[Aeronotix]

Hi,
I had a persistent cyl #4, which was diagnosed broken piston rings by an indy shop.
I pulled the head but did not see any cylinder wall damages.
On the other side, i have noticed the cyl 4 is much cleaner than the other ones
And i have severe damages in the camshaft lobes on same cyl.
What do you think happened?

[rjahl]

Originally Posted by Aeronotix

Hi,
I had a persistent cyl #4, which was diagnosed broken piston rings by an indy shop.
I pulled the head but did not see any cylinder wall damages.
On the other side, i have noticed the cyl 4 is much cleaner than the other ones
And i have severe damages in the camshaft lobes on same cyl.
What do you think happened?

What to the valves look like? maybe your problem is
100% valve train related and your rings are still good.

[Dave92N54]

Cleaner makes me think leaky injector washing the cylinder? Dunno. I've never torn down anything other than a lawnmower lol

[iqraceworks]

Going too long between oil changes and/or lots of fuel in the oil from leaking injectors.

[ky0u]

+1 on injectors based on the cylinder cleanliness you mentioned

[Mustafa.e92]

Even if cyl 4 injector was leaking how would that correlate to the cam damage? Wouldn't it be more that the cam was worn which was making it run rich washing out the cylinder

[Dave92N54]

Originally Posted by Mustafa.e92

Even if cyl 4 injector was leaking how would that correlate to the cam damage? Wouldn't it be more that the cam was worn which was making it run rich?

Absolutely possible as well. Was only a guess. The wear on the cam almost looks like pitting to me. I'm wondering if someone really fucked up a walnut blast or something fell into the head :

I know early on, BMW's original procedure for cleaning the intake valves was complete removal of the head and they would do a full cleaning of it.

[lightmanek]

It's a closed deck, what boost and power this engine endured?
I'm also in the camp of leaky injector and the lobe damage could be caused by hydro-locking maybe on startup? There should be severe petrol smell when starting the car as if running very rich.

[rjahl]

Originally Posted by lightmanek

It's a closed deck, what boost and power this engine endured?
I'm also in the camp of leaky injector and the lobe damage could be caused by hydro-locking maybe on startup? There should be severe petrol smell when starting the car as if running very rich.

I always assumed that a leaking injector would wash the cylinder and cause some scoring on the cylinder walls. Same with broken rings. Don't see that here.

I'd really like to see the valves and springs. Could the rings be intact and the compression loss was valve train related.

Need more pictures.

[Dave92N54]

Originally Posted by lightmanek

It's a closed deck, what boost and power this engine endured?
I'm also in the camp of leaky injector and the lobe damage could be caused by hydro-locking maybe on startup? There should be severe petrol smell when starting the car as if running very rich.

Wow, didn't even see the closed deck. Adds plenty other possibilities, like what may have happened with that cylinder when building?

[bbnks2]

Originally Posted by lightmanek

It's a closed deck, what boost and power this engine endured?
I'm also in the camp of leaky injector and the lobe damage could be caused by hydro-locking maybe on startup? There should be severe petrol smell when starting the car as if running very rich.

Hydro lock on startup? that would bend a connecting rod unless the valve couldn't move at all in which case the valve would be badly bent.

Looks like the roller failed and wore into the cam based on the pics. The pitting seems to be common on BMW cams but the pitting in the pictures does look like more than normal. The roller does look like it ate into the cam lobe though.

Burning oil on that cylinder can cause it to actually be cleaner than the rest. I would not rule out a bad piston/ring. Pull it out and check... But usually the oil pushing up past the rings would leave a more specific pattern on the piston.

[beetle6986]

Did you already remove the oil and the pan? If not, collect some oil and send it in for analysis. That will give you a good idea of how much fuel is in your oil.

[cruizinmax]

Doesn't look like a closed deck to me. Looks like the old headgasket is still on there.

[Aeronotix]

Originally Posted by cruizinmax

Doesn't look like a closed deck to me. Looks like the old headgasket is still on there.

Hi,
Correct, it's not a closed gate. Head gasket is still on.
It was a stock engine; no massive horse power.
Oil analysis: i replaced the oil 200 miles ago, so that will probably be inconclusive.
The bottom end seems in good shape, usually rod bearing suffer first from oil dilution with gas.
It remains a mystery

[Dave92N54]

This is what a stock N54 block looks like. That is an open deck. What you're showing here in these photos is not an open deck. Your photos look very similar to the motiv closed deck motors (second photo).

[iqraceworks]

Originally Posted by Dave92N54

This is what a stock N54 block looks like. That is an open deck. What you're showing here in these photos is not an open deck. Your photos look very similar to the motiv closed deck motors (second photo).

The head gasket is still on the block.....that's why it looks like a closed deck.

[Dave92N54]

Originally Posted by iqraceworks

The head gasket is still on the block.....that's why it looks like a closed deck.

Oops. Looked to me more like leftovers of the rubber and not the whole gasket.

[lightmanek]

Haha, I did see pictures in a hurry on my mobile and didn't spot the gasket either ... 😅

Maybe because I have closed deck I automatically assumed this one is too.

Now looking at the cam picture I see the damage and have no idea how this could happen.