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

[Rod B]

Who'd love boats if they didn't love a challenge?

[PaulMarion]

I don't doubt the motor can be made to run again at all. However as a retired mechanic with 55 years experience I quickly learnt that doing patch ups on motor rebuilds always came back to bite you. Stains on cylinder bores from water ingress always caused oil consumption problems, as rings won't seal because rust creates porosity in the metal. Often a rebore won't remove that and I found that a bore and resleeve was the answer, if it was only on one cylinder. You can also manage with a stained crank too, however I always built motors that I guaranteed to last, no short cuts. After all, who wants a motor that "might fail" when they're crossing the Wide Bay Bar? Not me, or any one else for that matter, and I've seen it happen more than once too. Very different from just having your car stop down the road and being able to call the RACQ to help out. That's where I'm coming from. Hope all works out well for you. Regards, Paul.

[Wotname]

Thanks for your insights Paul, they are appreciated. One of the great aspects of CF is there is always some trade professionals willing to share their accumulated knowledge.

And thanks for the Wide Bay bar reminder! I have fond memories of my first crossing sometime in the mid 80's when I was still a banana bender!

[Wotname]

Well, the crankshaft is out now! The only thing left in the block are the liners but that is a job for another day.

I have mixed feelings about the engine at the moment. The crank journals clearly need some work and the bearings (rod and main) are toast. I will seek advice from the local well respected engine machinist regarding the crankshaft journals.

The pistons measured up surprising well. All the principle measurements (diameter, ring lands, ring gap) came in around about 50% of the wear limits. No measurable wear in the piston pin (wrist). No measurable wear in the oil pump. There is some staining on the cam lobes and tappet faces.

The pictures are self explanatory (I think).

[Reefmagnet]

I'm following this thread to see if either mine or your motor ever make it to rebuilt stage! I reckon a bad head gasket or perhaps even jacket corrosion has let the water in on yours rather than a failed water pump. Here's my confirmed raw water pump long term leak damage for comparison. The main difference is the timing gears have copped a hammering but the combustion chambers are fine which is kind of the inverse of the damage on your donk.

[Wotname]

Originally Posted by Reefmagnet

I'm following this thread to see if either mine or your motor ever make it to rebuilt stage! I reckon a bad head gasket or perhaps even jacket corrosion has let the water in on yours rather than a failed water pump. Here's my confirmed raw water pump long term leak damage for comparison. The main difference is the timing gears have copped a hammering but the combustion chambers are fine which is kind of the inverse of the damage on your donk.

Yes, your logic has some merit. I had expected to see more rust on the camshaft and PTO gears. I was rather surprised how good they were.

I had thought the damage to the head was a result of it sitting unattended for a year or more with the milky oil still in it but now I am not so sure. There wasn't anything obviously wrong with the head gasket and there are certainly no cracks in the head or the top of the block but perhaps there was a leak from a water gallery into the pushrod / injector pump side of things. Certainly there is enough rust in that area to be suspicious of that possibility.

The water pump leak idea originated because there was no other oblivious leak and because the water pup had been stripped down when I got the engine. Be that as it may, it is not confirmed.

I had discounted a leak between the water area of the block area the oil area as being too unlikely but as they say - never assume. I do need to look more carefully at the cast iron block and confirm it's integrity before opening the wallet ().

[Wotname]

OK, the liners are out.

It took me a day to make up a liner extractor from scrap stock which was lying around and maybe half an hour to remove them.

I was pleasantly surprised about how little scale was in the block and on the liners.

However I am now more worried about not finding the smoking gun for whatever caused the water intrusion in the first place. The next step will be removing the scale in the water side of the block and then testing the block for the "water side" integrity.

Probable method of testing will be to refit the liners (using existing O rings), refit the head with some temporary sealant in lieu of a head gasket and fill the water side with water and pressurise with a household mains pressure hose. Look for leaks .

Unless someone can suggest a better / easier method ???

[Compass790]

I'll see you two Jims & ( dunno if raise is the right word, some might say lower, lol) raise you a compass.
I'm not there but certainly looks like it should be a goer. I think your first priority should be to do the injection lines tho
Good you got the rack moving freely, good chance it will be ok if bottom roller ok too. Hate to think what Yanmar would want for a 2QM20 injection pump but probably around 2k $ Aus. I'd guess.
Gunna enjoy following the saga as you write a good yarn with good analysis AFAIK.

[Wotname]

Update!

After cleaning the scale from the upper parts of the block, I temporary refitted the liners in order to pressure test the water side of the engine. I used to old packing (O rings) assuming if the old O rings sealed OK now, then new ones (in the future rebuild) will also seal OK. Roofing silicone sealant was used in lieu of a head gasket. Again assuming that if the cheap silicone sealant held the water at bay during testing, then a proper head gasket would also seal OK.

The water side of the block and head was filled to the top and left for a hour without any leaks. I then sealed the system and fitted the air hose and set the regulator to 10 psi. This was slowly increased to 90 psi and left for another hour.

Still no leaks .

Finally after a 30 mins at 110 psi, a few drops of water started to appear inside one of the liners - the silicone sealant "head gasket" had finally let go. This was hardly surprising and for sure, a proper head gasket would have held.

There were no leaks anywhere else which was encouraging and proves the integrity of the cast iron block and head - at least it does to my mind.

After this successful test, I turned my attention to a problem that has been hanging around for about 18 months. Removing the pre-combustion chambers. . These have been stuck in the head ever since I managed to remove the injectors - which was an epic battle and well explained here https://www.cruisersforum.com/forums...ve-210170.html

The pre-com chambers have been soaking in ATF/acetone mix for some months (both sides) so today was show time. I heat cycled them several times but unfortunately I only had a MAPP gas torch - my mate with oxy/acetylene is away . I used more ATF/acetone for shock cooling. Then a large hammer and a brass drift was brought into service.

After destroying the brass drift, I admitted defeat!

I need more heat but that isn't about to happen anytime soon so I will have to take it to the engine shop - which is no real hardship. The head has to go there anyway for sorting out the valve seats/ guides etc.

So the next step is to take the liners, crankshaft and head to the machine shop for a professional assessment and see what they have to say!

[Malabarista]

Thanks for a really instructive read. Good on ya.
Dave

[Wotname]

Thanks Dave, good to hear someone somewhere is reading this and is enjoying the ramblings.

I am always open to criticism although I do prefer constructive criticism rather than the other sort. If anyone has a better way of doing this sort of DIY on the cheap backyard rebuild, please shout out!

[Reefmagnet]

Hitting stuck bits that are only going to be thrown away anyway with an arc welder does a pretty good job of getting them to release. I use 2mm rods at low amps for this kind of stuff.

[Wotname]

Originally Posted by Reefmagnet

Hitting stuck bits that are only going to be thrown away anyway with an arc welder does a pretty good job of getting them to release. I use 2mm rods at low amps for this kind of stuff.

Thanks for the reminder of the arc welder as a great source of heat, ReefM.

At this stage I am hoping to reuse the pre-com chambers so I won't explore that avenue yet.

This begs the question though - why remove them? Clearly they won't be leaking and it is highly likely there is nothing wrong with them.

But... pulling them out and having a decent look and refitting with new seals seems so much more satisfying - at least emotionally!!!!! A sort of do it right the first time kind of thing.

[Reefmagnet]

Originally Posted by Wotname

Thanks for the reminder of the arc welder as a great source of heat, ReefM.

At this stage I am hoping to reuse the pre-com chambers so I won't explore that avenue yet.

This begs the question though - why remove them? Clearly they won't be leaking and it is highly likely there is nothing wrong with them.

But... pulling them out and having a decent look and refitting with new seals seems so much more satisfying - at least emotionally!!!!! A sort of do it right the first time kind of thing.

I hear what you are saying. I suffer from the same affliction.



If you search for Free Range Sailing on youtube, I'm pretty sure Troy pulled something similar from the head of his engine and had a bit of a video on it. It was from the time they were at a Townsville slipway about 18 months ago. There might be a tip or two in there you can use.

[Compass790]

Originally Posted by Wotname

Thanks for the reminder of the arc welder as a great source of heat, ReefM.

At this stage I am hoping to reuse the pre-com chambers so I won't explore that avenue yet.

This begs the question though - why remove them? Clearly they won't be leaking and it is highly likely there is nothing wrong with them.

But... pulling them out and having a decent look and refitting with new seals seems so much more satisfying - at least emotionally!!!!! A sort of do it right the first time kind of thing.

Ya must be reading my mind Wotname as my question was gunna be why mess with the pre-coms if all the holes are clear?
However it just reflects a different approach.
Good news on the water test.
Did you try a drift & hammer on your v/v guides?