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Are after market exhaust valve prone to burning?


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#1 mh44d OFFLINE  

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Posted September 14, 2015 - 07:02 PM

Are aftermarket kohler exhaust and intake valves prone to quick wear and burning? I just rebuilt my k341 with a aftermarket kit that I bought from ebay. Kit came with aftermarket rod, piston and rings, both valves and complete gasket and seal set. This wasn't Stens,I don't recall aftermarket name. Everything went together well, all tolerances were good. After engine was run for 4 or 5 hours I readjusted the valves. intake was good, exhaust was a little tight. Ran for another 4 or 5 hours had rough running issues, backfire through exhaust, poor starting, just ran rough. replaced points, condenser, plug and coil again, Was all new at rebuild. Reset timing and carb, ran better but still not right. Checked valve adjustment again, both intake and exhaust were tight. Set intake at 0.10, and exhaust at 0.19 cold again. Not a big  improvement in operation, takes a lot of choke to keep it running until it warms up. Even after it warms up, it lacks power, but otherwise runs pretty smooth. Engine has ACR compression release so I can't check compression, but it seems low on compression when you turn it over on starter. I believe it now has a burnt exhaust valve, but haven't pulled head off yet to look at valves. I don't understand why I'm having such problems with valve adjustment, why they would come tight so quick is beyond me. I haven't ran engine hard, just using tractor for average mowing duties. Running Mobile one 10w30 full synthetic engine oil, have changed oil twice since rebuild. I have already ordered a new kohler o.e.m exhaust valve for it, just haven't taken engine back apart to replace valve. Just wondering if aftermarket valves are this poor of quality, or am I missing something, and new valve will do the same thing in a short amount of time.  I should also mention that I had machine shop replace exhaust valve guide and do all machine work to engine before I rebuilt engine. I had crankshaft balanced, removed balance gears, turned crank 0.20, bored block 0.10, planed head. Replaced crank bearings at the same time. I thought that I covered all bases for a long running rebuild, but I must be missing something. Any body else have this problem with valves? Would like to solve this problem, but not sure that a new exhaust valve and regrinding intake valve and seats will solve problem. thanks   MH44D.   



#2 Bolens 1000 ONLINE  

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Posted September 14, 2015 - 07:16 PM

Could very well be, probably the kit that was around $100 free shipping right?

 

 

Only way to check the valve for sure will be to dig in and take a look, hope you can get your problem solved let us know what happens

 

Those parts must be straight from china, I am a dealer for the top aftermarket company's out there and none of those parts or prices are in our catalog's , This is just my opinion but anytime a complete rebuild kit that should cost about $500+ is listed for $100 points to something being fishy about the quality to me........ Heck a Genuine Kohler piston should be around $100 itself....

There seems to be a "Chinese" line of stuff that hit the market a couple years ago and none of us local dealers can find any manufacture's name so far on this stuff, Being an import they probably dont have to meet the specs or quality checks the OEM's or the aftermarkets that are in the OPEAA have to meet on their products


Edited by Bolens 1000, September 14, 2015 - 07:25 PM.

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#3 dthomp17 ONLINE  

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Posted September 14, 2015 - 07:25 PM

Wish I could help but I don't have the answer.  I believe others on the forum have reported using after market ebay rebuild parts without any problems.   I recently completed a similar rebuild on a K341 using ebay after market parts, including valves, and so far no problems.  Didn't have to do any ;machine shop work and I didn't replace the valve guides.  The engine cranks easily and has plenty of power but it doesn't have many hours on it yet.  Probably less than 5 or 6 hours total. Haven't even checked the valves for re-adjustment yet, probably should do that after your experience.  If I start having similar issues I'll let you know.


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#4 propane1 ONLINE  

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Posted September 14, 2015 - 07:35 PM

I used am e bay kit, but didn't use the valves. Works great, so far. Noel.
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#5 propane1 ONLINE  

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Posted September 14, 2015 - 07:47 PM

Did you use a coil with the built in or external resistor. Any loose wires at points or condenser. Condenser grounded well. How did you set timing. Did you retorque the head ? Just some thoughts, Noel.
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#6 dodge trucker ONLINE  

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Posted September 15, 2015 - 05:43 AM

to answer your question,  "I hope not"/  I have a 12 HP Magnum here that is freshly rebuilt...... bored, crank cut, new rod, etc; it has all OEM Kohler parts in it except for the exhaust valve. I let the machine shop get me the valve when they were doing the machine work, I dunno what exactly they put in it, except that it was "cheap" compared to an OEM valve; they never asked me for brand preference or anything, just that "we can get it";  it has been a few years since I had this one thru the machine shop (still never been run, built as a backup engine for my mower)


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#7 boyscout862 ONLINE  

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Posted September 15, 2015 - 09:13 AM

Unfortunately, you may be running very lean. Try it for 15 minutes with Marvel Mystery Oil in the gas before disassembling. The tightening up of the valve lash could be the valve seat moving, the new guide being out of alignment, or the valve face eroding. The Chinese steel I've seen in construction was inconsistant in its properties. The valve stem may be stretching.

As you take it apart, take detailedpics and measurements. Especially look at the wear pattern of the valve seat and valve face.

One other thought, I thought that synthetic oil shouldn't be used until an engine is well broken in. I remember when STP OIL TREATMENT came out, people were using it in brand new engines and the rings couldn't seat because of the STP. Good Luck, Rick

Edited by boyscout862, September 15, 2015 - 09:15 AM.

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#8 pianotuner OFFLINE  

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Posted September 15, 2015 - 12:37 PM

. I remember when STP OIL TREATMENT came out, people were using it in brand new engines and the rings couldn't seat because of the STP. Good Luck, Rick

 

HOW OLD ARE you!?


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#9 mh44d OFFLINE  

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Posted September 15, 2015 - 08:35 PM

Did you use a coil with the built in or external resistor. Any loose wires at points or condenser. Condenser grounded well. How did you set timing. Did you retorque the head ? Just some thoughts, Noel.

 Yes, the coil has a internal resistor. All wires to points and condenser are clean and tight. The condenser is grounded right to the side of the engine at right side of coil bracket. I set timing with cellophane method when points started to open, rechecked timing with a timing light, it was dead on. Yes, I  re torqued head after engine was run for 1/2 hour. re torqued with engine hot, all bolts turned another 1/2 to 3/4 of a turn more, not sorry that I checked torque again.


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#10 propane1 ONLINE  

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Posted September 15, 2015 - 08:46 PM

Engine ground good ? Noel
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#11 mh44d OFFLINE  

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Posted September 15, 2015 - 08:56 PM

Unfortunately, you may be running very lean. Try it for 15 minutes with Marvel Mystery Oil in the gas before disassembling. The tightening up of the valve lash could be the valve seat moving, the new guide being out of alignment, or the valve face eroding. The Chinese steel I've seen in construction was inconsistant in its properties. The valve stem may be stretching.

As you take it apart, take detailedpics and measurements. Especially look at the wear pattern of the valve seat and valve face.

One other thought, I thought that synthetic oil shouldn't be used until an engine is well broken in. I remember when STP OIL TREATMENT came out, people were using it in brand new engines and the rings couldn't seat because of the STP. Good Luck, Rick

I thought I would try synthetic oil right from break in. Don't see any problems with it, engine only smoked for a minute or two after first start up.  I added about 1/2 a liter of oil to it in the 10 or so hours that it has run. engine doesn't smoke at all, plug is clean, I feel that rings have seated in just fine. I chose synthetic oil because it should help engine run a little cooler, trying to prolong life span of engine as long as I can. Figured this was the best I could do to prolong engine life along with a clean air filter. We all like our little massey ferguson 16, I'm trying my best to keep it around for a while by using good lubricants, and replacing them at scheduled intervals. In theory at least, this should produce good results.


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#12 mh44d OFFLINE  

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Posted September 15, 2015 - 09:10 PM

Could very well be, probably the kit that was around $100 free shipping right?

 

 

Only way to check the valve for sure will be to dig in and take a look, hope you can get your problem solved let us know what happens

 

Those parts must be straight from china, I am a dealer for the top aftermarket company's out there and none of those parts or prices are in our catalog's , This is just my opinion but anytime a complete rebuild kit that should cost about $500+ is listed for $100 points to something being fishy about the quality to me........ Heck a Genuine Kohler piston should be around $100 itself....

There seems to be a "Chinese" line of stuff that hit the market a couple years ago and none of us local dealers can find any manufacture's name so far on this stuff, Being an import they probably dont have to meet the specs or quality checks the OEM's or the aftermarkets that are in the OPEAA have to meet on their products

YA!    I don't recall the exact figure but I think it was around $150.00 for every thing including a really cheap, cheesy set of points and no name sparkplug. The two crankshaft bearings cost another 30 or 40 bucks bringing total bill up to less than $200.00, and yes free shipping and handling. (I DIDNT USE THE PLUG OR THE POINTS) It seems to me that the machine shop bill was about $50.00 more than my total parts bill. 


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#13 mh44d OFFLINE  

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Posted September 15, 2015 - 09:12 PM

Engine ground good ? Noel

Yes, double checked all grounds, all clean and tight. 



#14 boyscout862 ONLINE  

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Posted September 16, 2015 - 02:29 AM

. I remember when STP OIL TREATMENT came out, people were using it in brand new engines and the rings couldn't seat because of the STP. Good Luck, Rick

 

HOW OLD ARE you!?

64   I was very lucky, I grew up at the best time to be a kid. Good Luck, Rick






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