Yanmar Issues Still

[gasngo]

Well I thought I would do a quick bit of research on WWW and quite a few Yanmars require a valve adjustment. Does yours? I did not take the time to determine if that specific motor needs valve adjustments. If you have a manual I would think it would be in it? If the valve or valves are really tight that could drop compression with leakage around them. If you can get your hand on the rockers with the cam unloaded and there is some free play then they are not that tight if they dont have any movement at all then they could be keeping the valve open slightly which will leak and drop compression.
As you have said the blow by is high which brings the ? back to overall condition of the motor. A compression test will determine a lot. Confirm no fuel leaks either pressure wise or suction wise after that its time to do some testing. I have over 20 years Mercedes Benz repair experience and a lot of diesel and the death of one is low compression. Eliminate that ? before you chase a ghost. Good luck
Brad

[Charlie]

Have you tried doing a leakdown test? This will help u pin down a leak in the cylinder. I just bought a new toy and am dying to try it. U probably know this but u put the cylinder to.tdc on the compression stroke and then fill the cylinder w/ 100 psi of air. Then listen for where/if the air escapes. Exhaust or intake means leaky valves. Oil fill tube is rings (I think) radiator is head gasket. It is a great diagnostic tool. The one I have is fitted for spark plugs so a different fitting would need to be made probably to go thru glow plugs

[sailorchic34]

I checked and adjusted the valves and a bunch of fuel related things today. Nothing I've done has fixed a thing. The high crankcase pressure and oil burning to me anyway point to rings or a head gasket. I was hoping that its some little minor thing, but the more I think about it, the more I think the head has to come off.

Being a girl of very little means, a shoestring sailor, spending $100-$200 on a compression test, well lets just say I'd rather spend that $200 on rings, AFTER I pull the head. OK have a friend pull the head as I can not budge the big head bolts at all.

Though I'm going to check the secondary filter and a few other things first.

[gasngo]

Well I understand the $$ shoestring part for sure. I just got a bill for my Cobra stoker motor machine work at the tune of around 1800 bones. {SPUN A BEARING} Not what I wanted to deal with plus a minor restoration on a sailboat. Make sure the motor is drained well before you pull the head off. Im not sure you will see any evidence in the cyl walls since it runs. If you can drain and keep the area clean and try not to bang up the head gasket during removal. If you know someone who can look at it a really read it well to see if there is any evidence of internal leaks that would give you some confidence that a replacement might be all you need. Forgoing a comp test and diving in is what it is but if it is rings then the motor will need to come out. At that point the ? will be do a full rebuild. As I said good Luck.

[Cheechako]

The head removal is easy on those engines. My head was removed twice before a good mechanic determined it was a piston. If I remember right, about 30-45 minutes had it off the time I removed it. I'd start there, likely a piston issue causing all that blowby, not sure how a head gasket would do that.... If a piston, you need to get to it before you score the cylinder wall.

[sailorchic34]

Well that's odd.

This morning I tried starting the engine. Set the throttle to 1/2 cranked for about 10 seconds and the bugger started right up. Ran it for a bit and shut it off. 15 minutes later I tried starting it again with 50 percent throttle and the little bugger started up within 2 seconds.

Still smokes at startup a little light grey smoke. Also noted a tiny bit of black smoke, just enough to see it after the engine was warmed up at idle.

Maybe all that fussing about yesterday tightening fuel lines and bleeding did some good. Bet I still have high blowby.

Just went out and started it again. OK 50% throttle seems to be it. Odd it would not do that yesterday.

Yes, I'm confused.

[Boracay]

With a 1000 hour engine I'll put my money on glazed bores.

Propeller and running conditions don't seem to have been mentioned but if the engine is under propped (always reaches full rpm easily), synthetic oil has been used and/or it's been run for long periods under a light load these would be clues.

My suggestions would be to always run the engine at 80% power and a full load and to change to quality straight 30 weight (not multigrade) diesel oil. Yanmar would have a recommended specification.

[dannobee]

I'm not convinced that the problem is rings, especially when you say one cylinder "catches," then the others come online. I'd pull the injectors and have them pop tested. I could see a failed injector causing high blowby as the fuel just runs into the cylinder before it's supposed to.

When you say "light gray" smoke, is it white? White smoke (and verify that it's not just water vapor) is usually a pretty good indication that an injector has failed.

If you have access to a bore-scope camera, you can certainly look into the cylinders when the injectors are out and see if the cylinders still have a nice crosshatch pattern or are scored or glazed.

[sailorchic34]

Originally Posted by Boracay

With a 1000 hour engine I'll put my money on glazed bores.

Propeller and running conditions don't seem to have been mentioned but if the engine is under propped (always reaches full rpm easily), synthetic oil has been used and/or it's been run for long periods under a light load these would be clues.

My suggestions would be to always run the engine at 80% power and a full load and to change to quality straight 30 weight (not multigrade) diesel oil. Yanmar would have a recommended specification.

The boat is a bit over proped and don't use synthetic oil. Oddly enough I just purchased a gallon of 30 weight shell rotella T1 oil. I'm thinking it could be glazing also. Going to try the Itallian tuneup, I'm thinking...

Really the engine is a bit oversized for my 25' water line. If It was a 2gm20 I could run it at 80% no problem. But most of the time it's happy at 2200 rpm. Plus I get cavatation at 80%. Probably due to the aperture prop.

[s/v Jedi]

@SC: I would pay $200 for the compression test PLUS a camera down the cylinders to check out the walls. When that is done and fixed I would pull the injectors and have them serviced.

I know it costs $$ but you will be much happier having checked it all and knowing you can rely on it again

[charliehows]

Originally Posted by Boracay

With a 1000 hour engine I'll put my money on glazed bores.

Propeller and running conditions don't seem to have been mentioned but if the engine is under propped (always reaches full rpm easily), synthetic oil has been used and/or it's been run for long periods under a light load these would be clues.

My suggestions would be to always run the engine at 80% power and a full load and to change to quality straight 30 weight (not multigrade) diesel oil. Yanmar would have a recommended specification.

+1 above
You can, to some extent, tune the engine as you run it - give it a warm up/cool down period; as above, load the engine, but also vary the running pitch; change the oil a bit more frequently for a while; run it up to full power under load for bursts once its well warmed up.
My old dog is very sensitive to any variation in starting procedure - you might be onto something experimenting with that...
Not that any of that will help if some little nasty irritating bit of something has gone wrong somewhere in there...

[sailorchic34]

Originally Posted by dannobee

I'm not convinced that the problem is rings, especially when you say one cylinder "catches," then the others come online. I'd pull the injectors and have them pop tested. I could see a failed injector causing high blowby as the fuel just runs into the cylinder before it's supposed to.

When you say "light gray" smoke, is it white? White smoke (and verify that it's not just water vapor) is usually a pretty good indication that an injector has failed.

Actually today all cylinders are firing using 50% throttle at cranking, Started the engine a half dozen times and it was firing on all cylinders. May have been a vacuum leak at one banjo bolt that was a tad moist yesterday. Also bleed the system after I found the loose bolt.

Nope its grey smoke which clears after running. Was looking at the exhaust today and it was light blue smoke, just a little at idle after the engine was hot. Though that could be the few oz's of 2 stroke oil I added to the diesel. Read it somewhere that a dab of 2 stroke oil can help with sticky injectors. Will keep an eye on it.

Ok its true, I do play with snake oil from time to time. I'm thinking the 1970's design of the 3gm series may not be all that happy with the ultra low sulfur diesel out now a days. Thought the 2 stroke oil, might add back a bit of lubrication. Plus the light ash as it burns might assist to deglazing. We will see.

Please note that this is NOT an approved additive and only crazy blonde engineering chics would even think it was a good idea.

[lateral]

I reckon gray is low compression until it comes up with lube.
Mine does that @500hrs.
Black if I overload it. Same with all the 4x4's I've had.

I add 1 litre of benzine every 5 tanks in the truck.
If it works, do it.

[sailorchic34]

Originally Posted by s/v Jedi

@SC: I would pay $200 for the compression test PLUS a camera down the cylinders to check out the walls. When that is done and fixed I would pull the injectors and have them serviced.

I know it costs $$ but you will be much happier having checked it all and knowing you can rely on it again

I have rebuilt injectors on my list for santa. Though he's horribly unreliable now a days. .

Call me hard headed, lord knows it will not be the first time, but with oil usage and high blowby with oily smoke, its pretty much a given that there's a bit O'wenching in my future. Though I'm betting its glazed walls. A compression test will just tell me, what I already know.

I'm actually not too worried about the engine. To me its reliable enough, and I've got those sail thingies, if it get persnickity on me. Really it runs like a top. Now that its starting reliably again, I'm a happy camper. Maybe its a blonde thing. I also use to drive around without a spare.

[Blue Crab]

Good read.