Engine mount help needed - GQ TD42 front end vibrates like crazy

[BrazilianY60]

G'day everyone.

There is something bothering me for some time already which is that my GQ TD42 front end vibrates like crazy when at idle, much worse if it is cold off-course. So much that you can see the front bumper vibrating and if you hold it tight even the sound changes.

Engine mounts were changed after engine rebuilt, some 5 years ago, but that also represents only 2.000 Km ago. Upon inspection, the engine mount (injection pump side/Aussy driver side) has a bend on the lower steel plate that makes it closer to the upper steel plate, and it was contacting. Looking carefully it also reveals that the engine mount upper steel plate is a little bit offset to the rear of the engine.
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I had saved my old ones for an emergency, so I decided to compare. Alone, the old one seems to have a much bigger gap on that section of the upper and lower plates, so I decided to replace the new one with the old one to test.
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But out of the vehicle, both seemed to have the same gap. The older one only didn't have rubber in that section, making it look like it had a wider gap, but no.
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New one is definitely offset to the rear of the engine now, compared with the old one.
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I have then installed the old one in the engine bay and with the weight of the engine that part of the gap also rests one onto the other and the front end vibrates the same.

This car had a front collision at some point in its life and the front panels alignment was a bit rough, so my friend that is a panel beater had it straightened up a little bit for the panels to come more aligned. This was done with the engine in place, and I think this could have caused misalignments between the two engine mount brackets.

I am thinking of removing the engine mount brackets and welding them back with a better alignment to see if that helps. This would be a PITA cause the engine would have to come out. But I am still unsure about that bent part of the engine mount touching the lower part, since it does it with just the weight of the engine. I have even bought an engine mount for an local 80's truck that has parts easy to find here and an similarly heavy engine to compare, cause if I am to go the engine mount bracket removal route, I might as well change it to an easier to replace part, but the rubber on the Patrol one seemed so much softer then this test unit. And since I am trying to get rid of vibrations, the softer it gets, the better, I believe.
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Any thoughts? Does the engine mounts on your TD42s have this little to no gap on that bent plate? This is a 4-hole engine mount type by the way.

[mudski]

What brand is the engine mount? Mine sit close but don;t touch. I would say the mount needs replacing. As for the offset thing. Mine is the same. I put it down to the engine torque doing this.

[BrazilianY60]

It is aftermarket, but has a very nice appearance in terms of manufacturing.
Weird that yours is also offset, because my old ones are perfectly aligned. I mean, out of the car.


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[BrazilianY60]

I put it down to the engine torque doing this.

I was also considering it could be something related to gearbox mounts, as those are the other supporting point of the engine-gearbox combo. Like if one is bad, the engine could end up turning a little bit to the side? They are old off course but don't show signs of being torn. Never heard of these being replaced either.

Found this video where the torque movement of the engine mount seems the opposite way, moving the engine forward, not backwards. Engine mount seems a different type, also. I wonder if I cut that bent part of the plate so one plate can no longer rest onto the other, if it would make any difference to the vibration.

[mudski]

I wouldn't be cutting it personally. Its there for a reason and that reason would be to stop the mount collapsing any further than it already has. New engine mount time in my opinion.

[PeeBee]

I wouldn't be cutting it personally. Its there for a reason and that reason would be to stop the mount collapsing any further than it already has. New engine mount time in my opinion.

For such a heavily loaded element I would be defaulting to a factory original. You then get exactly what the engineers specified within the manufacturing tolerances, including rubber hardness and vibration resistance. Its always tempting to utilise aftermarket, and I have done so in less critical items, but I carry factory mounts for engine and gbox/transfer case. Aftermarket is a bit of a lottery I think.
Also, as Brassy has suggested, have a look with a wider Lense to see it there is additional components that could be contributing, tore tounts or simply aged and hardened.

[BrazilianY60]

Yet to buy and replace engine and transmission mounts, but some update: my rev counter on the dash only worked when it wanted and I have gone through the trouble of tracing all the harness down to the speed sensor on the engine looking for a crack in the cable to find none, which is good after all as I have at least penciled out this from my list (the harness). I have recently remembered I had a spare dash from my donor car, so I replaced it, and the rev counter is working beautifully now. With a proper working counter I could now see my idle was on the 500 RPM range.

I have searched the factory service manual on all the sections, even the IP rebuilding procedures looking for the "official" proper TD42 idle speed and could not find it there. On several searches here on the forum people comments all converged around 550 RPM, but that would not take away much of the vibration I had. I have later found on the internet a scanned copy of a GU user-manual (not the factory service, but the glovebox manual) and there it stated 700 RPM.

I have increased my idle to 700ish and it feels so much better now. Not only for vibrations but I'd say for all. Even the working temperature is now achieved faster. To the ear it does sound like it is high, but the counter reads 700 and it is happy engine now, so I am happy as well.

[mudski]

Yeah my TD is at 700rpm. As for the dash issue even though its fixed, look closely at the pcb on the back. I have read that sometimes the solder lets go and creates issues like you have had. The engine mounts issue? I'd put OEM mounts if you can. As Phil said. These are designed by engineers at the time for this engine, so they will be made to spec. Aftermarket mounts might be hit and miss.