YM336D Wet Stacking?

   / YM336D Wet Stacking? #1  
D

dumbfarmboy

New member
Joined
Mar 6, 2017
Messages
18
Location
Bangs, Tx
Tractor
Yanmar 336D
I completely rebuilt this engine a few years ago, probably doesn't have 100 hrs yet. Always starts right up but lately it's slobbering sooty oil out the exhaust. I'm suspecting I have low compression on a cylinder as I noticed white or light gray smoke recently. Today with temps in the upper 40s I let it run at high idle and checked temp at each exhaust port. Center and rear above 250F, front was under 180F. I guess my next step will be to pull the head and inspect HG, valves, cylinder etc. Up for suggestions. TIA DFB
 
   / YM336D Wet Stacking? #2  
I've heard that running a tractor under heavy load for a time to build up heat may eliminate the wet stacking but have no personal experience.
 
   / YM336D Wet Stacking? #3  
dumbfarmboy said:
I completely rebuilt this engine a few years ago, probably doesn't have 100 hrs yet. Always starts right up but lately it's slobbering sooty oil out the exhaust. I'm suspecting I have low compression on a cylinder as I noticed white or light gray smoke recently. Today with temps in the upper 40s I let it run at high idle and checked temp at each exhaust port. Center and rear above 250F, front was under 180F. I guess my next step will be to pull the head and inspect HG, valves, cylinder etc. Up for suggestions. TIA DFB
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Your first step would be to pull the injectors and have them checked out - or buy a simple tool and do it yourself. It might be the injectors and not compression at all. While the injectors are out you can do a compression test - be sure to use a diesel gauge - and with injector and compression info you will know where to go next.
I don't know what those exhaust port temperatures mean since the radiator is at the front too.
rScotty
 
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   / YM336D Wet Stacking? #4  
Rscotty is correct in checking the injectors before Condemning the engine. A leaking injector will fill the cylinder with fuel.
 
   / YM336D Wet Stacking? #5  
oldnslo said:
Rscotty is correct in checking the injectors before Condemning the engine. A leaking injector will fill the cylinder with fuel.
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Worse than that-it will make that cylinder run hot and it can burn a hole in the piston crown!
 
   / YM336D Wet Stacking? #6  
dumbfarmboy said:
I completely rebuilt this engine a few years ago, probably doesn't have 100 hrs yet. Always starts right up but lately it's slobbering sooty oil out the exhaust. I'm suspecting I have low compression on a cylinder as I noticed white or light gray smoke recently. Today with temps in the upper 40s I let it run at high idle and checked temp at each exhaust port. Center and rear above 250F, front was under 180F. I guess my next step will be to pull the head and inspect HG, valves, cylinder etc. Up for suggestions. TIA DFB
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How hard have you been working it? Before I did anything I'd work the snot out of it. You realize that a diesel, unlike a spark ignition engine, runs across a large range of fuel/air ratios. This means it runs across a broad range of peak cylinder temperatures. Running at high idle will not increase the peak temperatures much. You need to put it under load to get the peak temperatures to increase significantly. Hook it up to a plow or a disk and do 10 acres. That should cure the slobbers. Measure the temps while you are doing this or stop and immediately measure them.
 
   / YM336D Wet Stacking?
  • Thread Starter
#7  
Ok, so a little more history. From fall 2019 until fall 2021 it sat and wasn't ran because I moved and left it with neighbors until I could go get it. Yesterday I fab'd a mock injector body and was able to run compression tests. Cold all within 5lbs of 200psi. Warmed up wasn't much different up to 210 PSI. Oiled cylinders and all came up to 265-275PSI. Service manual specs 568-639 PSI with a CR of 21:1 which calculates to only 308 PSI. I checked valve adjustment and all were correct. One thing I noticed was the casting # on the head is 3T90T-J which is the model # of the JD 1050 engine that's turbocharged. I was told it would work on the 3T84-N but I'm wondering if the pistons or head lower the compression for the turbo engine. Assuming it's like gasoline engines and run lower compression for turbos. Also when using MMO do I put it in the cylinders and if so, how much?
 
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   / YM336D Wet Stacking? #8  
Is it wet stacking in all the cylinders or just one?

I dont believe diesel engines run less compression in turbo engines as with gas engines. Gas engines do this to prevent premature ignition. A diesel engine is injected.
 
   / YM336D Wet Stacking?
  • Thread Starter
#9  
nyone said:
Is it wet stacking in all the cylinders or just one?

I dont believe diesel engines run less compression in turbo engines as with gas engines. Gas engines do this to prevent premature ignition. A diesel engine is injected.
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I'm not sure how I would know since it's a 3 into 1 manifold. I'm beginning to think that maybe I haven't ran it had enough in the last few months. The specified compression test pressure has me baffled as that would mean a ratio of 35:1 form my calculations. The service manual says it's 22:1.
 
   / YM336D Wet Stacking? #10  
dumbfarmboy said:
I'm not sure how I would know since it's a 3 into 1 manifold. I'm beginning to think that maybe I haven't ran it had enough in the last few months. The specified compression test pressure has me baffled as that would mean a ratio of 35:1 form my calculations. The service manual says it's 22:1.
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Remove the manifold and look in.
 
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