# Yanmar 186 D



## afrank1982

Hello guy im new here and was hoping to get some help. I have a Yanmar ym 186 D That is giving some some trouble. I was using the tractor on my property the awhile back with no issues. I loaded the tractor on the trailer after a full weekend of work and when i got it home and first started it to unload off the trailer it started spewing water out of the over flow bottle. I drove it strait into my shop and shut it off. I pulled the thermostat and put it back together. I ran the tractor for awhile and had no water spewing from the overflow. With the radiator cap off i noticed bubbles coming up in the colant. I put the cap on and they moved over to my overflow bottle. I did order a new thermostat and installed it and the bubbles in the radiator stoped but still appear in the overflow. Im kind of leaning towards the head gasket being blow or having really really slight leak because im not getting any water in the oil and its not doing and weird smoking or anything of that nature. The only smoke i get is greyish black smoke when under a load or while accelerating pretty much the norm for a diesel. When i run the tractor now and let it cool off "it can be two days later" the cooling system is still pressurized a little bit. I have acually noticed some bubbles in the over flow for a couple years now but i have never payed attention to it so i didnt know if that was normal or not beings iv never had an issue till this. i did notice that if i relieve the pressure while the colant is hot it will suck the coolant out of the overflow like its supposed to. This tractor has been in the family since about 1984 and was purchased new in 1982 buy some freinds of the family so we pretty much know all the history of the tractor with 771 original hours and knowing for a fact the hours have not rolled back to zero The tractor has never been run really hard and is normally worked at 1500 to 1800 rpm. The tractor never showed sighns of overheating "Boiling over" or dummy light while i was using it on my property so its kind of hard to believe a head gasket would be blown unless its just from being old. Im really kind of puzzled especially since the tractor has been flawless since 1982 and very well taken care of and well maintained. Any advise would sure be nice
Thank,
Anthony


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## winston

If you are having a steady stream of bubbles your head gasket is most likely gone. Especially if it is doing it at first crank up before being warmed. Mine blew one time just driving down the road with my grand children so they can go bad without strain.


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## Mickey

winston said:


> If you are having a *steady stream of bubbles your head gasket is most likely gone*. Especially if it is doing it at first crank up before being warmed. Mine blew one time just driving down the road with my grand children so they can go bad without strain.


agree with Winston on this.


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## ErnieS

I'm going with head gasket too. With the overflow system, you're unlikely to get coolant in the oil, unless the gasket is blown between the cylinder and the water jacket AND between the oil galley and water jacket.


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