overheating?

[jft]

I have a '87 ('88?) kubota b4200 2 cylinder diesel mini tractor. i noticed some coolant puddling below the radiator a few months back but it only happened once and i couldn't find a leak. regardless, i flushed the radiator and ran sealant through it. there was a lot of sediment in the fluid that came out and i had to poke around in the drain to get anything to come out. it was really brown. it has never leaked since but every now and then i hear what can only be described as a loud "chirp" coming from the engine either while i'm running it or even after i turn it off. sometimes it sounds like escaping pressure (my impression). the coolant level is remaining the same but sometimes i find a strange splatter on the wheel that looks like spraying coolant. i also feel like the engine is running hot but again its only my impression because i don't have a temp. gauge. it is hot here this summer but parts of the tractor get so hot while i'm running that its uncomfortable to touch them and i feel like more heat is coming off the hood than i've noticed before. i'm wondering if the coolant isn't circulating like it should. my question is (1) how can i tell definitively that the tractor is running hot. can i install an aftermarket T gauge? (2) where do i start, to figure out what, if anything, needs replacing? my dad mentioned getting the radiator 'rodded'. should i just replace the whole thing? what about the temp pressure switch? i'm certainly not a mechanic but i like would like to learn more and do as much as i can on my own. does anybody have any suggestions? thanks.

 

[firemanpat2910]

I know a few simple things to check and defer to the experts for more detailed help. Is the water in the radiator getting as hot as the motor? can you see it circulating past the cap hole when the cap is off? can you feel it "pulse" through the water hoses? all these will help tell if water pump is pumping. Is the fan belt tight? is the fan slipping? Is there dirt or grass plugging the radiator? How long since last oil change? Have you mounted any thing (push bar, tool box, weights) in front of the radiator? Is the motor clean?

 

[Highbeam]

One of the simplest ways to check for a plugged radiador is to put your hand right on the core when it is supposed to be hot. Shut your engine off of course and feel for changes in temp. The dead and plugged areas are very noticeable. I had radiator pluggage that wiped out the centers of the cores on both a 1985 toyota pickup and a 1960s ford bronco. If your radiator passes this test and is evenly hot then the next easiest thing to check is airflow through the radiator. Run the engine rpm up to pto speed and the fan should full a very noticeable amount of air into the radiator, at idle the engine fan should still pull plenty of air.

So now you verified hot coolant to the radiator and air flow through the radiator. If you are still unsure, then I would go buy a cheapy infared thermometer. The kind that is like a gun you point at an object and the gun tells you it's temperature. These are not a bad tool to have around since you can check all sorts of things with them.

 

[3RRL]

Another thing to check is the "shroud" around the radiator fan. It is very important that air is sucked through the cooling fins and not from the side or hot engine compartment. Check for cracks or missing pieces. In my case, it is normal for my tractor to run hotter in the Summer too....usually 9°F to 10°F hotter than in the cooler Winter.

 

[firemanpat2910]

great idea on the shroud. Very comon for them to be removed when working on engine and left off cause they're such a pain. You can have the fan running like mad and if it is not encased in the shroud its not doing its job.

 

[normde2001]

I would replace that water pump ASAP and flush the entire cooling system in the process. The mysterious coolant loss, (check the weep hole), and chirping are dead giveaways on the water pump.

 

[Egon]

Is it a thermosiphon model? If so there may be tube comming off the top of the rad and down on front right side that has a whistle on it. If overheating this whistle will sound and vent steam. Also check the rad cap to make sure it is good and has a proper seal. This model probably does not have a water pump.

Having the rad cleaned may also be a good idea after your descrition of draining it. Flushing the coolant system with some of the commercial prducts made for this may help clean up the block a little.

 

[RobJ]

It seems not all models have a fan shroud. At least my L2500 does not. I don't see one in the parts manual either. Mines been running hot lately to. After flushing the system I left plain water in. The temp got up there but no weeping from the overflow tube. An this was while under a heavy load (disking). I'd heard a while back that plain water is best for heat extraction, but antifreeze keeps it from freezing and keeps rust out of the system.

A pic of a sticker L2500.

 

[deerhunterf350]

I'd heard a while back that plain water is best for heat extraction, but antifreeze keeps it from freezing and keeps rust out of the system.

Anti-Freeze also raises the boiling point of Water, water boils at 210 degrees at Sea level, lower than that at higher elivations. Depending on the concentration of Anti-Freeze will determine the increase in the Boiling temp.

If you run plain water at higher elivations, then you can be boiling the water out of the system. And depending on mineral content of the water, you can get some nasty Scale buildup in the cooling system, which will only add to the Overheating Problem.

 

[RobJ]

Didn't know that, I know that being under pressure with the cap raises the boiling point.

It'll sit for another couple weeks before I get the anitfreeze in it. Up at the weekend place the water is soft (slippery) in the shower, so I think that means less minerals. In Spring we have the hard water.

 

[deerhunterf350]

Correct the Pressure Cap raises the Boiling Temp, I took this from Wikipedia.com "Antifreeze is a water-based liquid coolant used in gasoline and diesel engines. Compounds are added to the water to reduce the freezing point of the mixture below the lowest temperature that the engine is likely to be exposed to, and to inhibit corrosion in cooling systems which often contain a range of electrochemically incompatible metals (aluminum, cast iron, copper, lead solder, etc.). The term 'colligative agent' is to be preferred as, in warm climates, the benefit of these compounds is to increase the boiling point of the coolant, which should then be more properly referred to as 'anti-boil', and as anti-freeze decreases and increases both properties, respectively, 'colligative agent' more accurately describes the liquid. The term 'engine coolant' is widely used in industry. " In addition to the Pressure cap, anti-freeze adds more anti-boil properties to the Coolant.

I don't remeber exactly what the product was called, but a Friend had a Bored and stroked 302 in and old mustang drag car, He bought an aftermarket Dual Core Radiator that was rated for a Big Block , and still had overheating problems. He bought 3 quarts of some Additive, removed 3 Quarts of coolant(50/50 water/antifreeze mix) , added this to the system and it dropped the Temp by 30 - 35 degrees. I don't know if it was acceptable for Diesel use or not.

 

[sandman2234]

Due to the nature of a diesel engine with wet sleeves, I don't think I would take the chance on a couple weeks without antifreeze. The consequences are too hard to repair. Resleeving a block is no fun, even for a veteran mechanic.
I would check the movement of the coolant as mentioned, with the cap off. You can also check the thermostat since you will only open the radiator cap when it is cold. By the time it starts getting warm, your pump should start moving fluid across the top of the radiator and you will know that they are both working. If no flow, check the thermostat by removing from tractor and putting on a pan on the stove. Use a candy thermometer if you have one, or just note how long before the water starts boiling when it opens. Lower temp and see if it closes. Repeat several times.
One thing you really need to make sure of it that you are getting air flow. Tiny amounts of grass and pollen build up to clog the air flow thru a radiator. Flush with a good pressure hose, in the reverse direction of the airflow.
Most of these things have been mentioned, just wanted to hit them again. A water pump on a tractor usually lasts a long time. I suspected mine, doing everything yours is doing, except the chirp, and it was just a radiator clogged with grass in the end.
David from jax

 

[RobJ]

Due to the nature of a diesel engine with wet sleeves, I don't think I would take the chance on a couple weeks without antifreeze. The consequences are too hard to repair. Resleeving a block is no fun, even for a veteran mechanic.

These little Kubota engines are more like a car engine. Solid cast with machined sleeves. The sleeves on my L2500(looking at the parts manual) are not replaceable like on My BIL's JD350 or his old International 384, both engine I rebuilt for him. So with a solid set up like this a couple weeks shouldn't give me to much trouble, but I plan on putting the anitfreeze back in. I plan on pulling the radiator and flushing it out to make sure. I've actually bought a new head gasket and may replace it this winter. So I'm holding off on the anitfreeze while I keep dumping the system. I flushed it again this weekend while scratching my head on the overheading problem.

BTW while looking at the parts manual I noticed the pistons and rings come in standard and a +.50mm (about +22 thousanths). Here's hoping I never need any of those.

 

[3RRL]

RobJ,
I've read many of your posts and see that you are a resourceful guy. If I were you, I'd fabricate some kind of shroud...even if it does not fit perfectly. IMO it would help tremendously. I'd definitely put anti-freeze in also...if for nothing more than lubrication (water pump etc.) and rust prevention.

 

[RobJ]

Resourceful? I call it cheap in most cases (not pokin fun at you..just me )

It'll all get in there it's just this boger really has me scratching my head. Fabbing a shroud might be something I will look into but as another overheater mentioned mine started doing this all of a sudden. I use it even during the winter but ran the FM one day and noticed the temps and the weeping water from the cap overflow tube. The only real problem I did discover was the thermostat was not working properly. It had plenty of green water in the radiator this winter. But with the tractor itself staying inside a garage and our mild winters it is really in no fear of freezing without a prolong cold spell. But "something" happened to make the change. And that's what is bothering me the most. What I've done...

new cap (slight tear in the seal)
thermostat - needed, not working correctly
flush radiator - lots of water
check water pump - run top hose(discharge) on the ground will filling with fresh water, plenty of water flow.
water flow when cap removed
removed suction hose - inspec
remove bypass hose - inspect
run with NO thermostat
clean radiator fins with gunk, then simple green, then Joy
Spray water on the radiator while hot and running, temp comes down
Flush radiator with water while not running, remove bottom hose, cover with hand, fill radiator, remove hand, radiator drains in seconds...I gues this shows good flow through most of the cores.

Next steps - remove radiator or make a high pressure device (bent tube) to force water down the core and fush.

Replace head gasket - Not seeing anthing in the water, blowby seems normal, but I know a slight leak causes high pressure air to excape. Even a small volume of air under pressure leaking causes the air temp to rise and anything around it to rise...IE head, water jackets.

??? if all else fails....as BIL would say...runit and "poof" test it.

 

[Doc_Bob]

new cap (slight tear in the seal)
thermostat - needed, not working correctly
flush radiator - lots of water
check water pump - run top hose(discharge) on the ground will filling with fresh water, plenty of water flow.
water flow when cap removed
removed suction hose - inspec
remove bypass hose - inspect
run with NO thermostat
clean radiator fins with gunk, then simple green, then Joy
Spray water on the radiator while hot and running, temp comes down
Flush radiator with water while not running, remove bottom hose, cover with hand, fill radiator, remove hand, radiator drains in seconds...I gues this shows good flow through most of the cores.

Have you checked the temperature of the coolant?
Bob

 

[firemanpat2910]

If spraying water on the radiator cools the temp down I would assume the problem is in the radiator,or air flow. You have eliminated most radiator spots so what about air flow?
1. is fan slipping
2. have you installed grill gaurd,FEL,brush gaurd or other restriction?
3. make a shroud even a temporary cardboard one and see if it helps.
4 are the "fins" bent or crushed on radiator?
5. are there hydro or trans lines in radiator possibly this fluid is overheating.
6. have you ever used stop leak in this radiator?

Good luck

 

[firemanpat2910]

on a some what related note ,I had a buddy once that had a leak in his radiator, he soldered it up and "pressure tested" it. Gain 3 more leaks,fixed them tested again got 2 more. I showed up and he was testing with a 120psi. air hose...on a 14# system so be carefull when you "pressure flush" a radiator.

 

[Egon]

check water pump - run top hose(discharge) on the ground will filling with fresh water, plenty of water flow

Just wonering wher the water pump is located?

 

[Doc_Bob]

i also feel like the engine is running hot but again its only my impression because i don't have a temp. gauge.

If you are doing all this work on a "hunch" that the thing is hot without knowing if it is hot, you are a better man than I am. Sounds like a lot of work without knowing if it needs to be done.
Bob