Help me diagnose my troubles, suspect timing chain related. (with Pics)

[vegaskyle]

The car is new to me. I was getting some noise from about 2300-2800 RPM that sounded like a diesel running. This is thought to be from worn out timing components. I planed to replace everything first thing.

The other day this happened.

I was about a mile away from home in 3rd gear doing about 35mph. All of a sudden the car started to make a loud buzzing sound. It sounded kind of like the "diesel noise" I was getting but much, much louder almost like the chain itself is slapping around inside. It sounds like it is coming from the timing case and you can hear it at any RPM. The noise isn't constant, it changes with the RPMs. The car still idles fine but you can hear the noise. I looked through the oil fill hole and you can see the timing chain is still in place.

My guess is one of the guides completely gave out or something similar happen with the tensioner. If this is the case and I can just replace the timing components, great.

My worry is that the chain jumped time and caused damage to the valves, pistons, and cylinders. Is this possible? Would the car still hold an idle if this is the case?

I don't want to buy all the parts to do the timing chain, replace everything just to find out this it wasn't the problem or there is more damage.

Today I pulled the valve cover and this is what I saw.






I pulled the oil pan when I first bought the car and found these bits of plastic. I haven't pulled it off since the troubles the other day.





Now I don't know what to think. The sprockets look like they are in good shape. Do you think the problems are caused by bad guides or something else? If so, should I still replace everything (all guides, chain, all 4 sprockets, bolts, gaskets etc.)?

[Dj Buttchug]

you sir need some new guides. all that plastic gives it away. Im suprised you didnt have trouble earlier on

[vegaskyle]

you sir need some new guides. all that plastic gives it away. Im suprised you didnt have trouble earlier on

I just want to make sure I didn't further damage the engine. I don't want to replace the guides, idler gear, tensioner and all the gaskets only find out something else is wrong.

[blalor]

The timing chain "idler sprocket" (my term) on my M42 gave way in March; the timing chain slipped, and all of the intake valves bent. This is what mine sounded like:

http://www.flickr.com/photos/blalor/4444562224/

I ended up replacing the engine. A couple of r3v members hooked me up. :D

If it's running ok aside from the noise, you may have gotten lucky and not damaged the head. The best way to do a health-check is to do a compression or leak-down test; that'll tell you if you have any bent valves. If there's any doubt, pull the head. You'll have to disassemble the entire front of the engine, anyway, to replace all of the timing chain components and it's not that much more work to just pull the head while you're at it… Getting the head repaired was more expensive than a new engine. So are just the parts for the timing chain job (~$500), for that matter.

I sort of documented my project on Flickr; it'll at least give you some idea of what things look like.

Good luck!

[vegaskyle]

The timing chain "idler sprocket" (my term) on my M42 gave way in March; the timing chain slipped, and all of the intake valves bent. This is what mine sounded like:

http://www.flickr.com/photos/blalor/4444562224/

I ended up replacing the engine. A couple of r3v members hooked me up. :D

If it's running ok aside from the noise, you may have gotten lucky and not damaged the head. The best way to do a health-check is to do a compression or leak-down test; that'll tell you if you have any bent valves. If there's any doubt, pull the head. You'll have to disassemble the entire front of the engine, anyway, to replace all of the timing chain components and it's not that much more work to just pull the head while you're at it… Getting the head repaired was more expensive than a new engine. So are just the parts for the timing chain job (~$500), for that matter.

I sort of documented my project on Flickr; it'll at least give you some idea of what things look like.

Good luck!

Fuck! that sounds just like mine. Well maybe its time to shop for a M42, I'll keep this one for the inevitable 2.1L stroker project.

[blalor]

Sorry, man. Do that compression or leak-down test, or just go and pull the head to make sure. Let us know what you eventually find!

[3bvert]

guides
if you caught in in time your golden.
but ....... you claim that months ago you dropped the pan and found that plastic........ouch

[vegaskyle]

guides
if you caught in in time your golden.
but ....... you claim that months ago you dropped the pan and found that plastic........ouch

I bought the car while on vacation. I dropped the pan and changed all fluids then didn't drive it until i drove it home about 1500 mi.

[vegaskyle]

OK, I had time today to go borrow a compression test kit from pepboys. I think you are supposed to run the test on a warm engine but I didn't want to run the engine for obvious reasons. The test was done on a cold engine (well its about 85* and the car is in the sun) I don't know how that is going to skew the results.

Cylinder #1 (closest to the front of the car) 195psi
Cylinder #2 200psi
Cylinder #3 197psi
Cylinder #4 202psi

So from the looks of it the valves are fine. I think I read somewhere a spread of 10% was considered ok.

So the plan now is to replace all guides, and gaskets, tensioner as well as the idler gear. Do you think to be on the safe side I should replace the crank gear, cam gears and chain as well?

[KenC]

The cam gears look fine, and the crank gear rarely wears out. I'd suspect it's fine based upon the look of the cam gears.

Compression numbers are great!

I'd just pop the front timing cover off and replace the guides and get a new chain tensioner.

Make sure you have a cam lock tool for timing when you reinstall the chain.

[KenC]

Also when you put it back together, run 4qts oil and 1qt ATF. The detergents in the ATF will clean all of the gunk out of your hydraulic lifters.

[vegaskyle]

Also when you put it back together, run 4qts oil and 1qt ATF. The detergents in the ATF will clean all of the gunk out of your hydraulic lifters.

Thanks Ken!

I was just going to run an oil with lots of detergents like Penz Plat and change it every 1500mi 3 or 4 times and see how that does. The next steep would be to try something designed to get rid of the sludge but if ATF works then Ill go with that.

[KenC]

Thanks Ken!

I was just going to run an oil with lots of detergents like Penz Plat and change it every 1500mi 3 or 4 times and see how that does. The next steep would be to try something designed to get rid of the sludge but if ATF works then Ill go with that.

Either or would work. I've just usually used ATF. I ran it for a full 3k.

[blalor]

I'd replace the chain, too. It took a beating with the guides gone. It's only $61 from Rocky Mountain.

The bolt for the crank pulley is a bear to remove. I resisted it as long as I could, but I finally used a block of wood on the driver's-side frame rail, a long breaker bar on the bolt, and the starter (eek!) to whack the breaker bar into the block of wood.

I found the tool to hold the flywheel at TDC on eBay: BMW Crankshaft Timing Pin M40 M42 M50 M52 M52TU M60. You'll want that — or something similar — when replacing the chain. A pair of adjustable wrenches and vise grips should do the trick for keeping the cams locked into place; put the wrenches on the square ends of the back of the cams and they should make a nice "X", then use the vise grips to hold them in place. Found that trick on this forum. :)

[KenC]

There's a tool in the trunk tray to hold the crank at TDC. But as long as it's out of gear, you shouldn't have a problem with it moving.
The "Two wrenches and a clamp" method of holding the cams in place always makes me weary.
If you can get the chain for $60, I'd replace it. Last time I was shopping, they were over a hundred.