water in oil on f115 - yamaha mech stumpped

[afn63537]

2000 model f115 starboard engine went to dealer because of water in oil making foam. Got call from shop and they said we needed a new head (since he said they can't be resurfaced) around $2500 just for part - maybe $7k total probably into used motor. They suggested a repower at about $19k total.
So far, $400 or so in diagnosis charges racked up.
We picked up the disassembled motor the other day and asked the mech to show me the bad spot in the head or head gasket because I couldn't see any obvious blown out spots. He had the nads to tell me he wasn't sure if the head was bad because they didn't send it out to have it checked for cracks and that the leak could have been the oil pan or another place beneath it.. "not sure how the water was getting in"

We decided to change mechanics at that point.
My question is, how can I tell if the head is actually bad? Should I get the leak detector kit from Magnaflux I've seen online? What other parts should I look closely at before reassembly? If possible, I'd like to test twice and assemble once!!! I've rebuilt a lot of engines for motorcycles, but this is my first 4-stroke marine engine, and it's been used in salt water, so I know I need to look for corrosion problems. I saw one post where someone had an "internal" corrosion problem with the oil pan, so I know there are issues I wouldn't know to look for. If you can tell me the spots to check, I'd greatly appreciate it.
thanks
doug

 

[rodbolt]

Re: water in oil on f115 - yamaha mech stumpped

you can dye check the head, once the head is reassembled you can make a plate and remove the power head and pressure test the block/head assy.
then dissasembl the oil pan,clean all surfaces and check surface flatness with a .004" feeler guage. time consuming but not hard.

 

[afn63537]

Re: water in oil on f115 - yamaha mech stumpped

Hey Rodbolt,

Thanks for the reply and advice. just a couple of clarity questions, if that's okay.
If the oil pan surface has less than .004" anywhere, should it be okay? I read a post yesterday from someone with a reference to an "internal" corrosion problem that he couldn't see (somewhere below the oil pan gasket). When he mounted his powerhead on another engine's lower half (including another oil pan), the mixing stopped. I've looked over the pan and the plate under it and the housing under that, and don't see any obvious problems, but I'll do the .004" check on those surfaces as well.

since the head's off, should I check it for deformity also, and what will the gasket be able to handle. Was the mechanic correct that you can't resurface the head? I'm assuming there isn't a gasket that would make that possible by adding a little more material to make up for the aluminum removed.

From reading many of your posts for others, I'm guessing that I should take the old gasket from the bottom of the block and make up the plate you suggested out of aluminum. Is there a cheap aftermarket place to get some gaskets for doing the pressure testing that you know of? I'd hate to have to keep buying OEM gaskets to do the testing, and making my own from gasket material is almost as time consuming as making the test plate!

I'm meeting my brother from orlando tomorrow to pick up the magnaflux kit for the head test. what way would you recommend to clean it up before the test? Should I just concern myself with the combustion chamber surfaces and valve areas? Should I take the valves out and try and check the surfaces down in there?

I know I need to buy new head bolts for the final reassembly, but I'm planning on using the old bolts for the pressure checks, if that's okay.
how much pressure should I use for the checks?

thanks
doug

 

[AGENT 37]

Re: water in oil on f115 - yamaha mech stumpped

Hey Doug,

That was probably my headache that you read about. It was very challenging because the motor had been used in saltwater and likely never flushed. The head was corroded, I had it welded and milled (resurfaced). There was also corrosion through to the oil pan, that is where my butt really got kicked. I had that power head apart several times before figuring it out, every time I had to use a new pan gasket and head gasket. It was not cheap. In the end I was lucky enough to have access to a scrapped lower half that worked.

My advice would be to assess the serviceability of the motor before going too far into it. If it has 10 years of saltwater exposure without proper corrosion preventative measures taken I would only expect the problems to grow. How does the rest of the motor look? Is there a lot of rust, signs of corrosion, pitting, powdery residue? If it doesn't look good on the outside, it probably isn't much better on the inside. Did the inside passages on the head look clean and smooth or chewed up and pitted?

It may be a simple fix, but on the other hand there are numerous places that you can't see or gain access to for damage control.

I think that you can get a new F115 for $9k. You can get a used one in good shape for under $4k.

NADA guide says that your motor in good working order after repair is probably worth $2,620 to $2,945. What is it worth to you to get it fixed?

Don't let me discourage you though. I fixed mine but it took me 5 months of spare time and nearly $2k in parts. (I did a complete rebuild due to damage).

~Brandyn~

 

[afn63537]

Re: water in oil on f115 - yamaha mech stumpped

Hi Brandyn,

Thanks for the reply. It was your posts I had read. The engine looks good inside and out with expected surface corrosion. You said you used a different lower half. Did that include everything from the oil pan gasket down (including a different oil pan)? I've checked the oil pan out, but can't understand how it could be corroded bad enough to let the water in without being able to see it. When you said "There was also corrosion through to the oil pan", did you mean the pan itself was corroded through? Was yours corroded through somewhere other than a gasket surface? Rodbolt suggested that I check for surface deviations over .004". Would that have found your leak? Was the plate underneath involved in the leak?

thanks
doug

 

[AGENT 37]

Re: water in oil on f115 - yamaha mech stumpped

I Bolted the powerhead on to an entire lower end, oil pan, transom mount, lower unit, etc. The oil pan itself is $346.54 on boats.net.

The gasket surface was smooth. The corrosion was down where I could not see it, between the cooling passage and the oil reservoir.

I'd suggest leak testing the oil system with 10-20 psi. Once again, time consuming, but maybe you will be able to hear where the leak is coming from.

I might try taping off the oil pan to seal in and put just a little pressure in it to see if you can hear a leak. You could do the same thing on the head if it looks like the gasket surfaces are defect free.

 

[afn63537]

Re: water in oil on f115 - yamaha mech stumpped

I've looked at the oil pan closely and I think I understand where your problem was and your solution. The pan I have is so clean I can't even tell the difference between the oil passages and the water passages. Can't even tell it was ever in salt water just looking at these parts. I'll try both methods (pressure testing and gasket surface deviation) to look for a leak that have been suggested before reassembly anyway since I'd like not to have to pull it down again.
Do you have a source for inexpensive gaskets you'd be willing to share?
Thanks again for taking the time to help
doug

 

[AGENT 37]

Re: water in oil on f115 - yamaha mech stumpped

The passages looked clean on my motor too.

I don't any magic source for gaskets and they are kind of hard to shoplift.

I use boats.net for a lot of stuff because it is easy...... but shipping takes a long time and is expensive here in Alaska.

 

[afn63537]

Re: water in oil on f115 - yamaha mech stumpped

I appreciate the help you have been able to offer me. I've been offered a chance to go catch some grouper tomorrow, so I'll be swappin' my Snap-on hat for one with some fish hooks in it for a while. I'll get back to work on this as soon as I can, so until then, keep the water outside the hull.
thanks
doug