Exmark Lazer Z Kohler CH740 problems

[NxtGoRnd]

Hi everyone thanks in advance for any help. I have a Exmark Lazer Z with Kohler Command SP27 model CH740s Spec PS-CH740-0045 serial 3416109201. Sometime around 2015 it started blowing oil and skipping so I put it in my building and started to use and older mower I had. I had been through cancer and chemo and dealing with chemo brain lol. Pulled it out couple weeks ago and dug in , the oil was leaking from the gasket at the crank case vent. I replaced gasket and filter, installed new plugs, oil change serviced it and fired it up. It ran for about 30 minutes of cutting doing excellent then lost power.

I took it to the building and it would idle but at full throttle pop through the carbs like maybe no timing advance. I ordered and updated the coils to the new Kohler style and removed the DSAM ignition and coils. It was still doing same thing. Checked Leak down and both cylinders were 80/75 and compression on both was 150 with engine cool, I would think even higher on a warm engine. I ordered a carburetor and installed same results with both carbs. Any pointers or suggestions would be greatly appreciated still dealing with chemo brain and old age so cognitive skills not what they used to be. Thanks again Tony

 

[mechanic mark]

Free Kohler Service Manual Downloads - OPEengines.com

Listed below are Kohler engine service repair manual in Adobe PDF format that you can download for free. Below we have provided a link to these manuals which can also be download. Click on your engine listed below to download. These service manuals provide general information, adjustment...

www.kohler-engine-parts.opeengines.com

See page 18 in CV740 Service Manual above, Troubleshooting Section. Please take your time & let us know how it goes, thanks Mark

 

[slomo]

Hi everyone thanks in advance for any help. I have a Exmark Lazer Z with Kohler Command SP27 model CH740s Spec PS-CH740-0045 serial 3416109201. Sometime around 2015 it started blowing oil and skipping so I put it in my building and started to use and older mower I had. I had been through cancer and chemo and dealing with chemo brain lol. Pulled it out couple weeks ago and dug in , the oil was leaking from the gasket at the crank case vent. I replaced gasket and filter, installed new plugs, oil change serviced it and fired it up. It ran for about 30 minutes of cutting doing excellent then lost power.

I took it to the building and it would idle but at full throttle pop through the carbs like maybe no timing advance. I ordered and updated the coils to the new Kohler style and removed the DSAM ignition and coils. It was still doing same thing. Checked Leak down and both cylinders were 80/75 and compression on both was 150 with engine cool, I would think even higher on a warm engine. I ordered a carburetor and installed same results with both carbs. Any pointers or suggestions would be greatly appreciated still dealing with chemo brain and old age so cognitive skills not what they used to be. Thanks again Tony

I feel you are way above most of the unsick cancerless folks we get on here. Cheers to you and keep up the good fight!!!

Popping through the carb is either early ignition timing, water in the gas or a blown head gasket. I'm not a Kroller expert like several others on here. Sticking intake valve??? Valves out of spec?

Verify good clean fuel from an aux fuel tank and lines to the carb. Rule that out. Then do a valve adjustment or yours might have hydraulic lifters maybe. Check your engine manual.

 

[NxtGoRnd]

I feel you are way above most of the unsick cancerless folks we get on here. Cheers to you and keep up the good fight!!!

Popping through the carb is either early ignition timing, water in the gas or a blown head gasket. I'm not a Kroller expert like several others on here. Sticking intake valve??? Valves out of spec?

Verify good clean fuel from an aux fuel tank and lines to the carb. Rule that out. Then do a valve adjustment or yours might have hydraulic lifters maybe. Check your engine manual.

Thanks for the reply it has hydraulic lifters a new carb and two tanks of ethanol free gas couple weeks old. Have wondered if it could be a lifter and checked the push rods they are straight and undamaged. Sticking lifter still a possibility. compression and Leak down test should rule out head gasket but I replaced both cylinder head gaskets just because LOL. Thanks and Cheers.

 

[NxtGoRnd]

Free Kohler Service Manual Downloads - OPEengines.com

Listed below are Kohler engine service repair manual in Adobe PDF format that you can download for free. Below we have provided a link to these manuals which can also be download. Click on your engine listed below to download. These service manuals provide general information, adjustment...

www.kohler-engine-parts.opeengines.com

See page 18 in CV740 Service Manual above, Troubleshooting Section. Please take your time & let us know how it goes, thanks Mark

I will check that out thanks! I have downloaded the service manual and parts manual for the CH740. Thanks again.

 

[VegetiveSteam]

Hi everyone thanks in advance for any help. I have a Exmark Lazer Z with Kohler Command SP27 model CH740s Spec PS-CH740-0045 serial 3416109201. Sometime around 2015 it started blowing oil and skipping so I put it in my building and started to use and older mower I had. I had been through cancer and chemo and dealing with chemo brain lol. Pulled it out couple weeks ago and dug in , the oil was leaking from the gasket at the crank case vent. I replaced gasket and filter, installed new plugs, oil change serviced it and fired it up. It ran for about 30 minutes of cutting doing excellent then lost power.

I took it to the building and it would idle but at full throttle pop through the carbs like maybe no timing advance. I ordered and updated the coils to the new Kohler style and removed the DSAM ignition and coils. It was still doing same thing. Checked Leak down and both cylinders were 80/75 and compression on both was 150 with engine cool, I would think even higher on a warm engine. I ordered a carburetor and installed same results with both carbs. Any pointers or suggestions would be greatly appreciated still dealing with chemo brain and old age so cognitive skills not what they used to be. Thanks again Tony

It almost acts like there is an exhaust restriction but let's start simple. Can you give us the part number you used to update the ignition coils? It should have been a kit with two MDI ignition models and a white wire pigtail for the kill.

 

[hlw49]

Thanks for the reply it has hydraulic lifters a new carb and two tanks of ethanol free gas couple weeks old. Have wondered if it could be a lifter and checked the push rods they are straight and undamaged. Sticking lifter still a possibility. compression and Leak down test should rule out head gasket but I replaced both cylinder head gaskets just because LOL. Thanks and Cheers.

Cylinder leak down test and compression test may not show either one of these even a crankcase vacuum test will not do it. In my experience with Kohler engines these test rarely do. Due to area they blow. The best indicator of a blown head gasket is the plugs will be black and oily and my use oil or may not. They blow between the oil return hole and the cylinder a very small area. Sometimes they blow outside the cylinder in the exhaust port area. Did you lap the heads down so they are flat? Could be an air leak.

 

[NxtGoRnd]

Cylinder leak down test and compression test may not show either one of these even a crankcase vacuum test will not do it. In my experience with Kohler engines these test rarely do. Due to area they blow. The best indicator of a blown head gasket is the plugs will be black and oily and my use oil or may not. They blow between the oil return hole and the cylinder a very small area. Sometimes they blow outside the cylinder in the exhaust port area. Did you lap the heads down so they are flat? Could be an air leak.

The factory gaskets were in great shape i found no evidence of any leaks, I installed the new gaskets it has same condition. I did not lap I have taken the engine back out again and will go back over everything. I did hook a remote to starter while it was on the bench this morning and turned it over with a car battery while listening with stethoscope (plug wires off). the number 2 cylinder plug has been a little black compared to the #1 cylinder every time I have checked. It will run with either plug disconnected and makes a difference when you pull either one. Thanks for the input will keep all posted as I go.

 

[NxtGoRnd]

It almost acts like there is an exhaust restriction but let's start simple. Can you give us the part number you used to update the ignition coils? It should have been a kit with two MDI ignition models and a white wire pigtail for the kill.

I actually put new old stock replacements then went to 25-707-03-S Came with Kohler sticker said genuine Kohler parts. I removed the old dsam and followed directions it did have the ground wire and disconnect 12 volt wire. Thanks for the help for sure and and you are correct on exhaust restriction. Oh sorry for the delay in answering. Cheers Tony

 

[NxtGoRnd]

As VegetiveSteam correctly suggested exhaust restriction. I turned it over with the valve covers off and #2 Cylinder head exhaust valve was not moving so yep restriction. I tightened the rocker bolt another 10 in lbs and when I turned it over the exhaust valve was opening. All bolts including rockers had been torqued to spec not saying my torque wrench was dead on. Put everything back and attempted to run it it ran same as before I removed the valve covers and the same #2 exhaust was not moving. I removed the rocker and pushrod pulled the lifter and bench bled it in the press put it back torqued it up same results. I have a set of lifters on order but concerned there was not much oil spillage when running at idle with rocker covers off. I checked the oil pressor sensor and it was working correctly. I have fuel service gauges, leak down gauges, compression gauges and others but nothing to check oil pressure with will get something this afternoon. I can push the valve in by hand and it springs back in place once i release it so failed lifter ? Once again thanks to everyone! Tony