[0464SteveB]

Hello all,
Any clues's anyone....
Friday 2nd Dec. Stuck in traffic/roadworks idling/stationary/crawling I notice this squealing noise from engine. Thought at first it was a vehicle around me; but it was me. Then noticed plenty of white smoke from exhaust and very lumpy running (on idle). Once moving again all seemed to clear and car running perfectly. But once idle again, squeal and smoke. When stopped, checked coolant and had dropped below min.. Topped up after an hour or so, started car, still warm and again squeal and smoke. Following day was fine for a quick run around block. Took to local garage 5th Dec. they replaced the water pump (said that's where the noise was coming from plus some coolant loss) but didn't have a clue about smoke/lumpy running at idle.
Now been with BMW since 13th Dec., who also don't have a clue! Still making smoke though, lumpy and squealing.....but no coolant loss as having pressure testing it.
PS, its a 2017 M240 and 55k miles.

[TrboMike]

Sounds like you overheated. Time to do a compression test on each cyl and see if you have low pressure anywhere. I would bet you need a new headgasket and probably need the head decked for flatness (overheating=warped head). That should show up in a compression test.

[TrboMike]

Also, if the garage you went to "had no clue" what might cause white smoke from exhaust and poor running after a low coolant and bad water pump event, I'd go elsewhere.

[XutvJet]

A bad pcv valve in the valve cover is the issue. Common issue on the b58 motors. I'm rather surprised the BMW techs don't know this.

[dmaxdmax]

I agree with pcv valve...you can get just the diaphragm from ebay...and/or kit for it. Bmw would replace entire valve cover.

[SonnieW]

Originally Posted by TrboMike

Sounds like you overheated. Time to do a compression test on each cyl and see if you have low pressure anywhere. I would bet you need a new headgasket and probably need the head decked for flatness (overheating=warped head). That should show up in a compression test.

1. Squealing noise when slow down/halt.
2. Stops when out to Neutral.
3. Turning off AC doesn't always help.
4. Sound somes in 90% of the time in city drive.

Mine is a 220i I brought to workshop and consultant said it's the AC belt. After replaced, the squeling noise had been reduced drastically. Still occurs some sometimes... but rarely.

[0464SteveB]

So, took from original (no clue) garage to BMW. They had it for 5 weeks and could not resolve. (Smoke tested manifold pipes and pressure tested for coolant leaks). I took it back as they refused to acknowledge a potential PCV issue. Checked out the PCV and membrane had a split in it. Replaced but clearly not the fault as still smoking and squealing. Plus a horrible mis fire still. So back to BMW next week for them to guess away until they luck on finding the defect. Next on the agenda is to remove Cat and inspect turbo. Regarding squealing, why would it stop when you remove the oil filler cap?

[XutvJet]

Originally Posted by 0464SteveB

So, took from original (no clue) garage to BMW. They had it for 5 weeks and could not resolve. (Smoke tested manifold pipes and pressure tested for coolant leaks). I took it back as they refused to acknowledge a potential PCV issue. Checked out the PCV and membrane had a split in it. Replaced but clearly not the fault as still smoking and squealing. Plus a horrible mis fire still. So back to BMW next week for them to guess away until they luck on finding the defect. Next on the agenda is to remove Cat and inspect turbo. Regarding squealing, why would it stop when you remove the oil filler cap?

Because there is still a problem in the PCV/vacuum system. Sure sounds to me like they didn't install something correctly on the PCV repair. Hopefully they can figure it out.