W109, 3.5: Steering Gear box is touching the exhaust manifold making bad noises - PeachParts Mercedes-Benz Forum

werminghausen · #1 07-25-2011, 12:06 PM

I was changing sub frame mounts and motor mounts and now I see that the engine doesn't sit high enough. The gear box is touching the exhaust manifold.
what can this be?
Well right now the axles are hanging because the car is on stand, not sure what makes the difference.
I attached pictures of the situation when the can sits on stand in the front.
The last picture is one taken form above with the gear box bolt touching the manifold.
Need help.
Does this sound correct or is something completely off?

werminghausen · #2 07-25-2011, 02:39 PM

When I shift into Reverse the manifold is touching the gearbox and it makes the rattle noise. Is the missing damper the reason for this touch? Or is it something else?

werminghausen · #3 07-26-2011, 07:05 AM

No one?.... This is too bad.

werminghausen · #4 07-26-2011, 07:11 AM

My only explanations are:

1) New URO motor mount I put in suck? I mean they are too soft for the weight of the engine? Cure : buy Mercedes mounts

2) as there are 3 mounts (a triangle: 2 motor mounts and 1 transmission mount) the transmison mount can be shot and the transmission is sitting too low? and therefore the engine is too low?

3) left side motor shock is missing and the left one is dead anyhow.
With new shocks the engine won't move that much under load?

For the time being I could put a 5mm shim between arm and motor mount on the left side in order to lift the engine slightly an avoid touching the gearbox?

Need advise

meltedpanda · #5 07-26-2011, 01:54 PM

not sure but doubt the box is the issue and more likely the mounts. I once put a "new " set of motor mounts on my SD , supposedly OEM , just to have them collapse after 3 miles!! I would do all three mounts, make sure they are as originally designed, and I dont want to insult you intellegence , but put in correct side up

Same for the subframe

Motor mounts dont hold anything up but do a good job to dampen side to side movement, I'd do those while you are in there

werminghausen · #6 07-26-2011, 03:57 PM

Thanks Panda,
Believe me the manifold is touching the gearbox. You can't get a feel gauge in there!

As I said I have new URO motor mounts in and things are rather worse than better compared to before with the old mounts.
I am not sure what you mean with 'collapsed' motor mounts after 3 miles.
But mine are not collapsed. With the engine weight the mounts are 'flat' at the surface....while under no load the rubber is standing up like a cone.

As I said...I believe now that the engine is sitting too low and the steering gearbox is rattling as soon as I shift into R or if I am releasing the gas pedal with speed (and the engine turns to the left side just like in Reverse).
Also when I go over pumps I have a rattling sound and sometime a knock/ clunk that sounds like shot ball joint in the control arm....if it were a newer car.
It makes a difference if the engine is turned left (release pedal) or right (during acceleration or neutral coasting).
Under deceleration it makes the same sound as if I were at a stop in Reverse and over bumps during coasting it makes these clunks.
The clunks could be a shot transmission mount?

sjefke · #7 07-26-2011, 06:26 PM

I would replace the transmission mount for sure. Also, were there any shims before? I have never replaced MB mounts (yet), but on some other cars, I have seen shims. Bolts and nuts are tight?

Good luck,

Bert

werminghausen · #8 07-26-2011, 07:48 PM

Quote:

Originally Posted by sjefke

I would replace the transmission mount for sure. Also, were there any shims before? I have never replaced MB mounts (yet), but on some other cars, I have seen shims. Bolts and nuts are tight?

Good luck,

Bert

Hi Bert

Yes, everything is tight. The only thing I didn't touch yet is the transmission mount.
I machined 2 shims 6mm thick for the 2 motor mounts to 'lift' the engine by that amount and hopefully I can avoid the connection manifold and gear box.
Not sure if you have a 3.5. If....Could you do me a favor and check what about your clearance is between manifold and gear box?
I also welded the missing bracket (by eye balling) for my so far missing left side engine shock. I ordered transmission mount and shocks ...should be here by tomorrow. Last day I can work on the car before it will be sitting in a container.

sjefke · #9 07-26-2011, 07:51 PM

I have manual transmission so clearance will be different.

Bert

meltedpanda · #10 07-26-2011, 08:34 PM

I think the tranny mount and shocks will do the trick for you

werminghausen · #11 07-26-2011, 09:21 PM

I tried to shoot a picture of proof for the hex on top of the grar box touching the manifold ...but unfortunately i couldn't...just 2 hands. I need a mirror to see this exactly. But it is true there is no gap.

So I took the transmission mount out: 2 pieces came out...
Here are pictures

One is the broken mount with the bracket for the left side engine shock and the second is the bracket and the shims for the motor mounts if I'd need them.
Third is the drawing from where I took some rough ideas. I just had 1/4 inch steel...should be strong enough.

With the transmission jacked up the clearance to the gearbox is great!
I should get the new mount tomorrow and then I'll see...also the TWO dampers.
Martin

GGR · #12 07-27-2011, 07:17 AM

URO parts do not have good reputation, at least on the W126 BW discussion board.

In your case I would see what the situation is with the new trans mount. You will also need to make sure the trans is properly positioned so that there is no distortion in the flex disk when prop shaft is rotating, otherwise you will get vibrations while driving. You need to check this with the car in driving condition with the weight of the car on all wheels, as both rear and front axles (and thus also the engine and trans) change position when the car is liffted. Then you can play with shims both at the engine mounts and trans mounts to get proper clearance and alignement.

werminghausen · #13 07-27-2011, 08:35 AM

Quote:

Originally Posted by GGR

URO parts do not have good reputation, at least on the W126 BW discussion board.

In your case I would see what the situation is with the new trans mount. You will also need to make sure the trans is properly positioned so that there is no distortion in the flex disk when prop shaft is rotating, otherwise you will get vibrations while driving. You need to check this with the car in driving condition with the weight of the car on all wheels, as both rear and front axles (and thus also the engine and trans) change position when the car is liffted. Then you can play with shims both at the engine mounts and trans mounts to get proper clearance and alignement.

Thanks for your response GGR.
I am hoping that the trans mount is helping with new shocks.
If not I'll put 3 shims in at motor mounts and transmission.

GGR · #14 07-27-2011, 08:39 AM

You don't necessarily need to lift everything the same way. You just need the angle with the prop shaft to be correct and the engine to clear everything. You may end up just lifting the trans, and/or any side of the engine only. MB was tilting the 6.3 engine on RHD cars so that it clears the stering box, so it's a "standard" procedure.

suginami · #15 07-27-2011, 04:49 PM

Quote:

Originally Posted by werminghausen

Last day I can work on the car before it will be sitting in a container.

Out of curiosity, why will this be car be sitting in a container?