88 300E cuts out at 4500rpm
 

I bought an 88 300E with 117K on it. It fails emmisions test. Took it to shop and they said the engine cuts out at 4500 rpm and there is a rattling noise in the top end and a little puff of blue smoke. The shop said the next step is to inspect the top end for problems.

What does this sound like (besides me getting ripped off on my recent purchase)? I did get the car 3000 below book so I don't mind putting some bucks into it if I have to. The question is what could the problem be and how much will it cost.

Any ideas?

Thanks,

AJ


01 toyota tundra
00 toyota camry
88 mercedes 300E

I suggest you start with a cylinder leak down test (take it to someone who can perform a leak down test rather than a simple compression test) and depending on the results go from there.

I suggest you try the RPMs on the road in low gear..
Some have a rev limiter for Park/Neutral when car is stationary to protect the torque converter...

You will know this also if you go above 10 MPH and put it in N and gas it to check RPMs...
Later 124s had this feature... give it a try

IF someone replaced the fuel pump relay with one from a 190E 2.3 4 cylinder, then that is the rpm that the engine will cut off.

Worn camshaft lobe caused this on my 89 230TE. With less movement than there should be the hydraulic lifter pumped up at high revs until the valve hit the piston, hence the noise. Loss of power at that speed was caused by the valve not closing.

The 4 cylinder fuel pump relay is worth checking out as this would cause the power loss, but not the noise.

update on 300e with issues
 

The mechanic took off the valve cover of the 1988 300e which was not passing emmissions and making a rattle in the top end around 4500 rpms. I saw for myself worn out cam lobes and dirty crud all over the valve springs/rockers etc.
He and the service advisor told me that they were afraid to think about what the bottom part of the motor looked like if the top half looked this bad. They recommended one of two routes. A new 300e motor (rebuilt by Mercedes) for around $5k plus labor. Or a used low mileage motor from some place in Texas for around $2500 plus labor. It comes with a 2 year warranty. I opted for the used motor. I think when its all said and done I am gonna be in for about $5000 worth of repairs. Thanks to everyone for their suggestions. I know many on this board say the bottom ends of these motors are strong but I don't think I want to take the risk that a new top end won't make the bottom end fail. Although the mechanic said the motors are usually good for around 300K miles, I figure one of these used motors might get me around 200k.

if you are going to replace the engine, you may as well pull the ehad on your engine and inspect the bottom end. The bottom ends are pretty much bulletproof.

Alon