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Engine bogs when PTO is engaged **FIXED**

#1

J

JD_Driver

Here is one for the masses
Lazer Z, Triton 66, 30hp
When PTO switch is engaged, engine bogs
just for a second or so just after activating the switch. It doesn’t die, but seems close. Within about 1-1.5 seconds, it resumes normal rpm.

New air filter, fuel filter, gas is good, checked for a bad coil, no issues there either. Cylinder pressures check good and they are even at 171. Checked spindles and idler pulleys with belt off, smooth, no binding.

Could the PTO clutch be engaging too quickly causing the bog? Any thoughts what to look for?


#2

B

bertsmobile1

Two things will cause this
1) blown head gasket on one cylinder
2) Running on one cylinder


#3

J

JD_Driver

Two things will cause this
1) blown head gasket on one cylinder
2) Running on one cylinder
I’ve thought about that. Pulled one plug wire while it was running. Bogged for a split second but kept running, same for both cylinders. Checked cylinder pressures and they seemed good. I’m not losing oil, no evidence of external leaks.


#4

J

JD_Driver

Two things will cause this
1) blown head gasket on one cylinder
2) Running on one cylinder
You actually may have nailed it. I paid attention to a few things and I’m getting kind of a puff puff sound when I stop the engine almost sounds like an exhaust leak but it’s more of a puff. Can’t tell where it’s coming from.


#5

B

bertsmobile1

The gaskets usually blow between the cylinder & the push rod tunnel
Cheap test is to remove the dip stick tube just after the engine stops
Wafts of light grey smoke confirm an internally leaking gasket .


#6

J

JD_Driver

I believe I and going to get two head gasket kits. I believe you are correct with a leaking head gasket idea.

Thanks for taking the time and the suggestions. Appreciate ya


#7

M

mechanic mark

Check air gap at PTO Clutch 3 places, should be 0.012" to 0.015".


#8

J

JD_Driver

I’ll try that as well

Thinking more about it being a head gasket
When it’s been ran a while, good and warm, it bogs much less


#9

J

JD_Driver

Air gap was big…….


#10

J

JD_Driver

Ok…..so I think I’m set.

I did a compression test and it was acceptable. After changing plugs, I noticed they carboned up very quickly. I also noticed a few videos about bad head gaskets, guys spoke of a puff, puff sound when the engine stopped.

I decided to take the advice of a few here and get a gasket set. I did #2 first, crap sake, it had a snail trail leak. While it was tore down, I pulled #1 head as well. It did have a leaking area as well. The gaskets I installed were the new style.

I noticed the puff sound when engine is stopped is gone. My issue with the bog is greatly reduced as well, nearly nothing.

If I throttle it down to about 3/4 and engage the PTO, it engages very smoothly. Then I throttle up.

Will know a bit more when the gov idle spring comes in. Previous owner had it on the "least sensitive" position. I was going to move it to the factory setting hole and dropped it. Can't find it….searched for an hour, still did not find. I had guess the best way to find the spring would be to order a new one, however, that didn’t work, so I am waiting.

Thanks for all those who provided input and suggestions, greatly appreciated.


#11

B

bertsmobile1

Sounds like a win
Thanks for the heads up


#12

J

JD_Driver

Sounds like a win
Thanks for the heads up
Thanks for the sage advice


#13

J

JD_Driver

Got the lost spring replaced. She runs good. Head gaskets were certainly the issue


#14

B

bertsmobile1

:giggle:(y)


#15

J

JD_Driver

And yet another.
Was chasing an odd sound, ended up being the PTO clutch. Replaced it, both bearings were in very poor condition. Engine side was dry and very rough. The aft bearing was dry & had some crumbles of what I think was lithium left from the grease.

Engagement is rather smooth now at 3/4 throttle.


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