Hi fellow Brickboarders:

I have a puzzle that I'm hoping someone with more experience than me can solve.

My 1989 Volvo 760 Turbo Wagon started making a knocking noise about a year ago that lasted for a few seconds on cold start up. Since then, it has gotten longer and longer but always goes away in about 1-2 minutes' time, give or take.

The engine is not the original one (overheated and melted by a Previous Owner), but instead, is a 1994 940 SE Turbo engine with the under piston oil squirters and about 110K miles on it. Regular oil/filter changes are performed with synthetic oil.

I took a video of the car starting up cold and filmed until the sound went away. I have tried using a variety of ways to locate the sound and can only narrow it down to the bell housing/rear of engine area.

Any one have any suggestions as to what is causing this noise? Any help would be greatly appreciated.

Here's the YouTube video I posted:

http://youtu.be/HkrL3VS5RjA

Thanks in advance,

Anthony

My car, Evander, was a '90 744T that had 153k miles on it - It was in great shape but the engine was a bit noisy when cold, two cylinders had questionable compression, but I needed a car quick.

After good maintenance for 50k the compression actually came around and the car never got noisier - it was nice and quiet when fully warmed up.

I always treated it kindly when cold, and ran it for several minutes before shutting it down if I got directly off a highway - for instance at a rest area. I drove it like I stole it when it was warmed up we even did plenty of snow donuts to teach my girls how to drive better. In the dry, I could drift it around a 1/4 rotary near my home (old snow tires).

We drove it to 235K and the woman I sold it to had 285k on it the last time I saw it. If you go to brix pix, search for 700 and go to the bottom of page 22 - possibly page 23 by tomorrow, you can see Evander.

At one time we had 3 850s and Evander - my girls and I would always use him if he was in the driveway.

I really miss him!
--
'96 855R,'64 PV544 driver, '67 P1800 basket case, '95 855, '95 854, the first three are mine, heh, heh, 485,000 miles put on 9 bricks

It surely does sound like piston slap but if your engine truely does have only 110K miles on it then I would say it's developing the problem about 100K miles too early. Do you do your own oil changes? It's just very unusual for your engine to have this problem so early. I believe the pistons have both the longer skirts and oil squirters to keep this from happening??

Hi fixit2002,

Well, after a recent oil change, I'm starting to believe the problem lies in the transmission interface with the engine block. I started the car up, which was on ramps, and after checking for oil leaks, put my ear right next to the oil pan and did not hear the knocking clearly. But, when I moved back and put my ear right next to the plastic covers that ventilate the bell housing, I could very clearly hear the knocking, loudly, which tells me somthing is wrong with the flex plate or torque converter.

I'm no wizard mechanic, but my landlord is, and he is not convinced it is a "tranny" problem, but did declare that it was not coming from the engine after having a look-see.

I'm considering whether or not to pull the tranny to see if something's loose in there. The engine was put in by another fellow Brickboarder some years ago (Hey Dave!) and appears to be a good swap but maybe some Locktite went missing in the process or the like.

The knocking happens now even when I start the car warm but always goes away after a few minutes' time.

Sometimes truth is stranger than fiction!

Onwards!

Anthony

This 'sounds' like what happens when a flywheel/flexplate bolt comes loose, as has happened to others.

If the flex plate or torque converter bolts are suspected--you should remove the lower brace (six bolts) so you can at least put a wrench on the torque converter bolts. -- Dave

Hi Fixit2002,

Well, the engine was installed by the previous owner before I bought it (he bought it and swapped the burned up engine out) and was rumored to have somewhere in the neighborhood of 65K miles on it, and I've put on another 50-60K or so since then. I'll have to take a look at the paperwork I have and see if my memory is correct.

The engine gets oil changes every 3000 miles with Mobil-1 and a new filter.

I don't know what piston slap sounds like, but I do know it's a well-known problem with these engines. Maybe the engine is not a 940 Turbo one?

In any case, if the only remedy is a new engine and the only problem is an increasing length of the noise as the engine slowly slaps itself to pieces, I might live with it until it does die.

At this point, the car isn't really in good enough shape to justify putting a "new" old engine into it to keep it going when this one chuffs. The car would then need a whole suspension going over, wiring, seat controllers, sunroof work, power steering pump, etc., etc. There are lots of other annoying things happening with the car but it's served me well as my daily driver and work truck.

How long do I have before it grenades, given the sound of the knock, in your opinion?

Thanks for your advice,

Anthony

Mines had noticable piston slap for a few years now. It did get worse after the engine overheated when the thermostat broke and it stuck closed but it's really just annoying when cold first thing in the morning. Not much oil usage either. It's a short 5 mile drive to work so I'll just keep plugging along.

IMHO that is how they sound. Serious knocks get louder as your oil thins out. A loosely built turbo Volvo gets quieter as the parts expand as they warm.

Be warned!!! You probably only have about 200k left in that engine.
--
'96 855R,'64 PV544 driver, '67 P1800 basket case, '95 855, '95 854, the first three are mine, heh, heh, 485,000 miles put on 9 bricks

It sounds like the pistons might be starting to slap a little. That happens as engines get old. Rings wear down. As long as you baby it, it should go awhile longer.