# YM 336 Cooling System Issue



## Mark Mahoney (Oct 2, 2019)

I have an odd thing happening with my YM 336 Cooling System. Had a blown out lower hose and replaced it, but noticed no water flow out of my upper radiator hose into my radiator and concluded that I needed to replace the water pump. Did that and still no flow! (I am in FL and run without a thermostat so I knew that that was not the issue). Radiator is not clogged. I took off the lower radiator hose and the upper hose and back flowed water through the engine and out the lower hose. Reconnected everything and had water flow while running. Thought I had fixed, however let engine cool and started it a few hours later and again, no flow. I repeated the back flow and achieved flow again while running, but after waiting some hours and restarting, it returns to no flow!!!??? I have back flowed several time, but keep getting the same result. Any ideas on this?


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## pogobill (Jan 31, 2012)

I had an air lock in a pickup once in the dead of winter. Engine over heating and the heater blowing ice cold! Maybe that's your problem.
Have you run it with the rad cap off.... maybe idle it up a little and then back down ans see if the fluid level has changed, or air escaping. A good place to observe flow as well.


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## bmaverick (Feb 20, 2014)

Hi Mark, 

There are a few Service Manuals and Parts Manuals here for the YM 3-digit machines here under the MANUAL tab. With that said, in some of the service manuals, it mentions the belt tension of the alternator to the water pump. There is a slight pressed deflection that must be had. 

In the YM336 Parts Manual, page-17 has the cooling system layout. 










Additionally, with the new water pump, did you burp out the air in the system? Did you use the drain-cock? Sometimes that will bind up after use and stop flow. 

None of the hoses look pinched? 

Is item 79 or item 1 locked in and allows the water pump to spin the impeller? Thus, the belt to the water pump shaft is spinning and not slipping.


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## bmaverick (Feb 20, 2014)

pogobill said:


> I had an air lock in a pickup once in the dead of winter. Engine over heating and the heater blowing ice cold! Maybe that's your problem.
> Have you run it with the rad cap off.... maybe idle it up a little and then back down ans see if the fluid level has changed, or air escaping. A good place to observe flow as well.



That could burp out the air by having the engine cold, take the rad cap off and run it till the flow dribbles out the top of the rad.


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## Mark Mahoney (Oct 2, 2019)

Thanks pogobill. I have been running with the radiator cap off and as the engine heats up, the water expands and begins to overflow out the top of the radiator, but still no flow out of the upper hose into the radiator.


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## Mark Mahoney (Oct 2, 2019)

bmaverick said:


> Hi Mark,
> 
> There are a few Service Manuals and Parts Manuals here for the YM 3-digit machines here under the MANUAL tab. With that said, in some of the service manuals, it mentions the belt tension of the alternator to the water pump. There is a slight pressed deflection that must be had.
> 
> ...


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## Mark Mahoney (Oct 2, 2019)

None of the hoses are pinched. The water pump impeller is spinning. Last week, when I back flowed the system, I got the coolant to flow and cut my lawn , took 2 hours with continuous running and had flow the entire time. I would think there would not be any air in the system after that, however, letting it cool and restarting the engine a few hours later... back to no flow. I know I can get it to flow and do the work I need to, but once I turn it off and let it cool, back to 0


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## BigT (Sep 15, 2014)

Hey Mark, put the thermostat back in it, and see if that changes the situation.


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## winston (Aug 19, 2008)

Make sure hoses don't have interior lining loose and acting like a check valve.


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## Mark Mahoney (Oct 2, 2019)

winston said:


> Make sure hoses don't have interior lining loose and acting like a check valve.


That is an idea Winston. I won't have another chance to work on it until the weekend, but I will check that out..


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## Mark Mahoney (Oct 2, 2019)

BigT said:


> Hey Mark, put the thermostat back in it, and see if that changes the situation.


Thank you BigT. I can try that this weekend, but I have been running it for several years without he thermostat, but maybe something changed..


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## Busted Tractor (May 22, 2018)

Not sure what YM does but often water is bypassed when the thermostat is closed. With some engines that bypass is closed when the thermostat is opened. If water is bypassing you may not see flow thru the upper hose. Just a thought


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## Mark Mahoney (Oct 2, 2019)

I fired it up today and the I actually have water flowing so not sure still at this point what might be happening here. One thing is sure. I have gone long enough with this worn out radiator and I noticed a small leak in the core. Since the core is very brittle, I think it is time I get it addressed. I know the re coring can cost a boatload of money and I do not see anywhere in my searches anyplace to get a new radiator. Do any of you have a suggestions on what I should do to get this radiator fixed or replaced?


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## winston (Aug 19, 2008)

Wondering if this would fit?? 67729 Radiator Yanmar 2500 3000 3110 John Deere 850 900hc 950 for sale online | eBay


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## FredM (Nov 18, 2015)

Just wondering if you have actually removed the top hose from the top tank spout and started the engine to check flow, or are you looking down into the cap opening, some top tanks had a deflector near the return opening in the top tank to deflect the hot water across the top of the cores instead of just flowing straight into the tank and if that was the case, then it would be hard to see flow, you say you have removed the thermostat, but what you describe shows that there could be a thermostat in place, not saying there is, but the water action suggests this, -- while I am talking thermostat, if you don't want to use one, at least pull the guts out of it and place the base back into the housing for some restriction to cause the water to slow down and collect engine heat and if your engine is diesel, more so to have a thermostat.

Your post #5 shows that the heated water from the engine is travelling up the top radiator hose to the radiator header tank for the water to expand and run out of the cap opening, the heated water doesn't run back down through the bottom hose and up through the cores of the radiator.

Have you placed your hand on top of the top hose to feel how hot the hose is when the engine is running or after working ?, if you can't hold your hand on the top hose for a short while, then the system is working, and another , if the system wasn't working, then your radiator would be blowing steam from the overflow.


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## bmaverick (Feb 20, 2014)

Mark Mahoney said:


> I fired it up today and the I actually have water flowing so not sure still at this point what might be happening here. One thing is sure. I have gone long enough with this worn out radiator and I noticed a small leak in the core. Since the core is very brittle, I think it is time I get it addressed. I know the re coring can cost a boatload of money and I do not see anywhere in my searches anyplace to get a new radiator. Do any of you have a suggestions on what I should do to get this radiator fixed or replaced?


My YM2610 came as a UTDA totally refurbished machine from Fredricks. The radiator was new, not a recore. YM336 radiator P/N 121253-44500. You may have to call them.

WEINGARTZ has your radiator as new
Yanmar Parts Radiator 121253-44500

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## winston (Aug 19, 2008)

If you check WEINGARTZ inventory it shown they have 0.


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## Mark Mahoney (Oct 2, 2019)

winston said:


> Wondering if this would fit?? 67729 Radiator Yanmar 2500 3000 3110 John Deere 850 900hc 950 for sale online | eBay


Yeah I wonder how I would know it it would fit? Looks similiar!


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## Mark Mahoney (Oct 2, 2019)

FredM said:


> Just wondering if you have actually removed the top hose from the top tank spout and started the engine to check flow, or are you looking down into the cap opening, some top tanks had a deflector near the return opening in the top tank to deflect the hot water across the top of the cores instead of just flowing straight into the tank and if that was the case, then it would be hard to see flow, you say you have removed the thermostat, but what you describe shows that there could be a thermostat in place, not saying there is, but the water action suggests this, -- while I am talking thermostat, if you don't want to use one, at least pull the guts out of it and place the base back into the housing for some restriction to cause the water to slow down and collect engine heat and if your engine is diesel, more so to have a thermostat.
> 
> Your post #5 shows that the heated water from the engine is travelling up the top radiator hose to the radiator header tank for the water to expand and run out of the cap opening, the heated water doesn't run back down through the bottom hose and up through the cores of the radiator.
> 
> Have you placed your hand on top of the top hose to feel how hot the hose is when the engine is running or after working ?, if you can't hold your hand on the top hose for a short while, then the system is working, and another , if the system wasn't working, then your radiator would be blowing steam from the overflow.


Yes I did remove the top hose and there was no water flowing when I was witnessing the non flow issue. However, this weekend, I was seeing water flow from the start.. (good sign), I do not think there is a deflector since you can clearly see flow when it is happening. I agree with your thought about putting in the thermostat guts to restrict flow there!


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## Mark Mahoney (Oct 2, 2019)

winston said:


> If you check WEINGARTZ inventory it shown they have 0.


Yeah, I saw that. I will call them an see if they still can get one.


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## Harleyron74 (May 31, 2020)

Mark Mahoney said:


> I fired it up today and the I actually have water flowing so not sure still at this point what might be happening here. One thing is sure. I have gone long enough with this worn out radiator and I noticed a small leak in the core. Since the core is very brittle, I think it is time I get it addressed. I know the re coring can cost a boatload of money and I do not see anywhere in my searches anyplace to get a new radiator. Do any of you have a suggestions on what I should do to get this radiator fixed or replaced?


I know this is an old post but it may help someone in the future.
I came across an article in Farm Show Great Shop Ideas Vol. IV. There is a shop in Sweet Home ORE. that builds all kinds of radiator's. Their phone # is 855-651-3002. Web site is radiatorsupplyhouse.com and their address is Radiator Supply House 1460 47th. Ave. Sweet Home ORE.97386.
I have no affiliation with these people and have not used their services but as radiator repair/rebuild shop's are as rare as hens teeth I thought someone may need a service like this.
I may need their services before long for my Farm All 400!


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## bmaverick (Feb 20, 2014)

Harleyron74 said:


> I know this is an old post but it may help someone in the future.
> I came across an article in Farm Show Great Shop Ideas Vol. IV. There is a shop in Sweet Home ORE. that builds all kinds of radiator's. Their phone # is 855-651-3002. Web site is radiatorsupplyhouse.com and their address is Radiator Supply House 1460 47th. Ave. Sweet Home ORE.97386.
> I have no affiliation with these people and have not used their services but as radiator repair/rebuild shop's are as rare as hens teeth I thought someone may need a service like this.
> I may need their services before long for my Farm All 400!


Typically people can re-core radiators locally. Shipping from OR is now higher as diesel prices are now at $7/gallon in areas of the country now. The FREE Shipping days at Amazon have diminished greatly too.


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