Thrust bearing flange gone

jean · 12-26-2001, 06:19 AM

The flanges of my main thrust bearing are totally gone.
I know it because:

1) My mechanic found the crank shaft end play to be 7-8 times the tolerance
2) I found a half flange in the engine while making my oil change (I removed it through the drain hole)

Otherwise my car works fine. No noise - no problems
I am not sure what I can expect if I keep driving ?
I am thinking to change the thrust bearing without removing the engine. I believe I can remove the cross member and pull down the oil pan from below. Anyone has done that?

Britwrench · 12-26-2001, 08:02 AM

Sorry to ruin the holidays for you but this is an engine out and strip down lower part to replace. You will probably find the crankshaft is worn out too. I would look around for a good used engine (usually less than $500.00) and install that.

If you wanted to you could replace the bearings, rod nuts, timing belt, water pump etc.. on the used engine.

This is not an uncommon problem with older 944s.

jean · 12-26-2001, 11:05 AM

I will still try to look at the crankshaft to see what is going on.
Do you know if the oil pan is easy to take down (without removing the engine) ?

Britwrench · 12-26-2001, 11:29 AM

Yes, you can remove the oil pan by pulling the cross member.
Problem is, you won't see anything. The 944 uses a lower crankcase bolted to the upper crankcase with the crank in between.

If you are going to pull the cross member, just carry on and remove the motor at the same time.

jean · 04-07-2002, 06:51 PM

I am persisting in changing my main bearings & rod bearings and embarked in a major overhaul.
I have so far removed the entire steering rack, cross member & oil pan (took at least 10 hours!)
As far as I can see the rod bearings are easy to replace (without removing the lower crankcase). I can also see that my main thrust bearing is really dead with the flange disappeared on one side, so the crank shaft has moved almost 1/8" on this side.
The problem now is that I am not sure if I can really pull down the entire lower crank case. There is something at the front of the engine that seems to be bolted to the lower crankcase as well. If it is so that's bad news because it seems I have to remove a lot of things then...
Anyway, I will persist even if it's a big job because I already spent 5,000 $ in repairs on that car (changed engine mounts, timing belt, water pump, transmission rubber disc, oil cooler & seals, flex plate, torque converter)

Scott R · Scott R's Garage

Engine out time. New cramk shaft as Brit said. Chances are the crank is out of round after riding in that bad bearing. Like the above post stated: "Used motor time."

jean · 04-08-2002, 03:37 AM

I am planning to measure the cranckshaft and change it if necessary, as well as the head gasket and balance shaft seals. After I spent on this car I really prefer to buy all defective parts and fix it completely.
I know a used engine is also a solution but I think it's like gambling. It can turn out to be worse than my engine. I have seen also rebuilt engines on Ebay for 1600-1700 $ but I don't trust those. It just seems to cheap to me when I see now the enormous work involved to rebuild those engine.
I would only trust a rebuilt from Porsche in Germany but it is expensive. I got a quote for US$ 6,200 including replacement.

jean · 04-09-2002, 05:10 AM

I have now removed the lower crankcase (was actually easy), measured the crankshaft bearing journals. The diameters are OK but the width at the thrust bearing location is a little bit off (but not much) because the thrust flange disappeared on one side.
What I am planning to do is replace the 5 lower main bearings halfs (those I can access). The reason is that I cannot remove the upper halfs because the crankshaft is still held by 2 bearings (I believe).
I know it is not a perfect fix but I expect this to work at least 20,000-30,000 miles.
I am hesitant to remove the entire engine because I have no idea how to detach it on the transmission side (I have an automatic)
I would be interested in any feedback.

Britwrench · 04-09-2002, 09:07 AM

Ever heard the phrase "wasting your time"?

If the crank is worn, then it needs fixing. So far you haven't taken any notice of anybody's advice, so why don't you just carry on in your own path.......

The engine will probably run ok for a while, but who knows how long.

jean · 04-09-2002, 11:00 AM

I am not saying that I am doing the right thing. Perhaps I am wrong and you are right.
If you know a supplier for a good rebuilt engine that I can trust and doesn't cost a fortune I am interested.
Do you know what has to be done in order to separate the engine from the transmission in order to remove it?
Can I remove the 4 bolts that attach the torque tube to the bell housing?

Britwrench · 04-09-2002, 11:11 AM

It sounds as if you have enough knowledge to rebuild the engine yourself. The most important thing is measuring the components and making sure you are not re-fitting parts that are excessively worn.

To remove the engine, remove the starter motor and unscrew the bolts holding the coupling to the flywheel. Then remove the flywheel housing bolts so that the housing is disconnected from the engine, then you can pull the engine forward enough and pull it out. If you have a engine hoist, pull from the top, if not drop it out from below.

Remove the rotor arm and sleeve and oil filter first as these parts always hit something otherwise

Before you remove the engine, loosen the crank pulley bolt as it's easier when the engine is bolted to something solid (like the car!)

Pull the crank out when you have it apart and measure the thrust faces..it will need another crank or metal-spraying to bring it back to the correct size.

jean · 04-09-2002, 11:34 AM

Thank you so much for your help. This procedure to remove the motor is still valid for an automatic, I assume?
I think I am going to take this engine out and clean up / rebuild everything because I noticed some metal dust in the lower part of the oil pan and I would feel bad re-assembling this engine without being sure it is perfectly OK.

Britwrench · 04-09-2002, 04:46 PM

That only refers to the automatic, the clutch type is removed with the flywheel housing attached.

If you have metal particles in the oil pan the engine must be COMPLETELY dismantled and cleaned.

drew1 · 04-09-2002, 05:55 PM

jean,

Like your go ahead & get to it. Britwrench is right smart & works on Porsches for a living so make sure & read his replies.

If you find a bad crank, I think ebsracing has one with better oiling for the rod bearings for $600-$700.

If it was me, I would go ahead, pull the motor out & tear it down & then if a lot of damage consider a used one.

drew1

jean · 04-10-2002, 12:44 PM

Drew1:

I believe what you tell me regarding Britwrench
His expertise must be very valuable in this country. I come from France / Switzerland and my experience so far here has been pretty bad. Last time I took my car to a Porsche dealer (so called "expert") to change the oil cooler seals I had to wait 5 weeks. When I drove the car back home I got stuck half way with the water boiling (perhaps this is what killed my bearings). The 2nd time I drove the car home I noticed the oil pressure was permanently at 5 bars (max) and never moved. I knew right away that the wires had been reversed on the oil pressure sending unit and I called the Porsche dealer to tell him so that he knows next time.
So if I want to rebuild this engine myself it is not for the money I save but because I really do not trust the dealers. I am not a mechanic and definitely not a Porsche expert but I have a MS in Mechanical Engineering (and a PhD in Applied Mathematics) so I think that I know what I am doing. It will just take me some time ...I also trust people on this board who are I think the real experts.
So, long life to the board!

jean · 05-27-2002, 05:30 AM

I am finally done with my overhaul/rebuild
The car really runs like a Swiss watch and feels like new.
What I changed: Engine main bearings, rod bearings, All engine gaskets and seals, valve seals, intake valves. I also rebuilt completely the steering rack (no more leaks) with the Transtec kit and the front suspension (shocks and lower springs).
I also did some major body work and came up with a new front & rear design that I will post pictures soon...
I found when I opened the engine that my rod bearings were in bad shape but the main bearings were far worse, with the thrust bearing flange completely gone, which was what I suspected. Overall nothing was really difficult, it just took some time. Thanks again for those on this board who gave me very useful advice..