Yet another “Water in Oil”

[DS_Hauger]

Greetings. New member, long time lurker. Have gleaned a ton of knowledge from this forum. Thank you!

3.0 Merc, 140hp (pre-‘90, 4 yr old reman engine), MC-1 (I believe) . 1973 Fiberform, 18ft.

Sooo... New to me “Great deal”, beautiful vintage boat etc, etc, etc. . Was really looking forward to joining this community and posting a few pics, background/history on this boat under much different circumstances. I will now save that post for a much later date...

Have owned this boat for 6 weeks. Went through just about everything. Had it starting/stopping hot and cold flawlessly, running beautifully, idle to WOT. Not a hiccup, ran very strong. Purred like a kitten. Was ecstatic.... Last outing found yellow, milky froth under the oil filler cap. A lot of it. Pulled dipstick. Frothy oil half way up the stick. Pulled transom plug, brown water..

Pressure tested cooling system. 20 PSI escapes within moments. Two obvious air leaks both sides of engine.. one near distributor/fuel pump, starboard, second one under manifold in vicinity of #1 Cyl., port.

Didn’t have the heart to compression test the cylinders... just sat down and cracked a beer. Actually two beers....

Question #1 - Should I even bother testing the cylinders? Or just pull the head and start the process.

#2 - I have a 165 hp merc and OD from another Fiberform of same vintage. Thoughts/advice on replacing the 3.0 with the 165? Feasible?

Thanks in advance!

~Jon

 

[Bondo]

one near distributor/fuel pump, starboard,

Ayuh,...... Welcome Aboard,...... Droppin' in the 470 would be a huge step backwards,......

Check what you've already checked, 'n use soapy water to pin-point the leaks,......

The starboard side of the block has no water passages,..??....... is the leak at the head/ block,..??

Head gaskets usually don't just blow out, without another "Reason",.....

 

[Scott Danforth]

yes, start with the compression test

then do a leak-down test

then drain the block and pressure test the block with and without pressurizing the manifold

agree with bondo, a 470 would be a giant step backward

if you boat in salt water, could just be bad manifold/elbow

if you ran over 4600 RPM for any length of time, you could have warped the head.

 

[DS_Hauger]

Appreciate the replies.

For clarification, the donor engine is the inline 6, 165hp merc. 250 cid, not the 4 banger 470. It’s actually in my fathers ‘76 Fiberform. That thing was a rocket back in its day. Solid engine. Not familiar with the 470, but understand it is garbage.

All fresh water boating, no salt.

Lil history... PO replaced the engine 4 years ago. Reputable company out of Wisconsin, I believe. I bought it this July. First outing/test run after purchase, it promptly overheated at idle before I got out of the no wake zone (5 minutes running). Cooled right down immediately with a little throttle. Replaced impeller & the stat. Never over heated again. Matter of fact, it’s running to cold now. Doesn’t even hit 140.

It has been at 4500-4600 rpm for a bit in the past few weeks.

I’ll get to soaping the engine, identify where these leaks are exactly, then compression and leak down tests.

Praying it’s only a warped head, not the block.

Thanks again. This forum is a literal goldmine of wisdom and experience.

~Jon

 

[DS_Hauger]

then drain the block and pressure test the block with and without pressurizing the manifold.

With and without pressurizing the manifold?

I isolated the block from the manifold. How do it pressure test WITH the manifold?

 

[chuckndiscs]

Following! I am starting work on my 4.3 with water in the oil as well. New boat to me. New problems for me too! BAH! In the end this will all be worth it.

 

[Rick Stephens]

If you have the room for it, the swap to the 165 would be a fun one. Needs new front motor mount with the longer motor.

You also can find a donor boat for cheaps with a decent 3.0L and newer outdrive. Toss the boat, swap the parts.

 

[DS_Hauger]

If you have the room for it, the swap to the 165 would be a fun one. Needs new front motor mount...

The more I think this through, there are two viable options. Rebuild the 3.0, or rebuild the 165 and swap it. The 165 will take a lil more work, but have the entire engine, out drive and associated mounts, wiring, everything... believe it’d be worth it. Put 100’s of hours out on the water with that 165. She’s pretty much bullet proof.

Not too mention, kinda liked the look on whippersnapper’s faces when their loud, expensive, newfangled, shiny wakeboarding, music bumping boat ate my wake. They’d always ask later at the launch “What’s in that boat??”

Aside from the engine, my ‘73 is identical to my father’s ‘76.. the swap should be pretty straight forward.

 

[DS_Hauger]

Following! I am starting work on my 4.3 with water in the oil as well. New boat to me. New problems for me too! BAH! In the end this will all be worth it.

I’ll post updates as I go. Let you know what I find. Next week I’ll check the compression and more than likely be pulling the head, but for now, parked it. Refuse to stay home and work on it this weekend. Headed to Montana to fly fish, from shore lol.

Have a safe weekend everyone! Safe boating.

 

[Rick Stephens]

Can't rebuild a cracked block. Don't waste your time trying.

 

[DS_Hauger]

Can't rebuild a cracked block.

Oh ok. Won’t bother checking any further, I’ll just yank the engine and take it all to the dump....