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Porscheaddiction

Ok heres whats happening and its the strangest thing I have ever seen.
start car, let it warm up and then idle the temp will go to the last white line and sometimes will drop back again too when the fan kicks on. Now shut off the car as if you were taking a quick run in the store for some milk about 10min car is off.. start car again this time temp is just over the white line and will not go down and doesnt seem to climb it just holds there. Now shut off the car again 10min go back fire it up this time the temp is half way between the last line and the red, again and holds. shut off car again for about ten minutes start up again this time its in the RED! and will not drop. I had this happen yesterday went to one store for about 10minutes then heavy stop and go traffic went to the bank again 10min roughly inside come back out start car, acceration was non-existant (thought CV finally let go) glance at temp and its pegged in the red I was in traffic no place to pull over just went slow and the temp went back down to normal(midle white line) and acceraltion came back too. Car has new antifreeze mix approx 50%, new thermostat and yes the cooling system was bled. If it was the water pump wouldnt there be noticiable leaks? wouldnt there be horrible noise? the temp to me with bad pump would just get pegged as the car heated up and not act like my car has? Driving the car is fine temp is normal. If it were the thermostat, same thing wouldnt the car just heat up constantly till pegged? I am very open to ideas what is causing this and a way to test and correct it.
Fan works and has been tested
Fan comes on when temp gets hot enough
Fan continues to run properly when car is shut off hot.
Outside air temp yesterday and today about 80F or 25C
Anyone out there had this happen? Anyone know what could be causing this?
Thanks
Chris.
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

Johno · Joined: 14 Oct 2003 Posts: 53 Location: Greendale, WI

I am not sure I am following you completely, but

1 - water pump may or may not make noise, usully leaks if there is a problem. sometimes you can tell if you can move/wiggle the pully that it is going bad - moves bad does not move - good
2 - thermostat can stick, might be the problem here.
3 - I suspect that your radiator might be plugged. I kinda had the same issue, run car in winter and gage never hardly moved. Run during summer and while moveing went up but not too high, in stop & go traffic it would go right up around the red zone.
Went to drain it and hardly got anything out.

So, you might try a different radiator. Some people have had luck having them cleaned.

Good luck,
I put in a Toyota, had to redo a quite a bit, but it worked great. - It was free so I made it fit. Big problem is to make sure the width is inside the frame rails.
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79 924 NA

Porscheaddiction · Posted: Sat Jun 17, 2006 5:03 am Post subject:

I dont know if its the rad being plugged or not my rad drains just fine.
stuck thermostat.....but its brand new the car only has 200miles on it since the top ends been rebuilt. something else I been told by someone I know is shouldnt have mixed the antifreeze with water but I have always done that for all my cars.

the only other major change I have done is I been using 94octane instead 87 perhaps that is where the addtional heat is comming from ?
Chris.
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

You have not given us that much to go on. And as I have written to other people with problems, if everything was right, then nothing dcould be wrong. Don;t rule out anything, until the problem is found and solved. Could be you have a combination of problems.

From what you have described, here is a list of possible problems. Just because you replaced a part, does not mean that the part you installed is good, or that the new part is not contributing to the new problem.

Valves adjusted incorrectly. Have you checked them to make sure that the clearances are correct since you noticed the heating problem?

Thermostat. You could have installed the wrong one (wrong heat range), the new thermostat could be defective, or you could have found a way to install it incorrectly (hard to install it backwards, but new ways to make mistakes are created everyday).

Camshaft and ignition timing. If you installed the timing belt incorrectly or adjusted/installed the distributor incorrectly the engine could have low power, run bad, or overheat. Maybe the ignition advance is stuck and the distributor is defective.

Defective exhaust system. Plugged cat, muffler with baffles collapsed and blocking the exhaust system, or cracked exhaust manifold causing the exhaust valves to overheat.

Defective waterpump. The impeller could be loose on the shaft and slipping or not turning, or the impeller could have corroded or erroded to nothing and be worthless. Did you inspect, and replace the waterpump with a new or rebuilt one when you had the head off?

Bad fuel injection components. Running too lean?

Blown headgasket. Yeah, you just rebuilt the head. That does not mean that you installed the headgasket properly, and it is not leaking. Overheating is a sign of a blown headgasket.

Porscheaddiction · Posted: Sat Jun 17, 2006 8:20 am Post subject:

ok to make myself look bad.
Clearances was set by engine rebuilder that redone the head. I questioned about readjustment and was told the way they had set them they wouldnt need to be adjusted (mistake #1)

As far as I know the thermostat is the correct one as it was specifed for my car at the parts place and around 82deg to open (if I rememeber correctly)

Camshaft timming correct
Ignition may be incorrect was set by ear as timming light was useless there is only a what a appears to be a indentation on the flywheel and that lines up with the window and the car will start and run with it there. (mistake #2)

Exhaust system manifold is not cracked was checked by machine shop.

I did not remove the water pump and check it (MISTAKE #3) I assumed it would be ok as it was working fine before.

Fuel Injection. Injectors were cleaned but not checked. Fuel accumlator is on its way out. Fuel filter is about 3 years old but only if at most 300miles on it.

The more I think about it it could be ignition timming related.
in which direction when the distributor is turned causes the car to create more heat then it should. Advanced timming or retarded?
Thanks
Chris.
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

Paul · Posted: Sat Jun 17, 2006 8:41 am Post subject:

Check you temperature gauge sensor and wiring to make sure you are really running hot.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

Did you put in a new temp sender?
_________________
1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

OutOfTheBox · Joined: 31 Mar 2006 Posts: 434

was the engine actually in the red hot, when the gauge indicated, did you get out and lift the hood ?

sounds like a poorly earthed or stuffed sendor/gauge

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

I'd check the thermostat first. If it's overheating but there's plenty of coolant and the water pump is new, and the fans are kicking on, it's certainly possible. I had a thermostat go out on a freshly rebuilt motor with only 20,000 miles or so, basically same symptoms, it would overheat. You can check it easily enough, just boil it in a pot of water & see if it opens. You're going to need snap ring pliars to get it out though.
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1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.

Ozzie · Posted: Sat Jun 17, 2006 6:11 pm Post subject:

Just be aware that a lot of items sold for a 924 are labelled wrong and are for a 924S.
Different motor and parts and just cos they fit dont mean it will work.
Make sure you have the correct thermostat.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Porscheaddiction · Posted: Tue Jun 20, 2006 12:46 am Post subject:

I decided to try an experiment I opened the the idle screw all the way started the car, let it warm up then I redone the timming by ear again (cant use timming light incorrect markings on flywheel) anyway when I warmed up the car it heated up quick so here is where it get interesting I turned in the idle screw (on the throttle body till it was just barley keeping the engine running then I advanced the ignition timming until the idle smoothed out again to about 950rpm. So far the overheating looks to have been corrected.
I wont know for sure until im idling a while but so far at traffic lights the temp goes up but not in to the red. and as soon as you start to drive the temp falls back down to normal and even surprisingly even better then it used to.
If Im lucky it may be ok now. I'm assuing the timming was too retarded and by having the idle screw adjusted to far out masking the problem that was causing the engine to labour and thus create excessive heat.
Chris
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

OutOfTheBox · Joined: 31 Mar 2006 Posts: 434

If you dont trust your markings

Pull out no1 spark plug(front), put a drinking straw or long plastic something, down the bore till it is resting on the top of the piston.
Turn motor over by hand until the straw is at its highest, make a mark against front pully and cover, with white paint, MAKE SURE the rotor arm of your distributor is pointing at NO 1 cylinder. Piston tops out twice for each engine cycle, fire & exhaust. you dont want the exhaust cycle.(you sure this is not why you cant find your flywheel markings)

Dont stick anything down the bore, that isn't at least 6" inches long and will not break or snap, make sure you dont poke all the crud that lives around the sparkplug seat into your bore.

If you have a friend to help and you measure the straw againt a ruler, you can get the top dead center quite accurately, swing the motor both ways forward and past the TDC, make a mark when you first can detect movement oneway, then do it the other way, half way between should be TDC.

Now you have a mark that you can use your strobe on, on the front of the engine.

It certainly will be more than accurate enough to set the timing on 924 NA.

If your motor was retarded enough to overheat, then once you set the correct timing, it should drive like a Porsche, and not a Trabant.

Porscheaddiction · Posted: Tue Jun 20, 2006 1:38 am Post subject:

intially we got top dead center the easy way. we made sure it was there when the head was reinstalled. There is one mark on the flywheel looks like homemade type indentation with paint on it. and its lined up in the center of the flywheel window when the cam is lined up but that is it there are no other marks showing -deg or + deg. So that is why its been timed by ear.
It seems to have worked out ok just had to adjust the throttle body idle screw as to not mask what the engine was actually running like.
Chris
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

You have a 81 924, which must be tuned differently than earlier 924s because of the electronic idle stabilization installed on the 81 and later cars.

You need to time the engine accurately. You should be able to find a mark on the crankshaft pulley that you can use as a reference point to make a new mark on the flywheel if you do not have a good TDC mark on the flywheel.

Lining the camshaft marks up does not do any good if you do not have the engine at TDC.

Trying to adjust the idle speed and idle mixture is a waste of time unless you have the crankshaft, camshaft, and ignition timing correctly set first, and the electronic idle stabilization disabled. You will never get the engine to run properly under all conditions without disabling the electronic idle stabilization before trying to make adjustments. Do a search of the archives for the correct procedure to set the idle and mixture on a 81 and later 924.

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

You have a 81 924, which must be tuned differently than earlier 924s because of the electronic idle stabilization installed on the 81 and later cars.

You need to time the engine accurately. You should be able to find a mark on the crankshaft pulley that you can use as a reference point to make a new mark on the flywheel if you do not have a good TDC mark on the flywheel.

Lining the camshaft marks up does not do any good if you do not have the engine at TDC. You can rough time an engine well enough to get it to run, but you will never get an engine to run right unless you use a timing light. You cannot set the ignition timing accurately by ear on a car that has electronically controlled ignition timing.

Trying to adjust the idle speed and idle mixture is a waste of time unless you have the crankshaft, camshaft, and ignition timing correctly set first, and the electronic idle stabilization disabled. You will never get the engine to run properly under all conditions without disabling the electronic idle stabilization before trying to make adjustments. Do a search of the archives for the correct procedure to set the idle and mixture on a 81 and later 924.