Komatsu D65e-6 overheat

[jasonharville]

I've been having some issues with my D65e-6 gradually overheating after about 2 hours of use. I have started troubleshooting based on engine/dozer service manuals but hoping to get some additional advice here. Here are the areas I've been focusing on:

• Low Fluids - I have been carefully watching coolant/fluid levels...hasn't been a factor.
• Stalling Torque Converter Excessively - I'm new to dozer operation and I realized I may have been stalling the torque converter too often when hitting large stumps. I think I have ruled this cause out as last time it overheated I was being "gentle" on her.
• Slipping Fan Belt - Belt appears to be properly tensioned and haven't noticed any lack of air flow.
• Dirty/Clogged Radiator - I noticed an inability to see through the radiator so I started pressure washing it yesterday. An hour later I was still getting muddy water from it but I think I finally got it clean.
• Failed Thermostat - Ordered a new thermostat as the housing doesn't look to have been touched in a long while.

I'm hoping the heavily clogged radiator is my main issue, but any other areas I should be checking?

One other thing I'll mention. When the machine hits the 200 mark, it will often stop running before I have the chance to let it cool down. It seems to be fuel supply related as it slowly dies then if I try to crank it a few minutes later it will start to fire for a few seconds and then nothing. Wait 30 minutes and it fires right up. My theory is that once the temp hits a certain mark the fuel lines running through the heads are getting vapor locked or something. This is a Cummins N855. Does this sound like a good theory on the engine dying?

 

[Junkyard]

Is the belly pan clean? Nothin packed underneath the motor all around the oil pan? 200 really isn't stupid hot. 215-220 is where I would get nervous. Assuming the gauge is accurate anyway. If you have your trusty infrared thermometer I'd take some temps when it gets to acting funny. Upper and lower hoses, tanks on radiator, heads, block, oil cooler, fuel tank, fuel filters, fuel lines etc. See what it's really doing temp wise and we might be able to narrow it down. Sometimes a seemingly unrelated issue can be the root cause. Any intake leaks? If she's running rich or lean it'll run the temp up. Several things it could be, I bet the others will chime in too.....

Junkyard

 

[Delmer]

Yeah, 200 over two hours is no problem if it's full of coolant. It sure sounds like you made it better with the radiator cleaning, even if it isn't spotless. I'd leave the new thermostat on the shelf until or unless you confirm the old one isn't opening properly by the temperatures of the hoses when it's as hot as you get it.

I can't help you with the fuel starvation if that's what you think it is. No smoke or noise when it's dying, right? Maybe a weak coil in the fuel system?

 

[John C.]

Have you drained any crud out of the bottom of the fuel tank? There is a butterfly valve on the bottom of the tank you can access from the back of the machine. Most time people don't know about the valve and the pipe plugs up with crud. I've had to drive a welding rod up the pipe to get it to drain at times. As I recall there was a fuel strainer in those machines towards the back of the engine. Trace the fuel lines back from the fuel pump and see what you can see. I seem to recall it was a small canister with a screw on cap on top. Take off the cap and there was a wire basket underneath.

Clogged radiator was the usual problem with overheating those machines. You should watch the torque convertor temperature gauge and the engine coolant gauge at the same time. What you want to know is if the engine coolant temperature is driving up the torque converter temp or vice versa. Two hours is about what it take to heat up all that transmission fluid from first start. Engine coolant temp should warm up pretty quickly to a normal run temp.

 

[Scrub Puller]

Yair . . .

John C. Mentions the outlet valve plugging . . . the fuel runs by gravity down to the float tank and is lifted from there by the pump.

If the tractor is working hard the float tank could be depleted and, if the gravity flow from tank is reduced by gunk and blockage and (say) low fuel in tank in theory the engine could starve for fuel. but would run fine if the fuel was given time to trickle down and replenish the float tank . . . if that makes sense at all.

In heavy dust I found I had to hose out radiators once a week at least . . . as mentioned by Junkyard I too always placed importance in maintaining airflow around the sump.

Cheers.

 

[jughead]

i have an old D75-S3 if i can turn the fan blade without the engine turning it will run hot on a 90 degree day

 

[JS300]

If I skip cleaning the radiator on the old Case for more than 2 days in the hot summer the operator will call me out on it. Says he notices a slight increase in engine temps. Hopefully the radiator was just dirty.

 

[jasonharville]

Thanks for all the suggestions! I'll attempt to answer all the questions:
*Belly pans are spotless as of 3 weeks ago(they were HORRID before that). Overheating has occurred since cleaning the pans.
*Fuel Delivery. I hadn't investigated that but theorized that it wasn't a problem given that it only seems to coincide with temps at 200+, but I'll check.
*Dying details. It acts just like if you turn the switch off....slow idle down...no smoke or abnormal noises. 5 minutes later if you attempt to start you get a bit of black smoke and it wants to start but seems to only have enough fuel to fire a few times.
*Finding the heat. Torque converter gauge is apparently not functional. Bought a new one to install last night. I have been suspicious of the trans b/c the first and worst time this occurred I could feel a fair amount of heat escaping from around the seat. I shot the trans pump and top of torque converter last time it threatened to hit 200 and it was definitely the hottest thing on the machine @ around 210. Top of engine and water manifold was 185ish, but it had been sitting for a few minutes. One other clue is that the aux hydraulic tank also got pretty hot on the first occurrence. I didn't have the temp gauge at the time but it got hot enough that it was causing pressure and hyd fluid bubbles where the two sides of the tank bolt together. If this happens again, I'll get better readings.

This poor machine has clearly been neglected so I'm gradually getting maintenance caught up. Trans/steering filters should be delivered today. I pulled the trans filter and it looked dirty to my untrained eye(pleats were almost black...assuming they are white when new). It also looked like the bypass valve at top had been activating as there were slight score marks on the metal from apparent motion.

My dad was telling me that he's seen some equipment have a mechanism to shut off coolant flow to trans oil coolers for winter operation. Is there a provision for that on the d65? I can't seem to find any sign of one.

 

[jasonharville]

Here's a quick vid showing how horrible the engine pan was. This was after 15 minutes of shoveling. The trans pan was about the same.

 

[d9gdon]

It could have a Murphy temperature safety switch installed that is killing it at 200+ degrees.

Overfueling will cause one to heat up as well. Look for excessive smoke.

More than likely, the radiator tubes are plugged inside with scale.

 

[Delmer]

Given the history of neglect, a cooling system flush and new coolant is a good idea whether it's overheating or not.

The failure to maintain the belly pans and blow out the radiator will overheat quickly. Neglecting the coolant (as long as it hasn't had swamp water added) will slowly rust out the engine, not good, but not as IMMEDIATELY dangerous to operation. Drain the old coolant after it's been running a while so all the junk is stirred up, drain into a clean white bucket so you can see how what settles out. Backflush the radiator by removing the hoses and cap, filling with a running garden hose in the top tank and blowing it out with an air nozzle and rag stuffed into the bottom tank. Take a look into the top tank before and after, the top of the tubes is where the deposits collect for some reason. Then fill it with rainwater and run it till hot, drain into the white bucket again, and repeat until comfortable.

 

[DMiller]

My Allis has a heat up issue when working hard, radiator is limed pretty heavily where when I get healed up I have a spare to swap to get this one tanked and cleaned. Other repairs while in there but still awaiting heal up from back/neck work.

 

[JS300]

Does it have a thermostat for the torque converter? If so it could be bad. I would bet cleaning the radiator helps though.
I've thought about adding a Murphy box to the dozer. A good piece of mind but also one more thing to give trouble.

 

[jasonharville]

Does it have a thermostat for the torque converter? If so it could be bad. I would bet cleaning the radiator helps though.
I've thought about adding a Murphy box to the dozer. A good piece of mind but also one more thing to give trouble.

It has a converter thermostat but it was broken. I have the replacement ready to install. I looked at the lines from pt pump to the heads and there are no electronic valves so unless it is further up stream i dont think i have the murphy setup.

 

[Scrub Puller]

xxxxx

 

[jasonharville]

Weekend update. I ran the dozer for 2 hours this morning after installing the torque converter temp gauge. The main temp gauge looked great the entire time, never getting about 180. The TC temp, however, steadily climbed to about 190 in the first hour and then fluctuated between 200 and 230 the second hour. Any time it got above 210 I would basically park the dozer and leave it at high idle and the TC temp would come down a few degrees per minute. I took IR readings at various points on the trans, trans filter, trans pumps and lines and they were all between 200 and 210, which matched the new gauge reading at the time. The oil cooler casing matched the temp at the thermostat(175), which I guess is not a surprise. The pipes going into the cooler that I believe to be the trans cooling pipes were strangely cool...around 130.

I started researching the cooling circuit for the TC to figure out how it works. I see that the oil has to bypass a regulator valve at about 50 psi to get to the oil cooler. I cracked open the outlet pipe and put something under the opening to see how much oil volume is passing. The flow was very low, probably well under 1 gpm. I'm assuming the flow would need to be much higher than that to cool enough oil to make a difference. So I figure the regulator valve is the most likely restriction point and I'm in the process of trying to investigate it. I'm having some trouble removing the top cap screw to inspect the valve but I'll take another stab at it tomorrow.

If you guys have any additional advice based on the new findings I'm all ears!

-Jason

 

[jasonharville]

The regulator valve appeared to be in good working order with no trash or obstructions to flow, although I can't be sure that the spool was within tolerances. I've gotten together some pressure gauges and I'm planning on checking readings this week to see if I can identify the problem.

Its actually probably a good thing that the water temp was spiking and causing me to stop working before or I might have cooked the transmission with not having a working gauge on the TC.

 

[Delmer]

Do you have "ranges" on the oil temp gauge? because the hot range for oil is higher than for coolant, coolant can't boil or you get hot spots, the boiling point of oil is much higher, hot is more relative.

The cool trans cooling pipes does seem wrong.

 

[jasonharville]

No its just a standard temp gauge. Service manual says operating temp on trans is like 170-190 degrees, so 210-220 starts making me nervous. I think i may have been reading the steering lines going into cooler. I checked the pipes from TC at a point before they disappear under engine and the hot line matched my TC temp gauge(200 at the time) and the return line was around 160. So cooler seems to be working but I am pretty sure the flow is too low.

 

[Delmer]

Yes, that makes sense. If the oil cooler is cooled by engine coolant at 160, then yes, the flow is way too low.

On the other hand if the coolant going through the filter is much cooler than the returning oil, then it would seem to be performing as designed. I don't have any knowledge specific to Komatsu to tell you how that circuit works. Some Deeres have a relief valve that allows fluid to BYPASS the cooler at a certain pressure, such as when the fluid is cold and stiff. I'd figure out the whole cooler system from the service manual to see what's supposed to go on, vs what is going on.