Yanmar 1gm10 - Blue Smoke - Help!

[um saudade]

Blue smoke does not have to mean oil on a diesel. Black smoke means a good engine getting too much fuel and the excess fuel is turned to soot, but blue smoke can indicate incomplete combustion, usually caused by low compression. In very cold weather nearly any diesel will burn blue on #2 fuel but should burn clean after some warm-up time.

An engine running a 140 degree thermostat (raw water cooled) may burn blue at that operating temp and not at 180 degrees. Heat is where you find it and if the block is cold the resultant heat of compression is less. Enough less and the engine burns blue.

Sticky rings means low compression means blue exhaust but also more blowby.

Takes a lot of oil burning before you’re going to see the crankcase oil level go down appreciably.

Did you over fill the crankcase? Have to ask! Rods churning the crankcase oil create all kinds of issues.

Also you have the misting oil and whatnot from your work which is not yet out of the system .

No crud in the exhaust is going to crawl back into the valves unless the whole engine is upside down.


I would not loose any sleep until you give it a couple hours under load. It does not have to even go away; just getting better would indicate sticky rings loosening up.
Um Saudade

[Ex-Calif]

I think we all agree it's oil of some amount burning in the chamber.

I'd run it hard as planned and check back.

The rings theory is valid and a compression test may be in order if things don't improve. The stalling could be consistent with a bad cylinder.

It is not out of realm to have a broken ring or in rare cases the rings migrate circumferentially and if two gaps line up you could get blow by.

[rtbates]

IF your 1GM has been run in the past with a bad exhaust elbow you might have the same problem my 1GM had. And that was a hole in the head at the pushrod galley through to the exhaust port. seems a PO ran it with a bad elbow long enough for sea water to sit in the exhaust area after shutdown. Do this long enough and a hole is created..

[Solitude]

Well I took it out and ran it today. It constantly spit oil out with the exhaust and with throttle a significant amount of blue smoke. For 1 hour 2500rpm up to 3400rpm

I docked and checked the dipstick and of course it was lower than before. Probhably a deciliter of oil less .

Next I pulled the exhaust elbow off and checked the the exhaust port. It was slick and wet with oil.

Next I pulled the stop cable and had a buddy turn the engine over with the crank.

With a flashlight I can peer right into the exhaust port on the head and see the exhaust valve move. I could see wet oil. I then had the engine cranked over by by the starter. As the oil then pumped up into the head i could literally see it run out of the exhaust port and I believe from down the valve stem.

Looks like I need to replace the valve seals.

Couple of questions?

1. It probhably isn't rings right? The oil is new and still yellow when it runs out. The engine is only turning over enough to fill up the head with oil. Could it resonably be from anywhere else?

2. Its one cylinder and I'm mechanical. Would it make sense for me just to pull it off and replace the valve seals and pop it back on? I have a couple good shop manuals. Is there anything to be aware of?

or....

3. Should I be looking at pulling it off and taking it to a shop to do the work because they could do more things than I could in my garage...... (top end rebuild?) re seat (gind) the valves? Anything else I should get done to the head? Injector?


Thanks

[Solitude]

One more question. Since I dont see any oil in the intake. Could I just remove the vave cover, put the cylinder at tdc and change the exhaust valve seal?

[never monday]

Originally Posted by Solitude

One more question. Since I dont see any oil in the intake. Could I just remove the vave cover, put the cylinder at tdc and change the exhaust valve seal?

it's just too easy to pull the head, lap the valves and replace both seals.

[Solitude]

Thanks.

Is there anything else that should be done? Valve guides? Injector?

[never monday]

Originally Posted by Solitude

Thanks.

Is there anything else that should be done? Valve guides? Injector?

at 1400hrs, if you have a good machine shop near by. Have them go threw it. It might need a light ream of the guides but probably not. any raw water cooled head could use a good hot bath.

[Solitude]

Thanks.

Im going to pull it this weekend and take it to the shop. They said $45-$90 to tear it down. Measure it inspect and tell me whats (if anything) wrong. If I need to fix it the diagnosis is included. Does this make sense?

I thought I could also take a look at the cylinder and piston condition at the same time. Any Ideas on what to look for.

Carbon Buildup
Rust
Scoring
Etc

[Chief Engineer]

Although it takes an experienced touch, bring the piston to TDC and with your fingers pressing down on the center of the piston see if you have any side-side play,,,,it will be very slight.....it is just a eyeball test to check rings....

Reminder...you will need new sealing washers of your precombustion chamber and injector....3 copper and one fibre..IIRC

[Solitude]

Originally Posted by rtbates

IF your 1GM has been run in the past with a bad exhaust elbow you might have the same problem my 1GM had. And that was a hole in the head at the pushrod galley through to the exhaust port. seems a PO ran it with a bad elbow long enough for sea water to sit in the exhaust area after shutdown. Do this long enough and a hole is created..

Well I pulled it appart this morning. After removing the valve cover I poured a little oil in the top over the valves. Nothing came out...

Next i poured a little more over the entire area and all of a sudden oil started running out the exhaust port. Nice golden oil!

So i narrowed it down to the point of the exhaust pushrod area. Next I pulled the rocker arm, and push rods.

I poured oil in the pushrod holes and out it came.

So I have now pulled the head and yes I can see a 1mm little hole between the pushrod area and the exhaust port. There isnt huge pressure there.

This all makes sense since the exhaust elbow inner sleve was broken. When I scraped out the carbon I scraped away the last little remaining wall.
Its important to note that the exhaust mixer looked brand new on the outside. I would recomend everyone who has this engine to check often by pulling it off.

OK so now what.

Before I leave it at a shop.....

1 Can this even be fixed? Its a cast iron head. Welded? Plugged? Successfull or very temporary?

2 Can you buy refurbished heads?

3 Buy a new one? Leave it to be assembled at the shop with some of the old parts and new replacement parts where needed. Lapp the valves etc..

4 Yanmar in Vancouver charges double of that in the Seatle area.......Bring my old one down to a comercial vendor there and have him put it together and bring it home. Any suggestions?




Thanks for all the help so far..

[never monday]

wow, that sucks

look for a new used or new, new head.

[r.furborough]

Damn, bad luck.....

Hopefully you can get the hole welded as a head is a $500 item. The Yanmar part number for the head assembly is 728170-11700

[Chief Engineer]

Complete heads for these engines are very pricey.

$800 bucks is the price I have seen on a couple of the sailing sites......Don't jump on them right away...let some of us look for you.

[Solitude]

To make things worse Yanmar in Canada has even higher prices than what you have in the states.


Weld potential...
Its not a high pressure area or an area that is affected by torking down the head.
Its not a water jacket.
Its not between valves or at the top of the piston.
Its not a crack.
It looks to be in good shape (water jackets clean)


Chief and Never Monday I would really appriciate any contacts you may have for rebuilt heads. I think Vancouver is to small of market for finding one here.