Jinma 284 Overheating

[TJW]

Has anyone had any success with head gasket sealers? I see on the internet a couple that have big claims, Steel Seal and Heal-a-Seal. If I do have a head gasket leak I think it is small. I would hate to have to remove the Head.
TJ

 

[RonMar]

With the ammount of pressure involved in a Diesel cylinder, I believe only a proper head gasket between a head and block with a true surface, properly torqued in place is going to contain it.

Another way to check for a headgasket leak is to hold your thumb over the overflow hose or attach a low pressure gauge(combination vacume/pressure gauge) with a hose barb fitting MOMENTARILLY to the hose while running to see if there is any pressure build up on that hose. You could also put the hose in a container of water to look for bubbles. If these things had an overflow resovoir, a leaking headgasket would be showing bubbles in the overflow resovoir. A leaking headgasket will add combustion gasses to the cooling system and pressurize it to the point that the radiator cap pressure is reached. The excess pressure is vented out the overflow tube. Just don't leave that overflow hose blocked. If there is a head gasket leak, the pressure will continue to build and without a way out, will eventually rupture the cooling system.

As far as cleaning the radiator goes, I made up a new blowgun attachment the other night from a old piece of aluminum arrow shaft about 3/8" in diameter(2217 shaft)and about 24" long. I capped the end and drilled a 1/8" hole in the side of the tube wall about 1/2" from the end so it blows air at a 90 degree angle from the tube. I can slide this straight tube down through a small gap in the radiator shroud located at the top rear corner of the radiator on both sides. Using this access point, I can get this straight pipe down between the rear of the radiator and the front of the fan and apply air directly to the entire rear surface of the radiator without having to disassemble anything. I have been using a shopvac to clean the radiator. I used this air tube after a vacume session the other night and got a ton more debris and sand/dust out of the air passages.

 

[sweettractors]

Is there anything in front of the radiator intake area. I have seen some of these tractors with battery mounted in front of the radiator. --Ken Sweet

 

[Soundguy]

You could also pressure test the cooling system.. etc.

Soundguy

 

[TJW]

OK. I was able to go out to work on the tractor this afternoon. I replaced the radiator cap with a 7 psi cap and did the bubble test on the overflow hose in a pitcher of water. After about 20 seconds of running I started getting bubbles coming out the overflow hose. About one a second. Nothing major, but there was bubbles. Looks like I have a leaking head gasket. I know you guys probably don't approve, but I'm going to try the Steel Seal. It's not a bunch of goop, so I don't think it will harm anything. For 50 bucks and a guarantee it can't hurt. I'll let you know how it goes.
TJ

 

[greg_g]

</font><font color="blueclass=small">( I replaced the radiator cap with a 7 psi cap and did the bubble test on the overflow hose in a pitcher of water. After about 20 seconds of running I started getting bubbles coming out the overflow hose. )</font>

Something doesn't sound right here TJ. Can't see where a head leak could increase pressure that fast in a cold system. With enough initial pressure to get past a properly sealed pressure cap, that is. Sounds more like
a) the pressure cap hasn't been turned all the way to the stops,
b) it's normal expansion from heat transfer via the lower radiator hose
c) a defective radiator fill neck (won't let the cap seal)
d) a radiator leak
e) any combination of the above

Guess this means you haven't pressure tested the system OR removed the radiator for cleaning yet (?)

//greg//

 

[RonMar]

</font><font color="blue" class="small">( OK. I was able to go out to work on the tractor this afternoon. I replaced the radiator cap with a 7 psi cap and did the bubble test on the overflow hose in a pitcher of water. After about 20 seconds of running I started getting bubbles coming out the overflow hose))</font>

TJ, I re-read my post and realized I missed an important point with my suggestion. The radiator should be completely filled with fluid and the engine warmed up to full operating temp before you look for bubbles. On these things, if the radiator wasn't topped up, bubbles while warming up would be normal. If it bubbles after fully warm when you started with a full radiator, that air is comming from somewhere that has enough pressure behind it to force it in there. The rate of bubbles will also most likley vary with engine RPM(more RPM, more bubbles).

Since these tractors don't use a overflow/recovery tank, it is normal to have some air in the top of the radiator. When you run the engine, the fluid absorbs heat and expands. As it expands, the system pressure increases untill the radiator cap pressure is reached. When this happens, the cap opens and vents to the overflow tube to keep the system pressure within limits. If there is air on the top of the radiator, the air gets pushed out fist as pressure builds. Since there is no overflow tank, this air or fluid goes to the ground. When you shut off the engine and it cools, the fluid contracts and places the system under a vacume. There is a small check valve in the radiator cap that in the case of a radiator without a overflow tank, allows air to be sucked back into the system through the overflow pipe. If the system used an overflow tank, as it cooled the system could only draw fluid from the overflow tank and the radiator would always be full.

Since the tractor typecally runs at the same temp every time, this is no big deal as the fluid expands/contracts about the same ammount every time and pushes the air on top out and is full of fluid while operating. It then draws the same ammount of air back in when cooling and the cold fluid level stays relatively constant. This is the state these tractors run in. The radiators have a large area above the cooling passages so they can deal with this expansion/contraction.

Greg, A bubbling overflow tank or symptoms of the radiator venting/boiling over are a classic cracked head/headgasket failure in liquid cooled 2 stroke engines. This also happens in auto's, just not quite as frequently.

 

[greg_g]

</font><font color="blue" class="small">( Greg, A bubbling overflow tank or symptoms of the radiator venting/boiling over are a classic cracked head/headgasket failure in liquid cooled 2 stroke engines.)</font>

I think you meant 4 stroke engines Ron, and I also think you might consider re-reading my previous response to Adam as well.

I readily agree with your point about visual cues to "a classic cracked head/headgasket failure" - on an engine at or over operating temperature. But the impression I got from Adam's post, was that he observed 1 bubble per second through the overflow hose of an otherwise cold engine - and one with a reportedly brand new radiator cap at that.

I don't believe enough ground has been covered to accept "cylinder head problem" as the final diagnosis just yet. As such, I believe it's also premature to arbitrarily start pouring in dubious "remedies".

//greg//

 

[Wayne_Freeman]

When this happened to my Jinma the symptoms were: slow loss of radiator liquid, slow overheating of the engine (depending on ambient temp it might go an hour before red lining) and finally with the radiator cap off and engine started you had a very active bubbling as seen from the top of the radiator. Now I am sure there might be some bubbling anyway but this was REALLY BUBBLING! One bubble per second in the overflow tube is not what I observed and would not be a proper diagnosis. I think if these three symptoms fit and you have tried the other remedies then you probably will have to replace the head gasket. It really is not that big of a job!

 

[RonMar]

</font><font color="blue" class="small">( I think you meant 4 stroke engines Ron)</font>

No, I meant 2 strokes, I said autos(4 strokes) after that to include them as well. It is less common on auto engines probably because they typically have a better head/block interface. It is fairly common on liquid cooled 2 strokes(less robust union, run harder).

</font><font color="blue" class="small">( But the impression I got from Adam's post, was that he observed 1 bubble per second through the overflow hose of an otherwise cold engine)</font>

I got the same impression, that is why I posted again. I realized I had forgotten to cover that part in my initial post. I also missed the word Cold in your response, sorry.
This symptom can show itself in cold engines also but it is usually pretty evident what it is. I bought a 88 Toyota 4X4 last year from some folks for cheap. Great body/running gear but it runs rough and "Keeps Overheating". They took it to a mechanic and he said it had a cracked head and gave them a pretty expensive repair estimate so they decided to sell it "as-is"(I don't think the mechanic even pulled the head). I got it home and did a cold compression test and the first 2 cylinders were chained together and to the cooling system. After cranking it for the test, a hissing could be heard, comming from the pressurized cooling system as the air pushed in from the cylinders escaped. I inspected the head and found nothing wrong and reassembled it with a new gasket. It has been running fine for about 8 months now.

</font><font color="blue" class="small">( I don't believe enough ground has been covered to accept "cylinder head problem" as the final diagnosis just yet. As such, I believe it's also premature to arbitrarily start pouring in dubious "remedies".)</font>

I agree with this 100%, but since this is such a simple thing to rule out from the beginning(look for bubbles in a container of water) that it would be a good thing to look at, especially since he said it had a possibly severe overheat 6 months ago due to loosing a fan belt. No bubbles at temp, the problem lies elsewhere(clogged radiator water or air passages, pump problem ect...). I am not a fan of "Dubious remedies" or "Mechanic in a can" at any time.

 

[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.