Loud squeal from engine (325i)

[Rtaylor2208]

On the way back from the Scottish meet the cabby decided to be a pain in the arse and occasionally would miss fire. Revs did not drop to nothing.

Car stalled about 2 miles from home and on startup this loud high pitch whine / squeal started from the engine bay. Appears to be comming from around the rocker, inlet or injectors.

Power does not seem to be down, oil level is fine, no signs of any overheating or mixing of oil and coolant.

Has Anyone had similar and can point me in the direction of where to check.

[Rtaylor2208]

The noise gets higher pitched depending on revs as well and when stopping the engine the pitch gets lower as the engine spins down.

[jonny323i]

Have you had the rocker cover off it could be starved of oil up top

[jonny323i]

Have you had the rocker cover off it could be starved of oil up top

[Rtaylor2208]

Rocker was off recently to be painted, but since then its had a new gasket, a full oil change, new filter and injectors refurbished.

[jonny323i]

I think id still have it off to be sure

[Rtaylor2208]

I take your thinking the oil spray bar might be clogged up or possibly oil pump?

Any tell tale signs of oil starvation to look for?

[jonny323i]

Loud sqealing lol worn lobes on the cam and a very dry looking head

[jonny323i]

Loud sqealing lol worn lobes on the cam and a very dry looking head

[Z3I]

Fan belt slipping? Hope so!

[Topblag]

Fingers crossed it's something simple.

Give it a hand crank and see if it's turning freely.

[Rav335uk]

Fan belt slipping? Hope so!

This, especially if it's changing pitch with engine speed.

[gooner1]

Fan belt slipping? Hope so!

This, especially if it's changing pitch with engine speed.

Wouldn't the Battery light indicate this?

[Rtaylor2208]

Doesn't sound like the sound a slipping belt makes. Plus checked all the belts and there nice and tight. It'll need to wait till tomorrow now for further diagnosis.

Bloody typical considering what I have spent recently on the engine.

[jonny323i]

A mate of mine had a fiat Brava and popped round to ask if his cambelt was slipping.
Turned out the garage had been using too thick an oil completely blocked the head and had worn a groove all the way round the cam nearly sliced my finger off

[jonny323i]

A mate of mine had a fiat Brava and popped round to ask if his cambelt was slipping.
Turned out the garage had been using too thick an oil completely blocked the head and had worn a groove all the way round the cam nearly sliced my finger off

[Rav335uk]

Fan belt slipping? Hope so!

This, especially if it's changing pitch with engine speed.

Wouldn't the Battery light indicate this?

Possibly, but it could also be the P/S pump belt too.

[Brianmoooore]

Are you certain the rocker shaft locking plate was in position when the rocker cover was replaced?

[Rtaylor2208]

Are you certain the rocker shaft locking plate was in position when the rocker cover was replaced?

Brain that would be a no, as I have no idea what that is, could you help explain please?

Also been back out, took the rocker cover off and everything is oily to the touch, and oil visible in the recesses between the rockers.

I think I found the source of the occasional misfire but have not had a chance to test drive the car yet. The CPS cable running behind the pulleys had escaped the clips, cable is slightly worn, so tapped for the moment and a cable tie added to hold it out the way.

Strangely enough the squeal has gone and its back to business as usual with noisy tappets like its always had.

A little concerned that it will come back but ill not know till I can get it back out for a good blast to get it nice and hot.

[Brianmoooore]

The little plate, #6 here: http://bmwfans.info/parts/catalog/E30/T ... cam_shaft/ , sits in a recess at the front of the cylinder head and slots into grooves in the rocker shafts, keeping them in place and preventing them from turning. This is important, since all of the oil for the top end enters the exhaust rocker shaft through a hole lined up with a drilled hole in one of the supports cast into the head, and is distributed from the exhaust shaft to the spray bar and the inlet rocker shaft. If the exhaust shaft turns, all the top end lubrication is cut off.
This small plate is kept in place by the rocker cover on top of it, although, TBH, it's very unlikely to have come out if all you did was remove the cover and replace it.

[Rtaylor2208]

Thanks Brian, yes all that was done was removal, new gasket and refit. But ill check this tomorrow to make sure its setup correctly.

[B7]

Water pump!

When they start to seize, the squeal horribly. But worse when the engine gets hot. I've heard 2 or 3 like this. Remove the drive belts and fan clutch assembly and turn the pump by hand. I bet it's very stiff / graunchy.

Remember when changing it, a new belt and tensioner is a good idea if it's not been done recently. While it's all apart, makes no sense at all not to.

[Rtaylor2208]

Water pump, belt, tensioner, tensioner pin and spring were just replaced I've only done about 200 miles since.

I hope that's not what it is but from what you described it could well be.