Judder on Takeoff/ Driveshaft Carrier Bearing/ Mounts

[v8volvo]

Looks like that one was well past its prime! Must have happened since the crossmember replacement, otherwise you would have noticed it then, no?

Interesting that it was worse in reverse, since the LH (i.e. driver's side) mount is in compression when backing up -- gets pulled on (and in this case presumably separated) only when driving forward. I had an old gasser 245 that I drove for one summer some years ago that this happened to -- it was an automatic, and with the trans engaged in a forward gear, you could power-brake it and watch the motor lift itself up a good 4 or 5 inches under the hood! Never had any symptoms except a single, very heavy thump that rattled your teeth if you accelerated hard and then suddenly got off the gas. Broken mount explained that one.... Kind of amazing that it never ripped any wires or hoses loose, given how far it was moving. Anyway, story aside, that was in forward. Wonder why yours was more pronounced in reverse -- other that just letting the motor jump around more. Maybe its semi-collapsed position had more to do with it than the separated rubber?

Did the coolant look new, like the leak just started during this job, or like it had been there a while? I think it would be difficult to hurt that flange or the hose that attaches to it by doing this particular exercise, since even if you had the front of the motor lifted way up, it seems to me like you'd run the rear cam gear into the firewall long before you were able to make contact with the hose barb. The barb itself just secures to the back of the head with one bolt and an O-ring. Conceivable that the O-ring could have gone bad and sprung a leak, but more likely I think that that short hose back there is leaking and might have been for a while. Those always get contaminated by oil from leaky valve cover gaskets and start to drip. Maybe it's doing that and making it look like it's the flange.

In any case, despite appearance of limited access it's not too hard to mess with that flange or the hose on it. Hose is most easily replaced IMO by cutting old one off, then new one can slide on all the way up the steel tube that runs between head and intake, till it reaches the right-angle bend, then pushed back down and onto the barb on the head. Not as bad as it seems. If the flange really is leaking, can remove it and replace O-ring. Last time I did one I used a very small amount of Reinzosil on the flat flange surface as well, just to be sure...

[ngoma]

Originally Posted by v8volvo

Must have happened since the crossmember replacement, otherwise you would have noticed it then, no?

Correct, the mount was intact (but visibly offset and collapsed) when changing the crossover a few months ago. That's why I ordered the new mounts and planned the R/R.

Originally Posted by v8volvo

Interesting that it was worse in reverse, since the LH (i.e. driver's side) mount is in compression when backing up -- gets pulled on (and in this case presumably separated) only when driving forward.

Well now since it is all tightened up, I am still getting a judder both fwd and reverse, but now it feels like it is isolated more to the clutch itself. Is there a way to visually identify oil-soaked surfaces or cracked/burnt areas?

Originally Posted by v8volvo

Did the coolant look new, like the leak just started during this job, or like it had been there a while?

Coolant looked new; I saw it dripping onto the floor jack. I now started closely monitoring the coolant level in the overflow tank; we'll see how bad it is.

Originally Posted by v8volvo

The barb itself just secures to the back of the head with one bolt and an O-ring. Conceivable that the O-ring could have gone bad and sprung a leak, but more likely I think that that short hose back there is leaking and might have been for a while.

Hose looks new and I didn't get any traces of coolant from it or its joints on the barbs. Coolant traces did show up at the bottom of the flange joint. Tightened up the hose clamps anyway, and tried to tighten up the bolt holding the flange-- only achieved a few degrees on that.[/QUOTE]

Originally Posted by v8volvo

If the flange really is leaking, can remove it and replace O-ring. Last time I did one I used a very small amount of Reinzosil on the flat flange surface as well, just to be sure...

Good to know. I have a full metric-size o-ring assortment.

[ngoma]

It really was the flange that was leaking; the o-ring was squished, hardened, and cracked. Replaced it with a nitrile 22mm ID x 3mm thick o-ring. So it wasn't caused by the fitting hitting the firewall during motor/trans mount replacement.

Starting to see a pattern here. Had to replace the tee (drain valve) fitting under the vacuum pump a couple of months ago. It was crumbling to pieces, could have been catastrophic but caught it blocks from home.