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Discussion Starter · #1 ·
I recently replaced the thermostat on my John Deere x495 and unfortunately cracked the thermostat cover (long story but bottom line, I broke it).

It turns out John Deere no longer has this thermostat cover available. The cover has an outlet on top for the hose that attaches to the top of the radiator. And it has a smaller outlet that connects to a hose that runs to the oil cooler.

I was not able to find a salvage part so looks like I'm going to have to improvise but would sure appreciate your thoughts on how best do so..

Any thoughts or advice would be appreciated. Thank you.
 

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Discussion Starter · #5 ·
Thanks for the comments and helpful feedback. I was able to fabricate a new part and it is installed and up and running. With the new thermostat I still have the tractor overheating intermittently when it is under a load (PTO engaged). I used a heat gun to verify to ensure it isn’t a faulty temp sensor. Got up to 255 at one point. Not sure what to look at next but plan to bleed the radiator and also tightened the fan belt. Any other suggestions on next steps or shared experiences would be appreciated. The grass just keeps growing so have to get this figured out :—). Thank you.
 

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Thanks for the comments and helpful feedback. I was able to fabricate a new part and it is installed and up and running. With the new thermostat I still have the tractor overheating intermittently when it is under a load (PTO engaged). I used a heat gun to verify to ensure it isn’t a faulty temp sensor. Got up to 255 at one point. Not sure what to look at next but plan to bleed the radiator and also tightened the fan belt. Any other suggestions on next steps or shared experiences would be appreciated. The grass just keeps growing so have to get this figured out :—). Thank you.
I would try a good quality liquid radiator flush (Prestone, Gunk, CLR). It's a relatively small radiator, so you can do it twice for the same price as an automotive radiator.

Does that Yanmar diesel have a water filter on it? Are you running any DCA? A lot of people have the misconception that a radiator is "clear" if they don't see any buildup on the tubes in the top tank. Radiators clog from the bottom up. By the time up see build up at the top, the radiator is pretty much plugged, because the flow is top to bottom. Any sludge settles at the bottom because of gravity and the flow rate slowing down as it passes through the tubes. Automotive sized flush kit cost less than $10.... What do you have to lose by giving it a try.

Product Motor vehicle Font Gas Auto part
 

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Discussion Starter · #7 ·
Thanks for the idea. That will be my next step. I have already replaced the thermostat, checked the radiator fluid and oil, checked the deck (fluid and grease), righted the fan belt… nothing has changed. The cooling system is just not able to keep up. So a good cleaning might just do the trick. Thank you.
 

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Thanks for the idea. That will be my next step. I have already replaced the thermostat, checked the radiator fluid and oil, checked the deck (fluid and grease), righted the fan belt… nothing has changed. The cooling system is just not able to keep up. So a good cleaning might just do the trick. Thank you.
I would look at adding some Fleetguard DCA4 when you refill the radiator. I was trained to never run any diesel engine without some sort of coolant additive. Over the years, I've seen many a cracked liner from cavitation in engines that were ran without it. Took over a 1,000 truck delivery fleet running DT466's and they didn't have any clue as to the purpose of a water filter, or DCA's. Replaced probably 50 radiators, 100 heater cores, and did 45 in-frame overhauls for cracked liners within the first year....

Fleetguard DCA4
 

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Discussion Starter · #9 ·
Well the flush didn’t solve the problem either. Still the same symptoms. Seems like the cooling system is working but gets behind when a load is applied and just can’t catch back up. I can’t figure it out and probably not worth going down the route with a repair shop. Maybe time to get something more dependable. Thank you for all the ideas and help. I really appreciate it.
 

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Have you blown through the radiator cooling fins??, seeing this hasn't been suggested yet, there may be a pre-screen that is clogged in front of the radiator.
 

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Don't know what size radiator hoses you have, but I've plumbed 1 1/2" clear PVC pipe into the radiator hoses to check coolant flow for an overheating situation Upper tells you the thermostat is fully opening and the flow rate coming out of the block. Lower tells the amount of suction flow going into the water pump. If you put them in both at the same time, you can judge/compare the flow rate through the radiator. The link to the pipe below says 140 degrees, but I've never had any problems with it getting to hot. How do you know it's overheating, are you checking it with a thermal gun, or relying on a temp gauge?? I point a thermal gun at the radiator and then thermostat housing and compare the two to each other and then what the temp gauge is actually reading.

1 1/2" Clear PVC Flow Test Pipe

Thermal Gun
 

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Discussion Starter · #13 ·
Well I worked all of the suggestions above without success. I have a lot to mow so decided to trade the John Deere in for a different machine (not a John Deere). One other contributing factor was just how completely unhelpful our local John Deere dealer was.

Again, I appreciate the suggestions and help from the group. And I did learn a lot through this experience.

Thank you.
 
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