Jinma 204 radiator issues

[Catch95]

My Jinma 204 started overheating badly on the weekend. TY290 engine. Hot day - mid 90's. It went into the red on the gauge so fast I thought it must be an electrical problem but sure enough when I got it back to the shed, the radiator was almost empty - and I had filled it before I left.

I called it a day, let it cool, down and refilled. No sign of a leak and when I checked in the morning the radiator was still full and no fluid on the floor.

But as soon as I got going it overheated again. Radiator had emptied it self again.

I checked all the hoses and clamps which seem fine. Nothing obvious. No sign of a leak from the water pump. Small rust trail at the bottom of the radiator so suspect that could be it but just surprised I can't find a leak when the pressure builds up. Tested the thermostat in hot water and it opened up ok. Fan and belt fine. I replaced the water pump about 200 hours ago and has been fine. Original radiator - now at 900 hours. Oil is black on dipstick so assume head gasket ok?

I have taken taken the radiator out and will get it checked by a cooling place. Bit expensive to get a new one sent to Australia and I can't find one here.

Any other thoughts? Much appreciated.

Mark

 

[quicksandfarmer]

These engines are really prone to head gasket failure. Fortunately it's not that bad a job to replace it. If you can't see where the coolant is going it's probably going out the tailpipe.

 

[pmsmechanic]

To me it almost sounds like the water pump isn't doing anything. Two experiences:

First was a 391 Ford irrigation engine. It ran hot all summer and we checked everything out and it all looked good. We got it to cool by spraying the motor with water until fall and we pulled it into the shop. Took the water pump off because we had checked everything else and all the fins on the cast iron impeller were broken off.

Second was more recent. Early 2000's VW Golf 1.8 liter gas. It would cool ok until you were driving down the road. In no time at all it was boiling over and by the time you got the hood open everything was fine again. It needed a timing belt and when I ordered the kit I bought a water pump to install as it wasn't that much more and you are in there anyways when changing the timing belt. Turns out the water pump had a plastic impeller that was cracked. When the engine revved up the impeller would expand and slip on the shaft because it was split and therefor no circulation. When the motor idled the pump would grip the shaft again and circulate coolant.

The other possibility here is a leaking head gasket. If the head gasket is leaking combustion gasses into the water jacket it will empty the rad. To check this fill the rad with water when the engine is cold and stretch a balloon over the rad neck. If the balloon fills with "air" then you know you have a head gasket leak. If this is the case and you replace the head gasket make sure you have the head checked for leaks and resurfaced.

 

[Catch95]

I am starting to think it may be the head gasket. Would explain why I can't see a leak.

I only ignored the head gasket idea because the oil wasn't milky but I gather that isn't always the case?

I did notice when standing next to the tractor, after turning it off, that I could hear a bubbling/gurgling sound coming from the exhaust pipe.

Would that confirm it?

Thanks

Mark

 

[nepa]

If you still have the original thermostat then I would change that first. They are cheap to replace and a good place to start diagnosing your problem. The originals tend to break the bridge that anchors the pellet that pushes them open. For about ten dollars, a good quality thermostat will keep a more stable engine temp.

 

[mrmikey]

Sounds like a head gasket to me as well. Like Quicksandfarmer said, it's not that bad a job. Just be aware that if it is the head gasket there's a chance that one of the cylinders could fill up when it's sitting for a while so when you go to start it it's hydrolocked...good by engine parts.....Mike

 

[Catch95]

Hi,

I pulled the head off and the head gasket had failed. Bit of pitting on the head and the block but it cleaned up pretty well.

What is concerning me is that when pulled the two fuel injectors out to get at the two head bolts hidden underneath - nice trap for young players - they both came out with brown sludge on them. Is that consistent with the head gasket going? They were also really tough to pull out.

Question is - does this suggest I need to do anything else other than replace the head gasket? Bottom of the valves looked pretty good, bit of carbon but not excessive.

I'll obviously change the oil and filter before starting it up and all new coolant.

Also can't seem to figure out the studs/bolts for injectors. I screwed them out to let me rotate the injectors to get them out. One hole is lower than the other in each case but the studs are the same length.

Any help much appreciated

Thanks

Mark

 

[quicksandfarmer]

I'm not an expert, but I'll opine that the brown sludge is consistent with coolant and oil getting into the combustion chamber. These engines are pretty tough so I wouldn't fix anything that doesn't look obviously broken.

Sorry can't help with the injector studs.

 

[Catch95]

Thanks for the thoughts. I must have been a bit weary because the next morning the studs for the injectors were obviously different lengths to compensate for the offset in the mounting of the injectors. So put the head etc back together.

Didn't get a chance to put the radiator back in so haven't tested the repair as yet. I took the radiator in to get a price on a re core but the guy felt it wasn't worth it. Cheaper to get a new one. But he did show me the signs that the radiator had been under enormous pressure with various bulges in the tanks etc.

Back up the farm this weekend so fingers crossed. Calving at present so a lovely time although very dry here in this part of Australia. Finally got some rain last night which we really needed to get some pasture growth.

No doubt will,post again when I try to start it up.

 

[quicksandfarmer]

"Enormous pressure" is kind of puzzling. The radiator cap should open at a very low pressure, and I'm surprised the hoses held. I'd replace the radiator cap while you're at it.