Antifreeze in Carburetor

Mon Oct 08, 2012 10:54 am

I think I have a problem here. 1954 cub. Battery was dead and the starter wasn't working so I tried to jump it (pop the clutch) in 3rd gear. This resulted in a mixture of gas and antifreeze spraying from the exhaust then draining back through the carburetor. No previous issues. Used the tractor this past Spring.
What am I looking at here? Appreciate any input.
Mike in CT.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 12:40 pm


Part of it sounds like a cracked head gasket/head to me - the part with the coolant coming out - probably via the exhaust valves. The fuel part doesn't quite make sense -- except of course it didn't fire so possibly the unburnt fuel was ejected out the exhaust valves at the same time as the coolant. Others with more experience with engines will be along to offer advice.

So, you are going to have to pull the hood and replace it. While you are in there probably time to check on other issues. Suggest you follow the links below - all the Service Manuals are in the Manuals link above and below as well.

Image to :big smile: Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to :arrow: the Welcome Wagon wherein you will find links to many useful sites and topics. One of which is the Cub Manual Server. Enjoy!.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 1:54 pm

Adding a second opinion, I also agree head/head gasket failure.

If you had your tractor running this spring, had it protected against freezing, and didn't overheat it, I'd lean towards head gasket failure and not a cracked head.

Pulling a tractor for a long distance in gear is the closest thing to the engine running without it running. At towing speed, there is plenty of vacuum or suction created at the carburator to draw the same amount of fuel through the engine as if it were running if the fuel delivery system and carburator are functioning as they should. Of course if it doesn't light, up the chimney the unburned gasoline, now condensed back to liquid form goes.

If your head gasket has failed in a spot allowing coolant to run into 2 adjoining cylinders, I suspect your no start was because those cylinders were being extinguished and could not fire.

Hopefully the gasoline/coolant mixture did not wash down your cylinder walls to the extent of scoring or excessive piston ring wear, one disadvantage of pull starting. Cranking an engine is accomplished at a much lower rpm and the battery normally gives out before it is cranked long enough to do cylinder wall damage.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 2:18 pm

Thank you both. I thought that might have been the problem (gasket) but was hoping I was wrong. Too bad because I was going to bring it up from the barn so I could sell it since I'm moving and can't take it with me. That's become a bit of a problem now I guess.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 2:32 pm

You are most welcome, glad to help troubleshoot your problem. Sorry we didn't have better news for you but it is what it is.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 2:38 pm

Suggest that you post in our For Sale Cubs sub-forum your Cub. Explain what the suspected problems is - refer back to this thread. For many of us a head gasket replacement is an easy task - an afternoon of enjoyment in the barn. Same with the head. If it is done as well these are available and again it is a nice afternoon in the barn.

Remember though that a non-running Cub is going to go for far less than one that is fully functional. The only way to ensure that there is no damage to the cylinder walls is to pull the

Unfortunately that is the way the ball bounces at times.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 4:34 pm

Valve over lap. Both the intake and exhaust valve are both open at the same time for about 15 degrees of the combustion cycle. It is quite possible for fluid to be pushed out both the exhaust and intake at the same time.

Couple of potential problems, besides the head gasket. Hydrostatic lock bending connection rod(s) and coolant draining into the crankcase.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 4:34 pm

Bring your Cub to Cubfest Northeast this weekend and get it checked out.

Re: Antifreeze in Carburetor

Mon Oct 08, 2012 8:23 pm

Now that is an idea :D Then we can get a first hand look at it. Didn't realize you were close to Cecil's