Newly Rebuilt Tractor Overheating

[dirtdonkey]

Thanks for everyone's comments. There is no thermostat in my motor and the elbow is part of the head so there is no where to mount one, that I can see. The radiator and cap were brand new, when I rebuilt the motor and only have 3 hours running time on them. I flushed both the block and head when they were apart and didn't notice any restriction in flow running water through them. My first thought was the head gasket so I took the head back off. Cleaned everything and then checked to make sure the block was flat to match the head, which I had planed when it was redone with 2 new valves in the #1 cylinder. I matched every water jacket hole to the gasket to make sure nothing was blocked. I have no water in oil and there are no bubbles when the motor is running and if I'm only using the tractor lightly then it doesn't overheat. It only occurs when I'm running hard pulling motor up hill and running 80-100% throttle. When I back off throttle and run easy it stops overheating.I called Hoye, where I bought my parts, and they suggested the mechanical temperature gauge I bought could be wrong. I bought the following Kintrex IRT0421 Non-Contact Infrared Thermometer with Laser Targeting and checked it when I received and it appears to be working correctly when I measured it against things I knew the temp of. When I ran the tractor the other night I filled the radiator to full and emptied the overflow tank completely. Started overflowing the overflow tank about 1/2 hour into the mowing job. You also notice the bubbles in the tank when it gets this hot. I was thinking of adding an additional shim to my injector pump to ****** the timing and see if that helps but wanted to try everything else first before I resorted to that. The tractor starts and runs great, minus the temp problem. I've replaced the radiator cap with 2 others last being 15PSI but no luck.

 

[winston1]

Doesn't seem to be any doubt for some reason it is boiling with hard work. What doesn't make sense to me is the temperature readings you are getting. I have an el cheapo Harbor Freight non contact thermometer and my 2002d runs hotter than your readings and doesn't boil over. I'm thinking the hottest area of the cooling system should be right at the neck where the top radiator hose leave the water pump area. What do you read there when the boil starts?

 

[careyo63]

Try a local big chain auto-parts they may rent or even borrow one of these. Another method is using a home made tester since it seems to be only doing it under a working load. Your need one like the Radiator cap but with a Gauge. Your know whats happening when it occurs. Lack of water? Pressured up? Lack of or restricted flow of Air? Could be a Cracked Block, Head etc. Your be able to watch how fast it looses pressure. Have I done this before?
Make an Auto Radiator Pressure Tester

 

[Car Doc]

Its obviously got a water pump what condition was the impeller in or did you even have it apart? Its sounding more and more like a circulation problem either there is no/low water flow out of the water pump or a restriction. How about the hoses coming out of the block/water pump any chance you mis routed the lower ones? On mine the front hose of the 2 coming out of the water pump goes to the lower radiator and the rear hose out of the wp goes back to the block.

You mentioned going all the way up to a 15#... well a water pump is centrifugal and will make that much and more pressure with no problems if the return is restricted. It will pump coolant out because it has no where to go if there is some restriction the rad cap is the easiest path just food for thought.

\\just for conversation but This is just an example of things that can happen-we put a cam in a chevy pickup a long time ago and my helper was the one that put the radiator in. Well he forgot or didn't see it to pull the cap plug out of the lower pipe on the radiator when he installed the radiator. It would idle fine and stayed at a somewhat normal temp but as soon as we take off down the driveway it would creep up to hot pretty quick.

I also noticed that with the radiator cap off revving the engine coolant would overflow the top of the radiator and when looking back that was a dead giveaway of the underlying problem.

After work while I was the only one there I started dissecting the truck. Well I noticed when I took the lower hose off coolant only came out from the block side BINGO found it. That's one another was a chevy van that had no impeller at all completely rusted off. The customers complaint was no heat it never ran hot just no heat above 10 mph at a stop it had a little. That one took me awhile to figure out. My point is dont overlook things you believe must be ok check everything. :thumbsup: good luck

 

[clemsonfor]

I had an older mercedees 300D in college. I was 5 minutes from my uncles house one night and all of a sudden a horrible screech and then nothing and all the lights for things like batteries came on and my alt gage pegged on the low side. Well i knew something had locked up what the screech was and then burned the belt off. Engine was still going fine so i kept going hoping that the belt to the waterpump was still fine, well no dice, it started creeping up instantly and i just kept going till right before it got to hot and pulled over. Was in the middle of the country and walked about 1/4 mile to a hill top to get a broken cell call out to my unlce to bring a chain to pull me to his house. Next day i started to pull it apart in the yard at that point it was obvious the problem was the WP it had seized up and thats what started it. So i pull it off, and what comes out behind it, but a mercedees bolt that looked like a WP bolt, but also fan bolts and many other bolts that size on the car. Where the heck did that come from? Was is dropped in the radiator and made it to the pump? or did it come out of the block on an engine redo (not as likely). But once i found that it was fine, the impeller was chewwed up from where it had not worked in just the right place to jamb the impeller, so i replaced it.

sorry off track but just another story that will make you scratch your head.

 

[SailorBob]

I rebuilt my YM1700 a few years ago. I retourqed the head bolts after about 10 hours. 300+ hours later all is well. I would try that before panicking.

 

[Car Doc]

Yeah I agree re-torquing is probably a good idea it sure wont hurt anything and a re-check of valve lash since he is in there.

edit: I am almost certain its going to be a circulation problem either a bad new radiator or defective water pump, could even be a passage blocked by something foreign maybe a gasket is wrong even. There is still a fair chance its just a temp sensor problem. my .002

 

[dirtdonkey]

When I rebuilt the motor I installed a new water pump. I started today, with no radiator cap on and there is definite flow across the top of the radiator. I mowed for about 1/2 hour and it overflowed into my overflow tank, which I had started with empty. After 3/4 hour the overflow tank was overflowing. The temp gauge never got above 190? I'm going to take all hoses off the motor and check to see if anything is wrong with them in any way. I spoke with Matt at Hoye and everyone tells me he has a lot of experience with Yanmar rebuilds and would probably be the best person to speak with about my problem. I went over everything I'd done and the temps I'm seeing on the metal parts and he says it doesn't make sense. The temps I'm getting should not be making anything overflow, like I'm experiencing. I guess this coming weekend I'll retighten the heads to make sure and then take off the hoses and flush the block to see if anything comes out when I flush from the Neck coming out the head back through the block. Then I'll flush the new radiator to see if anything appears blocked. I'm really at my wits end. The motor is performing perfectly. Starts with first bump. Oil is perfectly clean with no spec of water in it. If it wasn't for the overheating I would have a perfect scenario of a rebuilt motor. I'm sure we'll get to the bottom of this but it is frustrating getting there.

 

[284 International]

With the information you gave, my bet would still be on a blocked radiator, in some way or another. I think you should take the radiator out and stick a hose down the fill neck and turn the water on full blast. The radiator should easily flow all the water from a large diameter hose, without bubbling back out the fill neck. If it checks out, then you have a cracked sleeve, head, or a head gasket issue (Whether improperly installed, blown, etc.)

The 1/2 hour of operation before it bubbles over to me strongly implies that the engine isn't being sufficiently cooled. I think if the head gasket were bad it would bubble instantly, or, at the least, a few minutes after startup, once all the engine parts were at operating temperature.

Have you cleaned the radiator screen of chaff, and made sure there is nothing blocking air flow through the radiator? Is the fan in good shape, spinning properly, etc? Does it still have the fan shroud?

I also think you should get some water boiling and verify your IR thermometer is functioning properly, too.

Keep your chin up! You'll get it figured out!

 

[kenmac]

Hang in there man. You,ve come too far for something like this to happen. You'll find it.You may have already checked this ,but is Radiator hose collasping when hot ??