Engine Out of Balance?

sleeperstang · 03-11-2003, 01:53 AM

I finally narrowed down a powertrain vibration to my engine. It's been there for a while, and to be honest, I only think has gotten slightly worse. I know that Ford S/B's are externally balanced.

As far as I know, the engine damper has some sort of rubber that after a while might move or shift or do something that would affect the engine balance. Would it be a good idea to replace this damper with a new one? I know 289 v8's use a 28 oz imbalance, so would it be safe to assume that all 28 oz dampers are made the same and are exchangeable?

Eventually I will have to rebuild the engine anyway, but at the moment I fear the vibration could get worse and may damage the block in the long run. What suggestions are there to repair engine vibration other than a complete rebuild?

Thanks!

trevor'72 · 03-11-2003, 01:43 PM

It is possible that the balance has changed it's balance. I'd buy a new 28oz imbalance and put it on. See what happens. Sometimes the ruber peice that's between the two metal parts will shift causing the wieght to be moved in relation to the other balanced parts. This would cause a vibration, and if not repaired it could be very costly. Oil pumps crack and stop working, and cracks in the block form usually first allong the pan rail. A way to see if this is FOR SURE the problem is to check the timing. My stock balancer after rebuild was found to be 1degree retarded. To check put the engine at TDC #1 (top dead center for cylinder #1) and wee what the timing pointer is pointed at. It sound be zero. But remember that the crank makes 2 turns for every 1 turn of the cam, soo it must be on the compresion stroke. To make sure it is the compression stroke, hold a finger/thumb over the spark plug hole after removing the spark plug and coil wire. DO NOT PUT YOUR FINGER/THUMB IN THE SPARK PLUG HOLE!!!!! Simply hold it over the hole. Have someone bump the starter or turn the balancer (a braker bar and socket makes this easier). When the pressure from that cylinder making compresion pushes your finger away it will be close to TDC #1. Make minor adjustments to make sure it is as exact as possible to TDC. Now look at the pointer. If it points to 0 you're balancer is fine. Unless it made one complete ratation which is highly unlikely because the balancer would have split in half and fallen apart by now.

have fun.

matt1190 · 03-11-2003, 04:30 PM

another way to check TDC is to use a straightened coat hanger and put it into the spark plug hole so that it rests on the piston head. turn the crank with a breaker bar and watch the wire move up until u reach TDC , recheck it several times to reassure yourself.

sleeperstang · 03-11-2003, 05:58 PM

I'm just going to go ahead and replace the damper and see how that works. I know that the dampers are supposed to go in only one way. Is there anything else I should know to smoothen out the process? I'll work with your suggestions after that to see how bad the engine is. Thanks for the replies guys, I really appreciate them!

nielsmobers · 03-12-2003, 09:58 AM

I have the same problem but with a '72 grandé. I've allready replaced the damper and it got a little better (I think... ), but the vibration is still there. At this moment I'm replacing the flex plate to see if this helps. It could be that damper, crankshaft, pistons and flex plate have to be balanced by a shop. I'm not an expert but I would be very careful with choosing a damper, they told me that you can only use one type.

Now you know that someone on the other side of the world has the same problem!

sleeperstang · 03-12-2003, 10:52 AM

Quote:

Originally posted by nielsmobers
I have the same problem but with a '72 grandé. I've allready replaced the damper and it got a little better (I think... ), but the vibration is still there. At this moment I'm replacing the flex plate to see if this helps. It could be that damper, crankshaft, pistons and flex plate have to be balanced by a shop. I'm not an expert but I would be very careful with choosing a damper, they told me that you can only use one type.

Now you know that someone on the other side of the world has the same problem!

Now, that's one thing I need to be sure about. I assume that all dampers, 28 oz imbalance would be built or manufactured the same, so I guess that you are referring to the difference maybe between later model 302's with 50 oz imbalance. Does anyone know if there are other possibilities with respect to 28 oz dampers? I'm going to go buy one today or tomorrow, so it would be nice to be sure. Thanks!! Glad to hear I wasn't the only person with this problem

trevor'72 · 03-12-2003, 12:40 PM

take your old balancer with you to compare!

make sure things like the keyway are the same size/depth, the bolt holes line up and that the physical size is the same. Although I don't know if one is even made, it is possible to have a larger/smaller balancer with the same imbalance. This might complecate the instalation of your pulleys etc. later. And finally you'll definately want to check the center bore diameter. When comparing it would be great if you had a vernier caliper (measure's very accurately) but not all that necessary cause if they look the same and are approximately the same bore then it will probably fit on the cranshaft.

Getting the balancer off is always a job and a half. but don't be afaid to realy beat on that piece cause you're gett'n a new one any ways.

One suggestion for reinstalling the new balancer that makes life a lot easier is to set the balancer in a sink and let hot water run over it for a while mabey 5-10 min. or so. be carful when you pic it up you might need gloves, it'll be HOT

After that it should just about slide on. Now use a rubber malot or rubber ended hammer and whack that balancer on as hard as you can... before it cools.

PS. make sure the keyway is lined up and has the key in it!

Also I know it is a lot harder to remove tha balancer with the motor in the car sooooo have fun.

mustangII460 · 03-13-2003, 05:34 PM

They are all the same and go on one way. your should have three holes for the lower pully. I think after 1969 the balancer was four bolts. 1981 went to 50oz.

Did you check your motor mounts? This is a easy inexpensive vibration fixer.

sleeperstang · 03-13-2003, 05:55 PM

Motor mounts were replaced 6 months ago and they still look good, so I don't think that's the problem, but thanks for the info on the damper.

matt1190 · 03-14-2003, 06:06 AM

A while ago I thought that my engine was out of balance too, it ran rough, but the motor only had a couple g's on it and it was properly balanced. It turned out as I was under the car one day, I had loose bolts at the collector which caused an exaust leak that was almost inaudible. I installed dead-soft alluminum gaskets and the engine has never run smoother!! Just an idea! Good luck -Matt

03-11-2003, 01:43 PM	#2
trevor'72 Registered Member Join Date: Feb 2003 Posts: 35	balancer It is possible that the balance has changed it's balance. I'd buy a new 28oz imbalance and put it on. See what happens. Sometimes the ruber peice that's between the two metal parts will shift causing the wieght to be moved in relation to the other balanced parts. This would cause a vibration, and if not repaired it could be very costly. Oil pumps crack and stop working, and cracks in the block form usually first allong the pan rail. A way to see if this is FOR SURE the problem is to check the timing. My stock balancer after rebuild was found to be 1degree retarded. To check put the engine at TDC #1 (top dead center for cylinder #1) and wee what the timing pointer is pointed at. It sound be zero. But remember that the crank makes 2 turns for every 1 turn of the cam, soo it must be on the compresion stroke. To make sure it is the compression stroke, hold a finger/thumb over the spark plug hole after removing the spark plug and coil wire. DO NOT PUT YOUR FINGER/THUMB IN THE SPARK PLUG HOLE!!!!! Simply hold it over the hole. Have someone bump the starter or turn the balancer (a braker bar and socket makes this easier). When the pressure from that cylinder making compresion pushes your finger away it will be close to TDC #1. Make minor adjustments to make sure it is as exact as possible to TDC. Now look at the pointer. If it points to 0 you're balancer is fine. Unless it made one complete ratation which is highly unlikely because the balancer would have split in half and fallen apart by now. have fun.

03-11-2003, 04:30 PM	#3
matt1190 Registered Member Join Date: Jan 2003 Posts: 66	another way to check TDC is to use a straightened coat hanger and put it into the spark plug hole so that it rests on the piston head. turn the crank with a breaker bar and watch the wire move up until u reach TDC , recheck it several times to reassure yourself. __________________ 66 coupe: 351W 30 over. Fiberglass shelby parts + flares

03-11-2003, 05:58 PM	#4
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	I'll.. I'm just going to go ahead and replace the damper and see how that works. I know that the dampers are supposed to go in only one way. Is there anything else I should know to smoothen out the process? I'll work with your suggestions after that to see how bad the engine is. Thanks for the replies guys, I really appreciate them! __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

03-12-2003, 09:58 AM	#5
nielsmobers Registered Member Join Date: Jul 2002 Location: Holland Posts: 28	I have the same problem... I have the same problem but with a '72 grandé. I've allready replaced the damper and it got a little better (I think... ), but the vibration is still there. At this moment I'm replacing the flex plate to see if this helps. It could be that damper, crankshaft, pistons and flex plate have to be balanced by a shop. I'm not an expert but I would be very careful with choosing a damper, they told me that you can only use one type. Now you know that someone on the other side of the world has the same problem!

03-12-2003, 12:40 PM	#7
trevor'72 Registered Member Join Date: Feb 2003 Posts: 35	balancer take your old balancer with you to compare! make sure things like the keyway are the same size/depth, the bolt holes line up and that the physical size is the same. Although I don't know if one is even made, it is possible to have a larger/smaller balancer with the same imbalance. This might complecate the instalation of your pulleys etc. later. And finally you'll definately want to check the center bore diameter. When comparing it would be great if you had a vernier caliper (measure's very accurately) but not all that necessary cause if they look the same and are approximately the same bore then it will probably fit on the cranshaft. Getting the balancer off is always a job and a half. but don't be afaid to realy beat on that piece cause you're gett'n a new one any ways. One suggestion for reinstalling the new balancer that makes life a lot easier is to set the balancer in a sink and let hot water run over it for a while mabey 5-10 min. or so. be carful when you pic it up you might need gloves, it'll be HOT After that it should just about slide on. Now use a rubber malot or rubber ended hammer and whack that balancer on as hard as you can... before it cools. PS. make sure the keyway is lined up and has the key in it! Also I know it is a lot harder to remove tha balancer with the motor in the car sooooo have fun.

03-11-2003, 01:53 AM	#1
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	Engine Out of Balance? I finally narrowed down a powertrain vibration to my engine. It's been there for a while, and to be honest, I only think has gotten slightly worse. I know that Ford S/B's are externally balanced. As far as I know, the engine damper has some sort of rubber that after a while might move or shift or do something that would affect the engine balance. Would it be a good idea to replace this damper with a new one? I know 289 v8's use a 28 oz imbalance, so would it be safe to assume that all 28 oz dampers are made the same and are exchangeable? Eventually I will have to rebuild the engine anyway, but at the moment I fear the vibration could get worse and may damage the block in the long run. What suggestions are there to repair engine vibration other than a complete rebuild? Thanks! __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

03-13-2003, 05:34 PM	#8
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	They are all the same and go on one way. your should have three holes for the lower pully. I think after 1969 the balancer was four bolts. 1981 went to 50oz. Did you check your motor mounts? This is a easy inexpensive vibration fixer. __________________ Frank

03-13-2003, 05:55 PM	#9
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	Motor Mounts... Motor mounts were replaced 6 months ago and they still look good, so I don't think that's the problem, but thanks for the info on the damper. __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

03-14-2003, 06:06 AM	#10
matt1190 Registered Member Join Date: Jan 2003 Posts: 66	A while ago I thought that my engine was out of balance too, it ran rough, but the motor only had a couple g's on it and it was properly balanced. It turned out as I was under the car one day, I had loose bolts at the collector which caused an exaust leak that was almost inaudible. I installed dead-soft alluminum gaskets and the engine has never run smoother!! Just an idea! Good luck -Matt __________________ 66 coupe: 351W 30 over. Fiberglass shelby parts + flares

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