Pt 425 Almost Burns Up today

[Clarke]

Finished mowing today after cleaning mower deck started PT and pulled into workshop to drop the mower deck. Noticed smoke which I thought was steam blowing out of the hydraulic cooler. Thought it was steam because I just washed it. Pulled out of workshop noticed trail of oil. Shut down open hood machine was on fire. Extinguished muffler fire and let the machine cool a bit.
You would think it was a hydraulic leak, not so. Kohler engine breather cover gasket blown. Engine pumping oil into cooling baffle. Engine cooling fan blowing oil out of baffle all over everything including the hot insulated muffler.
I found this by diassembling a lot of the top of the engine. I never did like that hot insulated muffler. Now I like it even less. I have had a plan to put dual exhaust on for a long time. This will most likely motivate me to get that done.
The problem happened incredibly fast. The engine pumped about a quart of oil into the baffle in no more then sixty seconds. Hoping I can complete fixing it early this week.

sg

 

[MuncyBob]

well, as the saying goes....coulda been worse!! Glad you caught it quick with minimal damage. Now to install the new exhaust system and post some pics of course!

 

[Marks481]

I keep playing around with the idea of dual exhausts also. My PT425 has the external muffler, but the way that the exhaust is piped out of the engine compartment looks like it would cause excessive backpressure and heating of the exhaust pipe, since it doesn't provide a smooth path for exhaust path flow.

However, I am not sure that I am ready to cut a hole in the engine cover, so I am thinking about just making something like the attached arrangement, and putting a supertrapp muffler with resonance chamber attached to the exhaust pointing vertical outside the engine canopy. I am thinking about making the horizontal pipe across the engine compartment out of 1.5" tubing (the exhaust elbows from the flanges are 3/4" nominal tubing), and smoothly curved pipe will do a better job of directing exhaust flow then the 3/4" pipe welded straight into a 1" square tube, which is the current arrangement.

 

[Clarke]

PT fixed installed the new gasket. IMO If you have a PT 425 with the Kohler engine especially if its the model like mine with the tank in the lid and the insulated muffler between the battery and engine I would replace that gasket. The new gasket is much different then the one removed (picture Attached). The older units had the form a gasket silicon which they do not recomend. I am not exaggerating, if that gasket blows it will pump the engine dry in 90 seconds. Also the oil will be blowing out the cooling baffles and under the insulation on the muffler and it will ignite in an instant. It is hard to put this fire out because the muffler is so hot. If the oil that will be all over everything ignites just run. Old wimpy gasket on left neww gasket right.

sg

 

[catsco]

Glad to hear that you and the PT are OK. Things like that can be annoying on a good day and dangerous on a bad one.

I have exactly that configuration on my PT-425.

Where is that gasket located? I'm not clear from the description or its shape.

My PT has about 527 hours on it. Did the gasket fail before that?

Thanks in advance.

Again, glad you're OK.

Mark H.

 

[Clarke]

Glad to hear that you and the PT are OK. Things like that can be annoying on a good day and dangerous on a bad one.

I have exactly that configuration on my PT-425.

Where is that gasket located? I'm not clear from the description or its shape.

My PT has about 527 hours on it. Did the gasket fail before that?

Thanks in advance.

Again, glad you're OK.

Mark H.

The gasket is under the plate that the oil sentry sending unit is screwed into. It is under the air cleaner and throttle linkage in the valley between the cylinders. You can download the service manual on the Kohler web site pretty easy fix... It failed at 368 Hrs.

sg