Another overheating problem (long)

   / Another overheating problem (long) #1  

DaveNay

Platinum Member
Joined
Aug 13, 2003
Messages
811
Location
Waterman, DeKalb County, Illinois
Tractor
John Deere 855 MFWD; Oliver 1850 Gas
My JD855 has had an overheating problem since I bought it a year ago. I have read of several other people having similar problems with the x55 line, so I sort of chalked it up to a design issue, and I regularly kept topping of the radiator (first clue!). Well, this weekend it was worse. I started to mow, and after about 5 minutes noticed a different odor, and there seemed to be steam coming from the vent hose of the breather cap on the valve cover. I immediately stopped mowing, let it idle for a minute and shut it down to cool. Checked the radiator, and I couldn't see any coolant! I added about a pint and a half to top it off again, and started mowing again. I was able to mow for about 45 minutes when the temp light came on again. I let her cool down again, and added about another pint or more of coolant.

Time to investigate deeper /forums/images/graemlins/crazy.gif

My first diagnosis was possibly a blown head gasket, so I started it up with the pressure cap off on the radiator and let it warm up.....no back pressure from the cyliders in the radiator. Nothing was coming out the cap except the bit of splashing you would expect.

Next, I checked the thermostat. Take apart the thermostat housing, and what do you know? No thermostat! /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif I know that no thermostat will usually let an engine run cooler, but a thermostat is also a flow restricting device, so coolant may be passing through the engine too fast to work properly. /forums/images/graemlins/confused.gif

I put the thermostat housing back together, and checked all of the hoses and the water pump for leaks....no problems there.

So here I am:

<ul type="square"> [*]I am experiencing frequent overheating [*]I am consuming coolant when I overheat [*]I have no thermostat [*]I have a new thermostat on order [*]I have a new pressure cap on order [*]I am seeing white "smoke" from the breather drain hose [*]I do not believe there is any drainage from the cap overpressure hose [*]I do my best to keep the radiator clean, so there should be adequate air flow [/list]
Any insight that anyone can lend will be greatly appreciated. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Dave
 
   / Another overheating problem (long) #2  
I know absolutely nothing about your tractor, however overheating problems are nothing that I haven't dealt with in the past. A couple of question immediately come to mind and some of them have already been answered, so I will pose those that haven't. Is this a new tractor or is it used? If it is used, what do you know about its service history? One thing to look for is a slipping fan belt or a defective water pump. The one thing that I don't like the sound of is the white smoke from the breather tube. This indicates a water vapor problem. You can't tell a blown head gasket by looking into the radiator. That is just an old wives tale for the most part. Sure if it is blown out completely, then you will get compression into the coolant, but you will also displace the coolant almost instantly. The best test for a blown head gasket is to do a compression test. Also look for water in the crankcase. If you are lucky, it will be a bad water pump. If you are not, then it will be the head gasket. It could be a cracked head and or block. Sure, I am giving you the worse case scenarios, but you asked and I have to be honest. Someone removed the thermostat thinking that it was the problem. You should never remove the thermostat because it will allow the engine to operate too cool and that isn't good either. You didn't say if this is a diesel or gasoline engine, so some of the diagnosis will differ in technique. If it were my tractor, I would pull the head and give it a complete examination. A blown head gasket can put coolant into the combustion chamber and the water will be expelled as steam. The Ethel glycol (anti freeze) will remain in the cylinders and gum up the cylinder walls. Not a pretty sight and a difficult one to deal with unless you do a complete tear down. Sorry to be the harbinger of bad news, but overheating problems usually mean engine problems unless it is a blown hose or radiator. In fact, most engine problems of this nature are the result of a blown hose or radiator and the engine overheating. If you can borrow a radiator pressure tester, and pump up the cooling system with air, you will see if it is holding the pressure or loosing it. If it is loosing the pressure, then go looking for the location of the leak. It might be a bad hose clamp or pin hole in the radiator. The problem that I continue to see is the breather vapors. The more that I think about this, the more I lean toward a block problem. Just don't know for sure unless I was there in a hands on situation.... /forums/images/graemlins/frown.gif
 
   / Another overheating problem (long) #3  
Surely, you forgot to tell about flushing your radiator/cooling system. /forums/images/graemlins/wink.gif
 
   / Another overheating problem (long) #4  
If you dont have immediate access to a compression tester, the first place I would look would be the crankcase oil. You are describing the loss of a significant amount of water/antifreeze, and your crankcase is relatively small. If you are losing it through the head or block there should be too much oil, and it should look a bit creamy. This would of course be bad news, but would isolate your problem. I had an old kubota with a pin hole leak that would lose more coolant than you would think - but I found the leak through careful (and boring) observation of the engine running in the garage. But it would take weeks of running to go dry, not 45 minutes. You are losing a lot of fluid somewhere - gotta find it /forums/images/graemlins/confused.gif
 
   / Another overheating problem (long)
  • Thread Starter
#5  
Hi Steve,

I did check the oil on the dipstick and it looks ok to me. Level is good, and it is nice and "oil" colored. I have not drained the oil to look at it, but when I did an oil change about 5 weeks ago, I saw nothing unusual at that time.

Dave
 
   / Another overheating problem (long)
  • Thread Starter
#6  
Hi Junkman,

The engine is a three cylinder diesel. The tractor is used, and I do not have any good information about it's history. It was owned by a public park district, so there was no single person to take "ownership" of the equipment. /forums/images/graemlins/frown.gif By compression test, are you saying a radiator compression test or a cylinder compression test? I believe you mean radiator compression, 'cause I sure don't know how to do a compression test on a diesel (what spark plug do you remove to screw in the guage? /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif) When I was running the engine with the pressure cap off, I could see plenty of flow from the hot water return line, os I believe the pump is good. Tension on the belt is good....about 1/4 - 1/2 inch of give when I push on it. You mention that one of the unlucky scenarios is a bad head gasket.....I will take that a extremely lucky compared to a cracked block or head /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif Pulling the head off is one of the choices a little farther down the list, but not too far anymore.

Thanks,
Dave
 
   / Another overheating problem (long)
  • Thread Starter
#7  
Hi Norm,

I have not done a complete coolant drain and flush. Can you tell me why this might be usefull? I have not considered it, because I am looking more at a case of loosing coolant as opposed to ineffective coolant. But I am not ruling it out if you say it can help diagnose the problem. /forums/images/graemlins/grin.gif

Dave
 
   / Another overheating problem (long) #8  
Hi Dave,

If you have water in the crankcase, it will be in the bottom of the oil pan, and may not show up on the dipstick. You might loosen the drain plug and drain out a little of the "oil" into a clear glass jar. Then tighten the drain plug back up, and wait a few minutes for the liquid to settle out. If you have a band of different colored (pale greenish - tan to clearish) liquid in the bottom of the glass, you have water in the crankcase. Depending on how much you drain, it may be all water. Oil is lighter than water, and will float on the surface of water. From the description so far, I think if you have a blown head gasket you can be thankful that's it's not more serious.

<font color="green"> GOOD LUCK </font> /forums/images/graemlins/smile.gif
 
   / Another overheating problem (long) #9  
Diesel engines require specialized equipment for doing compression tests. I don't have any experience working on diesels, however, the general characteristics of gas and diesel engines are similar. The diesel operates with a higher compression than a comparable gas engine. Check the exhaust for condensation also. If you are not familiar with diesel engine design, they I would suggest that you let this be done by an experience diesel mechanic. If you damage any part of the injection system, it gets expensive quickly. The injector pump is timed to the engine and it is a delicate and difficult job to do if you are not experienced. Sorry, but I can't be of much assistance beyond what I have already said. I don't do diesel engine work beyond oil changes.... /forums/images/graemlins/frown.gif
 
   / Another overheating problem (long) #10  
</font><font color="blue" class="small">( Next, I checked the thermostat. Take apart the thermostat housing, and what do you know? No thermostat! )</font>

That right there tells me the previous owner had a cooling problem also.
 
 
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