Engine Vibrations

[AussieBronco]

My engine is vibrating to the stage where it shakes the whole Bronco. The engine is new in the Bronco being a 5.0 out of a Thunderbird. When I did the conversion there were no vibrations, and then it appeared after about 2 months of driving and gradually got worse (I think). So I thought it was possibly the clutch or the flywheel bolts from when I put the new flywheel on (T'bird was an auto) as I didn't use any lcoktite. I just removed the transmission, clutch and flywheel and nothing looks out of sorts here.

When I got the engine I never pulled it down, rather thought I'd just see how it went. When the car is in neutral it still vibrates as when I have my foot on the clutch so I don't think it is the transmission (NP435). Does anyone have any ideas or recommendations on what might be the problem and where I should go from here? Thanks

 

[brewchief]

Are you sure the flywheel and harmonic balancer are correct for the engine? Ford has changed the off balance over the years.

 

[JSBX]

I had the same problem with a 79 F-150 with a 302. The problem turned out to be a bad harmonic balancer.

 

[AussieBronco]

I'm pretty sure I have the right flywheel as I got a 50oz one so it would suit the 5.0 harmonic balancer. Also it was running smoothly for the first could of months.

Can a harmonic balancer go bad? I didnt know this. I think this should be the first place I should start.

 

[bluesbish]

check oil level!! overfull causes vibrations.

 

[AussieBronco]

I checked the oil and it's not too high. Is there anyway to tell if the harmonic balancer is bad? Is there anything else I should consider before pulling the balancer?

 

[EricLar80]

The outer ring is attached to the inner ring with rubber. It looks ok in the picture, but you should grab the outer ring and make sure it is on tight.

Are you sure that you have a 50oz harmonic balancer? What year motor are you running?

Eric

 

[AussieBronco]

I am running a 93 thunderbird motor. I have not changed the balancer, so I'm assuming it is the 50oz balancer. The weird thing is it ran smoothly for probably 200 miles before it started vibrating so I find it hard to believe it is the wrong balancer or flywheel, but I'm sure weirder things have happened.

 

[DirtDonk]

Assuming it's the right damper and flywheel too has anything else changed recently? Any work to accessories or a recent tune-up of any kind? Presumably not too, since you only have a few hundred miles on it, but I thought I'd ask.
When a friend's harmonic damper's outer ring literally fell off while on the way home from Wild Horses one day, we pulled it out of harms way and drove the rest of the way home without issue. No vibrations at all. So based on that, and the fact that yours looks good, I'd say it's not the balancer/damper.
Not disputing what JSBX said though. Just that in my case it caused no vibrations.

So first off, double/triple/quadruple check your plug wires firing order. Just in case some "friend" decided to mess with you and change your wires around.
Does the '93 T-bird engine use the 13726548 order like most late-model engines did? Or was it one of the hold-outs that kept the old 15426378 order for a little more time?
Just checkin'.

Run the engine for a few minutes without the serpentine belt (or v-belt?) installed. That will eliminate any of the front accessories from the mix. Not likely to cause major vibrations, but you never know.

If that's not it, re-install the belt(s) and, while it's idling and vibrating, pull one plug wire at a time to see if any one or two make no difference in how it feels. If a cylinder is working properly, your rpm level should drop and/or your vibration should get worse. If you get to a cylinder that is dead, you won't feel much, if any change.

If that doesn't yield any new info, pull the valve covers to see what the valves are doing.
Did you leave the motor as-is? Or did you change the cam for another? Presumably it's still a roller cam?

Good luck.

Paul

 

[AussieBronco]

Hey Paul,
I haven't checked the firing order, but I will when I get home, just incase a "friend" did change it around. For some unknown reason it does have the old firing order. When I first set it up I could only get it to fire on 4 cylinders, and then tried the old firing order for the hell of it and it ran smoothly. I never even considered it to be a ignition issue as the vibration was so harsh and it never smoothed out at high RPM. So that is a great idea.

I have never touched the cam, so I'm assuming that is not the issue.

Another thing I though I'd check with you guys is when I pulled the bell housing the header was pressed hard against the bell housing. Do you think this could attribute to any of the vibrations?

Finally would it be safe for me to run the engine without the transmission hooked up with just a jack under the sump. I would leave the fan off. If this is reasonably safe I see this helping me in two ways, it makes sure it has nothing to do with the transmission and it lets me test all these other avenues without having to wait until I put the transmission back in.

Thanks for all your help

 

[Bronco717274]

It won't hurt to run it with the trans disconnected I've done it several times but only at idle. Look at your flywheel and see if any of the weights have come off. I agree with other guy check and make sure it's not missing on one of your cylinders.

 

[Rustytruck]

If this only happens when your driving I would be looking at motor mounts and drive shaft. Make sure to check the slip yolk and that it isnt frozen in place.

 

[AussieBronco]

I'm pretty sure it is not drivetrain related as it vibrates from start up in neutral and will not let up under any conditions. However thats why I want to start the engine without the trany hooked up.
Cheers

 

[John Marinan]

If this only happens when your driving I would be looking at motor mounts and drive shaft. Make sure to check the slip yolk and that it isnt frozen in place.

X2 on the motor mount. May look good but be torn in half. I had that problem on a toyota. It vibrated like crazy.

 

[Mill KNOB]

Looking from the picture you have a 50oz balancer. Make sure your flywheel is a 50oz. But if it just started it might be that there is a bolt coming lose in the pressure plate section.

 

[AussieBronco]

So I put the flywheel, clutch and bell housing back in and started it up without the transmission and any of the accessories hooked up. It still vibrates like crazy so hopefully I'm down to ignition or the motor mounts, but I won't be able to see if it's the mounts until I get the transmission back in. I doubt it will be as they too have only done 200 miles. Thanks everyone for your help so far.

 

[DirtDonk]

With regard to the mounts, I'm thinking that unless the interlocking steel parts inside somehow are now in direct contact with each other (pretty unlikely I'd think), the only other failure that would allow this much vibration would be the complete separate of the rubber component. And even when that happens (over half a bazillion miles or so) you might not feel a vibration all the time.
And if the rubber has split or separated from the plates, you would see it when the motor twists, so you could theoretically see it by rocking the engine front-to-back while watching the mounts. Should be easy to do with everything else disconnected like it is.
At least that's what I think. I'm no motor-mount expert by any means, but they seam straightforward enough.

Usually then, with a full-time vibration like you're describing, if it's not something internal to the engine, then it sounds a lot like something hard touching the body, or maybe even the frame.
The header touching the bellhousing won't do it, but a header touching the frame or firewall would. So would the back edge of a valve cover, or EFI upper plenum hitting the firewall. But it sounds like you would have seen something along those lines by now.

So, with all that, can't wait to hear about your next step in the narrowing down process!

Paul

 

[dan1]

Did you ever figure out what the vibration was? I have an 89 5.0 from a mustang doing the exact same thing.

 

[Rustytruck]

maybe this information will help.
http://www.damperdoctor.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=DD&Category_Code=CAS#Ford

 

[desertoasis2b]

I had a bad vibration in my 93 bronco 5.8 I found the problem when the fan mount flange on the water pump seperated from the shaft, destroyed the radiator , shroud and fan