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Discussion Starter · #1 ·
What Went Wrong : (apart from forgot to check the bleep Oil level) I'll skip why for now.
Kohler command Twin 25 hp Revs dropped shortly after warm up and going to full revs. Revs dropped about 25% , initially thought fuel was out, nope , so I turned off. Oil was at lowest on stick and the rocker cover seems to have let go and it all looks like the start of a Seize up.

Drained oil, looks dark but dredging with magnet reveled nothing.. Letting sit all night and will check later. Will cut open oil filter and check that later too.
I want to know what to do next?
(I'm thinking)
Pressure check. followed by minimum pulling the heads off and check bores and if they are 100% just replace with new gaskets and oil filter (maybe do an oil flush) and test run monitoring head temps for idle and then if OK at full for at least 5 minutes I will call that a close shave.
1st Q, Do I need new head bolts if refitting for starters?
BUT if I need a strip down. how far?
and is it best to pull the motor onto bench, motor stand ,
what is the procedure if anyone has done it.
I'm dreading the whole thing going to a whole rebuild as parts are a stupid price this part of the world.
Any help would greatly be appreciated. summer is here and the grass is growing 1cm / day :(
Thanks Jonn
 

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If you had any oil on the dipstick at all you should be fine. Could be something as simple as peice of trash got into carb, pushrod fell off, or even head gasket issue. I'd crank her up and feel each pipe of the exhaust after running for a few seconds and see if they're equal getting warm (do not do this hot lol). That'll point you towards if there is an affected side then you can go from there by checking for spark, etc.
 

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In the event that you ran it dry of oil, the first thing to catastrophically fail is going to be a connecting rod. They will begin to transfer aluminum from the con-rod bore to the crankshaft, gall, seize, and then come apart inside the case.

I had one of these failures last year. The engine will actually begin to starve for oil, to the point that the hydraulic lifters will go dry and begin "ticking" but the engine will continue to stay running. Refilling with oil, the lifter tick would immediately go away.

For reference, mine went through about (20) of these empty/lifter ticking cycles before I had the connecting rod failure. I didn't keep track, but it was a lot...

Also - The biggest risk is actually pieces of the broken con-rod busting the cylinder walls at the bottom of the bore, and/or through the side of the case. In my event, I had both, which meant a scrap block. Had the cylinders/case been OK, I probably could have rebuilt that block with the original crank, and new rods & pistons.





In your case, refill it with oil, and run the engine. If it's free of noises, I'd just roll on with it to be honest.

If you are extra paranoid, pull the spark plugs to look at the cylinder walls (will probably be fine & unnoticeable really,) and possibly, pull the rocker covers to make sure that you don't have a broken/bent pushrod.

You'll be able to hear the engine running funny if you have a bent/broken pushrod = dead cylinder. If you suspect this, pull a spark plug wire off, and try to start/run it. If with one plug wire removed, it starts/runs rough, then that's your problem child. Look for the broken/bent pushrod on that cylinder.

I bet it's a minor issue, and the motor is still healthy. They're pretty resilient actually.

Best of luck.
 

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The engine has been apart?
If so, before anything, drain the oil and empty filter.
Refill crankcase, leave wet filter empty but install.
Take note of level.
Disable ign and crank.
Your checking to see if the oil pump is working. Crank engine 30 sec
and see if level goes down.
If you have a pressure gauge, install on filter head.
Will jump to 60 psi then drop down to 20 appx.
That will rule out a broken gear, pump or anything else in lub system.
 

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Discussion Starter · #7 ·
In the event that you ran it dry of oil, the first thing to catastrophically fail is going to be a connecting rod. They will begin to transfer aluminum from the con-rod bore to the crankshaft, gall, seize, and then come apart inside the case.

I had one of these failures last year. The engine will actually begin to starve for oil, to the point that the hydraulic lifters will go dry and begin "ticking" but the engine will continue to stay running. Refilling with oil, the lifter tick would immediately go away.

For reference, mine went through about (20) of these empty/lifter ticking cycles before I had the connecting rod failure. I didn't keep track, but it was a lot...

Also - The biggest risk is actually pieces of the broken con-rod busting the cylinder walls at the bottom of the bore, and/or through the side of the case. In my event, I had both, which meant a scrap block. Had the cylinders/case been OK, I probably could have rebuilt that block with the original crank, and new rods & pistons.





In your case, refill it with oil, and run the engine. If it's free of noises, I'd just roll on with it to be honest.

If you are extra paranoid, pull the spark plugs to look at the cylinder walls (will probably be fine & unnoticeable really,) and possibly, pull the rocker covers to make sure that you don't have a broken/bent pushrod.

You'll be able to hear the engine running funny if you have a bent/broken pushrod = dead cylinder. If you suspect this, pull a spark plug wire off, and try to start/run it. If with one plug wire removed, it starts/runs rough, then that's your problem child. Look for the broken/bent pushrod on that cylinder.

I bet it's a minor issue, and the motor is still healthy. They're pretty resilient actually.

Best of luck.
Thanks this has my heart working again. When the thunder storm clears I will check these out.
 

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2013 GMC Sierra 1500 WT 4.3L V6
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That's the problem with experience, we tend to take small problems as signs of impending doom. Fear not, you're not the only one with this dilemma.

Granted I can't say that it isn't the beginnings of a seized engine but at this stage I would say you really have nothing left to lose... If the engine is in fact about to seize then it's going to seize one way or another, I suppose tearing it apart might allow you to keep the worst from happening but you're still looking at a rebuild, at which point I would think it might be cheaper to just replace it.

The thing is, could it be out of fuel?
Could it be a gas cap's vent is clogged?
Could it be a linkage has become loose, gone missing, bent, seized or otherwise not functioning as it should?
Could it be a fuel line leak, or a vacuum leak?
 

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Discussion Starter · #9 ·
If you had any oil on the dipstick at all you should be fine. Could be something as simple as peice of trash got into carb, pushrod fell off, or even head gasket issue. I'd crank her up and feel each pipe of the exhaust after running for a few seconds and see if they're equal getting warm (do not do this hot lol). That'll point you towards if there is an affected side then you can go from there by checking for spark, etc.
thanks, I'll check these with IR temp gun which is coming in more handy than ever thought. cheers
 

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Discussion Starter · #10 ·
The engine has been apart?
If so, before anything, drain the oil and empty filter.
Refill crankcase, leave wet filter empty but install.
Take note of level.
Disable ign and crank.
Your checking to see if the oil pump is working. Crank engine 30 sec
and see if level goes down.
If you have a pressure gauge, install on filter head.
Will jump to 60 psi then drop down to 20 appx.
That will rule out a broken gear, pump or anything else in lub system.
Thanks Ricky, been apart? I think so as this is an x contractors who was a locomotive engineer before so alot has been beefed up.His workshop was to die for. I WILL get an oil gauge asap now with oil temp. Really appreciate the trouble shooting method. cheers
 

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Discussion Starter · #11 ·
That's the problem with experience, we tend to take small problems as signs of impending doom. Fear not, you're not the only one with this dilemma.

Granted I can't say that it isn't the beginnings of a seized engine but at this stage I would say you really have nothing left to lose... If the engine is in fact about to seize then it's going to seize one way or another, I suppose tearing it apart might allow you to keep the worst from happening but you're still looking at a rebuild, at which point I would think it might be cheaper to just replace it.

The thing is, could it be out of fuel?
Could it be a gas cap's vent is clogged?
Could it be a linkage has become loose, gone missing, bent, seized or otherwise not functioning as it should?
Could it be a fuel line leak, or a vacuum leak?
thanks for that, I have had both tanks off to thoroughly cleaned them last year but stuff does get back in, Murphy's Law. I will add these to the list I will be going thru. cheers
 

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thanks for that, I have had both tanks off to thoroughly cleaned them last year but stuff does get back in, Murphy's Law. I will add these to the list I will be going thru. cheers
Sounds good, my law is:
"When unsure of the source of the problem, start with the simple stuff. One way to do so is "cheapest parts first" and then work your way down, perhaps make a list for yourself for future reference?"

Spark plugs can give you a good indication, I'd pull those.

On a note of price, have you tried ebay or aftermarket for parts?
Granted, for mission critical components you might want OEM.
 
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