Blown Head Gasket

[Jinma284]

I have a blown head gasket. Not getting in the oil. I can run about 20 minutes and then have to refill with water. I need to run about 4 hrs. before I replace it. Will I cause more problems if I continue to run it and add water. Tractor is a Jinma 284. Pat

 

[RonMar]

So by replacing water, you mean that it is blowing it out the radiator overflow along with combustion gasses due to cooling system overpressure? Probably not the best thing to keep running on. You are adding contaminants to the cooling system, Continued use could open up different passages and contaminate oil. You also run the risk of inducing water into a combustion chamber at shutdown. This could do damage to the engine at next startup due to hydraulic lock(you should spin-up/start with compression release anyway) continued high pressure/hot gas flow thru the gap could cause erosion to head/block that might lead to more failures in this same place after a new gasket is installed. This would require head and block resurfacing to repair.

Have you tried re-torquing the head? That might buy you the 4 hours you need. Usually once they start leaking, they are done for. Did your head get retorgued before 50 hours? A headgasket is not a difficult job on these overhead valve engines and can probably be done in an hour or two. My tractor came with a spare headgasket. If I had the parts, I would be inclined to just fix it rather than risk any further damage.

Good Luck.

 

[3RRL]

I agree 100% with everything Ron said. A blown head gasket is a relatively easy repair in comparison to the damage it may cause. Especially since you know you can run 4 hours before refilling, it needs attention to get repaired.

 

[RobJ]

This might get you to want to get it going!!

http://www.tractorbynet.com/forums/.../92105-head-gasket-replacement-my-kubota.html

 

[Jinma284]

Ron and Rob. Thanks, I decided not to run it until its fixed. We will load it up and take it to my son-in-laws auto shop and repair Sat. morning. I can do what I need to do Sat. afternoon if we don't run into more problems. Will let you know how it comes out. Pat

 

[Jinma284]

We replaced the gasket with no problems. Also replaced the thermostat. Unloaded it off the trailor and started driving. Within 20 seconds it the temp was almost at 100. I shut it down for about 2 minutes and restarted. Temp gage stayed at 80. I work it about 3 times per week. About once per week for the first month it would repeat the heating problem immediately after starting. Shut it off and restart and everything would be fine. About a week ago after running about one hour with a box blade it overheated without me seeing it in time. Blew the head gasket again. Could this be anything other than a defective thermostat?

 

[RobJ]

I'm really concerned it blew a head gasket first. I would think you would get some water or steam through the pump bypass. But in the end it probably would blow the gasket again. IMO time to look at other things going wrong here. Check timing (maybe something in the pump changed), etc. If it's heating up that fast (that is quick), look for a compression leak. Air being compressed and forced out a small hole will produce plenty of heat.

In my case all my overheating were caused by a faulty new thermostat. When I replaced it with another new one problem solved. The old new one was check in hot water on the stove to. Can't explain that one.

Good Luck!!

Rob

 

[RonMar]

Well with head gasket issues, is it really overheating or is it a headgasket? A headgasket venting hot combustion gas into the cooling system can possibly mimic the symptoms of an overheat. Hot gasses rise to where the temp sensor is and cause it to display a temp on the gauge warmer than the actual coolant. The excess pressure goes to the radiator and causes the pressure cap to open and vent steam and water vapor looking like a boilover/overheat. AN IR themometer looking at the side of the head near where the water passage exits the front(near thermostat housing) can usually confirm if the temp on the panel gauge is valid. If it isn't, either the headgasket didn't take, which happens sometimes, or you have a crack/gouge/warpage issue in head or block.

If it is overheating, I always go back to basics. To get the heat out of the engine, you need colant flow. Is the belt and pump working? Is the thermostat opening when it should(remove it and heat it in a pan of water on the stove along with a thermometer and watch it open). Once the hot coolant reaches the radiator, it must flow thru it. Are the internal passages clean? You can usually see some of them thru the radiator cap to get an idea of passage health, but sometimes a small inspection mirror or a fiberscope are required to get a better idea.

Once the water can flow thru the radiator, it must have access to air passing thru the fins, a LOT of air. Is the fan in the shroud and turning properly? Are the air passages clean? I inspect these with a light held on one side and look from the other side. This is difficult with the shroud in place. To clean I use compressed air blown from the back or fan side of the radiator. I made a special blowgun wand that is a 1/4" aluminum pipe with a cap on the end and a hole drilled perpendicular to the pipe at the end. This allows me to reach thru the top corners of the fan shroud and reach all the rear surface area of the radiator and blow any crap back out the front. DO NOT use pressurized water as it will collapse/bend the fragile fins on the radiator.

 

[greg_g]

We replaced the gasket with no problems....I work it about 3 times per week. ...Blew the head gasket again.

The 1st time you replaced the head gasket -

• did you (or your dealer) re-torque the head bolts at the prescribed 50 hour mark?
• and what did the first one look like when you took it out?
• At that time, did you examine the cylinder head for warpage and the cylinder block for cracks?
• Did you look at the cylinder liners for pits/cracks?
• How many ft-lbs did you apply to the head bolts?
• Did you re-adjust the valve lash before putting the valve cover back on?
• what temperature range was the replacement thermostat?

What has you convinced this time that the 2nd head gasket is now bad also?

• is there gray stuff splashing out the exhaust?
• is there black stuff in the coolant?
• is there light colored foamy looking stuff on the engine oil dipstick?
• have you tried running the tractor without the thermostat?

Heed RonMar's advice closely - look specifically at the radiator fins behind the battery and behind the air filter housing. Park the tractor in a dark enclosure, then check for ANY blockage with a flashlight. You might have to remove the radiator to clean extremely compacted blockage.

//greg//

 

[Jinma284]

The first time that it blew was because I allowed the radiator fins to become totally blocked with weed seed and ran it in 100 degree temps. It did not get water in the oil. One spot on the gasket blew. The sleaves looked great, the head and the block were ok to visible inspection. The block was not pressure tested for cracks. We pulled the radiator and took it to a radiator shop for complete clean out and flush. The head bolts had never been retorqued since I purchased it in 02. We torqued the head and set the valve lash to book spec's supplied by a dealer. We have now sent the head to a machine shop. He put an edge on it today and said it is not warped. He will pressure test Monday. I knew the gasket was blown again because it used water the time I overheated it, was hard to crank the next morning and blew a lot of water out of the exhaust, which had been covered with a bucket over night. If the head is not cracked we plan to replace the head gasket again and replace the thermostat. I will certainly watch it close. If that dosen't fix, then we check furthur. With the latest info do you think I am headed in the right direction or is there something else we should do while we have it apart?

 

[RobJ]

if you don't have the head milled and the block decked, I like to take a file and/or a random orbitor sander and clean up the surfaces. You don't have to hit it much. it may expose good news or bad news.

Rob

 

[greg_g]

The first head gasket probably went because the 50 hour head bolt retorquing never happened. But that horse is already out of the barn. When you install a subsequent head gasket, the 50 hour clock starts again.

The second one could have gone for any number of reasons. Just out of curiosity, did you succumb to the popular misconception about oiling the head bolt threads? what tightening pattern did you follow? and how much torque did you apply?

//greg//

 

[RobJ]

The first head gasket probably went because the 50 hour head bolt retorquing never happened. But that horse is already out of the barn. When you install a subsequent head gasket, the 50 hour clock starts again.

//greg//

Greg,

Where are you getting this 50 hour number? My service manual says 30 minutes. No where in the shop manual or owners manual does it say 50 hours. Kubota doesn't even recommend adjusting the valves until 600 hours, then every 850 after that.

I've never gone back and tighten the head bolts on anything. Even my L when I changed out the head gasket. If it's overheating in less than a minute...I think something is wrong in that head.

Rob

 

[greg_g]

Greg, Where are you getting this 50 hour number?

Not from your Kubota manual, that's for sure. Odd are extremely high that the OP's Jinma has the YangDong Y385 engine. I took the 50 hour head bolt retorquing requirement straight out of the YangDong Y85 Operations & Maintenance manual.

The Y85 family of engines will overheat after a head gasket change IF you don't make provisions to bleed the air while refilling the cooling system. The easiest way to bleed is to loosen the temperature sending unit while pouring in the anti-freeze and water. Which reminds me, this is a wet sleeved engine. SCA (anti-cavitation) coolant should be used to reduce water pump wear and prevent premature performation of the cylinder liners. Not that I am endorsing any particular brand, but Final Charge 50/50 is available in most WalMart auto departments at ~$10/gal.

//greg//

 

[RobJ]

Interesting, as a former mechanic I had a tough time digesting the 30 minute rule on my L. Does Kubota really assemble an engine, run it for 30 minutes, then take it apart to tighten the head bolts? And I guess this is while warm??? My manual isn't specific on that that issue. Just says run for 30 minutes then re torque. MY assumptionis while hot.

I also learned about bleeding the coolant on my kids 3.8l mustangs because the engine parts are higher than the radaitor.

Rob

 

[Jinma284]

Rob, the machine shop in our town said he could not mill the head because of the stainless steel inserts. His machine would not cut them. We will follow your advise before installing.
Greg, we did not oil the bolts before tighting. We had a tighting pattern given to us by a dealor and used the proper tool to tighten. I do not remember the pattern off the top of my head. We will redo the tighten deal after 50 hours. I only had about 20 hours this time.

 

[greg_g]

MY assumptionis while hot.

Thanks for mentioning that, I forgot to specify in my earlier post. The Y85 manual says to do headbolts and valve lash on a cold engine

//greg//

 

[greg_g]

We had a tighting pattern given to us by a dealor and used the proper tool to tighten. I do not remember the pattern off the top of my head. We will redo the tighten deal after 50 hours. I only had about 20 hours this time.

I just hope "the proper tool" was a torque wrench. If you want the headbolt tightening sequence, torque spec, and valve lash specs, let me know.

Oh, and I mentioned valve lash because - every time you remove the valve train - you should at least verify the gaps haven't changed. That includes the decompression screws.

//greg//

 

[Dave_Lilly]

You have a problem of coolant leaking into one or more cylinders. Coolant leaking into one or more cylinders will blow a head gasket because water is not compressible and has nowhere to go except out through the head gasket.
Did you notice white smoke coming out of the exhaust pipe?
Both the engine block and the cylinder head should be checked for warpage before replacing the head gasket, along with checking the cylinder sleeves, head and block, etc using magnaflux.
Extreme overheating can warp both the cylinder head and the engine block.

 

[greg_g]

Coolant leaking into one or more cylinders will blow a head gasket because water is not compressible and has nowhere to go except out through the head gasket.

Not entirely true. Yes, water is essentially not compressible. But but opened valves permit water to be pushed out.

Did you notice white smoke coming out of the exhaust pipe?

If white smoke comes out of a cold muffler for more than a few seconds, that pretty much confirms that some form of water is coming out the exhaust valves. This can also be accompanied by thin (watery) grey oil. It can run down the side of the block, leak out of the exhaust manifold, or - under advanced throttle - spray out of the muffler.

That said, I agree that it's extremely important to clean the milled edges completely, followed by a very thorough visual inspection for damage. A trued metal straight-edge should be used to check both head and block faces for warpage. A crack doesn't always look like a crack. Any suspected areas or unexplained blemishes are candidates for MagnaFluxing.

But I'm not yet convinced that this is a head/block issue. Being a wet-sleeved engine, a hole in a cylinder lining would almost certainly permit coolant into the oil pan. So far, the OP says that's not happening. For now, I'm still thinking the issue is procedural.[/quote]

//greg//