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help!! Loud engine knocking noise... :(

Started by Ryan1980, 07 December 2008, 03:55 AM

Ryan1980

Hey guys,
Was just driving my 450SE and Suddenly the engine is running a little rough and making a very loud knocking noise...
What on earth could this be? It sounds serious, like perhaps its coming from the head?
Is this the end for my engine? :(

I did have a problem with a similar noise 6 months or so ago, not as loud, and it turned out that the LPG mixtures werent quite correct . But this is much louder and it was running fine seconds earlier...

Doesnt sound good does it :(

Here's a video..

http://hk.youtube.com/watch?v=JdS95wbH8FE

Ryan

WGB

Doesn't sound good.

Four engines from my past that made that noise and were broken
1) A95 pushed a ring up the side of a piston and caught pieces between the piston top and the head.
2) Dropped a valve in a Chev.
3) Ran a white metal big end bearing in a 1938 DX Vauxhall
4) Split a crankshaft in a Chev.

I would add another possible for a 450 V8 motor and that is that a timing chain may have jumped a tooth or two and the pistons and valves are only lightly "kissing".

What's the oil pressure like when running?

Suggest you check if there is anything metallic in the oil, remove the plugs and see what they look like, remove the RH camcover and check the valve timing and then do a compression test.

Lots of luck.

Bill

koan

Doesn't sound "meaty" enough for bottom end problems. sounds more like valve gear, No change when you took the oil filler cap off, try removing the breather hose on the other bank, see if the noise is in there - if you're game to run it again that is.

Or remove the rocker covers and have a look.

Maybe remove drive belts, see if the noise is coming from alternator, water pump or PS pump. A/C too if on.

Don't over look the obvious, a stick in the fan or a stone jammed in a pulley, such things make a lot of noise but don't cause rough running.

koan


Boogity, Boogity, Boogity, Amen!

13B

I reckon the chain has jumped a tooth.  My red 450SE did the same thing back in 1995 when i was just getting into these cars, made the same sound and I didn't drive it or put it under load.  Silly me didn't find out what they did to fix it at the time but I think they mentioned new timing chain and plastic rails ... oh yeah i did notice one of mine  (inner rail, closest to piston #5) was broken.

Refer to WGB's informative timing chain replacement post to do a check on the timing of the two camshafts.

If it hasn't been put under load in this state, a new chain and plastic rails and chain tensioner will probably fix the problem.

Just to get you started; you need to remove both your cam covers, all your spark plugs, and turn the engine to TDC.  Are the markers anywhere near the timing markers on the cam towers?  If not, turn the engine another 360 degrees and they should be there, then post pictures of the two cam markers and the timing marker on the front pulley and we'll be able to advise.

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

BAR

Loud noises from under the covers are always terrifying and terrifyingly expensive.

If it sounds like a little guy is inside there hammering away at a tempo the ratio equivalent to the engine revs, then it's likely that you have a frozen valve lifter.  Being hydraulic they can clog up and freeze.  Thus the valve rocker is knocking against the lifter.  This isn't so much to fix and usually just a lifeter needs replacing, if it's gone too far then the rocker should be replaced as well due to extraordinary wear.

If the timing chain has jumped a tooth, the chances are that one or more valves have bent.

If you try to drive the car, does it have reduced power - if yes, then look to chain and bent valves.

If it goes OK but makes lots of noise, then look to sticky lifters.

Ryan1980

Im tossing up on whether to have the car towed somewhere, perhaps the star shop in osborne park... and let them have a look at it (as im no expert) or pulling the rocker rovers off and having a look myself. If i posted pictures on here would you guys be able to help diagnose the problem?

In any case The star shop says its usually around $900 to replace the chain, guides and tensioners.
Sound reasonable?

I read bill's thread on replacing the timing chain, i just want to be sure what the problem is before decide whether to replace things or not!

BAR

Always a good idea to get the best adcive available.

$900 sounds 'on the money' for the chain job.

Hydraulic lifters should be around $70 each plus labour etc.

At least you'll have a professional opinion on the car and have it running well.

13B

Ryan's is a D-jet engine, so no hydraulic lifters on that engine.  That was on the K-jet and later engines.

$900 sounds pretty good, esp. if that includes the chain tensioner (its important and costs about $200). 

Cover's off there's probably not much to see except to inspect the 3 guides and surface of the tensioner rail, you can also look inside the cam cover where the chain runs and see if there are any gouge marks where the chain is slapping against the cam cover.

By turning the engine to TDC and observing where the markers are on the cams, you can determine a) whether its jumped a tooth or not, and b) how much chain stretch there is.

To me it seems unlikely but maybe a failed or seized chain tensioner (it sticks out the side of the engine, behind the alternator) causes the chain to flop about and thats whats making the noise.  If so they are cheap and easy to replace (1hr job).

Ian.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

s class

I agree with the advise so far.  I'm concerned that the engine is 'rocking' from one or more cylinders not running.  This could be due to bent valves.  In addition to checking the cam timing, you do need to do a compression test. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

s class

Another idea - judging by the amount of noise, it sounds like the oil pump may have given in. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

WGB

Quote from: Ryan1980 on 08 December 2008, 12:01 AM
Im tossing up on whether to have the car towed somewhere, perhaps the star shop in osborne park... and let them have a look at it (as im no expert) or pulling the rocker rovers off and having a look myself. If i posted pictures on here would you guys be able to help diagnose the problem?

In any case The star shop says its usually around $900 to replace the chain, guides and tensioners.
Sound reasonable?

I read bill's thread on replacing the timing chain, i just want to be sure what the problem is before decide whether to replace things or not!

It's not hard to pull off the rocker covers yourself and check the timing marks and to do a compression test but Herbert at "The Star Shop" will know exactly what it is and will have a scope to let him look into the engine if there are suspect valves etc.

A 450 chain job is about $400 to $500 in parts with a new tensioner so his quote sounds quite reasonable.

I wouldn't try starting the engine again until someone has checked it.

Bill

TJ 450

That sounds terrifying alright.

I would be getting it towed to The Starshop for an inspection, don't start it again.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Ryan1980

I started it for a second just to check if there was oil pressure - and there is.

I took the cam cover's off and thought i'd found the problem - one of the plastic slider's on the RHS was broken! Half of it had slidden down into where the timing chain goes. I managed to get it out with a screwdriver. I was hopeful that was all that was making the noise! However, upon starting the car, the noise is still there. I assume it's skipped a tooth.

Im not sure how to check if it's skipped a tooth... I read in your writeup bill about checking for timing chain stretch. Is it just a matter of turning the engine until the rhs cam timing mark ( I can only see 1) lines up with a link in the chain?

Anyways ill post some pictures. The chain and plastic slider's look new to me... which doesnt suprise me as the previous owner told me he  had the head rebuilt and chain replaced. Guess ive just been unlucky?

http://i246.photobucket.com/albums/gg105/Ryan1980_photos/LHSChain.jpg
http://i246.photobucket.com/albums/gg105/Ryan1980_photos/RHSchain2.jpg
http://i246.photobucket.com/albums/gg105/Ryan1980_photos/guide-1.jpg
http://i246.photobucket.com/albums/gg105/Ryan1980_photos/lhschain2.jpg
http://i246.photobucket.com/albums/gg105/Ryan1980_photos/RHSchain.jpg

TJ 450

#13
That will be the problem. That's exactly the piece that broke off on my 450, although I think it may have got caught in the chain/sprocket on your car, so whetever you do don't start it until this is fixed.

BTW, you have a very clean engine !

Tim

P.S. Here it is...
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Ryan1980

So im guessing the process of fixing this problem is the same as replacing the chain anyway?

I might as well just have the chain replaced.