Got the head off my YM1702D, now need help with diagnosis.

[WillaminaOR]

So it was the studs that were holding the head in place. After soaking for 36 hours or better in PB Blaster I went out and tapped on everything with a hammer to shock the corrosion and then tapped the tip of a screw driver between the head and block like a wedge, it slowly came off, then a little more prying and a lot more tugging and it's off.

Now I'm not sure what is wrong though. My tractor used to start like a champ with no smoke at all. I got it pretty hot one summer day tilling up a horse arena, right around the red zone on the gauge but not well into it, and noticed it was dripping oil down the side (I freaked thinking I had cracked the block or something). I shut her down and took it home where I could get a closer look and found it was dripping out the crank case / valve cover vent tube at the rear of the engine. I started it back up and it smoked a lot as it begrudgingly started. After it caught well and came up to speed it just doesn't quite sound right and there was a lot of blow by, which is what was pushing oil out the vent tube. I thought for sure I warped the head or blew the gasket which was allowing oil from the head to get into the cylinders making it hard to start and allowing a lot of blow by while running. Only thing is the head looks strait and the gasket looked to be intact when I took it apart. Cylinders look good too.

What are the usual failures when you overheat? I didn't boil over or anything so it can't have been that darn hot, grrr. What else should I look for? I had also read to take the exhaust manifold off and start it to see if one cylinder seemed to be the cause. I couldn't get the manifold off without removing a hydraulic line so I just pulled it out about a half inch. It looked like it was the rear two cylinders smoking but it's possible it could have been only one.

Lots of information but I'm sure I'm leaving some key detail out while rambling on. Any help appreciated.

Thanks,
Bryan

 

[irwin]

. Only thing is the head looks strait and the gasket looked to be intact when I took it apart. Cylinders look good too.
....snip.....
. It looked like it was the rear two cylinders smoking but it's possible it could have been only one.
Thanks,
Bryan

Hi bryan: the head looking straight may not be telling you enough. Obviously you're not afraid to get your hands dirty, that's a good thing (most of the time)....
I'd take the head and the head gasket to a machine shop and get an expert opinion. This is too important to halfarse a repair, you need facts. You could post some pictures and it would help us a bit, but without the input of an expert right there all we can do is guess.
My guess is rings, but I don't know. It's possible the the head is just warped enough to leak by gskt. I've had to really look hard to see the failure of more than a few head gaskets over the years.

 

[WillaminaOR]

I can post pictures, what should I take them of?

LMK,
Bryan

 

[irwin]

Lets start at the beginning. A lot of smoke and no power doesn't automatically point to head gskt. Could be injector, or injector pump problem,(or something else) only now the head is off. This makes it hard to isolate the failure area, without perhaps a tear down.

Some pictures of the cyinders, how scored up are they? shot of the head gskt, although may need to hold it in my hand to see any failure. Maybe put a straight edge tool (not something fairly true) on head to see if within spec.
A tiny crack in the head w'be hard to see. (machine shop)

Soo you need to decide how far you want to rebuild this without knowing whats wrong.

If the head is sound and true, maybe put it back together with a new gskt set, and pay a tractor tech to diagnose for you, then if you need to do serious engine repair you'd have a, boots on the ground, expert opinion. Truth is no-one on the other side of a pc monitor will be able to see as clearly as someone there.

Keep us informed and keep the faith, good luck

 

[irwin]

Don't know if you saw this thread..http://www.tractorbynet.com/forums/yanmar/106847-2610d-engine-issues.html#post1214766... You're not alone..

 

[DavesTractor]

All good advice so far. I'd send the head to a machine shop, have it checked, touch up the valves and replace the valve guide seals. Pull the pistons and assuming the cylinders look good, hone them and replace the rings, then the rod bearings. Put it back together. Doing all of that yourself is cheap, and you should be good to go. Of course it could still be an injection problem, but unlikely.

 

[rock2610D]

William, you are already 3/4 of the way done. I would urge you to pull oil pan takes about .5 hours including oil draining.

Get new rings and rod bearings, you already have to get a head gasket so for a few extra dollars and some time you will know its done right.

DO check head. I could tell immediately my head was in need of work. Remember though that if there are cracks it could get expensive to fix. Mine was cracked between injector and intake valve. Was able to purchase a remaned head from fredricks. Was $550, so if your head work will cost more than that get the remaned one.

 

[WillaminaOR]

'If' it was down on power it wasn't a whole lot, the reason I pulled the head was I suspected problems because of the excessive blow by, enough to blow oil out the breather tube. Only smokes a bunch when it is starting, or trying to start, after it fires and evens out there seems to be a little more smoke then the normal 'diesel engine running' amount, slightly more then before at least.

I figured the head gasket was blown between a cylinder and an oil drain back passage allowing a lot of blow by while running and letting oil drain into the cylinder when I shut it off, making it difficult to start with oil in the chamber and smoking a lot till it cleared. Makes sense to me at least. Not what I found though, at least it's not readily apparent.

I'll take the pictures and post them to my gallery when I get up in the morning. I spent all afternoon today putting a shift kit into my Valiant so didn't see the replies till tonight.

I may just put fresh rings and bearings into it as it's only about $85 more dollars but money it tight and the tractor was what I was using / doing to earn some of the extra.

BTW, who's William?

Thanks,
Bryan

 

[Skyco]

Did you run any compression or leakdown tests before pulling the head? If you did, and you should have, that info would be helpful to remote diagnosis

 

[rock2610D]

Did you pull injectors? This can help diagnos problems. I noticed that with two bad cylinders the injectors (only 4 hours old tractor time) pulled hard. Yet the one good cylinders injector came out by hand.

On your tractor is blowby tube on valve cover or side of engine? Do you have wet sleaves?

If it got hot enough for you to think a HG blew then it could also be rings..

Then again it could be a cracked head. IE crack between combustion chamber and oil return holes.

I am going to vote for rings though!

SORRY Misinterpeted your name!! Willamina