Jinma 284 Overheating

[TJW]

I did take a lot of time blowing out the radiator before this test. Sorry about the confusion between hot and cold. I will try it after it gets to temp. But after this check, and blowing out the radiator, I did a little mowing and only made two passes (about 5 minutes under load) and I was at 100C. I packed it in. Like I said before, I knew nobody would like the idea of the "dubious remedy". I only have a few weekends before it starts raining here agian and I can't mow until next August and I'd rather not spend them wrenching. I don't have a pressure testing tool, and I didn't see one at the Auto parts store. I'll look for it at another one.
If I pressure test the system, and it doesn't hold pressure, would that also indicate a blown head gasket? I'm not getting white smoke from the exhaust, so I don't think there is coolant going into the combustion chamber. I also don't see any water in the oil, foamy oil. So, if it is a head gasket then it would seem that it is only leaking in one direction - from the combustion chamber into the cooling system??
TJ

 

[greg_g]

</font><font color="blue" class="small">( No, I meant 2 strokes )</font>

Not that it's really germane to the topic, but are you perhaps confusing diesel and gasoline as 2 and 4 stroke engines respectively? Because these tractors may be diesels, but they're definitely of the four stroke category; intake, compression, power, exhaust.

//greg//

 

[greg_g]

</font><font color="blue" class="small">( I did take a lot of time blowing out the radiator before this test. )</font>

Sorry about harping on this, but others that have been in your shoes will attest (or already have attested) to the fact that the only way you're going to be absolutely positive that external blockage is not the root of your problem - is to physically remove the radiator from the tractor for cleaning.

Until you can visually confirm 100% daylight through those cooling fins, any other troubleshooting is purely speculative.

//greg//

 

[RonMar]

If the air and water passages are all clear and it is pumping fluid and air through the radiator properly then it must be something else. That overheat from the fan belt loss could have done some damage. I forget how many hours you said you have but it is reccomended that you retorque the head at 50 hours. Have you checked the head bolt torque. Here is a link to a retorque procedure on Johns site. http://johnstractor.homestead.com/JMretorque.html

This might be a silly question but have you confirmed the actual coolant temp as compared to the gauge? You see if it is a head gasket, it is not actually overheating. If the radiator is flowing air/fluid properly and coolant is circulating through the system, it is dissipating the heat generated by the engine. A leak in the headgasket dosn't generate any additional heat, it just redirects hot exhaust gas into the cooling system that would normally go out the exhaust pipe.

When running under load, the combustion gasses are very hot. If this hot gas is injected into the cooling system, it immediatly rises to the highest point, in this case up through the thermostat heading for the top of the radiator. As it does this it passes the temp sensor in the thermostat housing. The sensor dosn't care what it is measuring, it just measures whatever is flowing past and that hot gas in the water makes the gauge go up while the average water temp is not much different than normal. The increased pressure from the added combustion gasses forces past the radiator cap and can make it look like it is boiling over by venting fluid and steam out the overflow or if it is really bad, around the cap itself.

Liquid cooled 2 strokes typically have the temp sensor right in the top of the cylinder head. When they loose a headgasket, the temp gauge will act like a throttle position sensor, more throttle, gauge goes up, less throttle, gauge goes down. More throttle, overflow tank erupts, less throttle overflow settles down.

If it turns out to be a head gasket, they are not all that difficult to change. In fact only a few additional steps added to that retorque procedure in the above link would have it done. I don't know what you received for spare parts with your tractor but the toolbox that came with mine from the factory in addition to some hand tools included a headgasket as well as most of the seals used in the tractor It even had light bulbs and a set of intake and exhaust valves/springs. It was quite extensive. The only thing required beyond basic hand tools would be a torque wrench. Since it is an overhead valve engine, and there is pretty good access to the engine, I would guess you could replace it in 2-3 hours or less.

 

[RonMar]

No Greg, I am not confusing 2/4 cycle operation with the fuel type being used by the engine. The diesels on these tractors are indeed 4 cycle. I am just using my experiences with 2 strokes as an example as I have seen more headgasket leaks into the cooling system with them than on 4 strokes. At any rate, compression/expansion gas being forced into the cooling system is the same for both 2 and 4 cycle engines.

 

[Harrygoodwrench]

</font><font color="blue" class="small">( I did take a lot of time blowing out the radiator before this test. Sorry about the confusion between hot and cold. I will try it after it gets to temp. But after this check, and blowing out the radiator, I did a little mowing and only made two passes (about 5 minutes under load) and I was at 100C. I packed it in. Like I said before, I knew nobody would like the idea of the "dubious remedy". I only have a few weekends before it starts raining here agian and I can't mow until next August and I'd rather not spend them wrenching. I don't have a pressure testing tool, and I didn't see one at the Auto parts store. I'll look for it at another one.
If I pressure test the system, and it doesn't hold pressure, would that also indicate a blown head gasket? I'm not getting white smoke from the exhaust, so I don't think there is coolant going into the combustion chamber. I also don't see any water in the oil, foamy oil. So, if it is a head gasket then it would seem that it is only leaking in one direction - from the combustion chamber into the cooling system??
TJ )</font>

TJW,
I think you must verify with a known good gauge that it is in fact running hot or overheating. It is so easy to chase ones tail when there is indeed no problem. I would suggest a direct reading gauge or if you know someone with a infared thermometer that will lend it to you will suffice. Then we will know whether the concern is there.
Assuming that you engine is running hot here would be the most logical to check.
You already eliminated the thermostat so its not that. Fan is direct drive so its not that.
Although you cleaned the exterior radiator fins there is still the possibility that the inside tubes in the radiator are plugged and causing the problem. You might be able to see the top tubes but that is only part of the tube. The only way to truly determine is to flow test or at least partially lower coolant and run engine for a few seconds and look down rad neck and observe the flow. Still this is open to what is good. Lets check a little more before condemning radiator unless it looks pretty poor.
The infamous "Head Gasket" problem. Yes, I've done my share. Some will immediately overheat engine, cause engine misfire, cause hydrostatic lock, some leak externally. Then there is the type that causes the engine to run hot, push coolant into oil.
Alas, this is the one that makes one question oneself. Most will agree that if it puts compression gases into coolant system it will push coolant out, may skip, run hot, etc. Also if if you pressure test it it should NOT hold pressure. The last statement can be incorrect. It is possible to have a "slight" head gasket leak and have it push the gases only one way into the coolant but not coolant into the cylinder.
Being that the water pump pushes the coolant around and causes turbulence which may appear to be bubbles here is what I want you to do. Assuming your 284 has the thermostat goes upward like my Y380.
Remove thermostat and leave out but put housing back on, leave upper hose off.
Fill cooling system until the thermostat housing almost overflows.(I would use plain water)
Remove fan belt that drives water pump. This will remove any possible water pump turbulence.
Start engine and let it run for a few seconds. Start engine and observe coolant in thermostat housing. If you see any bubbles you have no doubt that combustion gases are entering the cooling system.
This would be best done on a warm engine.
Caution: DO NOT RUN ENGINE LONG. It will overheat for sure.

This is how we always diagnosed this type of frustrating problem. That is before they came out with special chemicals in a tool kit to check for cumbustion gas presence in the cooling system.

 

[TJW]

Thanks for all the good stuff.
I do think that it's overheating because when it hits 100 I can see the coolant coming out the overflow hose, at least until the coolant is drained down to the top of the fins.
I will try the test with the fan belt off and the upper hose removed. I will also torque the head bolts, since I have 114 hrs on it. I guess I am not up on my maint intervals. I am going to try this tomorrow morning and I'll get back to you guys. I have a torque wrench and a new T/stat and I've printed the instuctions.
Thanks,
TJ

 

[TJW]

</font><font color="blue" class="small">(
Remove thermostat and leave out but put housing back on, leave upper hose off.
Fill cooling system until the thermostat housing almost overflows.(I would use plain water)
Remove fan belt that drives water pump. This will remove any possible water pump turbulence.
Start engine and let it run for a few seconds. Start engine and observe coolant in thermostat housing. If you see any bubbles you have no doubt that combustion gases are entering the cooling system.
This would be best done on a warm engine.
)</font>

I performed this test over the weekend and confirmed gases entering the cooling system. I also checked the torque on the head bolts and it was fine. At least I have a nice torque wrench now ($81 at Grainger) for the head gasket job. I am guessing a warped head. The Steel Seal didn't work, just as everyone said. I was able to do some mowing and got the last of the really tall stuf knocked down by taking it slow and stopping to raise the hood and let it cool off. I can mow the shorter stuff without overheating, at least for a while. I just need to make sure I keep the radiator clean. I will probably tackle the head next month when it starts raining and I can't do any work any way.
One strange thing that happened when I removed my valve cover was that my starting circuit is somehow screwed up. The only wire I removed was a green one that looked to be connected to a ground bar. I connected it back up with no problems. Then I couldn't start the tractor using the key. I have been having problems with the ignition switch, but only for the gauges. I got a new one at NAPA and the gauges work fine, but still no starting. Anyone have any problems like this?
Thanks for all your help.
TJ

 

[greg_g]

</font><font color="blue" class="small">( Anyone have any problems like this? )</font>
The file I uploaded (see attachment above) will probably do the trick

//greg//

 

[bruce1966us]

I was able to do some mowing and got the last of the really tall stuf knocked down by taking it slow and stopping to raise the hood and let it cool off. I can mow the shorter stuff without overheating <font color="blue"> </font>

<font color="black"> </font> Classic symptoms of an internally stopped up radiator.