Mercruiser 3.0L / Alpha one leak through transom?

elwood206

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Jun 4, 2008
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16
Hello everyone,
I just picked up my first boat a few weeks ago, it an 1986 sunbird 175 with a mercruiser GM 140 3.0L alpha one outdrive, its not the prettiest thing on the water and im slowly repairing what I can, but I think its a decent first boat.

I noticed a leak last time I had it out on the water, I killed the engine to drift around a bit and heard a faint trickling coming form the engine compartment. I opened the compartment and found water leaking in from a small machined hole near the water inlet tube, I wasn't sinking fast and The bilge pump got most of it out but it didn't stop leaking even with the engine on, I have the muffs for it and ran it at the house for a few minutes, not water in the bilge at all, So I connected a small dia. tube and fed water in to the small hole, hoping to see it shoot out the back of the boat and identify the leak. The water didn't come out the back of the boat, It sounded as if it was coming back IN underneath the engine?

Any ideas anyone?

Here is a picture of the hole where water was trickling in

100_3978-1.jpg


Ive got the clymer manual, and didnt come across any reference to the hole, I probably could plug it up, but Im afraid its a witness hole trying to tell me I have water somewhere it shouldn't be.
 

Fishermark

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Oct 19, 2003
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5,617
Re: Mercruiser 3.0L / Alpha one leak through transom?

Ive got the clymer manual, and didnt come across any reference to the hole,

Problem #1 - Ditch the Clymer and get an OEM - there are links for an online manual.

but Im afraid its a witness hole trying to tell me I have water somewhere it shouldn't be.

Problem #2 - Well, I've never heard of a "witness hole" - ;) but you're right. It's telling you water is somewhere it is not supposed to be. Specifically the drive bellows. Here is a picture showing where it is leaking from - without the engine in the way:

ventholetransom.jpg
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,321
Re: Mercruiser 3.0L / Alpha one leak through transom?

Pull the drive ASAP. sounds like a bad boot. It`s already cost you a gimbal bearing, U joints are next, then the carrier seal and yoke.
 

elwood206

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Jun 4, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

Thanks for the help guys!

So I need to pull the sten drive off the rear I take it?
Ill look into getting an OEM manual, just spent about 30$ on the clymer :mad:
I dont hear any grinding when steering, is there any chance at all of possibly bieng in time to save the gimbal bearing?
When you pull the drive off, do you replace seals as nedded or do them all at once?
 

jerryjerry05

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May 7, 2008
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18,052
Re: Mercruiser 3.0L / Alpha one leak through transom?

Pull the drive and inspect.The amount of damage might be slight(fresh/salt water)The gimbal might be ok .Reach your hand in and spin it and if it feels ANYTHING other than smooth then replace.Inspect it and get back to me. Jerry
 

elwood206

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Re: Mercruiser 3.0L / Alpha one leak through transom?

Its been run in fresh water it whole life as far as I know, Ill probably try to rig up a stand or hoist for the outdrive and pull it, probably should replace the torn exhaust boot while ive got it off.
 

Fishermark

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Re: Mercruiser 3.0L / Alpha one leak through transom?

Ill probably try to rig up a stand or hoist for the outdrive and pull it,

You certainly need to pull it, and while a hoist might be nice, it shouldn't be necessary. The outdrive is heavy... but not that heavy. What does it weigh? 80 pounds or so?
 

elwood206

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Jun 4, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

Yep, bout 75 according to the manual, so probably no sling needed yet. Looks like the outdrive is only 6 bolts and the trim actuators, but what its attached to might need to come off too, is that the "bell housing?" Need to order order the tool for special bolts.
 

Fishermark

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Re: Mercruiser 3.0L / Alpha one leak through transom?

Yep, bout 75 according to the manual, so probably no sling needed yet. Looks like the outdrive is only 6 bolts and the trim actuators,
Yep - (well, six nuts, not bolts ;) ) - also make sure the unit is in forward gear when you remove it.

but what its attached to might need to come off too, is that the "bell housing?"
Yep again. It will need to come off in order to replace the drive bellows. You ought to replace the gimbal bearing and shift cable and bellows while you're at it.

Need to order order the tool for special bolts.

If you want to order the special tool, go ahead. If not, you can use a 1/2" allen wrench. From the sound of it, most of the Mercruiser mechanics even use that instead of the special tool.
 

elwood206

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Re: Mercruiser 3.0L / Alpha one leak through transom?

If you want to order the special tool, go ahead. If not, you can use a 1/2" allen wrench. From the sound of it, most of the Mercruiser mechanics even use that instead of the special tool.

That good news, I just pickued up an allen wrench set with a 1/2 bit!
I will probably order a transom seal kit, looks like it has a gimball bearing and all the bellows I need, do yo recommend the use of the bellows sealant?
and that quicksilver 2-4-C multi lube grease that called up everywhere, is that something special or just rebranded marine grade grease
Thanks for all the Help!
 

elwood206

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Re: Mercruiser 3.0L / Alpha one leak through transom?

Transom seal kit should be on the way soon, outdrive came off pretty easy, thanks again for then manual links. There was water in the boot when I pulled it off, so I guess the leak must be at the top of the boot somewhere :confused: ? gimbal rolls pretty well, just a little off totally smooth so I guess I might as well replace it while I'm in there. U joint looks ok as far as I can tell, anyone see anything obvious that damaged or should be addressed in the pics?

100_3982.jpg


100_3985.jpg
 

bigbob_FTW

Petty Officer 1st Class
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May 10, 2007
Messages
290
Re: Mercruiser 3.0L / Alpha one leak through transom?

looks like your in pretty good shape. I'd just do the gimble bearing and bellows.
 

Fishermark

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Re: Mercruiser 3.0L / Alpha one leak through transom?

Looks good! I see freshwater stuff so little that I forget what things look like when run in something other than saltwater. The damage would have been MUCH greater here in our salty sea.

While you're at it, I would go ahead and put a shift cable and boot on as well. Easy to do with everything apart. That makes it: gimbal bearing, drive bellows, shift cable and boot. I would normally even suggest replacing the shift shaft bushing with the newer type.... but from the picture you seem to be good.
 

MIsearay

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Jul 6, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

fishermark, Over this past weekend while my boat sat in the lake it filled up with some water, after I pulled the boat out and inspected things I see the shift cable boot have some holes in it. Is this most likely my trouble? I pulled the stern drive off and also see the end of the cable is fairly corroded. Is it possible to replace without tearing anymore apart? any input would be great.
I also see you are from port charlotte,Fl my parents have a place in alligatorpark in puntagorda just south of you, thanks again, Aaron
 

MIsearay

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Jul 6, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

Also when I pulled the stern I had a lot of white milky oil come out, is that normal? I can take pics if needed, Is there a recommened place to order the parts from?
 
Last edited:

Schillio

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Jul 6, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

The milky oil from the lower unit is gear lube. The fact that it's milky indicates that water has been/is leaking into areas it shouldn't be. The gear lube should be clear-looking and blue in color. When working on your other fixes, be sure to replace that with a fresh quart. It's not too difficult, but can be a bit of a pain. You'll need a special hand pump (also the oil) and fitting to be able to do it - something I'm sure your local marine shop would have for $10 or so.

Good luck with the rest of it!
 

MIsearay

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Jul 6, 2008
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Re: Mercruiser 3.0L / Alpha one leak through transom?

where do you think the water might be getting in at, the ujoint and exhaust bellow looks good, the shift cable one is shot for sure, is this where it got in at?
 

Haut Medoc

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Jun 29, 2004
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10,645
Re: Mercruiser 3.0L / Alpha one leak through transom?

where do you think the water might be getting in at, the ujoint and exhaust bellow looks good, the shift cable one is shot for sure, is this where it got in at?
Welcome to iboats.....:)
I suggest you start a new thread with your specific problem & what year your drive is.....
You do have a problem if you have milky oil in your u joint bellows....
You need to drain & inspect your gear lube, & if milky, you will need to pressure test & see where the leak is....
A leaky exhaust bellows will have no effect with regards to water getting in the boat.....
The shift cable boot will....;)
 
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