# Craftsman DYT 4000 No power to mow



## ddeblance (Jun 29, 2007)

3yr old Craftsman DYT 4000 -48" deck / 24hp B&S v-twin Intek OHV. 

Ok, wife was mowing and noticed the engine bogging down while blades engaged on even the lowest of grass. Pulled hood and noticed while sitting idle the engine would down rev and spit oil from somewhere near the bottom of the right head. After a minute the engine would rev back up to a normal idle and then the oil smoke. Then again after a minute the down rev and oil appeared. Sears came out and said either blown head gasket or valve issue. I pulled the head and looked like there was a blown head gasket on the side of the head where the oil is drawn in to the valve and it was also blown at the bottom, where I was seeing oil. So I cleaned up the head, valves and replaced gaskets... Both sides for good measure. Gapped the valves at .005. Engine sounds good, but now when I engage the blades it sounds like the engine has a hard time starting the blades spinning. Oh yea, I replace all three belts and put an edge on the blades... It takes like two seconds before the blades sound like they have come to their full rpm. Now, with the deck at its highest point, it still has a hard time cutting and bogs down the engine. Double checked that the belts where on right and started researching the problem. This mower has an electric blade engaging mech. PTO I think it's called. Could this be causing this. The engine sounds like it has plenty of power until the blades are engaged. In fact I drove the mower, front tires, up to a railroad tie and the back tires dug down three to four inches and the engine never stuttered....


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## Live Oak (Dec 22, 2003)

Welcome to Tractor Forum ddeblance! Have you run a compression check on the engine?


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## ddeblance (Jun 29, 2007)

Chief, thanks for the response. 

Yes, I did a compression test on both cylinders and the gauge showed 75 on both sides. I did this before I pulled the heads off and replaced gaskets. 
I'm about to pull the carb off, check for water or dirt, and clean it up. That carb has only one adjustment screw and it's for the idler. So I can't adjust the mixture.


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## Live Oak (Dec 22, 2003)

75 psi sounds kinda low. Is that within allowable limits?


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## ddeblance (Jun 29, 2007)

Chief, 

I'm not sure of the spec on the compression. I spoke to a friend that works with rental equipment and he didn't say anything about the pressure being on the low side. I need to look into it. 

Good news is that I pulled the carb in mind to clean and found a small brass fitting that fell out when I removed the bowl. Keep in mind I'm not by no means certified to work on these engines! Anyway, the part looks like a jet. Small with a rubber o-ring around it. It had a twin that was plugged in one of two hole in the middle of the donut style float. I cleaned out any debre I saw and pushed the part back in it's hole. Put it all bacl together and it a new engine!!!!
It must have only been getting about half it's fuel. Now it is running fine with no miss, back fire, bumps, or anything.


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## rbig (Sep 5, 2004)

Glad you got it going again.

However, do some more checking on that compression. Normal should be up around 120lb or so. Actual compression down at 75lb is a good chunk of potential power the engine can't develop.

It can still run smooth, but it won't be making anywhere near full rated power.


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## ddeblance (Jun 29, 2007)

rbig,

I'll look into that compression again. I used a friends compression gauge and no telling how old it is and whether it even reads right. But both sides read the same. Wouldn't the be reading different pressure if there was a ring problem?

Also, went to mow this morning and same issue. No power when mowing. So I again pulled the carb and there was the brass jet laying in the bowl. Put it back in place and tapped the side of the carb. It stays in place fine...... Why is this happening??? I have three acres up to my butt right now and I've borrowed my friends tractor three times now... Just can bring myself to do it again. 

Any idea why that "jet" is falling out??


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## rbig (Sep 5, 2004)

If rings are bad: can be in one cylinder only, or equally in both. 

Many of the modern OHV v twin engines have an ACR (automatic compression release) feature to make startups easier on the starter. 

Because of this, it's very easy to get a low compression reading. I bet if you do a cylinder leakdown test you'll find your compression and rings are fine. 

You power loss is most probably due to the carb problem.


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## ddeblance (Jun 29, 2007)

When I had both heads the cylinder walls didn't have a scratch or grove one. Nice and shiny.... 

When that jet is in place there's is no power lose. Just need to know what I can do to keep it in place...


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## rbig (Sep 5, 2004)

Can't help you on the carb thing.

Go to perr.com and post your problem there. There are a bunch of very knowlegable guys there. 

You'll need you eng Model and spec #s. 

Your carb issues will be resolved at PERR.


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## HYDROGUARDIAN16 (Feb 14, 2007)

*Spark plugs off*

it has a v twin one of the spark plug boots might have popped off. that has happened before to a guy with a 3 year old simplicity regent. If it bogs down check the gaps on the plugs and check to see if the plugs spark when you turn the key.


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