Porsche Enthusiasts Club Forum

Hi everyone I'm new.

I have recently purchased my first Porsche and for the brief amount of time I've driven it, it's been great (1984 944 lux). First job I had done was the cambelt, it was only done 4000 miles ago, but that was 8 years ago so thought this should be replaced straight away. Although I'm fairly handy with spanners I wanted to get it done by a specialist and have some evidence it was done properly in case I later decided to sell the car. 250 miles after having the belts done I noticed a loud rattling metalic sound coming from what I thought was directly behind the cam cover the car had no loss in power and apart from the noise it drove fine. Obviously I drove the short distance home turned it off and got it towed back to the specialist.

They were really apologetic and said they would get it apart and check everything they had done. I spoke to them today and in their words it's "bad news". All the belts and pulleys they replaced are all 100% ok and it's not coming from the cambelt area, but they believe it's a main bearing or a bent rod. I don't disbelieve them, but I will get a second opinion. They also said to be honest the cost of them rebuilding or replacing the engine is probably not economical to the value of the car.

So my questions are:
1. Are these engines prone to main bearing failure or bent rods my car has done 115000 miles
2. Would it still have power and run well with a failure like this, the garage seem to think the engine has started to seize while they've had it, but it ran fine for the short amount of time the noise was present.

Lastly does anyone have a good spare engine they want to sell?

Did you notice if the oil pressure dropped when the noise started ? Perhaps pull the plugs and spin the engine over briefly and see if there's oil pressure. Before buying another engine I'd think about dropping the sump in situ and checking if the oil pickup pipe is intact, and check the big end bearings while you're in there.

My first reaction would be to look closely at the engine as any noise has an effect on what is making it!
The early 944 had a web inside the cam cover that damaged the belt so Porsche removed it.
How was your oil pressure when it was running?
Did it run hot?
The noise you describe came from the cam cover.
I smell a huge specialist rat IMHO.
They hope you find an engine and get them to replace the evidence.

I have just rebuilt a Dolomite Sprint engine that ran for a little while until it died and there was a lot wrong in it for instance 8 valve TR7 pistons fitted when it should have had 16 valve Sprint ones etc Oh and that was built by a Triumph specialist

Oil pressure seemed fine. About 2 bar at idle and 4.5 when running. I know I shouldn't have, but I drove about 10 miles after the noise started (needed to get my 1 year old home) and it ran perfectly. I have a friend of a friend with a ramp so I'll try and get it up in the air to have a look. I'm guessing I have to drop the cross member to get the sump off.

Oil pressure was good and it didn't run hot. I was sure the noise was coming from the top of the cam cover area, but I didn't want to touch anything until they'd seen it.

I do have my doubts about specialists. I'm going to call their bluff tomorrow and tell them I'll do the work myself.

You'll need to support the engine before dropping the cross member, not sure if lowering the cross member on longer bolts will let the sump come off. I'd get it on the ramp and make sure the noise is coming from the bottom end before diving in.

I feel your pain. I had to replace my engine a 2 weeks after buying my car. The HG went within a week of owning it and when they pulled the head off they discovered a badly scored cylinder 2.

The actual engine wasn't too pricey though. I found a second hand engine of the same year still working and in a car being broken for £300. The labour was painful though. I got the clutch replaced at the same time while it was out.

Would have been nice to get all the gaskets done on the new engine but the piggy bank was empty.

I also had a metallic rattling sound occur a little while after I had replaced the belts, rollers, etc. It turned out to be the belt required re-tensioning as it had stretched in use. It was an unusual sound but when I took the cover off and looked at the belt moving I could see that it was flapping slightly as it came off the cam pulley (this is the long drop down to the bottom crank pulley). It was quite straightforward to sort, just ensure that the tension is equal on both sides of the cam pulley. Noise disappeared and has not come back.

Your specialist is probably right is saying that everything looks fine, but a re-tension of these belts is always required, they should know that and do it as part of the service..?

Why are they suggesting a 'bent rod'? A main bearing sound typically comes from the bottom of the engine - not the top!

One other thing to check is does the sound lessen as the engine warms up to operating temp? If it does then it is the belt as the head and block expand and take up the slack.

A bent rod?

They have run a compression test on that cylinder, found the compression down, run a leakdown test, found its leakdown to be fine, checked the camshaft lobes and timing, found that to be fine and then somehow measured the relative piston crown height to the other pistons?

Never seen a bent rod on a 944, even when the engine hydrolocks following entering deep water at high throttle the bore splits way before a rod bends.

Main bearing failed?

Never really see main bearings fail on a 944 either, normally number 2 con rod bearing fails with the snightest sniff of oil starvation and that makes such a horendous noise that the owner stops the engine long before a main bearing fails.

However, when number two does fail, it can make a high up noise, sounds a little like a worn cam, which is the piston crown kissing the cylinder head as the blown bearing allows the piston/rod assembly to go further up the bore due to the play in the bearing...

It also would not seize with a number two bearing usually, they will often keep running as the bearing material is soft and soon vanishes into wafer thin slivers, leaving the big end of the con rod slapping around the crank not able to seize against anything.. It makes a mess, but usually keeps running, unless the engine has been turned off at just the wrong point where it has failed but a millisecond before the bearing material has been completely destroyed...

What can happen with number two bearing though is that the oil pickup pipe can fracture/crack if the balance belt is not fitted correctly, this is due to vibration... when this happens the engine can draw in air through the crack causing air bubbles, but still good oil pressure, leading to a blown number two big end bearing... Or it completely brakes causing a loss of pressure, usually causing a number two big end failure followed by a complete engine failure.. But if you have good oil pressure then the second scenario is not yours.

Good luck.. I think you need a second oppinion.

When the Master speaks it is worth listening .... Grasshopper!

I think you're bang on the money here! I failed to mention earlier that after the event the oil was on the low level mark on the dipstick also the garage said there is a lot of metal on the sump plug so number 2 con rod sounds logical.

Also referring to the balance belt: When I picked the car up from the garage / specialist after having the belts done I noticed a vibration when the engine was cold which sounded like the exhaust touching the body somewhere, this noise then disappeared when the engine had warmed up. I assumed this was one of the engine mounts, not having the car for long before having the cambelt done I can't be certain the vibration noise wasn't there before the belt change, but I don't think it was. I do know that when I briefly drove it after the engine started making a horrible sound there was no vibration from the engine / exhaust....... If the belt wasn't fitted correctly I guess I now have no recourse as I bet when I get it back they will have made doubly sure it is.

sorry to hear a new owner having issues right away, the good thing is that engines for lux are cheap and plentiful. if you do require a new engine, then I have a running 2.5 lux engine still in a rotten car here that would be available cheap.

good luck

regards

I will heartily second this comment
Last year my daughter raced her boxster in an endurance series and the Birkett six hour (a win here!) and JMG built that engine to standard spec and it never missed a beat.
Thanks JMG from her old codger dad

How much are we talking? I've had a couple offers, but they're all miles away. I think you're fairly local to me.

There are a lot of Porsche specialists out there who really are Porsche specialists, which means that they only work on Porsche cars, and only have done for a number of years/decades, and even many of these will step away from 944 belt jobs because their technicians might not do them very often, if at all.

Then there are Johny come lately breeds of Porsche specialists, who for whatever reason have decided to stop fixing trains, refridgeration trucks and all manner of other hardware, to become Porsche specialists, who will dive into any job where they can read a how-to on the internet and charge money for it.

These people are more dangerous than a DIY enthusiast, as an enthusiast will always ask questions, research and perform the work with care.. .But the wrong mechanic, without the experience of a particular job on a Porsche, will barge in and make a lot of assumptions based on every other car they have worked on and changed belts on, which can often end in tears, as the 944 belts, in particular the balance belt, are a bit unique in that their tension needs to be just right, very loose by cam belt standards.. But also the sprockets both have two orientations, depending on if they are the upper shaft or the lower shaft.. Getting this wrong kills engines.

The shafts are there to smooth out the vibrations and harmonics in the engine, get the balance shaft installation wrong and the hamonics become destructive, even worse than not using a balance shaft at all.. The oil pickup is only held in with one bolt on a bracket that has a tiny weld holding it to the tube.. The tube has a heavy strainer on the end, so any vibration travels down the tube and is amplified by the strainer which then travels back up the tube, often to be met by another wave coming down it.. The result is often the tube cracking around the top where the welds are, which will suck in air as well as oil up the tube.. This results in foam being created in the oil pump, which will still compress, the oil pressure relief valve will stay closed to maintain oil pressure, but the air bubbles will shoot down the first oil gallery, causing starvation of number two big end bearing... Its then good night nurse!

Take the sump off carefully, look for the crank turning blue near number 2 conrod and look for a crack in the oil pickup tube.