Oil & Fuel YM2500 Pushing Coolant Out the Radiator

[RayIN]

Let’s see if this video will post…

Yup, that's the sign of a blown/leaking head gasket.
Fix it right away, anti-freeze can seize an engine if ran that way.
My first action would be to remove the valve cover and re-torque the head bolts, then run a compression test.
That likely will not fix the problem, but its a shot.

 

[aba4430]

Try and replace the radiator cap with a properly specced one. See if it stops. Cheap enough check.

 

[George2615]

I don't have a Yanmar. I watched the video and it looks to me to be full of brown water. Is there antifreeze coolant in there?

I'd drain and flush the radiator, replace the thermostat, refill with 50/50 AF and replace the cap.

 

[careyo63]

No Thermostat on a YM2500
Warning light switch # TS-44901 which is like my YM2000.
Radiator cap # RC-28
Overflow Tank/Bottle # OFT-4450

 

[Travis_R]

Try and replace the radiator cap with a properly specced one. See if it stops. Cheap enough check.

New radiator cap will be here Tuesday morning from Napa. Sparex #S.68401.

 

[Travis_R]

13 PSI Cap.

 

[careyo63]

You have massive air in the Radiator. Pressure build up! The video shows a problem. Does a radiator cap go bad?. Sure it can but when they do It leaks Anti freeze around the top. A dry Residue will appear and you will see it on the top of the Radiator and shroud. A cap Rated 0.5 PSI? Should be 13-15 PSI so that is a problem. Did it get used to keep the PSI in the Radiator pressure down and release pressure could be very possible. Until you Pressure Check the Radiator PSI you are guessing and just Throwing parts at it!!. NAPA has quality Auto parts but mine local Doesn't even stock a Ford fuel filter. Having problems with one now! They used a NAPA filter that's sucking air at the fuel line connection. Which is going to Ford and get replaced this week. Told them to use Org. Ford parts. So it's Going to the dealer. They told me they see a problem with them often. I looked at the receipt and sure enough 13$ Napa filter and 59$ from Ford. Go figure! Cut the motor off and it won't start back up! Let it sit for a few minutes and the Gas pushes the air out and it fires right up!
0.5 pressure cap is going to be a problem if that is true! I would call Hoye or Fredricks and get the correct Yanmar cap for sure!

 

[Travis_R]

The radiator cap coming from Napa is actually a Sparex part. It’s Sparex part # S.68401 and is Napa part # BK S68401. The specs state that it’s a 13 PSI cap. I believe the cap will be just fine, although it may not be the problem.
The day I bought the tractor at Fredricks, on 11/22/2024, I remember checking the coolant in the radiator and one of their mechanics had to add some water to it because it was low.
I agree with you, I’m not gonna throw parts at it. I shouldn’t have to. I’m calling Fredricks again tomorrow morning. The tractor came with a 1 year warranty and I paid very good money for the tractor. I believe Fredricks will take care of whatever’s wrong. They have treated me good so far.

 

[careyo63]

Fredrick's is Top Notch! Refurb. Tractor and parts. I actually have been there! Drove from ATL. Ga. for a Yanmar Tiller. Many Yrs. ago though! My church Purchased the Refurbished YM2500. Retired Catholic Priests retirement home. I cut the property with my YM2000 until I no longer could. The YM2500 and my all Org. YM2000 came from Spalding in Ga.. Who was Fredrick supplied. What the 2000 looked like in 2008 when I bought it. I still have and use it to the day!

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[ruffdog]

If you are getting bubbling in the radiator like that, you have a bad head gasket. Combustion chamber pressure is being forced into the coolant passages.