6.9 Engine Mount Replacement

[WGB]

With a lot more low end torque off the line after the timing chain replacement and the aircon finally working reliably full throttle starts produced a vibration and noise as the high pressure A-C pipe union grounded on the right hand chassis rail briefly.

I tried some gentle "Re-alignment" of the pipe but decided new mounts were really what was required.

The 6.9 engine manual gives about 5 short (terse) instructions on what to do and gives no mention of how tight the space is - particularly as they use allen key type bolts in blind locations.

First thing I did was loosen the fan shroud by removing the two 8mm bolts so that when the engine is lifted no damage is one.

The large bolt is accessed from underneath with a 10mm allen key and someone had done my left hand side up to about 120Nm.

The manual then says to remove the bottom 10mm nut of the engine shock absorber but it is only an extra 10 mm nut to remove the top as well and take it out to give more clearance all around.

The engine is then lifted on that side using a jack with a block of wood on it, the heat shield pulled out and that leaves two inaccessible 5mm headed allen key bolts. The mount is slanted at an angle so it is easy enough to remove the inner one with a 1/4 inch drive ratchet with a short 5 mm allen key on the end but the outer one seems very shrouded and although the book says to remove it from below it is easier from above using long extensions and a universal joint.

Here is a photo of the LH one with two long 1/2 inch extensions  a universal and a 1/2 inch allen key socket on the end.



I did similar with the RH side but space is tighter so used a smaller 1/4 inch socket set. It would have been simpler to remove the battery and tray for access.

Here are new and old mounts side by side from the bottom surface



And the top surface



They were actually not as bad as they appear in the photo but the right one was 6mm thinner than a new one and the left was 4 mm thinner and they are less than US$40 each.

I also replaced a serviceable transmission mount(US$15)



And now when full throttle is used from rest there is only engine and tyres - wonderful.

Bill

[TJ 450]

That's excellent. I'm sure it brought about a marked improvement in terms of overall synergy.
When I replaced all three mounts on my 450, it was like night and day. Admittedly, they were in far worse condition than yours, flat as pancakes. I chickened out on the flex discs and the centre support, which were done at the Star Shop. The two stops were actually riding on the chassis, and the transmission mount was completely separated. In terms of driveability, it was appalling. It's still not perfect, though as there is still some vibration at 50 km/h and at about 80km/h that hasn't been pinpointed as yet.

Tim

[s class]

Well done Bill.  Just this morning, I remounted my engine after the sump refitment saga.  I discovered that the left mount was completely lacking the two bolts that secure it to the chassis - the engine was just resting on the mount by its own weight.  I quickly discovered why - after fitting some bolts, I had a bugger of a time trying to get both mounts bolted to the engine supports - the misalignment was just too much.  I think the existing mounts have compressed that way - eventually I'll get new ones.  Money is a bit short now with unemployed wife.