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  #11  
Old 10-24-2012, 10:33 AM
Kewadin Kewadin is offline
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same problem

It's been a long time but there was a problem getting parts. First I took the head off and looked at the cylinder and valves. I thought the valves looked kind of burnt and I thought the cylinder didn't look so bad. But now I wish I had a good second opinion. Anyway , I hand ground the valves and am pretty sure I got a good seal when I was done and put new head gasket and fired it up....same problem. Won't even make 2000psi before engine is over worked. So I went back to the pump side and replaced valves and pressure seals, still same problem...I did a compression test and only get 60lbs max. But after a little more research, the motor is supposed to have an automatic compression release below 700 rpms ...So I went to harbor freight and bought a leak tester. I never used one before but following the instructions it tests in the green as far as percent air loss? ....I pulled the pump and I am going to try to get it tested at a pump shop to see if it can make 4k psi. I can rotate the pump shaft by hand . but it is stiff. The Kohler 15hp starts and sounds pretty good. Much easier to start without the pump ....I am going to try to get a rpm reading to see how fast it can go with no load and then try to get a reading under load.....If the pump can be tested and is good, I guess I'll have to open up motor and do cylinder and rings/piston....Has anyone heard of an auto de-compression getting stuck? What would the motor sound like? Any ideas or suggestions welcome, thanks.
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  #12  
Old 11-07-2012, 11:58 AM
Kewadin Kewadin is offline
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motor not making rpm's

I pulled the pump and bought a photo tach. The motor can only make 2600rpms with no load. I think it is supposed to make 3600 no load. Could my problem be the carb? Would a worn cylinder give similar symptom? What do you think,carb rebuild or motor teardown? What should I do?
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  #13  
Old 12-07-2012, 10:11 PM
Kewadin Kewadin is offline
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Cam lobe

I found a old thread '06 with the same unit and symptoms. Their problem turned out to be excessive wear on the cam lobes. I tried to gage the lift of the valves and the exhaust seemed very small,the intake seemed ok. I opened the cover and pulled the camshaft and the exhaust cam lobe was only about a third as high as it should be, ground right down. The fuel pump lobe also showed wear but the intake looked like new? The exhaust lifter didn't't show wear either. I bought a new one and will try to get it all back together next week and see what happens.
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  #14  
Old 12-08-2012, 12:05 PM
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BigFish BigFish is offline
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Quote:
Originally Posted by Kewadin View Post
I found a old thread '06 with the same unit and symptoms. Their problem turned out to be excessive wear on the cam lobes. I tried to gage the lift of the valves and the exhaust seemed very small,the intake seemed ok. I opened the cover and pulled the camshaft and the exhaust cam lobe was only about a third as high as it should be, ground right down. The fuel pump lobe also showed wear but the intake looked like new? The exhaust lifter didn't't show wear either. I bought a new one and will try to get it all back together next week and see what happens.
Here's what I do when installing cams ( if I have the time).
Get a tube of moly type assembly lube. Most speed shops carry it.
Use carb spray to degrease the cam lobes. Blow dry it .
Warm the cam up slightly in the toaster oven or use a propane torch ( optional) The heat opens up the "pores" in the iron.
Spread some lube on the lobes and work it in with yer bare fingers.
The moly wears into the cam and keeps it from wearing.

I also use the moly lube on valve stems.
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  #15  
Old 12-11-2012, 10:52 PM
Kewadin Kewadin is offline
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Cam ware

cam lobe dimensions: old:1.361"int. 1.044 fuel 1.160"exh. . . . . new:1.375"int 1.046 fuel 1.366"exh . . . The lifter surfaces look alike, why so much ware on exhaust cam? I have cleaned the case and cover and hope to re-assemble it tomorrow. I'm not sure how to pre lube the part. It came with small tube of Thixotropic cam lube and I have a tube of molly-graphite assembly lube. Should I grease up the whole thing,lobes,shaft ends,gear teeth,ACR mechanism?...Is it ok to use an oil stabilizer like Lucas with conventional 10w30? Once I get it started how fast and how long should I run it? Thanks for the help.
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  #16  
Old 12-12-2012, 01:18 AM
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BigFish BigFish is offline
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I take it you don't have a shop manual. Go to Kohler's site and download one.
Did you not read my post?????? Use assembly lube on the lobes.....the L O B E S only!!!! Use oil on the rest.
As for the Lucas..........don't forget to add Seafoam ,Mechanic in a bottle, and the ol' standby STP.
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  #17  
Old 12-17-2012, 01:07 AM
Kewadin Kewadin is offline
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put it back together

I got the manual and put it back together,even used a heat gun to warm it up before I greased it up. Started on the second pull,ran very smooth, and can rev up to 3600 rpm like it used to. I ran it 15-20 min to get the Lucas blended in,lol. I don't normally use that stuff,but this engine needs something to keep it from eating the exhaust cam lobe off. Why would it do that? Faulty heat treat? Thanks for the help. I have another question about this motor but I'll start another thread.
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  #18  
Old 11-29-2013, 11:34 AM
pb3 pb3 is offline
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thanks for sharing and good job on finding the issue. as far as your question on why it occurred, do some searching on bobistheoilguy.com regarding the reduction of zddp in oil and it's results on camshafts. either that or poor oil change intervals are what come to my mind immediately after reading of your woes.
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  #19  
Old 11-29-2013, 07:23 PM
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Richard Martin Richard Martin is offline
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Quote:
Originally Posted by Kewadin View Post
I don't normally use that stuff,but this engine needs something to keep it from eating the exhaust cam lobe off. Why would it do that? Faulty heat treat?
The zinc levels used to be a whole lot higher in motor oil but the EPA forced reductions. With a reduction in zinc came an increase in metal to metal friction. Oils designed for small engines usually contain higher than normal levels of zinc.

You are not alone. Most high hour engines have the same problem with cam lobes being wiped unless they've used small engine oil for the life of the engine. The problem is most people don't know it. The reduction in performance is so slow that it's impossible to tell it's happening in most cases.
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  #20  
Old 11-29-2013, 07:51 PM
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Richard Martin Richard Martin is offline
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Double post.......
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