95 Mercruiser 4.3 LX Vibration Issue/Alignment?

[AShipShow]

Hi all,

Fairly new around these parts and to boating in general. I purchased a 95 Stingray 606zp with a cracked block and just completed swapping the engine with a used 4.3 that's been "marinized"... I replaced the gimbal bearing while at it and used the alignment tool before installing the outdrive. It felt like I was chasing the alignment forever. I would get heavy spline marks on the top, so i would adjust the engine and then I would get heavy spine marks on the bottom etc. I got it to a point where the spline marks were fairly even and I was able to push the alignment bar in with two fingers. That being said, when I installed the outdrive, it didn't fully seat against the bell housing, it pushed on until there was about 1/4inch between them and i had to use the nuts to fully seat it.

1. Is this possibly because I replaced the o rings on the outdrive shaft and they were difficult to get through the gimbal bearing since they were new?
2. Does this sound like maybe the engine still isn't aligned?
3. I started it up on muffs yesterday and let it get up to temp and when revving up to about 3000 there was a pretty good vibration coming through the hull at around 1500-2500 rpms, could this be related to engine alignment?

When looking at the outside of the coupler from the engine compartment I cant see any run out when the motors running, it just looks stationary. Is there a chance since this boat sat still for 2 years that the u joints or coupler could have a "set", kind of like a belt that sits too long?

Appreciate any help, hoping to do the inaugural float test this week.

Thanks

 

[Rick Stephens]

Vibration can be a number of things - you touched on a couple good ones. I would suspect bad u-joints first. And alignment next. If set correctly, the alignment bar can and should just slide in with the barest amount of pressure. That also depends on the quality of the rear mounts. Those have to be perfect for a perfect alignment.

You did lower the outdrive before starting on muffs? And does turning the outdrive increase of decrease the vibration? I have replaced u-joits for making vibrations when turning when by feel the u-joints appeared in perfect shape. Replacement resolved that issue.

One test you can make is pull the outdrive, shove a cutoff hose in the water passage on the bellhousing and fire it up. If the problem is a balance issue on the motor it will still vibrate.

Rick

 

[AShipShow]

Yea, I was pleased with how easily the alignment bar was going in when I called it good. The outdrive was not fully lowered as it was on the trailer but it was reading about the middle on the trim gauge. I didn't try turning the outdrive left or right when the muffs were on, I was afraid the muffs might come off and I wouldn't know it, but I can try tonight.

I can try pulling the outdrive off again, as much as I REALLY don't want to for the 5th time in 2 weeks lol, but I guess its better than pulling it off so I can pull the motor to replace the coupler.

Is vibration like this a normal thing? Just wondering if I'm concerned over nothing since its my first boat.

 

[Bt Doctur]

You never need to "pull the drive on with the nuts" It should seat within an 1/8th inch if everything is correct..
What did you use to install the gimbal bearing and is it seated fully?

 

[AShipShow]

I put it in with a wood block I made so it would only push on the outer carrier... I'm pretty sure it seated, the sound changed while driving it and I gave it a few more whacks... If the bearing isn't totally seated, would that keep the drive from fully seating

 

[Bt Doctur]

Only if the shoulder on the inputshaft was pressing against it when you tightened the nuts to install the drive

 

[AShipShow]

If I pull the drive again, how do I check if the bearing is seated?

 

[AShipShow]

Also, is using a chain hoist on the center lifting eye a better method to align the engine? I've seen people just use the front mount nuts and some people do it the other way.. I was only using the nuts on the front mounts, I'm concerned that maybe the engine wasn't finding its own level and maybe its slightly skewed...

 

[Bt Doctur]

It depends, a chain hoist on the lifting eye will get you close, so you can "rough it in" the adjustment by hand but the final adjusting is done with the nuts
The lifting eye is most useful if the stringers are being replaced to locate the correct height of the new stringers

 

[AShipShow]

Okay, well I feel like I was very close before... Like I said, I was able to push the alignment bar in very easily, but the outdrive went on until there was about a quarter inch left to go... I didn't know if that could be the orings hanging up or what... I didn't think twice about it until I felt the vibration when running on the muffs.

 

[Bondo]

I didn't think twice about it until I felt the vibration when running on the muffs.

Ayuh,..... Welcome Aboard,..... Which flywheel did ya use,..??

The one from the blown boat motor,..??
Or the one that came with the new motor,..??

Did they look "alike",..??

The 4.3l has used some really weird flywheel balancin' over the years,...
One off a V-8, or I-4, or a Different 4.3l will fit, but won't be Right,...

 

[AShipShow]

Used the marine flywheel from the blown motor cuz to donor was an auto and only had the flexplate...

 

[AShipShow]

Just an update, pulled the outdrive tonight and messed with the alignment a bit more... I was able to install the drive without using the nuts which is good... While I had the drive off, I ran the motor as suggested above and the same vibration was present... Feels smooth as can be at idle, but from 2000ish to 3000ish the whole hull vibrates pretty good... Any ideas?

 

[Rick Stephens]

Pull your plugs, make sure all 6 are firing properly. Inspect your harmonic balancer at the front of the engine. Do a compression check. And if that doesn't get it, tune up and rebuild the carb.

Rick

 

[AShipShow]

I know the harmonic balancer is okay since I swapped it from the marine engine, but that brings me to another question... Do you think the harmonic balancer and flywheel could be weighted some weird way for a non-balance shaft engine vs a balance shaft engine? The marine motor was balance shaft and the donor motor was not, however I'm using the harmonic balancer and flywheel from the marine motor... Its just a thought I had.

I will also check your suggestions above.

 

[Rick Stephens]

I thought the balance shaft motor used a different harmonic balancer. That the non-balance shaft was a different diameter. Also the location of the timing marks can be different.

 

[AShipShow]

Yea, the harmonic balancer on the marine engine was larger, but I needed to use it because my v-belt pulley wouldn't fit the non-balance shaft motor. Do you think a larger diameter harmonic balancer could cause this vibration? As far as the timing marks, I manually found TDC on #1 and made a mark on the timing cover and then transfered the marks from the timing tab to have the 2? increments. I had to do this since I had to cut the timing tab off my timing cover since the harmonic balancer was larger.

 

[Rick Stephens]

There are so many combinations of block/balance shaft/balancer/flywheels that is makes your head spin. Example, easy reading history or the 262ci 4.3L Chev V6. I don't know what will happen combining the harmonic balancer off a pre balance shaft motor with a balance shaft. I don't know how they changed balance function/weighting between the balance shaft, flywheel and harmonic balancer. Undoubtedly someone around here with more brains than I though.

 

[xltier]

Yea, the harmonic balancer on the marine engine was larger, but I needed to use it because my v-belt pulley wouldn't fit the non-balance shaft motor. Do you think a larger diameter harmonic balancer could cause this vibration? As far as the timing marks, I manually found TDC on #1 and made a mark on the timing cover and then transfered the marks from the timing tab to have the 2? increments. I had to do this since I had to cut the timing tab off my timing cover since the harmonic balancer was larger.

I wonder if you could mount them up on a tire spin balancer somewhere and see if they spin the same.i know in the auto transmission business we see different configurations of crank balancing with the flywheels and torque convertors.some engines r balanced with the flywheel and some with the torque convertor.jat.

 

[AShipShow]

So, I've done some googling over my lunch break today and found plenty of evidence that suggests all 4.3s '86 and newer are EDIT: EXTERNALLY balanced... I have also read a lot of "pre-balance shaft 4.3s are shakers"... So I'm wondering if thats just the nature of this motor and the amount of vibration is normal... Plus being on a trailer and out of the water, I wonder how that affects things. So, I guess my question now is, if its externally balanced, are all 86 thru 95's balanced the same? Ugh, I really hope I don't need to pull the motor back out.