Balance Shaft failure?

[Roger_850T]

Today my 2005 XC90 V8 (143k miles) came home making this noise:



I fear it's the balance shaft. It seems to be coming from right under the intake plenum, and seems to be what I imagine it would sound like if the bearing had failed and the back of the shaft is whipping around. I thought I was clear because I've owned the car 6 years and never washed the engine. (I figured if it was washed before I owned it, it would have failed by now.) Alas, maybe not.

Has anyone actually dealt with a failed balance shaft bearing? Is this similar?

Also, what your your thoughts on repairing (disassemble, replace bearing and maybe balance shaft, add the drain hole, reassemble) vs. just replacing the engine?

Thanks for the input.

[SuperHerman]

I looked at buying a V8, but was scared away due to the balance shaft bearing failure.

See here a general description, near the bottom: http://australiancar.reviews/Volvo_B8444S_Engine.php

See here and do some digging - appears one guy has done the repair: http://www.volvoxc.com/forums/archive/i ... 14846.html

Here is a YouTube on it, where the engine is pulled, but it shows what the issue is:

From what I recall the job can be done with the engine still in the car, but one head has to be removed as well as some other parts. I read many posts on the subject and opted not to buy a V8. It can be repaired, but it is not an easy task. If the damage is really bad the engine needs to be pulled.

For now, based on the first link I posted, I would minimize running the car until you figure out if the balance shaft bearing is indeed bad as running the car can take out more parts and increase the cost of repair.

[jimmy57]

That sounds like it.
A head has to come off. It can be done in the car but you will hate life.
Usually the whole subframe is dropped with engine on it and then front cover and head is WAY less of a problem to get apart and to get back together. Oh, head comes off regardless as the cap over that sealed roller bearing has bolts that you can't get to without one head off. You will still use a chisel to get the ones under the hed you don't remove loosened. The bolts are.....get this....security Torx head. Yamaha was worried someone would steal the balance shaft cap??? You put regular M8-1.25 bolts back so you can tighten them with box end wrench.
There is a chance the block is damaged. Usually not the case if you heard and didn't drive hundreds or thousands of miles with the noise.
I wish it weren't so.
Most of the V8 euro models have lots of access issues. Audi puts their timing chains on back of engine with a back engine cover over them. BMW V8 models are like the Volvo, you can do it but any broken bolt or rusty fastener or something dropped due to working in cramped areas and you're going to spend way more time that if you have dropped the package. If you drill the drain only go 5/16 deep with bit. There is a top wall of crankcase a little more than 1/2 " below the layer you drill through into the hollow cavity for drainage.

[ggleavitt]

https://forums.swedespeed.com/showthrea ... ure-thread as another point of reference. I would not run the engine further until it gets fixed, if the chain breaks you'll be replacing a whole bunch of other stuff.
Engine SN out of curiosity? This screengrab

CB Shaft Rework Snapshot.JPG (57.55 KiB) Viewed 5361 times

sort of shows the pre-6833 rework, there's more to it in VIDA.

Very sorry to hear about your failure.

[Roger_850T]

Engine s/n is very early, #0266, so definitely within the range. I'm pretty well versed in the concept of this failure, and have not washed the engine since I've owned it (6 years, 70k miles), so I thought by now I was in the clear. Alas, not so.

Since the engine was running smoothly (albeit with the clanking sounds), I hope I have escaped the "bearing seizes, causes timing chain to skip, causes valves to hit pistons" ultimate failure scenario, and it seems to be sounding like I can pull the cylinder head and replace the bearings (and likely the shaft too) and be good. I've been about ready to do the valve cover gaskets / timing cover gaskets to stem an oil leak, so I guess that's a silver lining. (If I had just done the oil leak re-seal, and THEN had this happen, I'd be really pissed!)

Continuing to research; thanks for the input!

Roger

[ggleavitt]

Once you tear everything down, I would be very interested in seeing photos, I've only personally gone down as deep as to pop the valve covers myself- https://goo.gl/photos/tcLSKkYEp6KqkbaR9

Good luck!