Engine probs

TBirdUK

TBirdUK

TBirdUK

Soldato
Joined
9 Jul 2005
Posts
2,650
Location
High Wycombe
Got a bmw 520i, every time I start it when cold I get a rattle/severe vigration coming from the engine - but only when cold and as it goes 1500-2000 revs. Cant take it to a garage cse after about 2 miles it stops and doesnt happen again (due to some heat storage in the engine) for hours!

Anyone got any ideas - doesnt loose power, just his very noisy rattle (rapid)

Cheers
 
Thanks for the reply, i dont think its the tappets (and they are hydraulic), much more of a harsh noise than that, coming from near the frount of the engine - thought it could be the viscous bearing in the fan but that doesnt seem to be worn either.
 
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get a screwdriver and put your ear to the handle and put it on the block, cylinder head etc until you can find out where it is and that at least narrows the problem down. you will need to someone to blip the throttle a bit though.

once you find out top or bottom, find out left or right and if its even inside the engine...

might be something else as your description is pretty vague.

does the car do it stationary or only when pulling off?
 
My Focus does exactly the same, I have been told it's piston slap, others said it was a Ford :p :D .
 
Does it when stationary, in N or P but as I am on my own its hard to check. Does it mainly when driving around the 2000revs mark, just till its warm. If I start it and let it idle for a few mins it doesnt do it - and then as I say, have to wait a good few hours before its cold enough to do it again - could it be a water pump on the way out?
 
lubeless pistons, or a more professional explanation would be,
The noise called piston slap is caused by one or more pistons having too much clearance between its side skirt and the cylinder walls. In effect, the pistons become too small and wobble in the cylinder bores. It can be cause by an engine simply wearing out (not common any more), a piston seizing because of a lack of lubrication (it runs out of oil) or it's put together wrong.
Click to expand...

Hope this helps mate.
 
jeez, sounds terminal, any idea how to get it sorted - seems like it may need a strip down and a new piston - now thats an expense that I cant do at the moment - hope I didnt buy a lemon, as it only has 83000 on the clock I thought it would be ok!
 
if I take it to a garage and leave it there would it be easy to diaganose - I have one of these warranty things which covers breakdown of major mechanical parts but I am unsure whether this would be covered - if a garage can say the piston is knackered then it may be covered (but the warranty will only cover upto £500, will that be enough?)
 
Well, took it to a BMW specialist - not a dealer but good reputation etc. Found a split pipe - thought great - cheap fix but no - still did it! they then looked deeper and said it probably wasnt piston slap, possibly could be the hydralic tappetts not getting oil when cold but they said it sounded expensive and they couldnt diagnose it fully as they were just doing it as a favour (too busy at the time to take her in)- suggested I take it to main dealer who may have heard that kind of sound before or had one of the really expensive computers that may say something- they hadnt heard an engine make that sound before so were a bit stumped!

not having much luck with this! :(
 
It's probably piston slap, but it's worth making sure it's not something more serious like a big end, you can damage your crank very quickly running on a worn big end.
 
Try turning the air con off before you start the car.

I say this as my old mans e39 made a nasty rattling sound when starting from cold, turned out to be the aircon compressor, nothing to do with the engine at all.
 
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Could be a crack in the manifold. You say it dissapears over certain RPM and completely when hot and not returning until very cold? That sounds like a crack in the manifold to me?
 
Rattles and noises such as this could be almost anything - you would be mental to read this thread and go away thinking "Oh well, I have piston slap and it's new engine time"

Get a proper mechanic to have a proper listen to it.
 
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