2.8L M20 build - Now with 2.7L!

[acolella76]

Just curious, did you have the bottom end balanced before assembly? I don't remember.

Crank yes, entire rotating assembly no.

How does the crank look?

Crank still looks good

[Bearmw]

How does the crank look?

[digger]

A tenth of an inch should be fine. Cam timing does not cause preignition, only ignition timing does that. That rattle sounds pretty substantial to me, like a rod knock or similar. What were your rod bearing clearances?

not that it adds anything to the diagnosis but strictly speaking cam timing can affect cylinder pressures and hence can cause knock etc.

[liquidgroove]

LOL..... my engine had exact same issue over this weekend.

Noticed knock noise on 03/17 afternoon while on track. Open up the oil pan and found #1 bearing and crank a bit mess up. Replaced all rod bearings. Didn't replace main bearing.

Gone racing on 03/18. Stupid knock noise still there. Did 3 laps and engine effectively seized.

Havn't open up the engine yet, but believed bottom end was toasted. We suspect something clogged up the lubrication system and kill the new bearings.

Learn from my mistake. Make sure you found the root cause before putting new parts back in.

[MR 325]

Just curious, did you have the bottom end balanced before assembly? I don't remember.

[5Toes]

Im pulling the engine tomorrow. Going to pull head and pan and all the goodies and make some money!

[acolella76]

Dude. Atleast this is a sort of easy fix

I am postive my car has rod knock now, cause mine started out sounding just like yours!

Then it turned into this. I will pull the oil pan for sure to sell and check my rods too now!

The oil pan is pretty easy to get off, definitely worth a look!

Acolella, the two pictures to show the caps are both pictures of cylinder 1, the normal looking one.

Did you plastigauge the bearings when assembling to make sure they were within tolerances?

Whoops, thanks! Edited.

And no, I did not plastigauge. I just measured bearing inner vs journal outer diameters and used the difference to measure the clearance. I probably should have used plastigauge to double check though.

[TurboJake]

Acolella, the two pictures to show the caps are both pictures of cylinder 1, the normal looking one.

Did you plastigauge the bearings when assembling to make sure they were within tolerances?

[5Toes]

Dude. Atleast this is a sort of easy fix

I am postive my car has rod knock now, cause mine started out sounding just like yours!

Then it turned into this. I will pull the oil pan for sure to sell and check my rods too now!

[acolella76]

Well... shit on my dick. This sucks!



Cylinder 1 and 6 move front to back a little bit, which I THINK is because they might not be torqued enough? Popped the bearings off and they both look normal.

Cylinder 1 bearing:



Clyinder 2 and 5 were a little... worse as you can hear in the video.



As you can see the bearing is razor thin. I need advice... where do I go from here? What caused this?

[acolella76]

What I want to know is how the timing belt "skipped". Bent valves are a likely result.

You and me both!! I am going to check all of the pulleys, replace tensioner and belt AGAIN.

Posted this on e30tech: one of the cylinders had a CR of 90, I'm HOPING it's due to a bent valve not something wrong with the rings.

[MR 325]

In any event, I forgot to post my findings here. The timing belt skipped quite a bit. The cam gear is turned too far clockwise if the crank is at TDC, so that means it was too advanced, correct? I am taking the head off to make sure I don't have any bent valves, but just wondering if that knocking noise could have been preignition due to it being so far advanced instead of rod knock? Here's to hoping!

That's a mechanical "bad" noise, not predetination.

What I want to know is how the timing belt "skipped". Bent valves are a likely result.

[acolella76]

Gotcha. So I guess I should go ahead and try to get that oil pan off huh?

[LJ851]

Oh? I thought the cam controlled ignition timing via the rotor. Oh well.

The ecu controls ignition timing based on the CPS and a few variables, the rotor on the cam dictates which cylinder fires via it's relation to the cap but has no effect on ignition timing.

[acolella76]

A tenth of an inch should be fine. Cam timing does not cause preignition, only ignition timing does that. That rattle sounds pretty substantial to me, like a rod knock or similar. What were your rod bearing clearances?

Oh? I thought the cam controlled ignition timing via the rotor. Oh well. Not sure what the clearances were... I think I have them written down somewhere, but I remember the clearance being between 0.03-0.07mm which is what the bentley suggests.

just read the whole thread, was excited at first to see it all come together, but then.... :(

You aren't the only one :(