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Mercruiser lower unit noise

M

mixer_029

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"We have a older Sea Ray with

"We have a older Sea Ray with a Alpha 1 lower unit. We just replaced the gimbal bearing and all bellows (kit). After reassembly, first time in the water, we have a low rumble in neutral, after shifting into forward it gets worse as RPMs are increased. We aslo have a not-too-high pitched whine we've never heard before (coming from the lower unit). Gimbal bearing was lubed (aligned for grease)and unit seems to go into gear correctly in all 3 positions. Any suggestions would be greatly appreciated."
 
Yikes; those sound like expens

Yikes; those sound like expensive sounds!!
I would immediately drain the drive lube and check for metal.
Rod
 
"Ok...one more question before

"Ok...one more question before we tear back into it. The piece the gimbal bearing actually locks into (can't think of the term it's the "housing" or "race" in the transom) has been used on 2 sucessive gimbal bearings due to our inability to remove it. We have done everything short or removing the engine to replace this. However...there are no grooves or signs of wear. How important is it to change this along with the bearing each time? And last but not least...if the engine mounts are worn, will the gimbal bearing "pivot" a small amount to compensate for a small amount of offset?"
 
"Sorry....pick your brains on

"Sorry....pick your brains on one last symptom...LOL

After running at medium speed for about 10 mins, and the engine being shut-off, it seems as though the engine has a hard time cranking over (maybe as something heats up, it binds to "lug" the engine) We have a brand-new battery and when cold cranks right over. Does this sound familiar?"
 
"You can leave the gimbal reta

"You can leave the gimbal retainer in place and reuse it as far as I know, if it's difficult to get out. As long as the new bearing is snug you are good. The ring you are talking about is a kind of corrugated band, right?
You say this is the third replacement gimbal bearing? That sounds like excessive replacement and indicates poor engine alignment.
How would the engine mounts get worn? The rear mounts sit on double wound flat spring washers. Do you mean these washers are collapsed? You may need to jack up the rear of the engine (drive leg out) and replace these if they are old and flattened out. The newer Mercs have gone to trial and error shims instead of the srpings. Takes longer to set up, but maybe lasts better.
You need to check this with an alignment bar and get it fixed, otherwise you will continually be replacing gimbal bearings and U joints. Any misalignment causes excess side loads which tears these up fast.
You will likely find when you get the alignment right that the noises dissapear (hopefully!)
Hard starting when hot is apparently a common problem for the 4 cyl engines, if that is what you have. If its a 6 or 8 cyl this should not happen. May mean your oil is thinning out too much at higher temps and leaving you under lubricated.
Rod"
 
Rod - Wanted to say thanks for

Rod - Wanted to say thanks for the information! Greatly appreciated and I can't say enough good things about this forum to help "shade tree" boat mechanics!
 
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