Help me diagnose my troubles, suspect it's timing chain related.

[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.

Today 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 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? How can I find out if this happen? Would I be able to tell just by taking the valve cover off?

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.

[DesktopDave]

It's possible for the car to idle with timing chain & valve damage.  It'd sound really bad, very rough running & idle.  It'd likely be running two cylinders, depending on how far it jumped time.

I think you've caught in in time, just be sure it's the chain before you tear it all apart.  Can't hurt of course, it's just expensive in terms of time & money.

[VegasKyle]

It's possible for the car to idle with timing chain & valve damage.  It'd sound really bad, very rough running & idle.  It'd likely be running two cylinders, depending on how far it jumped time.

I think you've caught in in time, just be sure it's the chain before you tear it all apart.  Can't hurt of course, it's just expensive in terms of time & money.

It sounds bad but the idle is smooth at 700 RPM.  Will I be able to figure out the source of the problem by just taking the valve cover off? Or do I need to take it apart further than that?

[Petebee]

Based on the amount of junk in the photos in your other post I would not try to start the car again. I think you dodged a bullet getting the car home...no need to push things.

Remove the cam cover...at least you'll get a better idea of what is going on, but you won't really be able to assess the guides until you remove the upper and lower timing case.

[DesktopDave]

That idler gear that we're suspecting is buried on the front passenger side of the block.  You'll have to remove the belt(s), crank pulley & front covers to see it.  Number 11:
http://www.realoem.com/bmw/showparts.do?model=AJ93&mospid=47318&btnr=11_4367&hg=11&fg=25

[VegasKyle]

Based on the amount of junk in the photos in your other post I would not try to start the car again. I think you dodged a bullet getting the car home...no need to push things.

Remove the cam cover...at least you'll get a better idea of what is going on, but you won't really be able to assess the guides until you remove the upper and lower timing case.

Will I be able to see if it jumped time?  I know the guides need to be replaced.  Like I said I just don't want to go through the time and expense of replacing the timing components just to find out the valves are bent.

[B318M42W]

if you don't want to take anything apart/off, start with a compression test. here's my theory: if valves are bent, it won't be able to build up the same pressure as unbent valves, therefore significantly lower compression. However, low compression can be also caused by a few other things (worn rings, cracked head, blown head gasket...) either way, this could help you decide if it's worth it tospend time/money on the engine.

[VegasKyle]

Ok.  I had a chance to take the valve cover off today.  The teeth on the cam gears were not sharp at all.  They look like pictures of what others call "good shape".  From what I could tell the timing looked to be good.  The lobes of the cams furthest from the front of the engine looked to be pointing at each other.  The arrows on the sprockets also looked to be pointing in the same direction also, the bolts that held on the cam gears looked to be centered in the holes. Here are some pictures of what I found.

The rear lobes of the cams

Pic of the teeth.

One more close up.

From the top.

I took more pictures and can easily take the cover off again if there is something I'm missing that could help diagnose the problem.  

Is it possible that the sprockets could look this good and the guides be so bad that they are causing the problem?  Or could the problem be unrelated to the chain guides?

[Petebee]

Based on the plastic and metal chunks in the pan from your other post I'd still vote that the guides (and possibly chain) are degrading. Someone could have replaced the cam gears and not replaced those items. If I were you I would tear down the front of the engine based on the noises you are having.

Good news is that your cam gears are in decent shape.

[VegasKyle]

Based on the plastic and metal chunks in the pan from your other post I'd still vote that the guides (and possibly chain) are degrading. Someone could have replaced the cam gears and not replaced those items. If I were you I would tear down the front of the engine based on the noises you are having.

Good news is that your cam gears are in decent shape.

Should I keep the cam gears and replace everything else? I always thought if u replaced the chain everything else was to be replaced too.

Do you still think this is the cause of the problem? What else could cause what I was talking about?

I don't think the cam gears were ever replaced. The car was dealer maintained for most of it's life, I have most or all of the receipts.

[Petebee]

No need to replace those gears. Get new guides, tensioner, new chain along with all of the gaskets. How old are the thermostat and water pump? Might as well replace those since they have to be pulled to get at the guides/chain.

[DesktopDave]

That is odd that you have perfect cam gears and you're getting cam chain noise.  I'd be really sure that the noise is coming from the chain before tearing it all down...that's a lot of work and money.

OTOH, if you do replace a bad tensioner or idler gear it'll save the valves & head.

There is one other option before you tear it all down.  I've heard that you can request a complete service history of your car from your local dealer.  Grab your title or registration (BMW NA told me that they require proof of ownership), get to your local dealer's service department & ask them nicely if they'll give you the mechanical history.  They'd likely have the list of parts replaced on that job, depending on how thorough the mech was that day.  You could see if the guides, idler or tensioner was replaced before you tear it all down.  IMHO, it'd be nice to have a secondary source of info about how your car was maintained.

[monko141]

First you need an e36 Bentley manual.  It has the m42 in it.
To find out if you are still in time manually spin the motor until both arrows on the cam sprockets point up.  Next remove the spark plug in the #1 cylinder and stick a long screwdriver in the hole.  Manually turn the motor back and forth till you see the screwdriver reach its peak.  If the arrows are still pointing upwards then you are still in time.  Do a compression check and see what kind of numbers you get.
Looking at your cam gears, I doubt that you need to replace the crankshaft gear.  But from your pictures I don't think I would trust the Idler gear.  It's inner workings are plastic and since your engine has been hot enough to turn engine oil black, I wouldn't trust it.

[VegasKyle]

That is odd that you have perfect cam gears and you're getting cam chain noise.  I'd be really sure that the noise is coming from the chain before tearing it all down...that's a lot of work and money.

I don't know what else it could be.  I fear I've been so worried about the timing chain I may be over looking something else.  The only thing I know for sure is there were pieces of plastic chain guide in the lower pan.  The engine was making a sound similar to what others have described in the 2300-2800 RPM range.  Now that sound has intensified 100 times and can be heard through the whole rev range.  That's all I know for sure, everything else is speculation.

I don't know what else I can do to pin point the problem without taking off the timing case.  What parts should I get?  I was originally going to order everything.  Now I'm thinking; Idler gear, all 4 guides, tensioner and all gaskets. What about the chain and crank sprocket? I figure the chain should be kept with the sprockets and the crank sprocket should be good if the cam gears look like they do.

I'll go to the dealer and see if I can get the maintenance history that way.

[nickmpower]

it might just be the picture, but it looks like one of your cams jumped several teeth. The squares on the back of the cams are supposed to be aligned with each other aka at the same angle as each other. If this is the case I would just look into picking up a used engine. It could just be the pics though, check the squares