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View Full Version : swapping big-end bearings


WhizzMan
11-09-10, 22:52
Can it be done with the engine and transmission in the car? I think at least the transfer case needs to come off, which means it will be just as easy/hard as to just pull the engine out. I really don't want to (yet) since I'd rather just get it through MOT and do it some time this winter.
wrinx
11-09-10, 23:37
Not a clue, sorry...Jack might know though.

wrinx
AlfaJack
12-09-10, 00:03
Sorry Whizz, not sure - I did all this be taking it to a million bits. I think it may be do-able by taking the lower sump cover off....
WhizzMan
12-09-10, 07:35
There is a baffle plate in the way. Can you take that out from the bottom as well? I took 2 bolts off and then decided that I needed to get the car off the lift so I could do another one, so I put it back together again.
AlfaJack
12-09-10, 21:07
Would you do the main bearings at the same time? I found that was what was worn on another Q4 I had - never heard it running as when I had bought it, it had thrown the cam belt. Do main bearings cause knocking noises?
WhizzMan
13-09-10, 06:46
Can't do the mains without the crank out, so that would be a no. I don't think main bearings would cause knocking noises, since they'd all have to be gone for rattle to be able to occur. Most engines would have seized long before that. Big ends will rattle when just one has too much play, so if you have a low rattle, that'd be the thing I suspect first. Mine has a distinct "toc toc toc" sound when starting and as soon as I have oil pressure it fades to the background, but it's still there if you know what to listen for. As soon as the oil warms up, pressure drops. I hope I haven't busted the crank driving it to the workshop. Only way to find out is to measure I guess.
#84
14-09-10, 19:50
I changed main + big end bearings when I had the gearbox and clutch off. Then it was no problem with the crankshaft in place.

The most troublesome moment from the engine's point of view is to tighten the oil sump screws. Even if you tighten them more than they should, according to the workshop manual, the screws will be a bit loose after heating up the engine a few times - and you can't tighten all of them without removing the transmission.....
wrinx
15-09-10, 08:13
Thread lock?

wrinx
WhizzMan
15-09-10, 22:12
Well, if I have to take the transmission and gear box off, I might as well do that with the engine out of the car and give it a proper rebuild.

Yes, threadlock is what is probably smartest here. I'd probably won't use it, because I tend to put blue silicone on both sides of the gaskets. This always ends up in the threads for the bolts, so thread lock isn't required anymore. ;)