# Deere gt 235 loss of power



## badgerdude (Mar 18, 2015)

Hey Folks,

I have a GT235 with the 18hp Kawasaki. About 1,000 hrs, but I've only put about 35 hours on it since I bought it. Last fall I engaged the PTO and heard a very loud pop and the tractor died. Wouldn't start for a while, but I let it sit and eventually got it started. Now it has a fairly significant loss of power both with and without the PTO engaged. No PTO going up hills it struggles. When I engage the PTO it takes a long time for the deck to get up to speed and I have to mow slow.

So what do you think a logical approach is to diagnose? Did I blow a piston ring? Something else? It seems to run fairly well, but does sound a little different to me. Trying to decide if the first step is a compression test (assuming I can look up the normal range). Also though I could try running it on one cylinder and then the other. Any thoughts on order of operations would be appreciated. Doing some searching many people indicate clutch issues on the deck, but given I have power loss regardless of PTO, I assume this is engine related. Trying to figure out if I need to rebuild this thing entirely.

Thank you!!


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## badgerdude (Mar 18, 2015)

Didn't get any feedback from anyone, but for what it's worth, this is what I did:

Pulled one plug wire and tried to start: worked ok.

Reconnected the wire and pulled the other one: would not start, so something is wrong on the connected side.

Swapped the coil and wire from the working side to the other: still would not start, so not a coil or wire issue

Checked for spark on the bad side: Pulled the plug (kept connected to the wire, grounded against the valve cover and cranked the engine): have spark, but did notice the plug looks pretty fouled. Other side does not show same fouling. 

Cleaned up the fouled plug and tried to start again. Pulled plug and it's dirty again. Swapped plugs from one side to the next, still no dice.

Bought a cheapo compression tester from Harbor Freight and sure enough, very low compression on the bad side. Checks OK on the good side. 

So I think I likely have a bad head gasket or a bad piston ring. I suppose it could be a bad valve also. Anyhow, I'm going to just pull the head and take a look and see what I find. Hopefully is jut a bad head gasket which is easy to replace, assuming the head isn't warped.


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## FredM (Nov 18, 2015)

One thing you didn't mention, was, did you check the valve clearance, usually a cylinder will run with a blown head gasket if it is not badly blown, even when trying to start the engine, you should be able to hear the pft, pft, pft of a blown gasket.


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## badgerdude (Mar 18, 2015)

FredM said:


> One thing you didn't mention, was, did you check the valve clearance, usually a cylinder will run with a blown head gasket if it is not badly blown, even when trying to start the engine, you should be able to hear the pft, pft, pft of a blown gasket.


I did not check the clearance yet. So prior to pulling the head you suggest I pull the valve cover, check the clearance, adjust the valves if needed and then try starting on that cylinder again (if I had to adjust the valves?). I need to figure out what the clearance is supposed to be. My only question is if it's a valve clearance issue, why the fouled plug? Seemed like oil, but maybe was just a mixture of carbon and fuel?? If the valve clearance is good, than that eliminates one more piece of the puzzle I suppose.


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## Bob Driver (Nov 1, 2017)

Kawasaki valve specs
https://outdoorpowerinfo.com/engine_specs/kawasaki_valve_gaps.asp


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## badgerdude (Mar 18, 2015)

Final update.

Pulled the valve cover gasket on the bad side, immediately noted one of the push rods had slipped off the rocker arm. Pulled the head, and noted several things. One bend push rod, one sticky valve, and the valve guide for the sticky valve had come unseated and pushed into the head. Bottom line is that the head must have overheated and caused a chain of issues. The correct way to fix this would have been to get a new head. I tried the cheapo method and used a C-clamp and socket to push the valve guide back the other direction and then used a tiny fine point cold chisel and tacked it in place by pushing up some aluminium from the head around the guide. This may or may not hold in the long term but this is a far from pristine example of a 235 and so I cheaped out, which I typically don't do. After that I cleaned the head, got a valve lapping tool and some compound and cleaned up the valves. Ordered new head gaskets, valve oil seal, push rod, and intake and exhaust gaskets. Put it back together, adjusted the valves on both sides and then checked compression. Back to around 120. Power washed the entire engine to get the gunk out of the fins and I've put about 3 hours on it so far and it runs pretty well. Time will tell if my rigged up method of dealing with the valve guide holds. I ordered spares of everything and will just get a new head if it unravels again. All in all, maybe $100 for compression tester and parts and I have enough spares to do it again if needed.


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## Bob Driver (Nov 1, 2017)

Kawasaki says 300 hours on a valve adjustment. Briggs says 500 and runs an aluminum exhaust pushrod. V-twin Kohlers have hydraulic lifters.

Kawasaki usually runs a much smaller diameter push rod than Briggs for the same HP engine


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## badgerdude (Mar 18, 2015)

Thanks for the info. I'll be sure to check em around 300 hours. That'll be quite a few years though. Not sure I'll still have this old thing by then.


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