Newb w/ old boat - milky oil and rusty u-joints

[kar1179]

Hi folks - just bought my first boat and am looking to get it into reliable working order. The forums here have been incredibly helpful thus far, so big thanks to all the contributors.
I picked up a cheap old boat as I am happy to work on it myself and would rather make my learning mistakes on something of low value, and sure enough it I've already done so. 1994 merc 4.3L w/ Alpha gen 2.
Prior to first time out I went ahead and changed fluids, impeller, plugs, wires, rotor, etc. with the thought I should just assume this hasn't been done. I didn't dig any further before the first trip out.

Took it out and it overheated, both at low and high rpms. I'm pretty sure I stupidly didn't get the water tube lined up. It only got up to about 220F so I doubt I did any serious damage, but I'll be doing a compression test shortly.

Question 1: Took the drive apart for a look and found milky drive oil. Could this have been caused by a water tube not connected and thus water pressure blowing water past the shaft seal?

Question 2: I went ahead and took the upper unit off for a better inspection. Gears look ok, but the u-joints and double cardan assembly are all rusted. There is no water in the bellows so I am wondering if it previously leaked and was replaced. Any advice on what I should check/do? Just lube it up and put back together, or replace the bellows as a precaution?

Sorry for the long post, and thanks in advance!

-Kris

 

[harringtondav]

The milky drive lube isn't from your water tube miss instillation. It's from water entering the drive through bad seals or a broken lube monitor hose in the gimbal assembly. Rusty U joints point to a bad drive shaft bellows, maybe past. This can deteriorate the seal around the upper drive hsg. yoke and let water in.

I think your drive needs a complete re-seal job. This means a complete tear down. This means several special tools to disassemble and to set the seals. Get a genuine Merc. Alpha Gen II manual ($90-$100) and see if you think you're up to this. Sierra and others sell the tools under Merc's numbers.

It sounds like you're not afraid to dig in. The cost of the tools will pay off in time if you stick with boating. Good Luck.

 

[Alumarine]

Welcome, You can pressure test the drive to see what seals are leaking.

 

[Rick Stephens]

Make a pressure tester: https://forums.iboats.com/forum/eng...e-pressure-gauge-for-less-than-20-00?t=461923

 

[kar1179]

Thanks guys. I'll start with the pressure test and see what is leaking, and then consult the manual to see if I want to do just what has already failed or get a little more ambitious - which will likely depend on skill level required, cost of additional tools, etc.
And thanks Rick for that link, very helpful.

 

[tpenfield]

:welcome: to iBoats

As far as the u-joints and bellows. . .

pump some grease into the u-joints and see if you get any rusty grease coming out of them.

You can can inspect the bellows for signs of cracking or wear.

You will definitely want the Mercruiser service manual for the Drive and engine.

 

[KJM]

if you replace the u joints use automotive equivalent as they are cheaper and no different in my opinion. if the bellows are good then they shouldn't even get wet. i'd definitely do the pressure test instead of replacing all seals, don't fix what ain't broke. i was having water in my lower unit, turned out to be the shift shaft seal.

 

[harringtondav]

if you replace the u joints use automotive equivalent as they are cheaper and no different in my opinion.

If you pull a needle cap off the Merc/Sierra U joint, and pull the cap off the automotive 'equivalent' and compare the cross' trunion journal sizes you will see why Merc/Sierra cost more. 15% more bearing area.

 

[KJM]

that may be but my automotive ones have been on mine a few years now with no problems....

 

[harringtondav]

The alpha gen II is pushed by a 350 Mag, and is rated for 300 hp. I recon around 250-275 ft. lbs to torque max. So if someone has less hp. and doesn't go nutsy with full power hard turns, automotive U joints can last as you note. Sierra over Spicer, etc. is around $35 more per joint. I'll pay this difference on my 185 hp. 4.3LX, and not worry about my drive shaft coming unwrapped. That would really cost me.