Smoke but no fire...Yanmar SB8

[braol]

So...after bleeding my engine until well after the cows came home I have progress, sort of. Now I have eliminated all bubbles from the system and am now getting some diesel smoke out of the exhaust. My Yanmar still won't fire up but at least I know that something is going on inside there.

Has anyone had success with starting fluids of any kind to help get it hot in there? My engine is a non-glow plug diesel so it needs all the help it can get.

It looks like I might start the season with a kicker motor hanging off the back...:cry:

 

[stollo770]

Hey Barol. I have had this same problem with my engine, except it eventually ran. I had all your symptoms, heavy smoke coming out of the exhaust, long start times, and a delayed throttle response. The only difference is my smoke only happened when I throttled up to harshly, then the exhaust pipe would puke up thick black smoke and black water for about 5 seconds before returning to normal.

What I did to solve this problem was a complete tear down of the engine. I'm sure you were hoping for an easier solution, but the job is easier then you think. All you need to do is expose the valves and the cylinder inside the engine. Your not removing the piston, your not changing any settings. I found that my valves had so much gunk on them they didn't fully close (or close tight enough) and in addition to that, there was rust on the top of my piston. So I cleaned everything with degreasing fluid from Autozone and got the rust off the cylinder and presto! It took hours of work and a shocking amount of crap was removed but the engine fired right back up and ran like a dream. I also added no-smoke (for diesels) to my oil to try and cut back on the exhaust smoke when I throttle up quickly. There is still smoke coming out of the exhaust, because its exhaust, but I don't get any more of that super thick black stuff. The engine was pretty easy to put back together, I just labeled everything and remembered what bolt went where and in what sequence. Not rocket science at all.

I also found that the reason why there was rust on my piston is because the inside of my exhaust elbow had turned into dust. So every time I started the engine, small amounts of water from the cooling loop would backwash into the cylinder. It took some doing but I eventually found a replacement (perhaps the last in NJ) from a Yanmar dealer down the shore.

 

[braol]

Was re-timing the engine required?? I don't mind taking off the cylinder head, I just don't want to go down the retiming hole because I don't particularly like the manual I have. All the pictures are blurry so it is hard to discern what is what in the diagrams. I can see myself getting the thing apart and then back together only to have the timing out of whack and no way to get it right again.

Just out of curiosity, how much of the valves could you reach after removing just the intake scoop?? (I have visions of sending a flexible Dremel/drill extension down the intake.)

 

[Benny17441]

Just a few ideas;

Is the diesel fuel fresh and free of water?

Did you bleed the high pressure pump?

Is the engine cranking fast enough? Help it by opening the throttle all the way and using a well charged battery. In cold weather pre-warm the engine with a heater.

Was the engine starting and running OK before? What changed?

Replace fuel filter and drain the water separator.

Remove the oil dipstick and place your hand over the tube as the engine is being cranked, a nil to low air flow is desired as a high flow indicates compression loss by blow-by through the piston rings. Turning the engine by hand can also give you an idea of the amount of compression. Refer to your manual for the proper direction of rotation.

Not familiar with the SB8 but would think it is an overhead valves engine with pushrods. Removing the head will not alter the cam position and all you would need to do after replacing the head gasket would be to re assemble and adjust the valves clearance.



Good luck.

 

[Ralph Johnstone]

You may ultimately be faced with all of the above, however I would suggest you start with simplest ($$$) things first as suggested by Benny. The mixing elbow is always a source of problems. These engines are built like a brick shirt house and more often than not, it's something simple that is causing the problem.

 

[braol]

Just a few ideas;

Is the diesel fuel fresh and free of water?

Did you bleed the high pressure pump?

Is the engine cranking fast enough? Help it by opening the throttle all the way and using a well charged battery. In cold weather pre-warm the engine with a heater.

Was the engine starting and running OK before? What changed?

Not familiar with the SB8 but would think it is an overhead valves engine with pushrods. Removing the head will not alter the cam position and all you would need to do after replacing the head gasket would be to re assemble -and adjust the valves clearance.

-Fresh diesel.
-Fresh filters all around.
-Racor separator all new.
-Bled the whole system for you-don't-want-to-know how long...
-Two brand-new batteries. Cranking like a charm.
-Getting a little grey/white smoke out the exhaust while cranking (didn't get any smoke until whole system was bled).
-Engine last ran about 3-years ago (like a champ).
-Mixing elbow and whole exhaust/cooling water system refurbished (by me).
-After I posted earlier I sort of figured that as a pushrod engine (thanks for the reinforcing info though), reassembly would be no big deal. I rebuilt the engine myself in my old BMW 6-series...how hard could this be?!

-I have heard the suggestions before about pre-heating, but that doesn't boost my confidence. What happens on Lake Michigan in September when I want to go sailing and it's 50 degrees overnight like it is now??? No, it should start without preheat (just like in the good old days). It sounds like I might try: 1)some starting fluid/spray, 2)get someone to disassemble and clean my injector (I can't get it loose for the life of me), 3)remove and clean the head. Between these three items I should have success...I hope!

 

[kito]

You may ultimately be faced with all of the above, however I would suggest you start with simplest ($$$) things first as suggested by Benny. The mixing elbow is always a source of problems. These engines are built like a brick shirt house and more often than not, it's something simple that is causing the problem.

I was even going simpler so don't kill me Is the de-compression cable in good shape and activating the lever on the engine?

 

[Redbeard33]

do not use starting fluid on a diesel!!! it will likely crack your rings, without a preheat system i have trouble getting it (2QM15) to come to life in cold weather sometimes too. try decompressing the engine and letting it spin like crazy with no fuel, after the friction has warmed it a bit try again as normal. also i have had great luck with a hairdryer preheating the injectors and fuel lines in the winter however that only works to start it dockside.......

 

[Redbeard33]

if all else fails you can use WD40 to help jump it back to life, its more flammable than diesel but not enough to blow by your rings

 

[Amos Cape]

I had the same problem so I changed out the injectors. It runs like a dream now. Cost around $200. But it was worth it. I also pulled the exhaust manifold and mixing elbow to check them and they were good. Changed the diesel fuel out with all the filters. All before the injectors were replaced.

 

[Benny17441]

I agree it should start without pre-heat and at 50F there should not be a problem. The concept of pre-heating the engine has to do with the thickness of the oil. The engine will crank easier and faster when the engine is hot or in hot weather. When cranking a cold engine compression is built up through a succession of revolutions which is why cranking speed is so important. As we know diesel fuel heats up and ignites when compressed. Speaking about oil thickness, a thick oil will help increase compression by better sealing the gap between the cylinder wall and the piston rings. It will reduce blow-by in worn engines and help them start. Don't know what oil your using but I would recommend 20W-40 for the SB8. Did you try turning the engine by hand? It is the easiest way of determining if there is adequate compression to start with. I know you do not want to hear anymore about the fuel delivery system but if a solution is not found elsewhere I would remove the fuel line that goes from the high pressure pump to the injector and crank the engine to make sure there is fuel shooting out of that pump. ( In the past I have seen the plunger on these pumps get stuck after a long lay over). You should not have to bleed again as the air that gets in the line will be expelled through the injector. You report white smoke as evidence of fuel but after repeated cranking it could also be engine oil getting past the rings. Sometimes a partially clogged injector does not provide the optimum air/fuel spray and it makes it harder to start the engine. Such a condition might not require a tear down if you can get the engine somehow started as fuel running to it at high speed will help unclog it. I'm just very inclined to think that your problem is a simple one that should not require a tear down to at least get the engine started. I believe the exhaust port on the h27 is above the water line so you will not have a water lock problem with prolonged cranking but try to limit each try to 5 seconds or less and in sets of no more than three thus giving the batteries a chance to recover.

 

[braol]

Head almost off

So yesterday I got everything out of the way, valve cover off, and all head bolts loosened. I got the head to rock back-and-forth but it is a bit resistant to come up and off. Everything got a good spray-down of Liquid Wrench and my next step will be to fashion some wooden wedges that I can tap in between the head and the block in order to pop the head loose. Any other suggestions about head removal would be happily accepted.

What prompted my decision to go ahead with the head removal was both the great tips I read here and the fact that when attempting to start again for the umpteenth time yesterday I noticed that some of the "pre-combustion" smoke that was being generated was coming out of both the exhaust as well as the intake. Knowing that smoke out of the intake is not supposed to happen, I concluded that the intake valve must be a bit fouled-up with gunk preventing complete closure. I also noticed what looks to be excessive rocker/valve clearance...also indicating potential carbon build-up around the valve seat.

In the end, provided I don't break anything, I see no down-side to removing the head...other than the extra work involved. Those valve stems looked awfully dirty when I peered into the intake chamber, which means that the inside can't be much better. The exhaust side of an engine is always worse too. Also, my valve-spring compression tool has been on vacation for way too long...so it will be good to take it out of retirement! My only worry is bad valve guides, as I don't think these are easily sourced anymore.. Since I'm providing the free labor by doing the tear-down, I don't mind spending a little coin to make the head pristine since it really is the heart of the engine. Perhaps a coat of red engine paint like a Ferrari would be in order????

Who knows, I may just treat myself by sending the head to a local shop for professional cleaning

 

[RIVERCRUISER]

Top Overhaul... always a good thing...

Let us know how it turn out.

 

[kloudie1]

BRAOL.. Have you talked to the folks at Toad Marine ?
http://shop.toadmarinesupply.com/marine_diesel_direct/Yanmar/
They can probably get what ya need.. Pre-chamber gaskets, valve seals, valves, etc.. Sounds like new seals and a good valve job are in order.. Good Luck..

 

[braol]

Probably just a real good cleaning and maybe seals at this point. In a pinch I could get custom made valve guides for not too much money. Valve seals are really more of an oil control thing anyhow and don't really contribute to performance. I never really burned any oil in the past...heck with a diesel, burning oil is more a sign that there is still oil in the tank! (It reminds me of working on old F-4 Phantom jets, if it ain't dripping something's wrong.)