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.

 

[Ilikeurtractor]

Exhaust gasketing and manifold begs of more questions. I'd have to say the manifold came off another engine although I'm surprised the bolt pattern matches so well. Apparently if the gasket bolt holes line up it's "good enough" - and even if the gasket was meant for the other side (or rotated 180 degrees) this is what I saw upon disassembly. I ended up grinding the rectangular pattern into the manifold to match the new gasket to help things out. We'll see what happens...

 

[Ilikeurtractor]

Crank pin journals check out ok - less than 0.001" wear. Need new piston rod bearings though as I can see some copper/grooving showing in the existing bearings and they are about 0.004" out of spec on wear. Rings check out as far as gap and side clearance although the ring thickness and piston groove dimension are not what I have listed in the service manual (both much less) so I'm a little wary of getting replacement rings since they won't even fit in the piston groove according to the literature I have. Both top piston rings show damage on the bottom sides. I think I'm just going to flip them over (keep the good side down on the ring groove) and re-hatch the cylinder and go from there.

Also found where previous repairman must have lost a rod nut and replaced it with a smaller one :confused2:

Oh, and the ring gaps were not staggerd like they should have been. Top two ring gaps were nearly in-line, the 3rd was about 180 degrees out on both pistons. I didn't really pay attention to the oil ring placement but will stagger all gaps 90 degrees upon reassembly as shown in the manual.

 

[evan price]

Hmm, almost sounds like one of those Chinese rebuilt grey-market jobs, there. What a situation.

 

[Ilikeurtractor]

Hmm, almost sounds like one of those Chinese rebuilt grey-market jobs, there. What a situation.

Yeah, it's definately grey-market. Not sure where the repairs were made. Tractor has a California tractor shop sticker on it.

 

[Ilikeurtractor]

Well got it running again but very little improvement in performance was noticed. The good news is that the blowby went down to almost nothing and both cylinders read almost the same compression now - 320 psig after eight cranks and both top out at 390 psig after about 16 cranks.

I'm not really sure what to try next - maybe my expectations are too high for this motor but I don't really have anything to compare it to other than my craftsman riding mower which I think runs circles around this as far as acceleration and power goes. I realize the riding mower is half of the tractors weight and is rated at 7 more hp but I would expect the diesel to be much closer in low end torque and acceleration which it certainly is not.

It seems like it shudders in neutral under acceleration (I'll get a video of this). When I go to full throttle in 6th gear it just puffs black smoke and it doesn't even get louder like most diesels I'm familiar with with almost no acceleration.

I'll see if I can upload a couple videos of it running when I get a chance - probably in a couple weeks as I'll be out for work stuff. Maybe then someone can confirm or deny it running properly based on their experience with these engines.

 

[Ilikeurtractor]

Tried to upload .mpg videos. Looks like the site sees them as invalid. I'll have to find another way...

 

[Ilikeurtractor]

Does anyone have an experience with the governor control system on the KE70/5? It seems like I may have an issue with that but I don't know of a good way to test it. I've noticed that the "fork" that connects the the IP rack is quite loose (you can move the fork really easily back and forth about 3/4")when the pump is removed. In fact, the spring that is attached to the throttle handle linkage inside the gear case only starts to tension up at full throttle and it tends to follow the throttle handle rather than the governor. Shouldn't the governor be trying to put the rack at the full position when the engine is off? I'd like to think there is something wrong here, but the engine seems to respond to throttle commands just fine although it's hard to tell if the governor is compensating at all. I guess I need to know if the governor spring is just there to compensate for a "hyper-extended" throttle handle or if the spring should always be under tension during normal operation (?).

The service manual tends to shy away from governor specifications and only makes statements like - if part "X" of the governor system is "bad" then replace it which is of very little use to me. Oh, and the spring is designated as "specific to the application" in the parts manual so I wouldn't even know what one to replace it with if I thought it was bad. Also, my electronic copy of my service manual is missing Figure 10 which diagrams the governor parts which is inconvenient at this point.

It would be great to know what the position of the rack is at any given time, but I don't know of a handy way to do this. I even thought of mounting a small battery powered wireless camera in the voids in the gearcase to see what is going on in there but that is kind of a crazy impractical idea - and I don't believe the signal would travel through the metal anyway (Faraday cage?). Getting wires out for a slide resistor and such things also seems difficult. Any suggestions?

 

[Ilikeurtractor]

Finally got a replacement spring today for the governor control. Although somebody has clearly tampered with the original spring, it is close enough in spec. that I don't believe it to be the culprit. I guess I'm back to injector timing and I'll do my best to check/correct it going back together. The only other thing I think could be wrong is possibly the keyways are slopped out/have been altered (why wouldn't this surprise me?) and that is throwing off timing between the crank and cam slightly. I probably won't pursue that theory as it is more than I want to get in to. For future reference, a "good" spring has a free length of 82.5 mm and a spring constant of 6200 N/m.

 

[Ilikeurtractor]

Well after checking valve timing and confirming IP timing things are back together and still the same results. Here's a youtube video trying to start at 20 deg F - throttle at 3/4 full, going to full throttle helps some but pretty much same thing. Glow plugs (new and tested) were on for about 20 seconds before the first attempt and about 10 seconds between attempts. I've watched a few diesel cold starts on youtube and it seems like either the engine fires and runs or does not fire. This one acts like it's "kind of firing" - and some black smoke which I would think is good. Has anyone experienced this before? The pump has just been gone through and I have new injector nozzles although this doesn't necessarily mean either are correct.

So... anyone wanna take a stab at it and diagnose it as low compression or fuel issue (or other?) Other symptoms include poor acceleration and weak low end power (low torque). Top end seems pretty good. Engine does start ok when hot and will eventually start after continued cranking. Valve clearance has been correctly set. Thanks in advance.

TX1300 cold start 20 deg F.mpg - YouTube

 

[BillS2009]

Mine does the same black smoke thing. I preheat for about 15-20 seconds, and try to start. At the first puff of black smoke, I go back to preheat the glow plugs for an additional 10-15 seconds (glowing red resistor) and then 1/4 throttle and it will start right off.