1983 - 944 Engine question

Magnet · 08-13-2008, 07:42 PM

Hi, I have a 1983 944 Euro and I have to add alot of oil.

The car smokes alot and there is oil in the air box. How would I test to precisely to know if only the cylinder head needs to be redone or the entire motor?

Note - the rod bearings have been replaced 3000 km ago.

Thanks,
Darcy

Outback Porsche · 08-13-2008, 08:21 PM

Could be the o-riings on the Air Oil Separator, or the AOS itself need replacing.

Magnet · 08-13-2008, 08:39 PM

by the AOS..are you referring to the 2 o-rings where the oil filler neck attaches to the top rear side of the head/block?

if so, I have replaced the 2 filler neck o-rings, all the gaskets from the the cam tower upward, rod bearings and OPRV.

hpservertech · 08-13-2008, 08:53 PM

Look under the cap of the oil fill tube. If it's clean then I would look elseware. But if it's caked in oil then either the new o-rings aren't doing their job or the fill tube is cracked.

Outback Porsche · 08-13-2008, 09:11 PM

Quote:

Originally Posted by Magnet

by the AOS..are you referring to the 2 o-rings where the oil filler neck attaches to the top rear side of the head/block?

if so, I have replaced the 2 filler neck o-rings, all the gaskets from the the cam tower upward, rod bearings and OPRV.

Yep, they are the o-rings I was referring to. I had a similar issue 6 month ago (oil in air box and smoke in engine bay). Ended up replacing the AOS - problem fixed. Also found all my vacuum hoses full of oil, hard and brittle, and replaced them at the same time.

Cheers

Magnet · 09:14 PM

The oil filler cap did at on time have a light film before I changed the 2 o-rings but was never caked in oil. Now under the cap is clean.

I don't have any smoke in the engine bay, but there is a continuous stream of black/blue smoke out the tail pipe.

hpservertech · 08-13-2008, 09:14 PM

You sure you got the rings on right? If I remember right they are different size for the top & bottom.

Outback Porsche · 08-13-2008, 09:17 PM

It depends on the engine number. Look on the PET - mine were both the same size. The engine number will also determine the part number of the AOS.

hpservertech · 08-13-2008, 09:19 PM

I very well could be wrong....most likely am.

Magnet · 09:25 PM

I don't remember exactly because I changed the o-rings over 1 -1/2 years ago, but i did get the 2 o-rings from the Porsche dealer and recall that they went on nice and snug with a good fit of the filler neck to the block.

All the hoses and engine seems to be dry and not have any oil residue.

With this and a few other issues, I haven't driven the car since

Outback Porsche · 08-13-2008, 09:45 PM

It could also be time for a compression and a leakdown test.

Magnet · 10:11 PM

Quote:

Originally Posted by Outback Porsche

It could also be time for a compression and a leakdown test.

Yes....I will do a compression test this weekend and hopefully a leakdown test too?

I will take some pics and post the results

Outback Porsche · 08-13-2008, 10:04 PM

There may be something a Clarks - haven't looked. Here's a faq I found on the web - looks alright.

http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm

Cheers

Slam · 08-14-2008, 11:52 AM

How are your valve stem seals? When you changed the rod bearings, you probably got better oil pressure, and if the valve seals were marginal they may have let go. And a compression/ leakdown test won't find this.

Magnet · 08-17-2008, 08:02 PM

[QUOTE=Magnet;4119099]Yes....I will do a compression test this weekend and hopefully a leakdown test too?

These are the results of the compression test after the car was warmed up to normal operating temperature and spinning the car over 10 - 15 times....

Cylinder # 1 - 145 psi
Cylinder # 2 - 151 psi
Cylinder # 3 - 152 psi
Cylinder # 4 - 149 psi

So...what do the above compression results tell me? The compression range between the four cylinders is ~ .048 (145 * 4.8 % = 151.96)

I'm thinking that a leak down test is next? What will a leak down tell me.

Any other information is greatly appreciated,

thanks,
Darcy

Magnet · 08-17-2008, 08:05 PM

Quote:

Originally Posted by Slam

How are your valve stem seals? When you changed the rod bearings, you probably got better oil pressure, and if the valve seals were marginal they may have let go. And a compression/ leakdown test won't find this.

How do I check the valve stem seals. When I changed the rod bearings, the oil pressure got better, but not by much !!!

Magnet · 08-24-2008, 08:01 PM

Quote:

Originally Posted by Magnet

How do I check the valve stem seals. When I changed the rod bearings, the oil pressure got better, but not by much !!!

rudidelange · 08-28-2008, 12:30 PM

Valve stem seals may become hard after 20+ years, add to this some valve guide wear and your car might start using oil. A tell tale sign is smoke on starting, as well as smoke from the exhaust we you decelerate from high speed. Oil escapes past the valve stems into the combustion chamber - smoke and oil consumption.
The only way to rectify this is to remove the head, fit new guides and stem seals. The valves are pretty hard and could be used again. Fitting new guides will require that the seats and valves are cut to ensure proper seating.