engine get noisy and shutsdown

[Santos]

Hi,

I've been doing light maintenance work on my '83 944 non-turbo. Today I turn on the car and took it for a spin. In 1st, 2nd, 3rd, and 4th gears I noticed loss of power when I was hitting 4,000 rpm; engine would sound extra noisy and whiney. Even at low RPMs the engine exhaust was loud and low tone (as if an exhaust leak). I got home and let the car idle while I took a look at the engine. I heard a dull knocking noise every second or two coming from the engine. After a few minutes the knocking noise got a little louder and the car misfired and turned off.

I haven't tried turning the car back ON afraid that maybe the timing belt went out.

Any tips on where I should start? Basic checks?

And I thought I was making good progress in making a better car of my porche 944.

Thanks,
Santos

[Santos]

I should add that I have owned the car since 2005. I have never replaced any internal engine parts. I've only changed coolant hoses and the alternator. Other work has just been regular maintenance (oil, filters, spark plugs).

[gmorken]

Santos:

How many total miles on your car? How many miles have you driven it since 2005?

[Santos]

My speed cable is broken and I was not able to keep record of the mileage. I would say easily over 70k miles in 5 years. I would use the car every day for work (20 miles each way).

[Izzy Does It]

Timing belt let go?

[Rasta Monsta]

Two theories:

1. Timing belt slipped (power loss, wrong exhaust tone), then slipped again (misfire, knock and die).
2. Ignition rotor came loose (conceivably, same symptoms as above!)

Checking the rotor for attached-ness would be a ten minute job. Stripping the front of the motor to check the condition of the timing belt is probably under one hour.

When you say, light maintenance, what have you done on the car, exactly?

[Santos]

Thanks for the tips. I will start with the easiest first (ignition rotor) and move on to timing belt.

For light maintenance I have replaced the alternator, cooling fan thermo switch, clutch slave cylinder, brake discs and pads, filters, oil, spark plugs, and some cosmetic fixes. Just basic stuff I have had to replace in the past 5 years.

Thanks

[Rasta Monsta]

Ugh, you provided that info above, sorry for asking you to repeat it.

[ernie9944]

If I understand rigth it's been ten years since the timing was done,hope for you it's only only the ignition rotor that came loose and that you are aware that the timing belt should be done every five years or 35-40k miles which ever come first.May I suggest your overdue on that part of the most important maintenance done to any 944 & if not to late you do it ASP.

[Santos]

I confirmed that the timing belt went bad. I took a picture and attached to the thread. Notice a bunch of teeth missing on the timing belt right on the crank's camshaft belt drive gear.

I am able to rotate (360 degrees) the crank with ease using a ratchet. I hope that means the valves are not bent. My car has the eccentric roller timing belt arrangement (1982-1986).

Any tips on checking the valves without removing the head?

I rotated the camshaft sprocket a little bit. About a 1/4 turn each way. It feels harder to rotate than the crank, but not so bad. I would expect a vent valve would make the camshaft sprocket really hard to rotate. I did not rotate the camshaft a full cycle because I'm afraid to cause valve damage.

Is there a way to setup the crankshaft so that I can freely rotate the camshaft without risking valve damage?

Thanks,
Santos

[Rasta Monsta]

Checking valves without head removal. . .do your belt service and take a compression test.

But, this is a waste of time. . .that head's coming off.



P.S. Where are you located??

[theceilingfan]

+1

Head removal isn't terribly difficult if you have the time/tools. The real PITA is retensioning the timing belt correctly... Ask anyone here about the notorious tool...

[Pete R]

You could do a leak down test right now. You'd even know which valves were bent.. or not.

[Santos]

I'm located in Austin, Texas.

Looks like all I need are two wrenches to do the timing belt retensioning. My timing belt arrangement uses only one tensioner roller which looks pretty easy to adjust.

[Santos]

I already set the crankshaft-flywheel to TDC. I can't find the answer to the following question.

Now I want to turn the camshaft gear to set to TDC. Which way (clockwise or counter-clockwise) do I rotate the camshaft gear such that the valves do no hit the 1st piston which is in TDC position?

[zedsn]

If your car was running and your timing belt broke you have bent valves. This is an interface motor.

[bazar01]

Originally Posted by Santos

Is there a way to setup the crankshaft so that I can freely rotate the camshaft without risking valve damage?

Thanks,
Santos

You can rotate the crankshaft so all pistons are all just halfway the cylinder, the you can rotate the camshaft. You have to remove the spark plugs and get a wooden stick and stick it in the spark plug hole, rotate the crank and watch the stick go down halfway the stroke.

If you tried to start the car with a stripped timing belt, it's 100% sure some valves are bent.

[ernie9944]

Sorry about what happen to you man,but will never get over the fact that peoples leaves there belts on for over five years without changing them on their 944.This is beyond my understanding.Either you refresh that head completely or maybe buy a good use one, they are cheap and a dime a dozen for the 2.5.Also while in there may I suggest (if it not done yet) to upgrade your water pump with a new style one (turbo) if not done yet. You can get it has a kit with all parts need including thermostat,for your infos I've use Conti-Tech belts on my 83 for years & had nothing but success with them.Good luck

[smokin_944]

Originally Posted by zedsn

If your car was running and your timing belt broke you have bent valves. This is an interface motor.

I'm guessing you mean an interference engine?

[Santos]

I recorded my car as I turned ON the engine. But, unfortunately I am not able to attach a video with sound in this thread.

I got done installing the timing and balance belts. The car did turn ON but I can clearly hear the valve noise. The car will not idle smoothly; I have to give it a little gas to keep the engine ON. I tripled checked the timing marks, so I know that installation of belts is correct.

So, as expected, you guys were correct on the bent valves.

I found an "1986 PORSCHE 944 LOW MILEAGE 2.5 ENGINE CYLINDER HEAD" on EBAY for $140. Will that head fit my 1983 955, non-turbo, 2.5 engine?

On seconds thought, I might not even have time to fix my 944 as I am in the middle of moving out of state. I think I will sell the car as is. How much do you guys think my car is worth right now? Everything works fine, except the head , and the body is in good condition. Tires are nice Yokohama with about 70 percent thread left. I paid $600 just for the tires alone, 2 years ago. Brand new $100 battery.

I hope I can atleast sell the car for $600 to get my tire money back. Anyone think that's a fair price?

Thanks,
Santos