dr bob

Jeff--

Best to pull the engine, then both heads and the sump. Remove that piston for a full inspection. Do all of them, what the ehck.

I don't know how you can sleep at night knowing the ring end gap might be a little too tight.

Tom928

I checked the piston, it shows no evidence of any damage on the ring lands or any contact in the valve recesses.
The valve's in the head show no apparent contact. The new machine shop indicated that cylinder #4 passed the pressure test without any modification.
Bearing looks good. The cam could be a concern but appears to be good. Lifter also appears to be good.

I'll get new rings, rod nuts and head gasket. Then leak check again.

Mrmerlin

Jeff anytime you install new rings they should be measured, its entirely possible that the new rings might be the wrong size.
Since you skipped this step and you have proof tested the engine you got the right rings.

Imo000

You need to figure out why the ring broke before putting it back together. If the end gap was too small, the rings would buckle and put one heck of a stress on the ring lands. I would be worried to put that piston back in the engine. Also, pull the rest and have a look. The issue with the valve is bizarre but can't see ho it's related to the rings.

Tom928

I took some photo's of the piston. I do not see any damage to the ring lands. Also photo's of the bearing which look good.
Looking at the broken edges of the rings, there appears to be a lot of carbon build up. I tried taking a photo of this but to small for detail.
This was a used motor. I pulled the heads and the bores looked good so I did not go into the bottom end.
I was concerned about the cam. But the photo below does not show excessive wear.

I found 2 sets of tolerances (ring side clearance and ring gap). One is for Mahle and the other is K.S. Not sure which they will be?
Whats the best way to install rings? I had a ring spreader at one time but I think I loaned it out!

Oh - passenger side (cyl 1-4) is the Right side correct? So right side head gasket should be 928.104.361.07?

Tom928

With new rings installed in cylinder #4, leak down now passes with 5-6 sec with the old head gasket.
Ring gaps were 0.48mm and 0.52mm which are out of spec but I understand for Goetze rings this is not uncommon.

I noticed that the new valve that had the "tip height" issue that was fixed is shorter than the rest!
I put a straight edge across the valve tips and measured the difference = 0.813mm! Checking an old set of 4.5L heads shows every valve is the same height!
Hmmm I wonder?

Imo000

At this point, I would look for a good used engine, replace the head gaskets and put it into the car.

Mrmerlin

might need a new valve for that seat

Tom928

Hi Stan - Yes I don't think the shop did that right. I find that new valves are quite expensive.
I have a set of 4.5L heads and I see that the exhaust valve is the same and well as the seat.
I might just swap an exhaust valve from the 4.5 to the 4.7.

Thoughts on this?

Mrmerlin

check PET to verify the PN of the valves

Tom928

PET shows 928.105.417.03 for both. Roger checked it this morning when I called about a new valve.
New valve seals put in when the heads were done. I should be able to just swap the valves.
I'll pull it and soak it overnight in simple green then install it. Leak down should tell if it seals.
Height should be very close.

I need to get this back together soon. The WYAIT syndrome is beginning!
I've started thinking about better cams!

Imo000

If you are replacing the valve you need to lap it.

Tom928

I was thinking about that and could not find the spring compressor, so this morning I took the heads to the shop.
In a day or so I should be able to start putting it back together.

Mark Anderson

We have new valves for $19 each

Tom928

Hi Mark,
Thanks for the offer but I already took the 4.7L head and an old 4.5L head to the shop to have them swap the valve.