W463 GD300 - My engine has an intense rattle sound
I know old Mercedes normally is a noisy engine with a rattling sound. But, my engine has a intense sound, more than normal.
It is worst when idling, but almost disappear when the engine is running on low RPM with some resistance.
I think the engine has suffered from poor maintenance, and e.g. valve clearance has probably not been adjusted for a long long time. Could this be the reason?
Could the injection nozzles cause it?
The engine runs fine, but sometimes, after a cold start it runs on only 3 cylinders, and sometimes die after 5 second, after starting it again, it runs fine.
Any suggestions to make it run smoother?
Check on your engine oil level initially; check and replenish as necessary.
Make sure you use 15W/40 oil. If still rattling at idle, most probably it is the hydraulic valves (self adjusting), these can be replaced or I did see a utube clip showing it could be dismantled and cleaned up but fiddly work.
Other than that, it could be worn timing chain or slack chain tensioner but tensioners are usually very good on M/B engines.
Yes, the OM-603 has hydraulic tappets. I think they are the noise you are hearing. If your engine has suffered from poor maintenance, then I suggest you flush your engine with a detergent oil and then refill with a good quality oil. Run with premium diesel, such as shell V-Power diesel, for a while, which is a cleaner diesel with detergents. This will help clean your pump and injectors.
Thanks for info!
Can I drain the oil, fill the oilsump with diesel and run the engine with diesel for lubrication for a minute to clean the engine? Or will this damage anything in my engine?
I use to do this with older diesel engines to clean them out before refilling new oil.
Any opinions?
seems like a reasonable thing to do for a minute or two, but I've never tried that.
I have now drained oil, filled with diesel for cleaning, drained and new oil. Also changed the diesel filter and oil filter. But the rattling sound is still the same..
Seems I also have a lot of smoke. White-blue.ish... I am starting to think there might be something seriously wrong, like worn out crankshaft bearing or something...
The engine has clocked 318 000km..
Sticky tappets will sound like metallic regular clicking . If the sound is very loud and irregular, it may be something else. Blue smoke could be from oil ingress into the cylinder, either through the piston rings or valve stem seals. Probably will need some detailed examination to determine the state of the engine.
Sticky tappets will sound like metallic regular clicking . If the sound is very loud and irregular, it may be something else. Blue smoke could be from oil ingress into the cylinder, either through the piston rings or valve stem seals. Probably will need some detailed examination to determine the state of the engine.
Arnie, White/ blueish smoke could be un burnt diesel. Maybe an injector issue and knock or if one or more valves not operating that would lead to un burnt fuel. What do you think?
I would have the injectors checked. A bad injector will cause a horrible sound.
Yes, bad combustion with a diesel could cause vibration and noises. That reminds me: check your engine and gearbox mounts - very important on these engines.
As for smoke, I guess unburnt diesel might cause this, but that is usually black smoke. White smoke might be from leaking coolant and blue-grey is usually oil.
At 300,000 km I think it might be time for an overhaul ?
I had white smoke on my 463 when the water pump was going....
It sounds like the timing chain tensioner needs attention. The rattling noise will stop once lube oil pressure builds up and the tensioner will pull the chain away from the guide. Do you have enough oil in the sump and does the oil pressure go to 3 bar ? It also sounds like you may have sticky fuel injectors resulting to poor combustion. Perhaps you may try running the engine with the diesel fuel mixed 50:1 with 2 stroke oil. You will find that the engine will run smoother and the insjection rattling will quiet down. Failing this, it will be about time to have the pump and injectors overhauled by a competent service center. 300k kms on a Mercedes diesel is not unusual, most taxis in Europe clock over a million kms on these type of engines.
did you get the head checked too, mine went together, water pump and head gasket at the same time
did you get the head checked too, mine went together, water pump and head gasket at the same time
Snap 
I have heard of a few going off at about 150k which was mines mileage when it happened
did you get the head checked too, mine went together, water pump and head gasket at the same time
Isn't this always bound to happen - if the water pump fails (and you don't realise quickly enough) then the engine temp goes off the scale and as a result the head gasket goes.
Or is this me being simplistic as usual?
Is it just me? Does anyone else see the irony of running an engine with diesel in it instead of oil and wondering why it rattles.
Just a thought
Can you post a video of the engine rattling so we can hear the rattle and have some idea what we're listening for
Gordon
Gordon,
I've been wondering about this as I've never heard of flushing the lube oil system with diesel and running the engine albeit for a couple of minutes. For a start the time is is not sufficient to remove any sludge and secondly, the lubricity of the diesel is not sufficient to protect the bearings. I do however know that it is possible to flush the lube oil system with light oils, but you will need an external pump for this and the right connections.
Gordon,
I've been wondering about this as I've never heard of flushing the lube oil system with diesel and running the engine albeit for a couple of minutes. For a start the time is is not sufficient to remove any sludge and secondly, the lubricity of the diesel is not sufficient to protect the bearings. I do however know that it is possible to flush the lube oil system with light oils, but you will need an external pump for this and the right connections.
That would be ok, it's a lubricant, and a viscous one at that
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Does my -91 G-glass 300GD have hydraulic valves?
I think I saw a post regarding adjustment of valve clearance for this engine...?
But I will try to replace my oil :-)