my engine started shaking 99 e300
 

so my engine just started shaking in my car and i'm not sure what the problem is. i bought it with 166k, and the po said he had changed the engine mounts not that long ago. I'm at 200k right now and not sure what would cause the engine to shake like it does now.

also the belt tensioner is rattling and making a lot of noise, where can i get a replacement for that?

Could be low compression in one cylinder, or no combustion in a cylinder.

the car runs just fine with no problems, its just got a shake at idle. Could it really be that big of an issue? I was just thinking something like engine mounts.

Is the shaking consistent over all temperature ranges or does it occur when cold or hot?

I find it difficult to believe that your mounts have gone south this quickly.


Steve A

I had some problems with my 96 e300D for some time. I had air getting into the fuel system, and the o rings on the fuel pump were leaking. I would check for fuel leaks and check the o rings on the pump.

Engine mounts go south on that car at about 100K miles. At least that's close to when I replaced mine. Shaking at idle? No clue - mine has never done that, not yet anyway.

If the belt tensioner is rattling, I would suggest that you find out the cause, and correct it before you delve any deeper into why the engine is shaking. If the tensioner shock has gone bad, that can cause the belt to have a lot of slop to it, especially at idle, hence that may be the cause of the vibration or shaking you describe. You can check with any of the parts suppliers for most of the belt tensioner parts that need replacement.

A rattle sound from the tensioner is usually one of the bushings on the damper shock going south.

Before you replace it, test your motor mounts. I have had a bad vib at the tenisoner, repalced every part 1 to 3 times and with Gilly's help over the course of a few weeks finally isolated the problem to bad motor mounts. Dont know why that vib showed up at the tensioner, but it did.

Mounts can be measured to determine if they are good or not. Measuring from the top most rubber rim to the frame they measure 17mm new and are considered collapased at 13mm. Use an appropriate sized bolt head as a feeler gauge.

+/-100k does seem to be the typical mount life span on a 606.

Its just the tensioner in the bushing going bad, its always been a little noisy, i just never got around to swapping it out.

as far as temp, it seems to do it worse as the car gets to operating temp.

i'm going through and doing the lubro moly purge tomorrow as listed in the write up.

I'm a little confused on how to check for bad engine mounts? Where do I actually do the measuring?

I'm stumped, I wish I knew more about diesels.

I think an Air Leak is more likely than the Motor Mount. So of the Motor Mount measures out OK I would suspect an Air Leak.

If your Engine has a Fuel Heater that is also one of the areas that is I have read is pron to haveing Air Leaks.

well i just did the lubro moly. I gotta say it helped a lot with the way it sounded and it seems like the shaking has stopped, but i'm still a little leary. It was hard to get it started at first and i did notice the engine shaking and moving around a lot, is that a good indicator you have worn engine mounts?

injectors

crack each until found

if this reveals an injector, swap it to see if problem moves with injector or stay in cylinder

if it's the injector, and no injector service to date, do them - new nozzles and pop pressure

what do you mean by crack each until found?

How hard are the injectors to remove?

It sounded better burning Diesel Purge because the combustion of the fuel, like Bio, is different than D2.

You measure the MM from the top most rubber ring to the top of the mount (or supporting arm it mounts to). Or, you can use your floor jack and a very large rubber bushing (i use a sway bar bushing) between jack and oil pan and take the weight up off the motor mounts and then fire it up. DONT lift more than 1/4" or YOU may rip the mounts, break an exhaust connection, the intercooler pipes, the fan, etc, etc.

crack the nut (ccw, lefty loosey) holding the injector line to the injector, back it off a turn or two, while the car is running... does car get worse or stay the same when doing this? same -> you found the bad injector cylinder
Re-tighten it, move on, one at a time.
If you found a bad one, remove the injector 27mm socket, and remove a good injector too. swap them. Re-run car, repeat the cracking on those two cylinders, one at a time. Which cyl is bad this time? Did it move with injector, or not?
The injector is slightly harder to remove than it is to re-install at the specified torque.
Get a couple injector crush washers when you do this, when you're done with the experiment, pull the old ones out of the holes and put new ones down before you put the injectors back in the way you want them.