U-joints and bellows 96/97 Volvo Penta SX Cobra, 1.66, what else to replace?

White90GT

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Jul 5, 2011
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I have a 1997 Chris Craft with 96/97 Volvo Penta SX Cobra drive setup, 4.3L Vortec V6 motor. The drive is a 1.66 ratio. I had the transom rebuilt last summer and did a tune up and the boat was great during the winter and first outing of the summer. Then I just replaced the lower unit due to a cracked housing by the propeller. I thought all was good, but early this summer when I took it back out a couple of times, there seemed to be more and more noise coming from the upper unit area, just kind of a clattering sound, but I didn't really get in the water and listen closely.

Once I got it home after the last outing, I examined the driveshaft and exhaust bellows and found that the driveshaft bellow was cut open in several places and there was grease reside all over the pivot housing where it was slinging it (I had recently added grease to the zirk fitting on the outside by the transom to see if it alleviated the noise).

I still had a spare stern drive from the complete drive I had picked up cheap to get the lower unit off of, so I decided to remove the stern drive from the pivot housing on the spare drive just to get an idea of how hard it was and whether I wanted to tackle on my boat. It wasn't too bad, just took a little persuasion to get the two separated, but it finally came apart.

So the boat has sat for the last month or two unused and I finally got around to messing with it today. I thought I was going to have to remove the pivot housing to get the bellows off, so I started and spent an hour or two going around trying to find an appropriate tool to remove the pivot bolts. A T-60 torx got one out, but was too loose to get the other out. Never could find the tool, so I tried using a half inch hex headed bolt and welded a nut to it that I could get my socket on and broke two bolts trying to get that pivot bolt out. I finally paused and decided to go back and look at that spare drive and see if I could get the bellows out without removing the pivot housing, low and behold you can. So I pulled the spare bellow out of the spare drive, now hands covered in grease I decided this would be a good stopping point until I can get parts ordered and here.

Now that you've read through the story, here's where I stand on questions:

The current u-joints on my boat actually all feel good except the very outside one that is towards the input shaft (motor side). One side of it moves free and clean with no noticeable play, but try to pivot it the other way and it is fairly stiff. It does move with a little force (not much, but it does take one hand to hold the rest of the u-joints still so you can pivot this one).
That said, do I need to replace the whole front u-joint, or is it possible to take this one apart and clean it up and reassemble with fresh grease? How much are the u-joints? If they are cheap like $50 or less then I guess I would go ahead and replace it. Are they any harder to get separated than an automotive u-joint? Any tips for removal?

Next: Obviously the driveshaft bellow has to be replaced, no big deal, where can I find that part number and is Iboats.com the best place to order?

How about the exhaust bellow? It doesn't look bad at all, but if it's cheaper than maybe $40 go ahead and do it? Part number?

Anything else I need to look at replacing while I've got it apart this far? Where is the gimble bearing? Can it be replaced without removing the pivot housing? What seals to I need to get before putting the stern drive back on? Do I need to replace any of the nuts for the stern drive or the trim cylinders? I didn't mess any of them up, can they just go back on with some blue Loctite?

Please feel free to comment and suggest other things I need to do while it is apart.






 

j3rry

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Aug 2, 2014
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change the bellow,ujoints and the gimbal bearing while u got it that far torn apart. usually when one goes out the other is not far behind. ur joints and gimbal don't look to good in shape in them pictures, good luck
 

dypcdiver

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Nov 1, 2005
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1,018
Firstly the "U" joints look shot with so much corrosion they must have been like that for some time.
They are easily serviced/replaced just the same as auto ones. If you do a search on here you will find details regarding the part numbers of the internal circlip "U" joints that you have.
I made up a tool to push out the caps of the one nearest the outdrive you can then take the rest of the input shaft and work on it on the bench. 2 bars of steel with holes at the ends that can tale 2 lengths of threaded rod, a small socket to push and a larger one to receive the cap is all you need. A "G" clamp is all that is needed to replace them.

The gimbal bearing can be removed with a 3 legged puller and a slide hammer, as can the seal behind it. Some suggest that the seal is not needed, but it is the last stopper of water entering the boat should your bellows fail again. My boat sits on a mooring so I think it is well worth replacing. Have fun.
 
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White90GT

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Are there any automotive u-joints that are the same? Any particular reason they have to be "marine grade" u-joints when they are surrounded by the bellows and air-tight?
 

White90GT

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OK, this is the list of parts I've compiled, am I missing anything? Part numbers are from boats.net (first site I found when googled the engine number that had microfiche parts diagram). Anything I am missing or don't need? 3850812 U-joint $45.35 3852565 O-ring for u-joint $1.40 3854127 Bellow u-joint $48.59 3850426 Bellow exhaust $34.71 3853807 Bearing assembly u-joint (gimble) $63.13 3852548 Seal driveshaft $14.57 3852560 Seal water passage $2.80 3852352 Water inlet hose $14.92 $225.47
 

White90GT

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Marineengine.com is a bit cheaper because it has some aftermarket stuff, what are yall's thoughts on using aftermarket (looks like Sierra is manufacturer)?
 

White90GT

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boats dot net and marine engine dot com were two vendors I've looked at, about to price iboats
 

White90GT

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thanks dypcdiver for the link. I've tried parts searching iboats.com but it appears all they sell are accessories and maintenance items, couldn't find the above part numbers. I'll look for other vendors that support the site as well. What are everyone's thoughts on using non OEM parts like Sierra? Looks to save over $60 if I go with Sierra stuff vs OEM.
 

White90GT

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Have the Sierra Bellows been known to have issues lasting? How long do they typically last? My boat never sits in water overnight, its just a little 17 foot ski boat, so we don't stray to far from shore with it much. Just local rivers and lakes. That said, I don't want to risk ruining the new transom if those bellows are known to go bad within a couple of years. My current bellows are the original and 14 years old!
 

skydiveD30571

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There are/were a couple veteran Volvo mechanics here who really insisted on going with OEM u-joint bellows due to premature failure of aftermarket versions. And it is such an important part since failure usually results in an expensive repair. With that said, I've had great luck with Sierra parts for everything else.
 

White90GT

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Well, I got the new seal, gimble bearing, and u-joint and exhaust bellows installed. New gasket on pivot housing and new u-joints installed on driveshaft with new O-rings on the shaft as well. I started to stab the drive last night, but was having a lot of trouble. After an hour or so of trying to stab it, I gave up for the night and figured I'd attack it either this evening or tomorrow. Any advise on re-stabbing the drive? I'm not using a lift, just have it on a rolling furniture dolly with some boards and straps keeping it upright, then I have the front of the boat trailer on the ground and am using a floor jack under the back of the trailer to raise/lower the boat/pivot housing while I wiggle/wobble and try to stab the drive. Is it just a really tight fit or what? I know it was hell to get it apart in the first place, but it eventually separated. I guess I'm going to have to call a buddy over to help me stab it for some more muscle. Any tips/tricks/advice on stabbing the stern drive are welcome. I did grease up the driveshaft, u-joints, and even put some grease around the housing where it fits into the pivot housing to help slide things into place. Right now it seems to be stuck with the housing inserted into the pivot housing at the point where the 6 mounting bolts are just barely touching the holes where they go through the stern drive. They appear to be lined up well, just can't push it in any further by hand.
 

Sparkinator

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Aug 15, 2009
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Don't grease the o-ring on the drive shaft. The grease can be a problem. Just use oil on the o-ring. Greasing everywhere else is OK.

I've had to bump my crank from inside the boat with a breaker bar. the get the teeth on the coupling to align with the teeth on the drive shaft. Make sure that isn't the problem.

I almost always have help when installing my drive.
 

bruceb58

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Mar 5, 2006
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Did you check the alignment with an alignment tool?

I can install the drive myself but I have a stand that it sits on. Way way easier using a drive stand.

This is the one I made for mine:
IMG_0729.JPG
 

White90GT

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Bruce, I did not check alignment with tool. I assumed since the motor and gimble housing wasn't moved that everything should still be aligned. I didn't mess with it last night, water heater at home sprung a leak, so I had to spend my evening jacking with that.
 

bruceb58

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You always check alignment when you take the drive off. Get a tool off of Ebay. They are pretty inexpensive.
 

White90GT

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Can you measure the tool and give me the diameters and length? I don't really have time to wait on ordering one and it to come in, perhaps I can make something that will work?
 

White90GT

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I got it back together and tested. The out drive hasn't ran this quiet in many years. Should have replaced those u joints sooner. My guess is I knocked them out within the first few years by running the motor with the drive trimmed up, not realizing that when the motor spins the drive shaft and u joints spin, no matter if it's in neutral or not.
 
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