Problem with Cylinder #6. Lost compression
07-12-2009, 01:24 PM
#26
07-13-2009, 09:19 PM
#27
MBworld Guru
Join Date: Apr 2002
Location: Diamond Bar, CA
Posts: 22,007
Likes: 0
Received 6 Likes
on
6 Posts
white and whiter
I have an update but it is not a story with a good ending (so far).
This past Saturday the shop completed the installation of a new piston #6, new timing chain, new exhaust valve and the rocker arm, crank position sensor and a few other things. I picked up the car and drove it for 35 mile while only twice reaching 3K RPM. Everything feels fine. Around 8:00pm I take my wife in this car to a party to celebrate her birthday. 10 mins into the trip, the CEL comes on and the car starts shaking. I'm dataloging the entire trip and I know that it crapped out at 3K RPM. I check the codes and it is again, P0300, P0304, P0305 and P0306.
I clear the codes, start the car, but they come back. Conveniently, I'm only a few blocks away from the restaurant and about 10 blocks away from the shop.
Come Monday, the heads are removed and my new piston#6 now looks like the one in Pullejo's picture and the valve is damaged again. After close examination it appears that a rocker arm from an E55 is installed in place of the C32 one. They look identical, but the part numbers are different (both start with 113). Can this be the problem this time? Who knows. We install the correct rocker arm leaving the scarred piston in place. This is not as bad as the original damaged piston and should be fine. Its already Tuesday afternoon. The car idles for an hour and appears to be fine. But I want my mechanic to road test the car for a day first. Well, on the way home, only after a few blocks, the P codes come back.
Good thing that he was driving.
At this point he doesn't know what to think. Is the misfire a cause or an effect? He is going to double check timing and I want him to check the cats. Specifically the drive side cat. I remember Jerry from LET having misfires and it turned out to be cats. #6 is the last cylinder on the driver bank, it is the exhaust valve that breaks every time. It may all be related. I'm open to other ideas
This past Saturday the shop completed the installation of a new piston #6, new timing chain, new exhaust valve and the rocker arm, crank position sensor and a few other things. I picked up the car and drove it for 35 mile while only twice reaching 3K RPM. Everything feels fine. Around 8:00pm I take my wife in this car to a party to celebrate her birthday. 10 mins into the trip, the CEL comes on and the car starts shaking. I'm dataloging the entire trip and I know that it crapped out at 3K RPM. I check the codes and it is again, P0300, P0304, P0305 and P0306.
I clear the codes, start the car, but they come back. Conveniently, I'm only a few blocks away from the restaurant and about 10 blocks away from the shop.
Come Monday, the heads are removed and my new piston#6 now looks like the one in Pullejo's picture and the valve is damaged again. After close examination it appears that a rocker arm from an E55 is installed in place of the C32 one. They look identical, but the part numbers are different (both start with 113). Can this be the problem this time? Who knows. We install the correct rocker arm leaving the scarred piston in place. This is not as bad as the original damaged piston and should be fine. Its already Tuesday afternoon. The car idles for an hour and appears to be fine. But I want my mechanic to road test the car for a day first. Well, on the way home, only after a few blocks, the P codes come back.
Good thing that he was driving.At this point he doesn't know what to think. Is the misfire a cause or an effect? He is going to double check timing and I want him to check the cats. Specifically the drive side cat. I remember Jerry from LET having misfires and it turned out to be cats. #6 is the last cylinder on the driver bank, it is the exhaust valve that breaks every time. It may all be related. I'm open to other ideas
i'm having issue with #4. all ignition checks out (coils, wires, spark plugs)
did a vacuum check and shows erratic vacuum pressure. thinking it's the valve, but certainly I hope it isn't as bad as yours or pullejo's that require me to pull the head. I'm told that it's possible to change the valve springs with just the cover off? but if it's the valve itself the head has to come off?
one good thing is unlike pullejo's I'm not losing power when it's warmed up.
Last edited by FrankW; 07-13-2009 at 09:21 PM.
