924Board.org

[JackRabbit]

like my unfortunate compatriot, my 924 also seems to have a habit of overheating. It's only been on the road about 2 weeks since a 12 year sit in a garage. As far as I can tell these are the symptoms... I'm hoping someone can piece them together into a possible explanation.

She burns oil like hell. I know these cars burn oil but I've gone through 2 quarts in about 600 miles. I check it all the time and am constantly topping it up. There is also a minor oil leak that causes oil to pool on the top of the engine to the right of the Valve Cover. The oil pressure seems ok. I'm using 10W-40 and it hits around 5-6 upon start-up and then drops to around 2-3 once hot. I considered trying this Lucas Heavy Duty Oil Stabilizer and their Stop-Leak fluid that's supposed to seal leaks and cure cancer. Anyone weigh in on their performance?

When at speed the car has no problems but when idling it can warm up very fast and if I shut the car off and it's between the middle and red, sometimes when i restart the engine it's right near red. I can easily hear the fan running when I kill the engine. Sometimes it runs for a minute, sometimes it runs for 10. I've replaced the fan switch, and was planning to replace the tstat today but didn't have time. After reading through the entire Mystery thread I ordered a Haynes manual and am waiting for it to arrive.

Something that has developed lately is a cold starting issue. When I first got the car out, I threw a new battery in it and it basically started right up. But now it seems to have some problems getting going. I'll turn the ignition on and off 10 times and all that but it will fire up and cough and sputter and die several times before it goes. Once I pull out once it seems fine. I can stop, and idle, and even shut it off and it will fire right back up. Any idea what could be causing this? Is it a potential fueling issue? I replaced the fuel filter on day 1 and added some Techron to the tank. I've been running premium fuel, but wonder if that's necessary. What do you guys run?

The other issue is that when I kill the ignition the car keeps firing. Like it wants to keep running even though I've removed the key.

The most important issue or the biggest priority for me is the overheating issue as I know that can be very dangerous for an engine. Any and all info/advice will be greatly appreciated.
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'79 Porsche 924
'05 Honda Civic
'07 BMW K1200R
'78 Honda Express
'52 Willy's
'58 Wheel Horse

[PORSCHEV]

I would try a t-stat. Seriously think of draining the coolant out and cleaning the rad out. Your obviously geeting ineffcient cooling and that can only be bad flow( t stat) or the rad being cruddy...or just beyond use due to external corrosion. I would run water for a few weeks and clean it out...drain it every few days to get the rust out. then once it gets clean add proper levels of anti freeze.
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1976 924
5 lug conversion, 17'C2 wheels,custom body work,327 vette engine.

1978-#53 "D" track racer.

[Smoothie]

Worn or sticking rings might explain a few things - it would cause excessive oil consumption, and also excessive blowby and this would be sending excessive oil vapor through the breather and back through the intake which could explain the oil puddles on the intake manifold (oil leaking out of the intake before the throttle body, onto the manifold).

To help flush out the cooling system, there are radiator flush products marketed by Prestone, Xerex, others, that you mix with water only and run for about 500 miles.

For the run-on, -if- it's not some kind of ignition switch problem, I'm thinking the engine's running too hot maybe due to something like too far advanced timing, too-lean A:F mixture, or non-functional EGR. -And with worn/sticking rings, and the excessive oil consumption there'd be ample carbon deposits on top of the pistons, bottom of the head and on the valves - these can become hot spots, as can too-hot spark plugs. Hot spots in combination with leaky injectors and/or leaky cold start valve could be causing the engine to run-on.

[ps: excessive oil burning could also explain EGR valve non-functioning, which as mentioned could be contributing to the overheating..]
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[Smoothie]

[JackRabbit]

hmm well that gives me a lot to think about... I really appreciate your help on this... As far as "worn or sticking rings" goes, how do I go about fixing that problem?

let me give you a little more info and see what you think...

I'm currently in Chestertown, MD (with the 924)... I'm leaving tomorrow evening to drive back to Clarion, PA (about 300 Miles). Since she seems to run fine at speed, (she sure did on the way down) what would you suggest I do to ensure a safe trip (for her) home?

Should I empty the radiator and fill it with water? Or run a radiator flush through tomorrow before I leave? I figured I'd dive into the tstat once I get back in Clarion and have the Haynes manual in hand. I know where it is and how to get at it, but as far as line bleeding goes, I have to admit, I'll need some solid direction.

In the Mystery thread, someone discusses the possibility of a faulty battery ground strap. I'm beginning to wonder if this is at least a related or unrelated problem. My electrical use directly effects the Temp Gauge. It goes up when I turn on the lights, foglights, turn signals... etc. I assume that's not supposed to happen. And Smoothie, you referred to this phenomena called "heat soak." If I understand you correctly are you saying that this normal? Or in other words isn't hurting the engine?

Aside from that gauge, my fuel gauge is also not working properly. When I fill the tank completely it reads 3/4 tank for 20 miles or so and bounces around. After that it mostly rests on negative fuel and sometimes bounces around the middle. Does this have to do with battery or the sensor or...?
_________________
'79 Porsche 924
'05 Honda Civic
'07 BMW K1200R
'78 Honda Express
'52 Willy's
'58 Wheel Horse

[Smoothie]

I'd leave it alone until you get home. Water alone provides 90%+ of your cooling, but the extra 10% that antifreeze/coolant provides would be good to have until you get home.

The stuff that happening with your gauges indicates grounding problems. There are about 5 main grounding points around the car, and a grounding ring hidden up behind the dash that should be cleaned up.

Yes, heat soak is normal - nothing to worry about, nothing to fix there.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[Paul]

Define your use of "overheating". Is it actually spewing coolant?
_________________
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.

[JackRabbit]

oh no... she isn't spewing anything... and by Overheating I mean that she isn't staying dead center all the time. At idle the temp gauge goes up to 3/4 or a little higher.
_________________
'79 Porsche 924
'05 Honda Civic
'07 BMW K1200R
'78 Honda Express
'52 Willy's
'58 Wheel Horse

[Paul]

Completely normal, they have done that since new.
_________________
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.

[Chrenan]

To get it to run at the first quarter mark, you'll need a low temp thermostat and fan switch. Fan running after shut-down is normal, time varies by heat.
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1987 951 - M193 Version for Japan

[Paul]

Your car's cooling system seems to be fine, but I would flush the system since it is supposed to be done every 2 years.

These cars have an electric fan that only runs when the temp guage hits 3/4.
_________________
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.

[gohim]

Are you sure that you are not leaking the oil, as well as burning it?

Early 924s are know to have soft valve guides that wear much more rapidly than the rest of the engine (often worn out in less than 80K miles). The front oil seals can also leak (the car is close to 30years old).

Your oil filler cap needs a new seal, or to be replaced. That's where the pool on top of the valve cover is coming from. You may be blowing tons of oil out from the cap.

Is the valve cover leaking? Don't just crank it down. Buy a new paper gasket, and use a torque wrench to tighten evenly.

Check the bottom of the exhaust manifold for cracking (the cracks glow red with the engine running). Early 924 exhaust manifolds cracked like crazy. Porsche produced exhaust manifolds that are reinforced with ribs on the bottom to try to prevent the cracking.

Check the timing belt to make sure that the camshaft and ignition timing are going to be able to be adjusted correctly. If the belt needs adjustment, you might as well install a new one.

These cars are VERY sensitive to vacuum leaks, and they have tons of vacuum tubing. DO NOT MESS WITH THE IDLE SPEED OR IDLE MIXTURE CONTROLS until you have replaced all of the vacuum tubing, checked the camshaft timing, AND the ignition timing.