Another dreaded Merc 3.7 (470) engine problem. Water in oil

[cclements716]

I did not smell any burnt rubber. I do feel like the engine sounded louder than it did when i owned it previously. (while we were under way) so it may have beeb slipping at that point and it them completely went... I dk. What are your thoughts on, while the engine is out of the boat, changing out the water pump gaskets, oil pan gasket, oil pump etc as a PM. The engine is in a 1988 JC Tritoon 266. If you have never seen one of these, the engine is in a hole below the deck. Its just wide enough to fit the 4 cyl, other wise i would be replacing with a 350. With it being in the hole it is near impossible to work on without removing the exhaust elbow and/or intake.

Personally i like the idea of these engines. Tons or torque and hp in such a small package, but everyone i have ever spoken with had problems with theirs. I am thinking about keeping this boat long term and would like something that is reliable. Whether that be i do a conversion and cut the engine bay to fit a 350, swap to an outboard setup or to a 3.0l which i am not really fond of due to the loss in hp from what i have now to that power plant.

 

[cclements716]

Went out to the boat this morning and thought about your comment. Had someone watch the output shaft as i turned over the engine. It was turning. Took the cap off the top of the outdrive and found that both gears are completely gone, i mean smooth. So i have priced a new gear set and they are some what pricey. Luckily i have found an entire outdrive (alpha one gen 1) from someone on craigslist for $500. So i think that this will be the route i am going to take. I have tried to upload pics but it says that they are too large

 

[Eric 3.7LX Alpha 1]

double posted.....

 

[Eric 3.7LX Alpha 1]

If everything is good with the new drive and it's the correct ratio, that's a good price. Buying used is always a gamble.

The lower on your current drive will have metal contaminating it from the upper gears so it would also have to be disassembled and cleaned out and reassembled, not worth the work and price to fix it.

You can also buy a new SEI aftermarket drive for around 1300 complete from here as well as other online sites. It will come with new u-joints and new impeller already.

Let us know how you make out....

 

[stonyloam]

Yeah, check the gear ratio, should be 1.84.

 

[cclements716]

I am about to head out and see if i can determine the gear ratio. Prior owner thinks it was a 1.84. If it is not what can be done? Could a prop change to correct the RPM fix the problem?

 

[nola mike]

If it was off of a 4.3, it's likely a 1.84. 3L is 1.98, the v8's are 1.50. Whether you can reprop depends on your new ratio, and what size prop you were running before. I was able to use a 1.98 on mine--I think I went from a 23p to a 25p. I don't notice any difference in performance between the 2.

 

[Joel Barton]

I have a Merc 470 that was getting water in the oil. I overheated the motor which caused the problem initially. First thing I did was replace all gaskets and seals on the water pump as they were bad., my problem still persisted. Upon inspection cylinders 3 and 4 had water in them. I replaced the cracked head with a re manufactured head. At his time lifters and push rods where replaced. Push rod were replaced with adjustable push rods to compensate for head milling and new vale height issues. Still had water in oil. Removed heat riser and there was a crack and hole allowing water to enter cylinder 3 and 4. After completing all repairs I have cruised for over 300 miles with no water in oil only a slight antifreeze leak on front cover which will be fixed. Hope this will aid someone with same problem.

PS Adjustable push rods can be purchased from Smith Brothers. The adjustment is 1 1/2 turns of push rod at zero lash from TDC. Insure all push rods are spinning with engine running.