[Jaminlow]

Hi all,

I have been experiencing a progressively worse coolant leak and occasional misfire, one Indy has claimed he thinks it is a head gasket failure where others think it could be a EGR leak?


Symptoms

Coolant leak - coolant level low warning appears after about a hour of driving and toping up

Misfires - Random around every couple of days or so, turn off and on and it disappears and engine runs quiet and smooth.

No white smoke but apparently coolant is entering cylinder 2.


Ive had different Indys telling me different things and just want to be sure its a head-gasket before even considering any work.

If anyone has any advise as to how to diagnose one from the other it would be much appreciated?

[therealdb1]

Sounds like you need a good old-fashioned compression test.
If water is getting into the cylinder then that cylinder is likely to generate a considerably lower pressure than the others and you will know you need to investigate further.

[Phil325i]

Originally Posted by therealdb1

Sounds like you need a good old-fashioned compression test.

+1 Good advice. All I'd say is that failed head gaskets are almost unknown in the N53 so that would be bottom of my list of possible causes. Cracks in the coolant header tank, on the other hand, are more common.

[0l0dom0l0]

Very unlikely to be a HG failure. EGR cooler is plausible.

Best thing is to remove the under tray when the engine is got and look for leaks. If you don't have any then you could remove the intake and check the EGR cooler. It will he obvious if you have a leak.

A good old sniffer test is also an option.

[Jaminlow]

Thanks guys,

Very helpful comments, i've pretty much done the above except the comp test, its been sat at the Indy with the under tray off with no visible external leaks or stains.

The indy left it overnight and then striped the plugs out to see if was water getting into the cylinder, he said when he turned it over coolant came out of cylinder 2 and that he certain its a head gasket failure but hasnt investigated the EGR cooler as he said it would be getting into more than one cylinder.

My issue is how do i trouble shoot if it is the head gasket thats failed or the EGR cooler, i imagine the both have similar symptoms and will let gas fumes into the coolant so a coolant chemical test wont.

I just want to make sure i've investigated every option before forking out 1800+ on HG change.

Il do a compression test next and maybe block off the EGR cooler?

Dose any one know if there are kits to block off the EGR cooler or a way of bypassing it?

[Phil325i]

No, not aware of anything to blank off the EGR cooler. I guess a pair of simple bungs should do it. It looks like a simple coolant hose on RealOEM. The only blanking I've done is to partially blank off the exhaust gas flow through the EGR iteself, to reduce inlet side carbon build up. I replaced gasket 6 in the diagram with one with a much smaller hole. Didn't entirely bank it off as I was advised that would throw all sorts of error codes.

https://www.realoem.com/bmw/enUS/sho...diagId=11_3974

[therealdb1]

The compression test should tell you.
If cylinder 2 is down in comparison to the others it is likely the head gasket if all the cylinders are close together then it probably isn't the head gasket.

[0l0dom0l0]

I would remove the intake manifold as the next step and you'll be able to see straight away if there's any signs of coolant ingress.

Has your water pump failed and overheated the engine in the past? Never heard of HG failure on the N53.

A compression test might be a good thing as it's relatively straightforward and quick but if it's a small leak you may not see it outside of the normal variation between cylinders.

Have they got a borescope? I'd be sticking that down the plug hole before stripping the head off as well. Could be a cracked liner but again nothing I've heard of on the N53.

Have they drained the oil out to see if its full of coolant? If it is sitting and collecting coolant in the cylinder then I'd expect to see some coolant come out the bottom of the pan.

[Jaminlow]

Thanks again for all your comments guys.

Phil325i thanks for the diagram and interesting to hear what you did with the EGR gasket, good point as well i'm sure blocking EGR off would freak the car out.

therealdb1 & 0l0dom0l0 Ok that makes sense and agreed no one ive spoken seems to of heard of a head gasket going on the n53. As far as i know the car has never overheated under my ownership but thats not to say it hasn't under the previous owner, id be surprised tho as i brought it with 1 previous owner and 50,000 miles on it.

Great advise, I think removing the inlet manifold, compression test and borescope is going to be next steps, It's strange because if i leave the car for a day or two it starts up fine and idles as normal runs smooth and powerful but after 30/40min of driving i get a misfire and engine light comes on then i presume the car shuts down the cylinder. stoping and starting it seems to resolve the issue temporarily but it really doesn't like idling when its running hot.

If anyone can recommend a good Indy who knows there way around a N53 that would be a great help, im located in London

many thanks

[Phil325i]

Originally Posted by Jaminlow

If anyone can recommend a good Indy who knows there way around a N53 that would be a great help, im located in London

Not quite London, but these are good:

https://www.independentbmwgarage.co.uk/