Sea Water and Oil - How Much is Too Much for an Engine (2QM20)!

[Wotname]

Or put another way - how long can an engine drink sea water and still be an engine?

OK, it's sort of a rhetorical question but one I hope to answer as I attempt to recover/rebuild a Yanmar 2QM20 that had been ingesting sea water for quite awhile. I will be posting photos and the journey on this thread for anyone who is interested. At this stage I don't know if the engine is recoverable or not but I am quietly hoping it will be.

Some background; the engine was starting and running in 2016 but it had apparently been running with sea water in the oil. It is not known for how long except to say it was at least months and perhaps much longer. It was then removed and placed under a house for some 18 plus months at which time I purchased it where is as is for $50 (Nov 2018). The previous owner thought it might have had a blown head gasket and his mechanic tried to do a compression check but was unable to remove the injectors. Note, the previous owner had not been the person running it with the water/oil mix, that person was a previous previous owner.

Some pictures before any disassembly and also the emulsified water / oil mix I drained in Nov 2018.

FWIW, I am not a mechanic - that might become obvious very soon

[Wotname]

First job was to remove the head. The pictures tell the story the best. Looks bad doesn't it. Anyone want to speculate at this early stage as to the potential for the engine to be OK again!

After that I drained the oil and replaced the oil filter. Then overfilled the crankcase with diesel and circulated that by spinning the engine over with the starter motor (with the head off).

Rinse and repeat .

Then I filled it up with oil (and another filter) and then left the block (and pistons etc) sitting in the shed for 17 months.

Meanwhile I stripped the head and removed the injectors (which was a tough job). The story of the injector removal was told here https://www.cruisersforum.com/forums...ve-210170.html

[GordMay]

Yanmar 2QM20 Service Manual ➥ http://www.hunter37.com/Yanmar_3qm30.pdf

I encourage anyone, who downlaods useful documents, from links (links often go ‘dead’ with time), to then upload the document to our
CF Document Library Downloads: ➥ https://www.cruisersforum.com/forums/downloads.php

[Wotname]

The head cleaned up reasonably well. The valves were toast and the valve seats will need some serious attention.

The old head gasket looked OK and at this stage I believe the sea water was getting into the engine via the camshaft driven raw water pump. Note, there wasn't a RW pump with the engine when I got it.

The piston tops cleaned up OK and the liners look OK(ish) apart from the rust patch as shown in the #2 liner. I don't have a suitable inside cylinder micrometer so it will have to wait until the liners are removed and I send them to the machine shop for measuring. There was no lip at the top which is reassuring.

I think the head will be recoverable but the jury is out with respect to the bottom end. The big mystery will be the condition of the crank journals, the liner wear and the state of the injector pump.

[sailon46]

I my humble opinion you just kissed goodby 50$ you can use it for anchor.

[Squanderbucks]

Don’t waste your time.
Not to say it is impossible. Some really mechanical types with metal shop and fabrication experience can get anything running. But from a time and $ point get another project engine if a running takeout is too expensive.
There are always people Who repower their boats for a variety of reasons and the ones you can get from them are often good to go.
I have repowerd my boat a couple of times with running takeouts over the past 30 years and got many years of good service out of each.

[Boatyarddog]

Originally Posted by Wotname

First job was to remove the head. The pictures tell the story the best. Looks bad doesn't it. Anyone want to speculate at this early stage as to the potential for the engine to be OK again!

After that I drained the oil and replaced the oil filter. Then overfilled the crankcase with diesel and circulated that by spinning the engine over with the starter motor (with the head off).

Rinse and repeat .

Then I filled it up with oil (and another filter) and then left the block (and pistons etc) sitting in the shed for 17 months.

Meanwhile I stripped the head and removed the injectors (which was a tough job). The story of the injector removal was told here https://www.cruisersforum.com/forums...ve-210170.html

Be sure to have the block boiled, there's a lot of crust in this engine.
Hate to see you do all that work and spend lots of cash only to have it overheat due to corroded thin metal walls, as well the oil passages, with any rust left in them can come loose as your running it and cut off oil flow to the lower end bearings.
Risky, but I've seen it before, be VERY thorough in clean out.
Pitted liners need changing, and inspect the ring lands for proper fit to the ring sets,I'd change the Pistons as well.
It's probably not going to save money on a rebuild here.
And, as mentioned still the question of A High pressure injection pump, $$.
SV Cloud Duster

[PaulMarion]

As "Boatyarddog" said. However, the crankshaft and camshaft must be stain free, wasting your time if these are stained at all. Remember rust eats into metals and any stain on the above items will not come out, even after the cost of refacing. The block will also need refacing as also the cylinder head a complete rebuild. Cam followers, and all bearings replaced. Salt water ingress left in a motor over this amount of time does devastating damage to all surfaces. Liners must be replaced, as they will still have stains even if honed and rings will not seal. All can be done, however the cost must be counted BEFORE lashing out, as already mentioned. Good luck, Paul.

[Wotname]

Thanks for the replies and the cautions.

No need to worry about me spending any real money before I know what actually needs replacing and the time taken to put it apart - well that time is cost-free!!

I know the conventional wisdom is that the salt will destroy everything but I do wonder where that wisdom comes from. Is it just internet chatter repeated over and over?

For instance, is a stained crank journal really toast. If it still measures as new, surely a 25 thou regrind would be more than enough to suffice let alone a 50 thou regrind.

Not arguing for such a viewpoint but wondering aloud why (or why not).

[BeforeIDie]

It will probably clean up okay, you will get it running!
is it worth it? only you will know.
Good luck.

[jimbunyard]

Well, in my not-so-humble-opinion (and I know you don't operate this way), but based on the pictures provided, I'd offer even odds that I could get it running satisfactorily enough for in-sight-of-land use without buying anything much beyond valve grinding compound, some cleaning and polishing supplies, and whatever seals and gaskets are necessary to put it back together...

[Wotname]

You are a breath of fresh air JimB.
I will only need the head gasket and some oil seals - even I'm not going to try to reuse them. The rest I will make.

A picture of the valves. The exhaust one looks sad

[Wotname]

It is time to go deeper. I always knew that undoing the flywheel nut and the front PTO nut could prove difficult. The flywheel nut is 55mm and the front pulley is 24mm.

I didn't have suitable rattle gun sockets or a slugging wrench but I did have a long lever so long lever it was. The lever was about 6'.

The breaker bar was springy and got maybe a 30 degree spring in it before the flywheel nut yielded to the lever.

The flywheel also took some force and the home made puller only had a 12mm bolt doing the work. However the flywheel popped off just before the 12mm bolt stripped it's thread.

[Wotname]

Next was the injector pump. It came off OK but the rack didn't move - it had some rust build up!!!

However some diesel, a toothbrush and compressed air soon had it clean enough to move under it's own weight when tilted.

I not planning on going deeper into the injector pump until I know more about the condition of bottom end. Right now it is submerged in diesel.

[Jim Cate]

Here's another Jim who thinks it will run again. You nay-sayers don't know Wottie... I think of him as a Snao-On bulldog once he's into the shed.

GO WOTTIE!

Jim