant after shutdown but otherwise seem OK in normal driving.

harveyf

Probably just your terminology but keep in mind that the system does not "boil" when operating properly. The 10 psi max operating pressure also allows the coolant to go above the standard boiling temperature of 212 degF. You can look at a steam table but I think at 10 psi the boiling point is going to be around 225 degF.

Now if the coolant actually boils i.e. produces steam, anywhere in the system, the sudden increase in system volume from the steam would certainly push some coolant out of the overflow pipe. So the question is where and why would it do.

Keep on checking various points of the system with your infrared thermometer. Read my article and try and get temp readings on all the key elements of the system. I would try looking along the cylinder head, for instance. The head gasket has some sections that block off the water in the block from the head and force it to go the long way around. It would be a weird failure mode but if one of these sections were to fail, it would allow the coolant to short circuit in the head. So make sure the temp profile on the head is uniform.

My track car has the same cooling system as yours. I've driven it hard on very hot days. I have never had the trouble you describe. That said, I do have Lindsey "steam kit" that sips a little fluid from the back of head, supposedly to prevent steam forming there. I don't think that would be a problem on a street driven car, though.

Keep looking. You'll find something!

Cameron Bishop

For anyone that ever has this issue it was just a bad thermostat. I felt really dumb, I just assumed it was right because it was replaced 1000 miles ago.