NeedPorscheSpeed

Fellow 951 owners,

Today, when I cranked the engine of my modified 951, I noticed that the engine was knocking (it reminded me of a diesel engine). I thought the oil might have been low, so I checked it, but it was fine. I made a small video (with sound, of course) so that I could post it here for some of you experts to listen to. I hope to take the car to my mechanic as soon as possible, but during the interim, I would appreciate any and all comments and advice about this matter. I am hoping that it will ease my troubled mind.

Although I had hoped to post a direct link to the video, when I attempted to upload to the Rennlist server, it would not recognize my Rennlist ID number... So, plan B was to post it at a Yahoo Group. Those of you who are Yahoo users, if you would do me the favor of: a) logging on; b) joining the group; c) downloading the small (478 kb) video; d) listening to the engine for a moment; and e) letting me know your thoughts, I would be highly appreciative!

The link to the group is:

http://autos.groups.yahoo.com/group/PorscheLiterature/

Thanks very much!

A fellow 951 owner who is a little troubled at the moment,

Jonathan

Skip Wolfe

Yikes. I hate to say this Jonathan, but that really sounds like a spun rod bearing.

I hope you don't mind but I uploaded your video on my Rennlist site to make it easier on the non-Yahoo members. Just right click and save as. I leave it up for a couple of weeks.

http://members.rennlist.com/skips951...0at%20idle.avi

atinybug

bad news is never good... but that sounds exactly the same way mine sounded when i spun a bearing.

hosrom_951

mmmmmmmmmm.............was your engineout or the head off befor you started the car and the noise came?

ian

I can't get the video to load, but I hope more than anything that its not a rod bearing. They are not that old, so they shouldn't have failed. When did the noise start?

NeedPorscheSpeed

First of all, allow me to say thanks for your responses.

Secondly, let me say: OH NO!!! A spun rod bearing? I certainly hope not, but after reading about the issue for the past several hours, my hope is dissipating fast. I first read your responses about three hours ago. I was exhausted before I read the terrible news contained within your responses, but somehow, I have stayed awake for three more hours, reading everything I could find in the archives about this problem. Isn't it odd that I had never heard that the 944 Turbo was notorious for the #2 rod bearing until the past few hours...

Judging from the things I have read, it appears probable that it is a rod bearing failure. I have no idea why this has occured; when I checked the oil today, it was a little above the min mark... Maybe I should have religiously kept it at the max mark on the dipstick. If that is so, I now feel like a dipstick! The car hasn't been near a track, and I haven't been driving it around that many corners all that hard, which, as I understand it, would have increased the chances of oil starvation.

I was hoping that it might have been a lifter or a valve problem... but that doesn't seem likely from what I have been reading. What really baffles me is this: the knocking disappears once the engine clears idle. In fact, the engine still runs like a champ! I know what you're thinking... "You actually drove it despite the fact that it was making that knocking sound?" I'm afraid so guys....
Because it wasn't making the noise above idle, I decided to see how the engine would respond under load, and it did splendidly. Now, I realize, after having read several threads, that if it truly has spun a rod bearing, that that "little test drive" may have damaged, among other things, the crank, which will require machine work. Hey, at least the rod didn't shoot out of the engine block, as it did for some unfortunate souls (and engine blocks)!

All I can say is that I am a very positive person, and I am going to look on the bright side. I will use this as a learning experience and attempt, with the help of the List, to repair this problem myself, or as much as I possibly can. Hopefully, it will not require a complete engine rebuild, but if it does, at least I will virtually have a new engine when it is all said and done.

I welcome any further comments and suggestions from you all, especially from those of you who have experienced this before. I guess I should have been careful as to what I wished for... I have been wanting to learn more about the inner workings of the 951, and it appears that I am going to be doing just that... the hard way.

(Ian, you have a PM.)

hosrom_951

"Because it wasn't making the noise above idle"

That is not a rod bearing, after watching and listening closely, it sounds more from the head, not the block.

If the sound inceased above above idle speeds, then i would say rob bearing

Again, place your ear (or use a occilisope, whatever it's called) and tell use where is the loudest point for this 'tappering' noise.

Here is the best method to confirm a failed rod bearing:

Take off the pan, and inspect everything! If all seems well, your probably need some head work done.

tommo951

I had a noise at idle that I thought sounded like a big end on its way however my oil pressure never gets below 3.5 Bar even hot & tested with a wet gauge. The noise seemed to disappear as soon as revs lifted. So I used a stethoscope and found the noise was emerging from the water pump housing. As I had fitted a new water pump recently I was doubtful the pump was the problem.
It turned out the Circlip holding the thermostat obviously hadn't seated properly and the thermostat was rattling around. A lot cheaper than a big end bearing but a lesson to be learnt!!!

Skip Wolfe

It's a mechanics stethoscope and that's a good idea. You can buy one from Sears. Crawl under the car and have someone work the throttle. You may be lucky since the knocking sound shouldn't go away with an increase in engine speed. Check the water pump, head, etc. I would be surprised if it was a collapsed lifter but you never know. Whatever you do, don't drive it if you can help it. Even if its not a rod bearing its still not good and you only risk more damage.

Cross your fingers and we'll light a candle for you.

hosrom_951

"Cross your fingers and we'll light a candle for you"

Candle lite for you

But i really think it's something in the head since the noise goes away above idel.........but who knows.......

fast951

Get a broom stick, place one end on your ear the other end on various places in the engine (cam cover, block, even oil pan). This should give you an indication where the source is. I didn't hear the sound, whatever you do, don't apply any load on the engine...

Bengt Sweden

With a spun rod bearing there will be metal glittering in the oil.
Tappets?

bengt

hosrom_951

Fast951: He already did and the sound went, but comes back in idle..............

hosrom_951

Don't have a broom stick?

Use a fairly long screw driver

NeedPorscheSpeed

Hello guys. Thanks for your opinions and words of encouragement. I especially appreciate the candle lighting ceremony, Skip and Hosrom.

I am glad to know that there is a chance that it isn't a spun rod bearing. I, also, was thinking the problem was in the head, Hosrom, and that is why I took it for a test drive under load. I haven't had a chance to inspect the car again yet (I have been sick in bed all day, this time physically, which matches my mental condition concerning that knocking noise), but, I am going to purchase a mechanic's stethoscope or try to find a broomstick asap, and listen to the car again. Also, I am going to check the oil for metal shavings, as that will be quite telling.

If I listen to it and still am not sure, the next step is to enlist my mechanic. My mechanic is only 4 miles away, but judging from what I have read, I would be a complete fool to drive the car, no matter how gingerly, even that far. Maybe I could get him to come and listen to the car at my house (with his stethoscope).

Here's to hoping that it is just in the head... (--Lights candle--)

Keep the suggestions coming, I really appreciate them!