KE70 engine low power?

[Ilikeurtractor]

Turbos are cool and there have been several TBN members that have retrofitted their tractors. If I remember correctly, one Yanmar owner did specifically because of altitude related performance.

I too think that you would probably be well pleased just to have the stock performance...to go from barely pulling itself to spinning tires would make a guy feel like he was in tall cotton. I think you have a solid tractor that is very well built...just needs a little freshening. I don't know what you have invested in it but I suspect that whatever it is, at this point an additional $300-$500 put into it wouldn't be a deal breaker on it.(?)

Yup, I agree 100% and hope to have that situation.

 

[Ilikeurtractor]

Well redid the valve clearance, checked for bent pushrods. Everything appeared ok. So I guess next is rings and valve job. I figure it will set me back a grand. Will probably do next year...

 

[Kernopelli]

Well redid the valve clearance, checked for bent pushrods. Everything appeared ok. So I guess next is rings and valve job. I figure it will set me back a grand. Will probably do next year...

Ouch, a grand for rings and valves? That hurts.

 

[Ilikeurtractor]

Ouch, a grand for rings and valves? That hurts.

Yeah, the piston rings and gasket kit alone is $750 which is the cheapest I could find it out there and it does come with main and rod bearings. You can get rings and gasekts separately but they'll be about as much from the sources I've seen. I'm guessing the valve job would run around $300 but that is just a guess.

 

[eccchief]

couple other possibilities for the power and smoke. First the smoke...if the valve guides are worn, you can get some oil through them which will burn off as smoke throught the exhaust. It's not much oil and can do so for a while before a noticeable drop in the oil level. Since diesel is a thin oil also, it may be hard to tell if it's diesel or motor oil that's making the smoke. There is always going to be the diesel smell in the exhaust. As for the low power, if the compression test with the oil in the cylinders did not make a very noticeable increase in compression, then the rings are probably okay and I would suspect a burned valve seat or two. This scenario would be more likely with those worn valve guides. If the seats are burned, the oil in the cylinders for the compression test really doesn't have much effect. Before I dove into tackling a ring job, I'd seat the valves and have the guides knurled or replaced...then bolt the head back on and see what happens. If you pull the valves out and look at them, you'll see if the valve or valve seat is damaged(burned). The damage will typically be on both parts where they mate when closed. They can be seated by hand with a little valve grinding compound, and more than likely, you can reuse the head gasket if you're careful taking it off...at least for the test. Be careful to torque the head properly when putting it back on. Good luck.

 

[Ilikeurtractor]

couple other possibilities for the power and smoke. First the smoke...if the valve guides are worn, you can get some oil through them which will burn off as smoke throught the exhaust. It's not much oil and can do so for a while before a noticeable drop in the oil level. Since diesel is a thin oil also, it may be hard to tell if it's diesel or motor oil that's making the smoke. There is always going to be the diesel smell in the exhaust. As for the low power, if the compression test with the oil in the cylinders did not make a very noticeable increase in compression, then the rings are probably okay and I would suspect a burned valve seat or two. This scenario would be more likely with those worn valve guides. If the seats are burned, the oil in the cylinders for the compression test really doesn't have much effect. Before I dove into tackling a ring job, I'd seat the valves and have the guides knurled or replaced...then bolt the head back on and see what happens. If you pull the valves out and look at them, you'll see if the valve or valve seat is damaged(burned). The damage will typically be on both parts where they mate when closed. They can be seated by hand with a little valve grinding compound, and more than likely, you can reuse the head gasket if you're careful taking it off...at least for the test. Be careful to torque the head properly when putting it back on. Good luck.

Thanks for the advice. I think that would probably be worth a shot at this point. As far as putting oil in the cylinders when doing a compression test, any recommendations on this as far as procedure? The closest I can get to the cylinder itself is through the glow plug port, but even that is not in the cylinder. I could maybe take a can of WD-40 and bend the straw through the swirl chamber to reach directly to the cylinder and spray some of that in it. Not sure if WD-40 is viscous enough to make a difference. The other question is how much to add. Would the equivalent of a teaspoon of oil be enough or too much? I've never really did this test before and want to be sure it is done correctly.

I've also been thinking about a post I read where guys would put compressed air on the cylinder to help find possible leaks with valves or cylinder blow-by. I think I can get an adapter that would let me couple up compressed air to the compression tester adapter that goes in the glow plug port. I would need to find the piston position in the cylinder where the valves are closed and hold it there while doing the test which I think I can do. I noticed the service manual states the valves are open when the piston is at BDC and the compressed air may tend to take it there depending on pressure applied. Any comments on this method?

 

[Ilikeurtractor]

Got the head pulled today. Looks like the exhaust valves and seats need to be fixed. There are some weird scratches in the cylinders - I never expected to see them being horizontal. Is this left over from honing/deglazing? They aren't that deep but I'd rather not see them. Looks like sleeves were installed at one time too. Cylinders both measure around 2.862" near the top of the travel of the rings (but below the ridge which is almost non-existant) in two directions which is around 0.012" less than stock according to the service manual. Not sure what is going on with that. I triple-checked all the readings and even gauged the micrometer since I thought that was off. I guess it has something to do with the sleeves which means pistons are under-sized too.

I'm having a shop redo the valves and then I'll put the head back on and recheck compression. I'm hoping not to have to mess with the rings especially because of the odd dimensions I'm getting. Attached are some pics.

 

[suntreemcanic]

Those scratches on the cylinder walls could be someones poor attempt to x-hatch the cylinder to help the rings to seat.

 

[Ilikeurtractor]

Well wasn't valves After they were cleaned up the valves and seats look fine (see pic of the same valve after cleaning) - a rookie mistake on my part. Evidently the fine pits that fill with carbon are normal which I wasn't aware of. The shop did suggest new valves though as they were worn but not leaking. So new valves, a light grind on the head seats and tested compression with a used head gasket (need to save the new one for now) with no gain. Off to rings now...

Other note - after reading this on the site:

http://www.tractorbynet.com/forums/yanmar/216695-rolled-my-ex3200-need-help.html

I decided to do a quick check on my piston travel with the head off and did notice that the rear piston travel relative to the block deck is 6-8 thousandths less than the front. According to some quick calcs, this is costing me roughly 12-16 psig of compression on that cylinder alone, assuming a 24:1 compression ratio. Hopefully I can track down the cause for this and I hope it isn't a bent rod or crank. For now I'm not too worried about it.

 

[Ilikeurtractor]

It's interesting the things you find upon disassembly and the questions they raise - I got to comparing the old and new head gaskets. The old gasket has cylinder rings with a dimension of 3.140" and the new 2.928". Cylinder diameter is 2.862". Do these rings normally expand under pressure? - seems pretty drastic if so. It wasn't helping my compression pressures any... Attached is a pic of the old gasket over the new and each on the block.