Hi all,
I have a 740 GLE 87'at 156K. I have vibration at 2000 rpm on 4th gear. I didn't try it on lower. You can easily hear the noise and feel the vibration. My rear wheels are old. But i don't think that they can cause a vibration like this. I hope it's not the shaft.
If you have any similiar problem and solution or any opinion please respond. Thanks a lot...

Volvo introduced the so-called "hydraulic" engine mounts in '87. When they fail (and the DO fail), you'll get excessive engine vibration in the car. The engine sags slightly, so the pan will sometimes rub on the crossmember.

When the mounts failed in my '91 740 at around 150k, or so, I got an annoying "humming-drumming" vibration in the car at highway speeds -- 2500 rpm and above. For me, the engine noise was not offensive at lower engine speeds.

Look at the space between the pan and crossmember -- it should be at least 1/2" or more. If less, the mounts are failing.

Replacement is not difficult, although it's easiest done by removing one of the mount brackets from the crossmember (left side, I think).

The mounts aren't cheap. Check with FCP Groton for prices.

Many months ago we had a BB'er who tried to change the mounts on his 240 and, evidently because of an inability to think, damaged his oil pan. He jacked the engine up with a wood block directly under the drain plug and then wondered why his plug was pushed in. Of course, he thought it was our fault that his pan was dented.

For this reason I am not recommending for or against you changing your own mounts. A really good way to fix this problem is to take your car to a reliable Volvo shop. However, many BB'ers would probably attempt this straightforward, 1-hour repair themselves.
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Don Foster (near Cape Cod, MA)

Thank you for your long response. What can happen if those mounts aren't changed? Can they cause serious damage? Thanks...

"What can happen if those mounts aren't changed? Can they cause serious damage?"

A good question -- and I don't really know. However, I've seen mounts so bad that the pan was scuffing the skinny rubber pad on the cross member. In other words, it was sitting on the cross member. It's possible that a pan might wear through after enough scuffing..... I certainly would.....
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Don Foster (near Cape Cod, MA)

Where is it coming from? Can you pinpoint at least the direction?

Also, have you ever replaced your engine mounts?
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

It's hard to say but I can hear most of the noise from front. I didn't replace the engine mounts. Is there anyway to point out the problem? How can I test it? How can I say that this is an engine mount problem? Thanks...

have they ever been replaced? see the post from Don above for a bit more information.

if they've never been replaced, you're definitely due in. having an engine sitting too low is bad for a bunch of components in your car, including your drive axle and your exhaust.

for my 90 740, i picked up the mounts for about $68 a piece (you need 2) i believe fcpgroton has it for even cheaper than that. i think you need the hydraulic ones. don't get the wrong kind (solid rubber)

if that doesn't help the vibration, that's okay, you didn't really 'waste' any money since it's a 95% chance that you were due in for a change anyway. :-)

i had my mechanic due it for about an hours worth of labor, which isn't too bad.

another way to check to see if you do need to replace it is to look at the position of your engine's fan relative to the fan shroud (the surrounding plastic thing that it sits in) if it's not roughly in the center (too low) then you need to replace the mounts

if it's rubbing or there are rub marks on the bottom of the shroud, then you definitely need to replace it (the mounts)
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

I don't know whether they have been replaced or not. But I have checked the position of the engine's fan relative to the shroud. It looks fine and there is no scratch. There is at least 1/2" space.
Do you suggest to take the car to a Volvo service? May old rear tires cause some of the vibration? What about the shaft and the bearings?
Thanks a lot...

it's not that there should be space. it's that the space around the entire fan (top and bottom) should be roughly the same all around.

try Don's procedure for checking the clearance of your engine and then see how it goes.

i don't see how old rear tires could cause vibration unless you busted a steel belt inside of one or it's not balanced.

as for the shaft and bearings, i'm don't know about that, so someone else will have to take you up on that :)
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'