Bent Rods Question - PeachParts Mercedes-Benz Forum

rdanz · #1 05-25-2003, 04:04 PM

My MB dealer was replacing a leaking head gasket on my car and they said they discovered that 4 of the 6 connecting rods were bent and replaced them and the rodbearings under Starmark. My contention is that if the rods were bent the rings must have been worn uneavenly and I should have gotten a rebuilt shortblock at the least. I also asked if the head was magnafluxed and checked for straightness and was told that it was not neccessary.
Am I right ? Shouldn't I have gotten a rebuilt shortblock?
Also when my starmark runs out which is soon any repairs after that I'm on my own. This is the famous S350 engine

All Opinions appreciated.

stevebfl · #2 05-25-2003, 04:51 PM

Unless there is reason to believe the rings are damaged they aren't going to replace them. If the compression is proper the rings are probably OK. The only way you might tell this is if the car misfires when first started cold for a second or two.

sixto · #3 05-25-2003, 05:31 PM

Steve,

How do they know the rods are bent? The piston doesn't come up as high as it should? Ridge line lower than it should be?

Thanks,
Sixto
91 300SE
87 300SDL
83 300SD

stevebfl · #4 05-25-2003, 06:29 PM

I don't know the measurement on 603 motors but on earlier diesels the piston actually comes out of the block and the head is flat. It fits within the thickness of the head gasket.

There is an exact amount this should be and is fairly easy to measure with the head off.

rdanz · #5 05-25-2003, 07:11 PM

Quote:

Originally posted by stevebfl
Unless there is reason to believe the rings are damaged they aren't going to replace them. If the compression is proper the rings are probably OK. The only way you might tell this is if the car misfires when first started cold for a second or two.

Steve
They also replaced the injection pump & mass air flow.
The car idols around 600 and the car shakes you can feel it while waiting for a light, once you give it fuel it evens out, also notice black soot on rear bumper now which I never had before. How much compression should it have and can I test it wet to see if rings are leaking?

rdanz · #6 05-26-2003, 05:19 PM

Bump waiting for steve to reply

stevebfl · #7 05-26-2003, 05:27 PM

Compression specs are tricky as gauges and techniques change actual values. The important thing is that there be no more than 10% difference from cylinder to cylinder.

The running at idle could be motor mounts or a performance problem. If you didn't have it before you might have them check into it. With all they did it should work as new.

rdanz · #8 05-26-2003, 07:54 PM

Quote:

Originally posted by stevebfl
Compression specs are tricky as gauges and techniques change actual values. The important thing is that there be no more than 10% difference from cylinder to cylinder.

The running at idle could be motor mounts or a performance problem. If you didn't have it before you might have them check into it. With all they did it should work as new.

I didn't mention they also changed the motor mounts and engine shock mount as well, Timing chain, radiator, and fan
Sometimes when it idles the engine will take a dip like a misfire and then come back up I mention this to them but they didn't seem to concerned. The engine also clatters at idle which it never did before. Could there be a problem with the injectors?
The biggest problem is that the service manager doesn't know squat about diesels and I think something is lost when he tells the mechanic. My car is the only diesel they have worked on in the past year and before that only a couple of 5 cylinder ones
which are noisy not like the 6 cylinder which is supposed to be wisper quiet.
Just hope there not doing all this work just to bill Mercedes.

Last visit over $9000. in parts alone

And they want me to bring in the car for more work.