GT2550 Kohler engine, valve train noise

[Enrico8n47]

I recently purchased a 2008 GT2550, and I have no experience with the Kohler CH670-0011. The engine ran a little rough, but evened out when it warmed up. Recent oil and filter change, along with hydraulic fluid. About 700 hours usage. Fresh gas and some fuel system cleaner, and it seemed to be running smoother. Today I was mowing for about 15 minutes when the engine developed a mechanical clatter in line with engine revs, sounding like an old engine with mechanical lifters from the 1960s. I immediately reduced throttle and disengaged the PTO, idled it back to the garage. Some smoke in the exhaust, not thick black or blue. Oil level is within the marks on the dipstick. After cooling down, I checked compression - about 120 on the left (sitting in seat), 100 on the right. Spark plugs were carbon coated. I cleaned and re-gapped the plugs (.030). Removed the oil filler cover, and some vapor escaped. It fires right up, but still has a valvetrain clatter. Before I put a camera in the spark plug holes, can anyone tell me what additional maintenance/repair can be done to ensure the valvetrain is at spec, or if this means the engine is no longer serviceable? What additional maintenance/repair can be done?

 

[5030]

I believe all Kohlers have solid lifters, mine does and valve adjustment is kind of complex as you have to remove the valves and grind the end of the valve stem to obtain correct clearance. Having said that I don't believe too little valve clearance is your issue. I tend to think your automatic compression realease has failed or at least the spring that keeps the follower on the camshaft has lost sufficient tension and is allowing the compression release to bang around inside and that is what you are hearing.

Problem is, to fix that, you have to remove the engine and split the case to access it. Just my observance of what your engine is doing.

 

[Carl_NH]

Check your Valve Clearance .003 and .004 and attached is the service manual for the engine. Also try Kohler Oil and a new filter.

 

[5030]

With an ACR engine, you won't see actual compression pressure ever because the ACR holds the valve slightly open to aid in starting. Kohler built good engines or at least did. Don't know about the newer ones now that Kohler sold out, but Stens will have replacment parts.

 

[RandyT]

I believe all Kohlers have solid lifters, mine does and valve adjustment is kind of complex as you have to remove the valves and grind the end of the valve stem to obtain correct clearance. Having said that I don't believe too little valve clearance is your issue. I tend to think your automatic compression realease has failed or at least the spring that keeps the follower on the camshaft has lost sufficient tension and is allowing the compression release to bang around inside and that is what you are hearing.

Problem is, to fix that, you have to remove the engine and split the case to access it. Just my observance of what your engine is doing.

Check your Valve Clearance .003 and .004 and attached is the service manual for the engine. Also try Kohler Oil and a new filter.

With an ACR engine, you won't see actual compression pressure ever because the ACR holds the valve slightly open to aid in starting. Kohler built good engines or at least did. Don't know about the newer ones now that Kohler sold out, but Stens will have replacment parts.

The Kohler Command or CH670 uses hydraulic lifters therefore no adjustment. And also doesn't use ACR.

To the OP Rehlko has a Minimum of 160 psi compression on the Command engines per the service manual. Also the hydraulic lifters sometimes will develop a groove in the bottom when they don't rotate which can cause a sounds like the rods are coming out of it sound, but then can go away and then return shortly after.

 

[Enrico8n47]

The Kohler Command or CH670 uses hydraulic lifters therefore no adjustment. And also doesn't use ACR.

To the OP Rehlko has a Minimum of 160 psi compression on the Command engines per the service manual. Also the hydraulic lifters sometimes will develop a groove in the bottom when they don't rotate which can cause a sounds like the rods are coming out of it sound, but then can go away and then return shortly after.

Thank you for the information, that saves me a lot of trouble. I will run it and keep listening for changes in valve train noise. Hydraulic lifters, that is good, I don't want to tear down and engine just for that. I have the manual from Carl_NH which has been helpful as well.

 

[Enrico8n47]

Check your Valve Clearance .003 and .004 and attached is the service manual for the engine. Also try Kohler Oil and a new filter.

Thank you for the manual, very helpful.

 

[Enrico8n47]

I began mowing again, and the valvetrain clatter went away, as Randy advised. I did see smoke coming from under the hood (not from the exhaust), looks like an oil leak. Is this engine prone to oil leaks?

 

[RandyT]

I began mowing again, and the valvetrain clatter went away, as Randy advised. I did see smoke coming from under the hood (not from the exhaust), looks like an oil leak. Is this engine prone to oil leaks?

Could be something as simple as a valve cover leaking and running down onto the exhaust manifold.

 

[5030]

Randy certainly knows as he repairs them for a living. Me. I just own 2 Kohlers, besides the commode in the bathroom....

One opposed twin 'Command Series' gas guzzler on the wife's zero turn and an ancient but stone reliable K series on my engine drive welder that I've never had any issues with other than required maintenance, oil changes, air filter renew and a spark plug in the last 25+ years.

I do like the sound of the K series engines produce when idling.