m52 start up rattle

[james318i]

hi all , my 323 e36 has a rattle on start up with soon clears but is there all the same , id imagine its the hydraulic lifters ? its done 120k now so i should think there a bit gummed up as the guy i got it off never serviced the poor thing

is it a case of just replace them or does this engine flush stuff (forte ive been reccommended) actually work as well as ive been told ?

[uzdubmwe30]

Could possibly be chain tensioner dude.

And forte is very good stuff.

[james318i]

hmm possibly

excuse my ignorance as i may well be wrong as im a motorbike mechanic not a car mechanic

on a bike if the tensioner is tired it generally rattles when not under load either hot/cold or whatever , they work on a sliding ratchet mechanism and the teeth wear on the ratchet part , no idea how the cam chain tensioner is set up on a bmw

my car rattles for maybe 3 seconds on start up from cold in the morning , then its super quiet , when i come out of work it may do it again but not often , never had hydraulic tappets out but id imagine they drain of oil when not in use and mine are taking a while to fill up causing the rattle or am i way off the mark ?

[uzdubmwe30]

The tensioner is hydraulic chap, just a piston that pushes up against the chain guide. If it's worn when the oil is cold and not upto pressure the tensioner will not be fully out and will cause the chain to rattle about but normally when took over 2500 rpm oil pressure builds up and releases the tensioner making it quiet.

It may well be the tappets as they are oil filled but bare in mind that if your changing tappets you should change camshafts, rockers (if fitted) and thrust pads (if fitted)

What oil grade and make are you using?

[E30BeemerLad]

could be the vanos unit, i believe that they can give a bit of a rattle on start up until the oil gets there. So long as it stops soon after I believe they are alright.

[james318i]

ah right , didnt realise there hydraulic

think the oil is semi synth 10w40 from memory

[james318i]

vanos ? all new to me lol

yeh stops about 2-3 secs after start up and then its nice and quiet

[E30BeemerLad]

I'm assuming all M52 engines have Vanos, pretty sure they do.

When looking at the engine, at the very front of it on the top where the cam cover is, there is the timing chain cover, does it have a bulge on the front of it?

[DanThe]

You dont need to replace the cams when changing lifters, chain tensioner parts are cheap and a lot easier to replace than the hydraulic lifters, I would start with some engine flush, diesel oil is supposed to be good for cleaning

[james318i]

il give it a go and let you know how i get on

im looking to sell it but i want it to be right for the next owner - then im after another e30 as ive been paid out for the last 1 i had which got hit in the side

[78dude]

It can also be so simple as have you checked the oil level on the engine?
If an engine runns on very little oil, it will sound like an old diesel the first seconds when you start it up from cold because there is no oil at all for the head of the engine.

[Ant]

pop a new oil pump on there dude

M50/52 to seem to like a pump @ those miles

a good flush and new pump seem logical and wont break the bank.

[uzdubmwe30]

You dont need to replace the cams when changing lifters, chain tensioner parts are cheap and a lot easier to replace than the hydraulic lifters, I would start with some engine flush, diesel oil is supposed to be good for cleaning

Considering that this engine has done 120,000 miles without being serviced I'd say that the cams are worn and probably micro pitted on the profiles, and with them touching the hydraulic tappets every time tdc and bdc occurs I would recommend that if your going to change the tappets change the cams also.

You rev an engine upto 6000 rpm the cams are spinning at half the speed but still taking a fair bit of shunt.

[DanThe]

Well, if you are going to change the cams a new pair of carriers are very necessary, got a spare £1k+ to throw at it James?

[stonesie]

uzdubmwe30.... Camshaft's turn at half the crankshaft Rpm.


I would get the oil pressure checked to see if the pump is ok and run it for a thousand miles on 10/40 oil ment for a Diesel engine, its got a lot more detergent than oil for petrol engines so will do the same as an engine flush but more gently, so no big lumps floating about the oil system.

[Andyboy]

Don't get involved. Run some oil flush through it, do an oil change and leave it at that. Changing the lifters on an M52 is a lot of very, very expensive ballache. £250 for the lifters plus a BMW tool to lock the vanos units etc. If it dies away after a couple of seconds, forget it. Sometimes they rattle away for a few minutes before finally pumping up.

Diesel oil is indeed very good for cleaning out engines as it has very strong detergent. Perhaps do an oil change and change it again after 2-300 miles?

[bmwbreaker]

this is a very common thing on an M50 or M52 engine. I dismantle and repair E36 BMW's for a living and they all do this. Its nothing to be worried about at all.

Its normally caused by the oil naturally leaving the top of the engine which in turn leaves the top of the engine dry of oil. Normally upon start up this rattle will settle down after 2 - 4 seconds and then be perfectly fine. In that time the pump starts, gets up to pressure and sends the oil back to the head.

[uzdubmwe30]

uzdubmwe30.... Camshaft's turn at half the crankshaft Rpm.


I would get the oil pressure checked to see if the pump is ok and run it for a thousand miles on 10/40 oil ment for a Diesel engine, its got a lot more detergent than oil for petrol engines so will do the same as an engine flush but more gently, so no big lumps floating about the oil system.

I know Stonsie! wrote that quick, typo edited for all,

Do agree with what your saying about diesel oil, ive heard good stories about slick 50 treatments also.

[james318i]

cheers for all the advice guys , much appreciated !