Oil & Fuel Gasoline in engine oil on PT 425

   / Gasoline in engine oil on PT 425 #1  

fnoergaard

New member
Joined
Mar 10, 2012
Messages
3
Location
Denmark
Tractor
IH B-275, Power Trac PT-425
Hi there, new guy here. I hope you have room for a European in this forum :)

After having read about the Power Trac and other machines for 3-4 years, I finally went ahead and bought a PT 425 a few weeks ago. I live in Denmark and bought the machine from a dealer in Holland. I think my PT may be the only one in Denmark.

I've been very satisfied with it so far, but have detected a potentially serious problem.

Last week, I changed the engine oil, as the dipstick unmistakenly smelled like gasoline. I let the engine oil out, and it was a very thin mixture of engine oil and gasoline. I drained approx. 3 liters from the engine, and that is twice the oil capacity of 1,55 liters.

Needless to say, that I now change the oil before operating the PT, but I'm worried, that the engine may have suffered some damage, as a result of the high pressure caused by the extra gasoline, before I discovered the problem.

As the machine has been in storage for a couple of years at the dealer, I suspected the carburettor float was stuck, letting gasoline seep into the cylinders filling them up, eventually finding it's way to the engine oil.

I contacted the Dutch dealer, and he informed me, that he discovered the same problem before shipping the PT to me. He told me, that he has had changed the fuel pump and cleaned the carburettor, making sure the float was not stuck. After this he thought the problem was solved, but unfortunately it's not.

I should tell you that I've put about 20 hours on the PT and it has the Robin engine.

The engine has been pretty hard to start, but I dismissed this as me having to get used to the machine. However, I now believe that it may have to do with this problem.

Have any of you guys experienced a similar problem, and what would be the solution to it?
 
   / Gasoline in engine oil on PT 425 #2  
I have had some Kohler command 20hp engines do the same thing. It seems the ones having a problem are on utility vehicles that bounce around alot. I have adjusted the float hight so there is less fuel in the float bowl. Some carbs that bounce around will let more and more fuel in when they should not.
 
   / Gasoline in engine oil on PT 425 #3  
Always check the oil level, and if it is high, it can only be gas or water.

inspect the fuel needle seat and that the rubber tip is centered.

I have the same leaking carb thing on a Honda engine. The float seems to cut the fuel off when I press on the float, but with the carb back together, gas leaks out the bowl. It has to be something like corrosion in the fuel inlet, or the needle seat is damaged.

You could install a fuel cut off solenoid before the carb to insure no fuel flows past the solenoid.
 

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   / Gasoline in engine oil on PT 425 #4  
I had this on a Chevy V8. It was the fuel pump diaphragm. The Robin engine fuel pump is run by pulsing engine vacuum. If there is a leak in this diaphram it might pull fuel into the engine. Try pulling a vacuum on the hose going between the engine and pump. Of course disconnect the engine end and tie your pump to that. I know the dealer replaced the pump, but it is worth a look.

Welcome to TBN. We are always glad to help anyone with a PT.
 
   / Gasoline in engine oil on PT 425 #5  
If it is not the gas pump, as bob suggested, then it would be the stuck float scenario you described.

Previous discussions that covered this included the info that the Robin user manual requires an inline valve on the fuel supply to prevent the flooding scenario when the engine is not in use. The solenoid valve on the fuel line does not shut off all fuel flow, and if the float sticks, the fuel will flood out the bowl and easily fill the crankcase through the rebreather line.

Oh, and if it is the fuel pump, don't buy the robin version. Apparently much cheaper versions available (B&S? Will have to look for that thread)
 
   / Gasoline in engine oil on PT 425 #6  
Although my Kohler engine has the solenoid fuel shut off, I added a manual shut off valve also. I have had those solenoids jam and not shut off the fuel.
 
   / Gasoline in engine oil on PT 425 #7  
Many years ago, I had a lawnmower with a Tecumseh engine and every time I mowed the yard, I had to change oil because the crankcase would fill up with gas. A dealer told me I'd need to have a new short block which would cost as much as a mower, so I just bought another mower with a different engine. When I got a little older and more experienced, I had a little old 3.5 hp Briggs & Stratton engine on a spray rig that did that. A new carburetor fixed it. I suspect that might have fixed that Tecumseh if I'd known what I was doing. I've no experience at all with Robin engines, but I wouldn't be surprised if it's a carburetor problem
 
   / Gasoline in engine oil on PT 425 #8  
I had this on a Chevy V8. It was the fuel pump diaphragm. The Robin engine fuel pump is run by pulsing engine vacuum. If there is a leak in this diaphram it might pull fuel into the engine. Try pulling a vacuum on the hose going between the engine and pump. Of course disconnect the engine end and tie your pump to that. I know the dealer replaced the pump, but it is worth a look.

Welcome to TBN. We are always glad to help anyone with a PT.

Most likely it is the carb. I just thought I would mention the fuel pump possibility.
 
   / Gasoline in engine oil on PT 425 #9  
Check the fuel cap to make sure it is venting. It takes very little pressure to overcome the needle and seat in the carb. If the cap is not venting pressure will build in the tank and push all the fuel in the lines past the seat.
 
   / Gasoline in engine oil on PT 425 #10  
Welcome!

It's not a bad idea to add a manual fuel shutoff valve in the fuel line.

Check the motor oil, turn on the fuel valve then start the motor. When you shut off the motor, turn off the fuel valve.
 
 
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