JD755 overheating final thoughts?

[BigNotEasyGuy]

I have posted in this forum in the past and read everyone's advice which was very much appreciated. I had been debugging an overheating issue on my 755. I can't use my brush hog or mower deck for longer than a few passes before it heats up to ~220 and I see antifreeze coming out the overflow from the radiator. I replaced the thermostat, and because of another issue (my fault) I replaced the radiator and oil cooler as well. Now I have a head gasket kit because that is the last thing I figured it could be. This all happened because I ran it hot trying to plow a garden and it had a coolant leak and subsequently burned up oil. I have since learned how to check my fluids and have been maintaining it much better. But I believe I might have ruined the head gasket and it's leaking hot air into the water. There's no sign of water in the oil.

So with that backstory my plan was to replace the head gasket but people said I should check the oil pressure. I have watched videos of this but I see that I need a special adapter. Does anyone have advice on a pressure gauge and/or adapter to buy? Is the harbor freight version gauge ok? And is there a better place to get the adapter than john deere, it's a bit expensive (like all their stuff).

Second, I have seen people mention the water pump impeller. When I put the idle down to 1500 rpms it does start cooling itself down so I theorized that the water was circulating and that meant the water pump was working. But it does take a long time, it's quicker to turn it off and read this forum on my phone while I wait. Is there a quick check to confirm the water pump is ok? Some people say to turn it on, take the radiator cap off and look for bubbles or listen for hisses. That doesn't work, the engine vibration makes the fluid pretty disturbed and I can't hear anything but engine noise. If there are some old school tricks to confirm that the water is circulating let me know.

Other than that, does anyone have any videos or advice on changing the head gasket? I read the instructions online and in my manual but they are a bit simple. I have looked on youtube but haven't found a video of a 755 or similar tractor with this job. Maybe I'll film it even though I'm a novice. Everyone can comment on what I did wrong.

Any other thoughts or suggestions? I've done a lot of debugging on this overheating. By the time I hook up the brush hog and drive to the other side of my house to mow it's already up to 190. Then after 2 or 3 circles it gets to 220 and I turn turn it off to cool down. It takes me 3 cool down cycles to mow the leach field which seems wrong. I'm not doing this on a 100 degree day or anything.

Thanks for any last minute advice before I try to swap the head gasket.

-jasen

 

[beenthere]

Good luck with the head gasket swap. Should be pretty straight forward.

I have watched videos of this but I see that I need a special adapter. Does anyone have advice on a pressure gauge and/or adapter to buy?

Can you put a pressure gauge in the block in place of the pressure switch?

What is this "special adapter" that you mention? What is the Deere part number that is so expensive?

 

[Industrial Toys]

I had major overheating isses with my Kubota Loader. Removed the RAD and gave it a thourough cleaning inside and out. Outside mattered more, I think. Problem solved, Cool as a cucumber in this heat wave.

 

[RustyA]

Infrared thermometer reading various points in cooling system should tell you if coolant is circulating. Smelling your overflow bottle for hydrocarbons should tell you if head gasket is allowing combustion gasses into cooling system. Typically a head gasket leak causes pushing out of coolant or combustion bubbles in overflow. If none are present I would suspect a circulation problem in cooling system. Radiator and thermostat is new so all that's left is poor water pump performance caused by cavitation of impeller or cooling blockage in engine?

 

[dodge man]

I am not trying to be doom and gloom but when you said it overheated and burned up oil there is a chance of major engine problems. If you are lucky just a head gasket. Could be a warped head. Worse case the engine is badly damaged, bad bearings, needs a total rebuild.

 

[Roadworthy]

While you have the head off take it to an automotive machine shop and have it checked for flatness. This will tell you if it was warped by the heat. Flush and reverse flush the block as well as the radiator. That may not remove all the gunk but it will take out the lion's share. Depending on construction and how far you want to go, if you remove the radiator you may be able to pull the water pump and inspect the vanes. Check it for easy spinning as well. While you were running are you sure your fan belt was tight? If you remove the temperature sensor a mechanical gauge should screw right in to replace it. The challenge will be mounting a gauge.

 

[BigNotEasyGuy]

Sorry, I was confusing terms. I don't know how to check the oil pressure. Any pointers on how to do that would be appreciated.

I actually meant to describe my research on how to do a compression test. I found a harbor freight kit for $30. Hoye Tractor Parts has a guage and and adapter for $80. The adapter itself is $23 which isn't that bad, I think I misremembered the price. I watched a youtube video showing how to check compression on a john deere lawn mower and they had several specific john deere adapters so I was assuming i'd need one for the 755.

 

[BigNotEasyGuy]

I am not trying to be doom and gloom but when you said it overheated and burned up oil there is a chance of major engine problems. If you are lucky just a head gasket. Could be a warped head. Worse case the engine is badly damaged, bad bearings, needs a total rebuild.

Yah, that's my fear too. I'm guessing a compression test would help figure that out? The consensus from my last post was to try the simple stuff first. Since I don't see oil in the water I was hoping it was just the hot gas heating the water preventing cooling from working effectively. Do you have any suggestions on tests to run to figure that out?

 

[BigNotEasyGuy]

I had major overheating isses with my Kubota Loader. Removed the RAD and gave it a thourough cleaning inside and out. Outside mattered more, I think. Problem solved, Cool as a cucumber in this heat wave.

Does 'RAD' mean radiator? This behavior existed since my plowing debacle and then I punctured my old radiator lifting a square hay bale (long story). I had to find another radiator and I swapped it out. The replacement was used but very clean. I get the same behavior after the swap. Since this happened right after the overheating incident while plowing and didn't behave this way before I assume I caused damage somewhere and I'm just trying to figure out where.

Thanks for the tip!

 

[BigNotEasyGuy]

Infrared thermometer reading various points in cooling system should tell you if coolant is circulating. Smelling your overflow bottle for hydrocarbons should tell you if head gasket is allowing combustion gasses into cooling system. Typically a head gasket leak causes pushing out of coolant or combustion bubbles in overflow. If none are present I would suspect a circulation problem in cooling system. Radiator and thermostat is new so all that's left is poor water pump performance caused by cavitation of impeller or cooling blockage in engine?

Oh, a thermometer, that's a cool idea (no pun intended). I see there are some at hardware stores for about $30, do you think one of those would work? I have one in my medicine cabinet but the range isn't high enough, (unless I want to check the JD for coronavirus).

So this tractor doesn't have an overflow, it just has a tube out of the cap that drips onto the axle when it's hot. But if I was going to check with a thermometer where would you suggest I check? I'm thinking inside the cap, maybe the in and out hose in the radiator? The out should be much cooler than the in I would hope? Any other thoughts?

I haven't figured out if it's easy to check the water pump yet. People seem to think the head gasket job isn't that big of a deal so maybe at the same time I could get to the water pump? I'll have to research that a little.

 

[BigNotEasyGuy]

While you have the head off take it to an automotive machine shop and have it checked for flatness. This will tell you if it was warped by the heat. Flush and reverse flush the block as well as the radiator. That may not remove all the gunk but it will take out the lion's share. Depending on construction and how far you want to go, if you remove the radiator you may be able to pull the water pump and inspect the vanes. Check it for easy spinning as well. While you were running are you sure your fan belt was tight? If you remove the temperature sensor a mechanical gauge should screw right in to replace it. The challenge will be mounting a gauge.

Sorry, my post was already long so I left out some details. The previous owner already added a temp guage, that's how I know the reading when it's overheating. The fan is attached to the front of the engine and spins all the time, it's not on a belt so I'm guessing that's not the issue. I think checking the water pump is a good idea. The technical manual doesn't address it so I'll have to do some research to figure out where it is on the 755.

 

[TimberHole]

A head gasket is not a huge job for a fairly experienced mechanic but is a big job for someone with limited experience. Still doable but you might want to recruit a little help or else Do your home work. You will need to set your valve clearance. Also, plan on taking the head to the machine shop and have it checked for cracks and flatness. Also a good time to check all the valves. Plan on spending 300 give or take on the head. Like others have said I would want to see some evidence the head was bad before pulling.

 

[beenthere]

BNEG
Water pump right behind the fan
https://partscatalog.deere.com/jdrc/sidebyside/equipment/66727/referrer/navigation/pgId/14578043

 

[dodge man]

Send in an oil sample to determine if there is bearing material in the oil. Black stone labs is a common one. To be honest with you I went back and looked at some of your old posts on this problem. It seems like you have been bouncing around with this problem for a couple of years and not making any progress. At some point you need to seek help and get it into an experience shop.

 

[BigNotEasyGuy]

A head gasket is not a huge job for a fairly experienced mechanic but is a big job for someone with limited experience. Still doable but you might want to recruit a little help or else Do your home work. You will need to set your valve clearance. Also, plan on taking the head to the machine shop and have it checked for cracks and flatness. Also a good time to check all the valves. Plan on spending 300 give or take on the head. Like others have said I would want to see some evidence the head was bad before pulling.

Thanks, that's great advice, I really appreciate it. I have done a head job on Chrysler K car in the past. It was a big job, and the most complicated thing I've done. I had to have the head ground at a machine shop, etc. It all turned out great so I thought I could handle the job on this tractor too. But I am trying to do as much research as I can since I've never worked on a diesel or tractor engine before. I will have to go look up videos on valve maintenance, if you have any links or anything let me know.

I assume the compression test would help to tell me if the head was bad? (As well as the infrared temp. check to make sure the water is circulating...) Is there something else you would check before doing the job?

 

[BigNotEasyGuy]

BNEG
Water pump right behind the fan
https://partscatalog.deere.com/jdrc/sidebyside/equipment/66727/referrer/navigation/pgId/14578043

Awesome thanks! I had the same thought after I posted, just poke around on the parts diagrams to figure it out. I wonder if there's a way to check the impeller without taking off the entire radiator and oil cooler. The oil cooler is tough to reattach and I don't want to give it a stress fracture by pulling it off.

 

[BigNotEasyGuy]

Send in an oil sample to determine if there is bearing material in the oil. Black stone labs is a common one. To be honest with you I went back and looked at some of your old posts on this problem. It seems like you have been bouncing around with this problem for a couple of years and not making any progress. At some point you need to seek help and get it into an experience shop.

You're not wrong Dave, my previous job had a lot of travel and I wasn't home long enough to devote time to this project. This March I changed jobs and then the pandemic hit so I've been home a lot more. I only use the tractor a couple of times a year on our property because of the overheating. I bought this tractor a few years ago and probably broke the relatively new engine by not checking my fluids (there was a leak in the old radiator that I didn't catch). I've fixed all the other problems and I'm learning as I go. I live east of Denver on 40 acres. I have looked for someone nearby to help me out but I haven't found anyone interested. I could go to the local dealer, but I'm just assuming the bill would be fairly significant and I've seen lots of posts about dealers not being able to fix things after multiple attempts so I'm a little hesitant to go that route.

This is an older tractor and my thought is that it's a good learning experience. I have more time now which is why I re-posted looking for advice before I tear into the engine. This forum and youtube are my primary information sources for tractor repair. I keep reading as much as I can and I'm hoping I can level up my skills so that the next tractor I get I won't be as ignorant as I am now.

Thanks for the tip on the oil test, I hadn't heard of that. I'll look into it, I don't think anyone brought that up before and it sounds like a good diagnostic. If you have any pointers on learning materials let me know. I've fixed a few old trucks so I'm not completely clueless around a wrench but I clearly got off to the wrong start with this JD. At this point I'm starting to become attached, the more blood, sweat and tears I put into it the more I want to get it running right.

Thanks for the tips.

 

[dodge man]

The oil sample should be done if you haven稚 changed the oil for a while. If you did a recent oil change it won稚 help. The report lists all sorts of things and I知 no expert at reading them but they highlight problem areas and explain what might be the cause. The big ones for you would be fuel dilution, anti freeze in the oil, and bearing material in the oil. I would hate to see you tear into the head to find out later the bearings are shot.

 

[Moukie]

I used the cheap HF oil psi kit to verify my JD755 oil pressure a couple years ago. A little difficult to get started, but worked fine.

 

[RustyA]

Possible if you know someone with a horoscope you could pull a hose off the water pump and get a look at impeller fins? That would save pulling the pump to check it out? Old antifreeze in diesels is tough on water pumps.