timing chain
 

Hi guys, I mechanic just told be the timing chain jump. Can this damage the valve or can the chain be adjusted? Help

The timing chain jumping is def not good. There are tensioners to prevent this. How exactly does he know it jumped?

Is this a BMW dealer? I'd ask for another opinion if not. A timing chain jumping is a serious (and rare) problem.

No, This is a guy claiming he is a expert in working on BMW! Also, the dealer said this is a rare event but they want to break the head down. They are starting with a quote of 2,500. The error the guy had on his OBII was The Blank cam B have over retarded it position and there is no compressor on one off the heads.

Thanks,

What is the car doing badly that made you bring it into a mechanic in the first place? What are the symptoms?

Ouch! No compression means bent valves too! What year and what mileage? 4.4 liter?

I have 60K and 3.0 liter.. I changed the valve cover gaskets that is it but the car internal condition of the motor was bad. A lot of oil built up on the cover and inside the engine.

The mechanic must have checked the camshaft sprocket and flywheel timing marks and found that they were not matching!
The timimg chain "jumping " a tooth on the sprocket gets your timing all wrong and your valves will be touching your pistons and bend!They need to open up that cylinder head and check all damage.As well as the valves,You may also have damaged pistons,rings and your block cylinder wall may be scratched!
This is a major engine job!You will only know the total damage by removing the head.

Is it possible that no valve or head is scratched? Are you give the worst case?

In regard to your sludge build in the valve cover and head, I'm curious to know what oil you've been using and what your oil change intervals have been.

Also, do you know which cylinders on that bank don't have compression, or is it just all of them?

The only way he's going to have bottom end (cyl wall, piston) damage is if he dropped a valve. That almost never happens. Even in manual trans cars that overreved, I've only seen a few cases where a valve dropped. I'd bet money that he just bent some exhaust valves.

It is possible that only a valve is bent if you have lost compression in one cylinder. However, your chain tensioner or something else must have failed to cause the chain jump. So best case is one bent valve and a failed chain tensioner. Make sure your mechanic is honest and capable. Good luck.

I am giving you the worst scenario because you say you have no compression on that cyl.head.This why they must open it up to check for loss of compression.

Hi vin,Love your signature by btw.

I agree with you!Very rare a valve drops!But I have seen cases where detonation inside the combustion chamber will make a hole in the piston or chip the sidewall and damage segments and scratch the head.I have a pisto here that I took off a VW Tdi and it melted!Dont know how?

Thanks :) .

There's no way that the chain skipping a tooth could've caused detonation though. The only way you can detonate is if you have too much air and not enough fuel. That wouldn't have have been possible at all. If anything, there might have been too much fuel and not enough air. The fuel injection timing would've still been accurate in relation to crank position. The only possible way, I can think of the valve dropping is if intake had opened at TDC of compression stroke; the chain would've have had to have skipped a LOT for that to happen; it's just very unlikely.

I mentioned detonation not because of chain jumping ,obviously,only as a guess for the lack of compression.
If you read again Xan's post#7 ,he mentions that they changed a gasket because there was oil everywhere(difficult to understand where exacly!).Could it be that Xan somehow lost oil pressure prior to the chain jumping?Now ,we both know that the chain tensioner works with oil pressure!Low oil pressure=chain jumping!This reminds me of a case we had here on a 180,000kms Bmw M3-E36 which also jumped a tooth!We traced this problem to a badly bleeded chain tensioner done by the dealer a few miles back!

Only had the car for 3 months, I bought the car for a local dealer car AutoMax. Do you think this is a lemon law case? The dealer had to know the condition of the the car engineer. I will have the engine taken apart next week.

Hi Xan,
What year is your X?How many previous owners?
What gasket exactly did you change?Was it the head gasket?Where was all the oil coming from?

Looks like its time you did some research on the history of the car and try to get that 60k mileage confirmed!

Maybe the engine had been opened before!

2002, I do not know how many owner. Valve cover. How can I get a car history report on this car?

i've only heard of one case where the guy didn't have internal damage after a timning belt break(on a nissan 300zx) other than that...its a very high chance something is bent/broke :(

Have your chassis number ckecked at BMW dealer to see of they have it on record, services and maintenance carried out at the dealers.

Xan,
Any developments on your problem?We are all eager to know!Keep us posted!

Hi Guys, I found out piston #1 is not holding any oil. He is claiming I need a new motor. Is it possible the piston to be bad? Do he need to take off the valve head and check the piston and the cylinder wall? I was told that you can have a cylinder wall welded and the piston replace. Any ideas? Also I found out FEMA reported the car to be sold out of a flood zone in La. I do not know by Texas law a dealer should tell you about this history on the car. He bought the car from an auction out of La.

You have to more specific!When you say that piston#1 doesnt hold oil,do you mean that they carried out a test by putting oil on top of thye piston and the oil disappeared?

You dont need a new motor because one cylinder is leaking!You just fix the damage!

Yes, He put oil in the top of the pistion and the oil disappeared. He did not say if the cylinder was crack. I told him to remove the head check for the block to be crack or the piston is have leak. I will have more new tomorrow. This guy is charging $450 to disassembly the head.