Overheated Tractor - Where to start

[SailorBob]

The tractor is a Yanmar diesel but, I decided to post the question here since it is more of a general than a Yanmar specific question. For the bad news. I severely overheated the tractor. The temp guage never showed the tractor to be hot. I was using the rotary cutter and noticed the engine was sounding different. I looked at the engine and noticed that the paint was starting to smoke. I immediately shut it down. I carefully removed the radiator cap using gloves and steam came out. I let it cool down and put water in it. The tractor started but sounded like some marbles were rattling around inside. So, i shut it back down. I am afraid i have cooked the engine.

I did have to add some water to the overflow bottle before i used it but, did not think to remove the cap and check the level there.(That may be my fatal mistake.)

Anyhow to my question of where to start.
I need to try to determine how much damage was done and what it will take to fix it or is it worth fixing? My first thought is to drop the oil pan and see what it look like down there. Then remove the valve cover and look in there too. I suspect that at a minimum I am looking at a rebuild to some degree..

The tractor had been using oil prior to this and the rate of consumption was seeming to increase. I also have been having to add water every time i used it but, I thought that was because the lid to the recovery tank kept popping off.. Maybe in retrospect I had a blown head gasket and did not realize it. The tractor seemed to run ok and had plenty of power too.

Anyone have any thoughts?

 

[BillyP]

It's almost impossible to tell from here but it doesn't sound good. I will tell you this though. If there's any way possible, never shut down an overheated engine. The best thing to do is get her down to an idle and go from there. Diesels cool down at idle. If you shut a hot engine down, it only gets hotter. That little bit could be the difference between ruining and saving an engine. I know it's most likely to late now but it's something you should remember.

Sorry I can't help.

 

[Ifixcars]

Wow, that baby got real hot. Well, I guess after it cools down, and it still might be hot now by the sounds of it, I would check the levels of fluids and attempt a restart. I would like to hear if it spins or if it's locked.

 

[frank_f15]

2 questions . 1) how old is this tractor? and 2) why did the temp gauge not show over heating?

 

[wushaw]

Frank, the temp guage will not register if the temp sender is not in water. I belive he was that low on coolant.

 

[DieselPower]

The temp sensor will still usually work even if it's not submerged in coolant. The air and steam will still heat up the sensor.

The tractor engine, doesn't sound good. If it was mine the first things I would remove is the oil pan, rod and main caps to check the bearings and then the head to check for warpage and cracks. Can you tell where the noise is located? Top end or bottom end of engine?

 

[skipmarcy]

The temp sensor will still usually work even if it's not submerged in coolant. The air and steam will still heat up the sensor.

The tractor engine, doesn't sound good. If it was mine the first things I would remove is the oil pan, rod and main caps to check the bearings and then the head to check for warpage and cracks. Can you tell where the noise is located? Top end or bottom end of engine?

I have seen many,many cases of temp. gauges and computer temp. sensors not registering properly when the system is out or almost out of coolant. When there is no liquid coolant in the system, the water pump isn't pumping anything - it can't pump air or steam. Don't know about the Yanmar but most engines have their coolant sensors very near the exit from the engine, just before the thermostat, and this is usually at the top of the engine, hence one of the first areas to lose contact with the dwindling coolant level. For a little while the coolant may be high enough for steam coming off it to reach the sensor, but as the level decreases, the sensor will start reading cooler.

As far as the engine goes, I would suspect the head gasket right away - fill system with water & pressure check it. If it was hot enough to cook the paint, the rings are surely toast. There's a slight chance the knocking could be caused by water getting into a cylinder - or it could be crankshaft related. Water in a diesel can actually bend or break a rod. The pressure test should pinpoint your water leaks - might have to remove the injector(s) to check in the cylinders for water.

 

[john_bud]

First off, you have gotten good advice so far.

You need to drop the pan and inspect at least 3-4 bearings. Both main and rod bearings.

As long as you had oil circulating, the lower end may be ok. Now, it could have been low on oil and heated up from friction, that would be "bad".

Assuming you find the bearings in ok shape, the root cause is probably the blown head gasket. Running it hot may have warped the head - but you can probably get it machined back to flat. Best thing is to pull the head off and visit a machine shop for a pro inspection.

While the head is off, clean the deck on the block, inspect the cylinder bores, piston top condition. Do a close inspection for cracks on the deck and in the bores.

It's up to you to determine if it is worth dropping money in the tractor. It usually is, but that is up to you and the $$ it will take.

Hope it's just a head gasket and quick valve grind!

jb

 

[MJPetersen]

Wow, that baby got real hot. Well, I guess after it cools down, and it still might be hot now by the sounds of it, I would check the levels of fluids and attempt a restart. I would like to hear if it spins or if it's locked.

He said that he started it afterwards but that it was noisy.

You possible that it took the temper out of the rings and I would suspect the head and check the block deck for straightness. There probably is some cylinder scuffing from the pistons. Very likely, if there are no cracks and the cylinder walls are not too scuffed that you will get away with just a valve/head and if you want, maybe rings (since you are that far already)to rebuild. But if you already needed a head gasket then you would have had to tear it down to that extent anyway.

If it had oil, and the oil does not smell burnt, then I would not worry much about the lower end. If you decide to pull pistons then you will see the rods anyway.

I had an old Ford transit van that overheated (faulty indicator) to the point that it lost power and died. I let it cool and filled it with water and ran it for 3 more years without another problem.

All in my opinion,

Mike in Warsaw

 

[SailorBob]

The tractor is probably about 30 years old. It was supposedly (snicker snicker) about 2 years ago. I have had the tractor a little over 2 years.


The Yanmar YM1700 does not have a water pump it uses the thermosyphon cooling method...It is possible to retrofit a water pump to it and I probably will do that assuming i can reasonably repair it. As far as the temp sensor it is located at the top of the engine near the water inlet. I can now see that if the water was low the water would not contact the sensor.

The more I think about it the more I believe that the root cause of this was a blown or improperly installed head gasket. The moral of the story is to not just check the overflow bottle when checking the water but, remove the radiator cap and check the level there too.

I am going to drop the oil pan this weekend and look at the bearings and take it from there.

Thanks for your suggestions..Hopefully, i can repair it without spending a fortune on it.

 

[oldmech]

My opinion! First I remove the head and send it for check (Flatness , leaks and cracks etc) AFTER RESULT If head is Ok! If your motor was taking oil you can remove pistons . I HONE the cylinders and put new rings and same time you check Connecting rod bearings clearance with Plastic gauge. Head gasket and rings are not very expensive and you have a new motor for a long time.
Good Luck ! Oldmech

 

[SailorBob]

I finally got around to opening up the engine. I pulled the head and dropped the oil pan. That was quite a job! Anyway, The head looks okay. I did not find anything apparently broken or bent. I am going to take it to a machine shop to be tested. If there is no major damage I will have the valves and seats done too. The number 2 piston is a diffent story. It looks like the piston may have melted on the upper edges. I found pieces of metal sitting on top of the piston. (see pics) Also, I can't really even see the rings. I am sure they are cooked. Hopefully, if the head is okay i can get away with replacing the rod bearings, #2 piston, and rings on both.

Hopefully, the crank and mains are okay. There was plenty of oil in there and it looks like most of the heat was in the pistons.

Does anyone have any suggestions?

 

[California]

Bob, I'm sorry to see what happened there. I don't have any suggestions, just couple of comments:

That's #1 cylinder by Yanmar's definition. They number the cylinders starting from the flywheel. (This can be a source of confusion when you rotate the engine to adjust the valves at TDC.)

Is there any chance that the loose metal in the cylinder is from a foreign object that was sucked into the cylinder and then dented the piston? That would be a less serious scenario compared to a melted piston.

Also, the original warning light will come on when there is no water in the upper hose connector, at least on my similar YM240 (YM2000.) One of several problems caused by the previous owner was that the new genuine Yanmar lower radiator hose (previous owner's repairs) developed a leak where the sloppy-loose new fan belt (installed by that previous owner), chewed a pinhole leak in it. I lost enough water to trigger the warning light a couple of times in the first couple of days, before I fixed it.

I guess I do have one suggestion: since the pistons are coming out, have you considered replacing the pistons and sleeves as a matched set?

 

[oldmech]

OK! Now I see your goods pics . I think you MUST remove Pistons for check Wall cylinders FOR CRACKS (AT the top cylinders walls If any Very bad Need new block. FOR DEEP SCRATCHS) ( We can remove lights smalls scratchs in honing process). If any deeps scratchs you can change sleeve (if your motor have) or rebore cylinders and put news pistons and rings. We can change one sleeve and piston but we must rebore the two cylinders and put news pistons and rings (expensive). You must evaluate the cost before begin. Good luck! Oldmech

 

[SailorBob]

Bob,
That's #1 cylinder by Yanmar's definition. They number the cylinders starting from the flywheel. (This can be a source of confusion when you rotate the engine to adjust the valves at TDC.)

Is there any chance that the loose metal in the cylinder is from a foreign object that was sucked into the cylinder and then dented the piston? That would be a less serious scenario compared to a melted piston.

Also, the original warning light will come on when there is no water in the upper hose connector, at least on my similar YM240 (YM2000.) One of several problems caused by the previous owner was that the new genuine Yanmar lower radiator hose (previous owner's repairs) developed a leak where the sloppy-loose new fan belt (installed by that previous owner), chewed a pinhole leak in it. I lost enough water to trigger the warning light a couple of times in the first couple of days, before I fixed it.

I guess I do have one suggestion: since the pistons are coming out, have you considered replacing the pistons and sleeves as a matched set?

California,

Thanks for clarifying the cylinder numbers. I replaced the overheat light with a temp gauge. The temp sensor was bad. Looks like the temp gauge does not work without being in contact with water either.

I have moved the pistons up and down and the liners appear to be in good shape. I could not see or feel any scratches. I know that I can replace the cylinders and pistons as a set. I just hate to keep putting money in this old tractor. The sleeves are nearly $200 each plus $90 each for the pistons. You get the idea. If the block is cracked I may just junk it.

I just don't know where the metal came from. I did discover an interesting thing while removing the head. There is supposed to be a gasket around the bottom of the breather where it is clamped to the flange. Well, there was. A homemade piece of inner tube that did not wrap completely around the flange. There was about a 1/2 inch gap. It had it had to have let a lot of debris into the intake. The intake was very dirty . The shade tree's that so called reconditioned this tractor did a fine job.

The metal is very soft. Looks a feels kind of like solder.

 

[SailorBob]

OK! Now I see your goods pics . I think you MUST remove Pistons for check Wall cylinders FOR CRACKS (AT the top cylinders walls If any Very bad Need new block. FOR DEEP SCRATCHS) ( We can remove lights smalls scratchs in honing process). If any deeps scratchs you can change sleeve (if your motor have) or rebore cylinders and put news pistons and rings. We can change one sleeve and piston but we must rebore the two cylinders and put news pistons and rings (expensive). You must evaluate the cost before begin. Good luck! Oldmech

Oldmech,

Thanks for your reply. The engine is sleeved. Maybe this weekend I can remove the pistons, and, check cylinders and block. A new block will probably push the cost of rebuilding the engine out of reach. Also, I don't have a garage or even a concrete pad to work on it from. I don't think I could split the tractor in the yard. Also, if I have to pay a mechanic to do the work it cetainly will.

 

[BTDT]

Bob, I have a Ford 1300 2 cyl. diesel that we rebuilt about 4 yrs ago, cost around $2000.00. This was taking the rebuilders the engine, they bored, new everything, including clutch and pressure plate. Ours was not sleeved. You may come out cheaper.

 

[CATMAN]

On older CAT engines that use fuel injection nozzles(direct injection); you must change the nozzles if the engine ever got that hot. The press-fit between the nozzle tip and the nozzle body loosens up during the extreme overheat and that tip will blow out into a newly overhaul engine after you start it up and run it under load for a while. I just bring this issue up, so you can ask an old Yanmar mechanic to see if this issue exists with your engine. You don't want a second failure immediately after an expensive overhaul.

Also, do the cylinder walls look like a mirror finish OR do they show any cross-hatch left on the cylinder walls?​

 

[john_bud]

California,

Thanks for clarifying the cylinder numbers. I replaced the overheat light with a temp gauge. The temp sensor was bad. Looks like the temp gauge does not work without being in contact with water either.

I have moved the pistons up and down and the liners appear to be in good shape. I could not see or feel any scratches. I know that I can replace the cylinders and pistons as a set. I just hate to keep putting money in this old tractor. The sleeves are nearly $200 each plus $90 each for the pistons. You get the idea. If the block is cracked I may just junk it.

I just don't know where the metal came from. I did discover an interesting thing while removing the head. There is supposed to be a gasket around the bottom of the breather where it is clamped to the flange. Well, there was. A homemade piece of inner tube that did not wrap completely around the flange. There was about a 1/2 inch gap. It had it had to have let a lot of debris into the intake. The intake was very dirty . The shade tree's that so called reconditioned this tractor did a fine job.

The metal is very soft. Looks a feels kind of like solder.

Sailor,

You may have sucked some solder in. The ahem - mechanics- ahem that did the work on your machine may have soldered a gap or done some other goofy thing.

I couldn't really see the pictures very well. Focus is out too much. You may try and use a nylon bristle brush to clean the top of the piston and see how it really looks. There is also some spray you can use to remove carbon. Can't hurt nothing at this point and you may find that you don't need a new piston.

jb

 

[Soundguy]

To complicate matters.. if this is a 4 -digit 'grey' yanmar under a 2000 series.. it won't have a water pump.. just thermosyphon. Thus the top end may have gotten hotter thant he bottom.. as there would be no water above the level in the radiator with no circulating pump going.

I agree witht he other advice.. drop the pan and check out a bearing.. then have a looksee at the valvetrain..

soundguy

I have seen many,many cases of temp. gauges and computer temp. sensors not registering properly when the system is out or almost out of coolant. When there is no liquid coolant in the system, the water pump isn't pumping anything - it can't pump air or steam. Don't know about the Yanmar but most engines have their coolant sensors very near the exit from the engine, just before the thermostat, and this is usually at the top of the engine, hence one of the first areas to lose contact with the dwindling coolant level. For a little while the coolant may be high enough for steam coming off it to reach the sensor, but as the level decreases, the sensor will start reading cooler.

As far as the engine goes, I would suspect the head gasket right away - fill system with water & pressure check it. If it was hot enough to cook the paint, the rings are surely toast. There's a slight chance the knocking could be caused by water getting into a cylinder - or it could be crankshaft related. Water in a diesel can actually bend or break a rod. The pressure test should pinpoint your water leaks - might have to remove the injector(s) to check in the cylinders for water.