Flames out of exhaust

[Digger 258]

This can't be right . . . I was working the PHD on my 425 for an hour or so, and when I idled down after the work, I noticed flames coming out of the exhaust. They were shooting out a good six inches.

The next day, I started her up, no flames. But after some loader work it did the same thing when I idled down again.

Does this mean I am running too rich? Any ideas?

I'm wary after reading about KentT's fire . . .

Thanks!

 

[Marks481]

Air cooled engines like being run full throttle. Throttling down actually makes it run hotter, not cool it off. Although I have never had flames when doing similar things.

Pull both spark plugs, and check the color. Both slightly black, or is one clean (sign that you have a bad coil)? OW, probably running too lean.

 

[Digger 258]

After a long search for the right carburetor rebuild kit (I have the Kohler CH730), I decided to rebuild the crab. I went with tmarks's thought that it was running too lean, causing flames at idle. Put the carburetor back in, and she fired up fine, and seemed to run smoother. I was really excited. A few days later (today) I did about 45 minutes of light fork work. When I pulled the PT into the barn to park, I opened the hood to turn off the fuel cut off while running, so I can park with a dry float. What did I see? The entire exhaust was glowing red. I moved the throttle from idle to full, and a long blue flame shot out for a second. Glowing exhaust has me a little nervous. Is this normal, and I never noticed it before? Or do I have a problem? As far as I can tell, the coils are working fine. I'll post a pic of the spark plugs next chance I can get to the PT. Thanks for your input - I love the PT and don't really want to burn her to the ground (nor my barn).

 

[PILOON]

Generally when running that hot indicates that the mixture is much too lean or timing way off.

Once had a tuneup done by a dealer ($$) and drove a long distance next day discover my manifold melted away.
While timing was OK at idle the mechanical advance was rusted and engine overheated to almost destruction.
All that happened at 2 AM on a highway to nowhere, almost lost the car to fire.
A tin can (found in the ditch) and some wire bridged the gap but I had to push start jump in to be able to continue driving as all the generator wires were toast and battery dead.
This was a Xmas eve in the '70's and B4cell phones.
Made it home with quite a story to tell.
Dealer never accepted his error and told me to never come back. Sold the car.
Shame was it was a pristine Volvo but only one dealer within 100's of miles.

 

[hawkeye08]

Generally when running that hot indicates that the mixture is much too lean or timing way off.

Once had a tuneup done by a dealer ($$) and drove a long distance next day discover my manifold melted away.
While timing was OK at idle the mechanical advance was rusted and engine overheated to almost destruction.
All that happened at 2 AM on a highway to nowhere, almost lost the car to fire.
A tin can (found in the ditch) and some wire bridged the gap but I had to push start jump in to be able to continue driving as all the generator wires were toast and battery dead.
This was a Xmas eve in the '70's and B4cell phones.
Made it home with quite a story to tell.
Dealer never accepted his error and told me to never come back. Sold the car.
Shame was it was a pristine Volvo but only one dealer within 100's of miles.

You know that battery had enough in it to fire the spark plugs (perhaps not start engine), I doubt that your Volvo had a magneto.

 

[Digger 258]

So I called Terry at PT and explained my glowing exhaust. He explained that the kohler motors heat up the exhaust until glowing, and most folks don't notice until they operate at night. He didn't seem concerned but just in case, he gave me a number to a Kohler Tech. The tech asked if just the headers were glowing or the whole exhaust. He said headers glowing is normal, but the whole exhaust muffler should not heat up that much. He suggested a number of things:
1) Exhaust manifold gaskets leaking air
2) Woodruff key on flywheel sheered, affecting timing
3) Fuel solenoid in carb not opening all the way
4) Carb set too lean (not adjustable)
5) Fuel pump not pumping enough.

So I'm looking for manifold gaskets, with little luck, but I don't see anything that would indicate a leak. I pulled the fuel shut-off solenoid and touched it to 12v, and it is working fine. I cranked the motor with the fuel line disconnected and was rewarded with strong pulses of fuel - I replaced the fuel line for good measure. I don't suspect I can check the flywheel without pulling the motor though. Here are what my plugs look like - best I can tell they look like the "normal" picture when you google image "how to read a spark plug."



So I really don't have a plan moving forward, except trying to find new exhaust gaskets / studs / nuts. I am questioning if I even have an issue, or if the exhaust glowing at night is normal. I don't really want to find out by hosting a huge fire behind me as I'm pushing snow.

Thoughts appreciated.

 

[MossRoad]

Which exhaust is on that machine? Is it a factory Kohler exhaust or a Power Trac manufactured exhaust?

 

[buickanddeere]

Probably not flame but instead just exhaust gasses and bits of carbon hot enough to glow and appear as flames.

 

[Digger 258]

This is the exhaust on it. I assume it's a PT "special," and not original Kohler. When I look through a gap in the silverish heat cover (probably asbestos cloth?) I see the glowing square exhaust and tailpipe. It gets hot enough to warp the expanded metal tub side that it blows through. Maybe that's not a big deal, but I thought I would have noticed it earlier if it were glowing all along

.

I've put a couple hundred hours on it this year.

 

[MossRoad]

This is the exhaust on it. I assume it's a PT "special," and not original Kohler. When I look through a gap in the silverish heat cover (probably asbestos cloth?) I see the glowing square exhaust and tailpipe. It gets hot enough to warp the expanded metal tub side that it blows through. Maybe that's not a big deal, but I thought I would have noticed it earlier if it were glowing all along

View attachment 491030 View attachment 491031.

I've put a couple hundred hours on it this year.

There were/are several folks on here with that version of the PT factory exhaust on the Kohler engine. Is it a 2002-2003 or so model with the battery and all three pumps in front of the engine and the engine all the way to the rear of the tub? I don't know who they are anymore, maybe they'll chime in. I think PJ in Montana had that version, but he sold it when he moved and has since passed away (RIP PJ Good guy!).