Performance after cam cover change.

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zaman125d
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Performance after cam cover change.

Post by zaman125d » Mon Jul 16, 2018 11:47 am

Hi All,

New to the site, so please excuse me if I'm not following any protocol.

I'd like to pick your brains if I could. I've got a BMW f20 125d (13 plate). I just got the cam cover replaced as the previous one was leaking. I got the car back on Friday and I've noticed that the car does not pull as strong as it did in the lower gears previous to the repair. It still accelerates well, but it feels like the engine has to work a little harder to build up the speed, almost like the turbo is working across the whole rev range, instead of giving a lot of its boost at the start. Also, it seems like the lag on the turbo has increased ever so slightly too.
Overall the car drives smooth and there doesn't seem to be any obvious issues - I'm quite particular, so I've picked up on it....not sure another driver would. I called the mechanic and he's unsure to what could altered the performance.


Can anyone shine any light on what might have caused this? Or any potential solutions? Any help would be appreciated.

Thanks,
Kay

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marco_polo
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Re: Performance after cam cover change.

Post by marco_polo » Mon Jul 16, 2018 11:54 am

Why was the old cover leaking, that's pretty unusual? Is the block pressurised? Crankcase breather blocked?
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Creepy Coupe
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Re: Performance after cam cover change.

Post by Creepy Coupe » Mon Jul 16, 2018 3:53 pm

I'd have thought "the mechanic " could have thought of a few things. Diesel injector not seated correctly?. Vacuum hose. cam position sensor loose.
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edbutler
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Re: Performance after cam cover change.

Post by edbutler » Mon Jul 16, 2018 4:18 pm

What those guys said ^^

I've seen several threads now about 125d's losing low end torque. Make sure you check the vacuum lines between the solenoid pumps to the waste-gate actuators, making sure there are no kinks.

We could really do with a MAP reading for these cars through the rev range - that would really help diagnose these issues.

OK51MON
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Re: Performance after cam cover change.

Post by OK51MON » Mon Jul 16, 2018 6:40 pm

Ensure you oil temps are up before making a judgement.

It usually takes about 20 mins of driving. Until then you won't get full performance from the car.

If you try to log the car and its mapped you'll also have difficulty reading whether you have a boost leak as the MAP sensor only reads to 2.5 Bar

zaman125d
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Re: Performance after cam cover change.

Post by zaman125d » Tue Jul 17, 2018 3:19 pm

Thanks for all the replies / input, guys - appreciated.

Admittedly, most of the stuff you guys mentioned is over my head, but I can potentially go back to the mechanic and ask him if these things have been considered. His thoughts are that if something was wrong, then the issue would exhibit itself to a higher degree. He also said that if there was a fault with the car, then the stop/start functionality would not work (which it does) - basically implying, based on the work he done, something would not be out of tune...either it would would work or not.

@marco_polo Not sure. Originally it was diagnosed as just the gasket needing replacing. But when the mechanic went to carry out the job, he discovered the actual cover was leaking. The car has only done 50k so I was kind of surprised too. Few of the bmw specialists I called said the same thing....they barely came across this issue.

@Creepy Coupe If an injector was not seated correctly, would this throw up a fault? Also, with a loose cam position sensor...is there a whats the possibility I would see other issues as well, and not just the slight loss of performance - outside of the issue stated, engine is smooth as before the replacement.

Thanks,
Kay

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Re: Performance after cam cover change.

Post by Ogb666 » Tue Jul 17, 2018 4:18 pm

Usually cam cover gaskets only blow at that kind of mileage due to excess crankcase pressure which can be caused by a blocked breather,faulty turbo or worn/damaged rings.....try taking the oil cap off while running and check for smoke

edbutler
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Re: Performance after cam cover change.

Post by edbutler » Tue Jul 17, 2018 4:45 pm

The mechanic is unfortunately having you on mate. Cars have wide tolerances so they don't throw warnings and panic people left right and centre. You could have a moderately severe boost issue without a fault showing up. Even then, you'd have to drive along a flat road at constant boost pressure for it to finally recognise it as an issue and go into Limp mode.

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