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.