'91 Volvo 945 B234 balance shafts. help!

[lankytim]

Hi, new to the forum, first posting!

My 1991 940 estate has an annoying oil leak from the front of the engine, Ive replaced the cam and crank seals but its still there. I think its coming from the balance shafts. I recently replaced the cam and balance shaft belts but I couldnt tension the balance shaft belt properly and now it whines away, but gets less noisy when the engines hot. My question to the all knowing forum is... Should I remove the balance shaft belt, as Ive read on this forum that they dont really do anything anyway, Is it easy to remove the balance shafts and their casings from the side of the engine and blank off the oil feeds? If I did this, could I replace the cam belt lower cover and the plastic backplate with one from a B23 engine to make it all look neater?

Would I end up with more viabration than I would get from a B230K? Would the engine become more powerful because of less drag imposed on it?

The cars done 186,000 miles, so not monster mileage but high enough.

Has anyone been in the same situation as me before? I dont want the danger of my balance shaft belt breaking, taking out the cam belt and killing the engine (and car):-(

Sorry for all the questions!:???:

Tim

[MikeSr.]

Tim- i have a 1990 740GLE 16V w/ B234. I removed my balance shaft belt about 30k miles ago when i did my timing belt maintenance.Absolutely no difference noted in vibration, and i feel i have removed a potential risk for my engine to fail. The balance shaft belt breaks and takes out the main cam belt and the valves are toast. I felt the balance shafts would provide little noticeable benefit versus the hassle of tensioning and the possiblility of breakage. I'm very happy with the results. Seals will need replacing, but with no belt or gears, should be easy.

[lankytim]

Thanks for the reply,

I read on your other posts that you were a fan of removing balance shaft drive belts. The oil leak only happens when the engines running, even then its only a "weep" rather than a real leak, still annoying though. Maybe with the belt disconnected the stationary balance shafts wont let any oil leak out. Ideally Id like to completely delete the balance shafts and their housings, modify the lower part of the cam cover and make it look like they were never there in the first place. Personally I wish I had an 8 valve, simpler is better on an older car.

The engine runs slightly "lumpy". The engine shakes from side to side when its idling, so maybe the balance shaft timing is out anyway. I need to repace the gearbox mount as its perished and collapsed because of oil contamination. With a new one perhaps it will decrease the viabration. Ive a million questions about my car, but Ill save them for another day!

Tim

[MikeSr.]

My front covers were cracking, so i took them off. Now it's easy to see the entire front end and i can change the seals easily.

My car idles smooth as silk - if you have rough idle, i would check mounts and vacuum hoses for leaks- many times it is just maintenance that causes idle probs.

[lankytim]

Ill check all the hoses around the engine and replace the engine mounts as well as the gearbox mounts as although they look ok, they will have probably gone weak with age. Im sure I could hear a leak around in the inlet hose area, the long black pipe that goes f rom the intake manifold to the AMM, Ive taken it off and it looks ok, but im SURE i can hear a leak when I move it around, I know that would cause a bad idle! It sounds like removing the balance shaft belt is an obvious thing to do, especially now the belts contaminated with oil!

Thanks for the advice! incase your wondering about all the spaces in my messages, its not my fault, the space bars broken!

Tim

[lankytim]

Ok!

Ive removed the balance shaft belt, and guess what? the engine didnt explode how I was half expecting it to. The engine is now MUCH quieter, revs more freely and seems to have more power, especially mid to high range. I think there is a slight increase in viabration, but I dont think I would have noticed it unless I knew the balance shaft belt was missing. Then again, I could be imagining more viabration. Now to steam the front of the engine off and see where the oil is leaking from!

[opeterson]

I had a B234F on an engine stand, so I removed the ballance shaft housings, put the drivers side housing on the passengers side, and vice versa. The castings are the same, but the flanges that seal the oil inlet and outlet are milled to match the block so some milling or filing will be required. The castings are the same, but the feed and return holes are drilled on one side or the other (housing is a two part piece), and therefor swapping the drivers side housing set to the passenger side, and the passenger side housing set the the left results in castings that act as plugs. The "new" drivers side housing can then be cut down to the 3"x1.5"x1" chunk needed to plug the holes, and house the two mounting bolts (which will need to be shortened).

So, to do this you need to pull both ballence shaft housings off, clean them, measure, mill (or file), and re-install (with lots of sealant). Then throw away the ballance shafts themselves.

Make sure to install all the bolts in the oil pump/front main seal plate. One of the rollers seats against the aluminum plate and is required to maintain proper seal. Otherwise the front cover will weap oil.

-Owen

[740Weapon]

so i guess next time i go home im cutting the balance shaft belt off...

[lankytim]

so i guess next time i go home im cutting the balance shaft belt off...

Personally I would have preferred to leave it as volvo intended. They must have put balance shafts on for a reason! If my volvo didnt leak oil all over the balance shaft belt, and didnt scream all the time I think I would have left it well alone. Although my car is in good condition and has never let me down, it was cheap to buy and would not be worth repairing should the balance shaft belt fail and knacker the engine. Atleast now I KNOW the balance shaft belt cant fail, because its in the bin at home :rofl:

Do you have to remove the engine to remove the balance shaft housings and modify them? If I can find a scrap 16v at a breakers Ill strip the housings from that to modify then swap them round. Problem is 16v 740s and 940s are rare in the U.K, but you never know whats going to be dropped off at my local scrap yard.

[740Weapon]

i do not know how easy it is to remove a balance shaft, but i do know that making block off plates is really easy usually.

get some thick aluminum plate. 1/4" or more. and remove the balance shaft housings and drill holes in the plates to match the holes in the housings, and cut the plates to kinda match the shape. glue on with mad form a gasket.

[lankytim]

Ive just been told by a mechanic friend of mine that its dangerous to disable the balance shafts as they dampen a kind of engine viabration that is not noticed by humans. He says that when I go up the motorway either the crank or a cam will fail :( Hes not a volvo expert though so wel see. All I can think is the 16v is just an 8v engine with a different head and the 8 V doesnt have any balance shafts! If my engine does disintergrate Ill let the board know!

[oo4playmrright]

If my engine does disintergrate Ill let the board know!
< ---- :omg: i'll be holding my breath

:-P

[Alex Buchka]

Ive just been told by a mechanic friend of mine that its dangerous to disable the balance shafts as they dampen a kind of engine viabration that is not noticed by humans. He says that when I go up the motorway either the crank or a cam will fail :( Hes not a volvo expert though so wel see. All I can think is the 16v is just an 8v engine with a different head and the 8 V doesnt have any balance shafts! If my engine does disintergrate Ill let the board know!


thats a load of baloney. the reason volvo put balance shafts on the 16v was because it was the higher powered "luxury" redblock and they wanted to combat the inherent imbalance present in all 4 cylinder engines. the balance shafts are only there to smooth things out and removing them will have no ill effects. the crank or cams will not fail because you take the balance shafts out. if there was a risk of that then why does every single high performance 16v build up remove them?

[lankytim]

thats a load of baloney. the reason volvo put balance shafts on the 16v was because it was the higher powered "luxury" redblock and they wanted to combat the inherent imbalance present in all 4 cylinder engines. the balance shafts are only there to smooth things out and removing them will have no ill effects. the crank or cams will not fail because you take the balance shafts out. if there was a risk of that then why does every single high performance 16v build up remove them?

Wel see if its a load of baloney tomorrow, Im driving 250 miles to Glasgow in Scotland and its all motorway driving. If you dont hear of me every again then I guess it wasnt baloney after all!:rofl:

Im sure that there are some engines that have balance shafts inside them to smooth ultrasonic viabrations that can cause cracks and eventually failiure on various parts. A friend of a friend had a mitsubish (or was it a toyota) that had much improved peformance after the internal balance shaft was removed but after a week of so the crank snapped and completely destroyed the engine. I guess it depends why the balance shafts are there. Ive been told by alot of people that on B234 engines they are only there for comfort reasons, or to recreate the smoothness of a 6 cylinder. If thats the case theres no problem I guess!

[lankytim]

Just arrived home from Scotland and there was no problems whatsoever. 500 miles and the engine was sweet as a nut! Got 32 MPG too, which is an improvement as I usually only get 28 ish. The trip was mostly motorway driving at between 70 and 80 MPH with a few miles of A roads doing 30-50 MPH. I would imagine the difference must be down to less drag on the engine from the balance shafts. There wasnt any real noticable increace in viabration either. Worthwhile "mod". Thanks Michael!

[MikeSr.]

I did nothing to my car except remove the balance shaft belt and the cracked plastic housings.You can remove the shafts, plug holes, etc. if you want, but it isn't necessary. Just change the seals and the leak will be fixed. Why do a lot of unnecessary work? the seals are no more likely to leak if not plugged and changing the seals is easier than trying to plug them or remove them.

[740Weapon]

i removed the balance shaft belt yesturday.

the shafts definately reduce vibration above 4000rpms.

but nothing too serious.

i dont think the belt is going back on... ever.