Rubber Review - 81 240D - PeachParts Mercedes-Benz Forum

JHZR2 · #1 06-09-2018, 10:00 PM

Im doing my engine mounts as soon as I can get my 8mm bolts out.

I wasnt planning on doing others, they seem fine. Actually, the engine mounts look fine to me, but you can't really determine until they are side by side with a new one...

The car runs and drives beautifully, but it has a very strong idle shake at slow idle with AC on in drive. Speed up idle and/or put in Neutral and take AC off and it can be as smooth as glass.

Since they have never been done, I figure its a worthy attempt.

I took a look at my other rubber parts. I see no issue or reason to replace them, but would like another opinion...

I assume this is the vibration reducing T mount? I dont know how to tell if it is bad. Supposedly they break, but this one seems just fine. I do have the vibration I mentioned above, so if this thing is supposed to help with that, its not...

Then the transmission and guibo.

I just want to get rid of the slow idle shake when loaded.

I suppose I should put a tach on it and verify how slow is slow...

But rubber parts and injectors always seem to be the first basis...

Any opinions would be great.

Thanks!

Rooster300SD · #2 06-10-2018, 12:21 AM

I just did my motor mounts and tranny mount and it made a HUGE difference.
I had a lot of shaking on start up when cold. The motor mounts weren't
collapsed but were hard as a rock.

When I lifted the engine by the oil pan it turned out that the passenger mount
was broken--the middle had separated from the rest of the mount.
I'm wondering how long this has been broken. My guess is a long time,
I was probably just used to the shaking until it finally broke free.

So, yes, change those mounts--it can't hurt.

My car now starts easier and runs smoother than it ever has.

Jeff

BirthdayBenz · #3 06-11-2018, 07:10 AM

That one mount, trans? looks totally shot. The flex disks have been replaced at some point with URO ones from your pic.

I like to take a pry bar and try to move things around under there. Prying near one of those mounts can show you how much play you've got in the mount. I had a trans mount on my 240D that looked fine but when I pried a little on the trans you could see all these large cracks and splits open up in the mount. You can pry, just putting a little bend on those flex disks too. If they are all cracked up when they bend you can replace them.

JHZR2 · #4 06-11-2018, 07:31 AM

At first I thought the flex discs said URO, but I realized they actually say JURID.

I have no record of flex disc replacement, and Ive owned the car since URO parts (by name) were as prevalent a thing. No replacement under my watch. Pretty sure they're original.

For the trans mount, how can you make that determination? There is no cracking at all. The outer layer of shiny coating is peeling off, but it does that in the pictures of new parts here at Pelican. It feels soft and does not exhibit cracks, which is rather surprising actually, and why I appreciate second opinions.

Thanks!

t walgamuth · #5 06-11-2018, 08:07 AM

I'd set up the idle. They are supposed to do it automatically when the ac comes on.

JHZR2 · #6 06-11-2018, 08:22 AM

Quote:

Originally Posted by t walgamuth

I'd set up the idle. They are supposed to do it automatically when the ac comes on.

Increase idle automatically with AC? My 240 certainly doesn't do that.

I need to get a tachometer onnit and verify idle speeds. It "sounds right" where it is, but it takes a few rpm to smooth out like glass. Low rpm and it shakes the hood!

Air cleaner is good though. No broken mounts there fwiw...

Rooster300SD · #7 06-11-2018, 08:40 PM

My car with the broken mount had terrible shaking when cold.
Pressing on the accelerator just a little evened everything out.
After it warmed up it evened out but was still on the rough side.

I thought it was an low idle issue. I bought a cheap HF digital
photo tachometer with the reflective tape and increased the idle
to almost 900 rpm before it smoothed out.

The car was also harder to start. After changing the motor mounts it was
so much smoother I ended up turning the idle back down to 750 and the
car has never been smoother.

Jeff

Diseasel300 · #8 06-11-2018, 09:07 PM

Quote:

Originally Posted by t walgamuth

They are supposed to do it automatically when the ac comes on.

I don't think that was a thing until the OM60x series with the EDS solenoid. Even then they don't raise idle, they only maintain it.

JHZR2 · #9 06-11-2018, 11:26 PM

Quote:

Originally Posted by Rooster300SD

My car with the broken mount had terrible shaking when cold.
Pressing on the accelerator just a little evened everything out.
After it warmed up it evened out but was still on the rough side.

I thought it was an low idle issue. I bought a cheap HF digital
photo tachometer with the reflective tape and increased the idle
to almost 900 rpm before it smoothed out.

The car was also harder to start. After changing the motor mounts it was

so much smoother I ended up turning the idle back down to 750 and the
car has never been smoother.

Jeff

Sorry, which mount?? The front stop T-mount??

Rooster300SD · #10 06-12-2018, 12:34 AM

I did all three--transmission mount and both engine mounts.