Engine overheat??? Rtv1140cpx

[Phil P]

Hello all

We have a Kubota RTV1140CPX S/N 18847 with the Kubota D1105-BJ engine.

We purchased this unit used.

I didn’t appear to have been abused and had 840 hrs on it.

We noted from the start that under load after about 45 min of operation the engine temp was approaching 235 by the electric gage.

I installed a direct reading gage that didn’t need electric. It reads the same.

We then had a genus use the machine and even after informing him that running in high brush causes the screen on the radiator to fill with debris and he had to stop and remove the cover and clean the screen. Well genus was too important to do a menial task.

So now I have replaced the cylinder head and all 3 pistons. All machine work performed by a very qualified machine shop. Connecting rods were twist and bend check etc.

I washed and back flushed the radiator.

I installed the radiator, a new thermostat and service the cooling system with 50/50 coolant.

I pre-oiled the engine using a suitable electric pump.

I bled the injection system while the electric pump was pumping oil and the glow plugs disconnected.

I connected the glow plugs and stated the engine with oil pressure on before cranking.

The engine started and ran like a Swiss watch.

I ran the engine at varying speeds in the shop until the cooling fan came on at about 180. The system cooled down and the fan shut off in short order.

Now my problem is the temp after about 45 min of running at 20 MPH gets up to very close to 230.

Removing the thermostat doesn’t change anything except the idle temperature. It only gets to about 140 after 30 to 45 min of idle time. The temp after running under load stayed the same about 230 when I stopped and let it idle after about a 10 min idle time the temp was down to 210.

My question is this normal and what is the max temp allowed for this engine installation?

Thanks in advance.

Phil P

 

[85Hokie]

I'll tell you this, diesels are inherently a cooler running engine - ever seen your local school buses or 18 wheelers have covers across the radiators? Diesel engines in cold weather that are running 60 mph down the road never get up to operating temps!!!

Yours is running hot!

You never mentioned your WATER pump......could that be the cause? OR the belt driving the pump?

Here is another example - we have a 7' reel mower that the AD uses to cut the football field - in the summer after about 30 minutes gets very hot - like hitting red!

Found out that the belt broke off along time ago .....and was running without circulation for a whole summer!!!!

I have an accurate meter on one of my B7100's - once warm it is at 175-180, If I cut grass for 30 mins or more - it hits 210 and stays.......if it ever gets hotter than that - I know to clean the front end.

One could say a head gasket - but you replaced all that - and typically a head gasket will heat it up quick.

Check the water pump ...and belt tension first.

 

[Bulldog]

Might pay you to flush the entire system with radiator flush. Could be the block itself is partially plugged up.

Obviously it has something wrong with the cooling system but you might also consider changing over to Amsoil 5w30 HDD https://www.amsoil.com/shop/by-prod...ynthetic-heavy-duty-diesel-oil/?code=HDDQT-EA.

When I first got my L3000 it would run hotter than I liked in the summer. I changed it to Amsoil and have never had another issue.

 

[Phil P]

I'll tell you this, diesels are inherently a cooler running engine - ever seen your local school buses or 18 wheelers have covers across the radiators? Diesel engines in cold weather that are running 60 mph down the road never get up to operating temps!!!

Yours is running hot!

You never mentioned your WATER pump......could that be the cause? OR the belt driving the pump?

Here is another example - we have a 7' reel mower that the AD uses to cut the football field - in the summer after about 30 minutes gets very hot - like hitting red!

Found out that the belt broke off along time ago .....and was running without circulation for a whole summer!!!!

I have an accurate meter on one of my B7100's - once warm it is at 175-180, If I cut grass for 30 mins or more - it hits 210 and stays.......if it ever gets hotter than that - I know to clean the front end.

One could say a head gasket - but you replaced all that - and typically a head gasket will heat it up quick.

Check the water pump ...and belt tension first.

Hi

I installed new belt during the repair, the system has been flushed, the radiator shows the same inlet tem as the gage and has a 40 degree drop at the out let there are no coolant leaks and no hot spots on the engine.

I am using a laser temperature probe and have check its accuracy with other units like my Duramax and fin it to be very close to correct.

As for the 18 wheeler their radiator is much bigger than this radiator and the cover over the radiator is not to keep the temperature up in the engine but to keep the temperature up in the radiator so the cab heater works. The engine in an 18 wheeler has a thermostat that closes and recalculates the coolant in the block.

I have decided to see if there is a radiator available with more tubes and a thicker core.

Phil P

 

[Phil P]

Hi

Here is a picture of a thermostat for a Cat C160.

Note the triangle port to your left. This is the recirculation port.

The thermostat is in the cold position. The coolant flows from the round hole in the bottom of the housing thru the recirculation port until the temperature reaches the proper temperature. Then that outer sleeve moves down until it seats on the round hole and the coolant flows thru the center of the thermostat to the radiator.

In extreme cold weather the thermostat may not move at all.

Phil P

 

[Phil P]

Hi

Now back to my original question.

My Duramax operates at 210 degrees most of the time and 180 degrees in cold outside air temporaries.

What is the normal operating temperature under load for this engine installed in this RTV?

Phil P

PS That triangular port is on your right. Sorry about that.

 

[85Hokie]

Phil,

If you understand the diesel large engines and radiators......then this ought to be a little simpler?

And this GENIUS you mentioned..........

So basically what you are saying is ........an OLD engine ran hot....and NOW a "new" engine is running the same hotness as the old???

WHY was the head replaced? Crack in it? And the pistons - you replaced them, I hope with all new rings, was the cylinder walls honed - over bored over?

"gaUge and has a 40 degree drop at the outlet"

I do NOT believe this is a good number!!!

I think it needs to be a bit higher drop off, ---- IF you are running 230 and it is dropping to 190......that aint a good thing. Now if you had 200 dropping to 160....THAT might be ok, on my B7100 engine, I get anywhere from 60-70 drop off, now that HAS no water pump

And removing a thermostat will tell you nothing other than improving flow, WHICH is why it should never remove it!!! Fast flow over a hot surface DOES not cool as well...........

The radiator was backflushed........what came out? What did you backflush WITH? Water?

Bulldog and me are both telling you there is a problem with the cooling system.......unless there is a blockage IN the block/head........this is where YOU need to focus on - the radiator and or water pump

AND to answer you last question....... "What is the normal operating temperature under load for this engine installed in this RTV?"

I have no idea........but I will tell you that typical diesels and gas engines should be NO less than 180 and really no higher than 220 (depending on cap)

Take the radiator OUT - take it to a radiator shop, have them to look at it. AND report back as to what you find out.

 

[Phil P]

85Hokie

If you read my first post you should know what caused the overheat the first time.

The machine is used in farm fields and cow pastures. The normal foliage includes plants that have a fuzzy ball or cylinder on them similar to a cattail. I had informed the genius of this and instructed him on how to clean the screen when the temperature got above 225.

The 8 year college graduate that was doing his internship decided that the machine should have an electronic shut down to keep it from being damaged by overheating and just deliberately ran the machine until it quit waited for it to cool down and started it again and ran it till it quit. This apparently went on for 5 or 6 cycles.

The reason for the first event was very clear. When I took the cover of the screen and radiator were completely blocked where no air could have gotten thru.


When I pulled the engine down there wasn’t any coolant in the system except for just a little that rand out of the bottom of the radiator and lower hose.

The center cylinder piston had swelled up and was hard to get out the other 2 came out normally.

The cylinders did not have a ridge at the top and a dial indictor showed no taper and the cylinders are round.

The center cylinder had some very light scratches up and down and both the machinist and I decided there was not a reason to bore the cylinder or cylinders.

The machinist has been in this business about 20 years less than me. He has bored a number of these engines and rebuilt them after an event similar to this one. He agreed with me that there is very little prospect that the cylinder block is damaged.

I bored my first gas engine cylinder in 1959.

I have worked on the Nordberg 6 cylinder diesel used in the flood control 3 tiers of scaffolding to get from the bottom to the top, as well as the Nordberg diesel radial that is about 12 feet across. The FM OP’s and grew up in a Wisconsin air-cooled industrial engine shop.

There is no need to go thru the turbine engine experience as that is not at all applicable here.

Now the V8 Isuzu diesel that is very similar to the Duramax except it wasn’t turbo charged and use in some small cranes normally ran at 240 degrees and I had to confirm that with Isuzu because I consider that too high. They said this was high normal and not to worry about it. It was the same for all of the little cranes a stone company had in Broward county Florida.

So now maybe you will understand I am just trying to find out what is normal for this machine before I spend a lot of bucks replacing radiators and water pumps.

So as you seem to have had these things apart before tell me about the water pump. Does it have a plastic impeller that would have been damaged by the overheat? The pump is not leaking, I am not getting gases in the cooling system and I am not loosing coolant.

As for the radiator there are no repair shops left the EPA has closed them all in Florida except for 2. I have sent this radiator to the one closest to me and they sent it back saying it was good. Now I did not specify what they were to do to it.

I agree that 40 degrees is lacking but indicates to me that the radiator is working however if it wasn’t designed to handle 235 degree heat there may not be anything wrong with it.

The thermostat supplied by the dealer is a 180 degree thermostat and sitting in the shop the unit will warm-up to 185 on the gage and then the fan come on and it cools down to just under 180 and the fan shuts off and it starts all over again with what I consider a reasonable time between fan runs.

So if you all are running the RTV1140CPX with this sideways radiator and are not experiencing temperatures above 180 to 190 degrees then I have a problem.

One other thing that can cause this I don’t get the 235 degree heat until I run about 4 miles flat out with the throttle to the floor.

I need to get a tachometer on this machine and make sure it is topping out at maximum RPM. The diesel injection system like this one with the governor in the injection pump when the RPM is set appreciably below the max RPM and you call for full power the injection pump will increase fuel and the governor will not allow the increase in RPM. This can cause over heating do to being in the wrong place on the torque curve.

The information I have is the top RPM is 3,000 is this correct?

Phil P

PS I forgot the cylinders where cleaned up with a dingle berry hone. Then checked with a dial indicator after that.

 

[Bulldog]

One thing that has always bothered me about Kubota is they don't leave any margin for error when it comes to cooling. As soon as it gets a little dirty they run hot. Maybe not over heat but runs hotter than it should.

Changing oil eliminated my issues. What's your thoughts on synthetic lubricants?

 

[Russell King]

Do you know for sure the outside of the radiator is clean? I assume that the shop checked it to but I know on my tractor the fins in the radiator get plugged up even though there is a screen in front of it. I have started putting an AC filter in front of the screen to help keep it cleaner.

Use a light to see if it looks clean if you can


Sent from my iPad using Tapatalk

 

[100 td]

It appears that you fan is cycling correctly, ensure the fan shroud is correctly installed. It's worth checking your thermostat is opening FULLY at the correct temperature, slowly heat some water in a pan and check the temp accurately and watch the thermostat open fully at the correct temp, not over temp. I would be also remove the water pump to check it fully, and the radiator hoses.

 

[Phil P]

Bulldog

I have had the radiator out and inspected and cleaned the outside remember the overheat that cracked the head in several places was caused by the radiator fins being plug.

I have added a second fan on the outside of the radiator to increase the air flow.

Russell King

See above about cleaning the radiator.

If you are operating this model RTV1140CPX what is you coolant temperature under load?

100 td

There is no fan shroud on this unit. I have replaced the thermostat I have also run the unit without the thermostat with no change in temperature. Remember the 225 to 235 temperatures are after a 4 mile run with the throttle full open. Then a 10 min rest with the engine idling results in a 210 temperature.

I am not a fan of removing the thermostat on a diesel diesels require 180 or above to get a complete fuel burn and running them cold results in excessive wear in the piston rings and cylinders.

As 85Hokie said you can increase your heat problems by removing the thermostat on some engines I know from experience that the Ford flat head 6 cylinder produce in the early 50’s will over heat if you remove the thermostat. It appears this engine doesn’t have that problem but that may also be the result of the size of the water outlet in the thermostat housing which is a good bit smaller than the inlet at the radiator.

I still need to know what the other units the same model as this one are running for temperatures under load.

I thank all of you for your help and I will keep you all advised when I find the problem.

Phil P

 

[sheepfarmer]

Phil, it would seem that no one has logged in that has the specific normal temperature data that you need. One other source of information is the technical services of Kubota. If you are persistant with the email help line on their main website you should be able to get the information you need. Do you already have the shop manual? If the first email attempt results in no answer in a day or so, resend. If the answer is incomplete or doesnt make sense, ask to have the question forwarded to a supervisor or the engineering department. I have gotten good technical information that way, but it required persistance. Finally maybe a local Kubota tech might help you out through his/her contacts with regional service reps.

Good luck and thanks for adding your expertise to the forum.

 

[Phil P]

Hi sheepfarmer

Yes it has become apparent that no one here has or operates this model RTV.

However I have contacted a very large Kubota dealer about 100 miles away and their service department ran the S/N and found out this is one of the machines with the radiator mounted on the driver side of the machine under the back seat.

They did verify there is a design problem with the machine and they all had this problem if they were used in the type of application we are using it in.

They are checking to see if this one is eligible for a kit to relocate the radiator.

I will keep you all posted on my progress.

Phil P

 

[lugbolt]

Look at your radiator, and filler neck.

The pressure cap has to seal in two places. Against the top of the neck, then down in the radiator neck itself there is a step.

It is not uncommon (very common actually) for the radiator and filler neck to become deformed. The cap won't seal. The system won't build pressure. Then coolant can boil, and more importantly, the water pump works more efficiently if the system is under pressure. Thus, a deformed filler neck can cause overheating. Also, I either overlooked or didn't comprehend, but was the thermostat replaced? An overheated Kubota can damage the thermostat; have had to replace tons of them over the years for this reason alone.

On the filler neck and radiator. Normally you can see the deformation from the top, and a lot of times there will be a white colored almost kind of a gel inside.

Also, did you use tap water/antifreeze or distilled/antifreeze? Tap water will boil quicker than distilled water will.....and tap water can (will) leave deposits behind when it does boil.

Just a couple random thoughts, just did one of these, and the filler neck, thermostat, and radiator R&R fixed it.

 

[Phil P]

Look at your radiator, and filler neck.

The pressure cap has to seal in two places. Against the top of the neck, then down in the radiator neck itself there is a step.

It is not uncommon (very common actually) for the radiator and filler neck to become deformed. The cap won't seal. The system won't build pressure. Then coolant can boil, and more importantly, the water pump works more efficiently if the system is under pressure. Thus, a deformed filler neck can cause overheating. Also, I either overlooked or didn't comprehend, but was the thermostat replaced? An overheated Kubota can damage the thermostat; have had to replace tons of them over the years for this reason alone.

On the filler neck and radiator. Normally you can see the deformation from the top, and a lot of times there will be a white colored almost kind of a gel inside.

Also, did you use tap water/antifreeze or distilled/antifreeze? Tap water will boil quicker than distilled water will.....and tap water can (will) leave deposits behind when it does boil.

Just a couple random thoughts, just did one of these, and the filler neck, thermostat, and radiator R&R fixed it.

Hi

All of this has been complied with the system is holding pressure after a good warm up I cracked the filler not the radiator cap they are in different locations. I had to replace the filler pipe / cap assembly and the reservoir cap.

If you haven't worked on the RTV1140CPX with the radiator under the drivers side back seat then here is a picture of the reservoir and filler cap piping that is located inside the engine compartment.

According to the dealer I spoke to Monday the temperatures I have are normal for this configuration.

For some serial number groups Kubota has made a radiator relocation kit.

I am waiting for them to call me back about that.

As for the antifreeze I purchase a common brand of 50/50 antifreeze and I don't see any where on the bottle anything about the quality of water.

Thanks again for all of your help.

Phil P

 

[Phil P]

Hi

I have a little more information.

With the second fan installed and wired to the ignition switch so it runs all the time the switch is on. And a 4 mile run full throttle I now get a steady 215 degrees.

Something else I tried was making the same run with the shift selector in the “M” position. This resulted in a 190 to 195 degree steady temperature but only 15MPH.

I have checked the radiator fins with a light again and they are clear. I also checked injection timing and engine RPM under full throttle both are within specs.

Now I have a much bigger all fuel engine to work on for the next week so probably won’t have any further information for some time.

Phil P

 

[martin family]

I'm going to spare engineering talk and straight solving your problem.
I purchased l2900 new, and 2012 rtv1140 cpx crew cab. Nothing I did would solve problem of over heating, spent months searching, with no answers.
kubota under sizes radiators, poor engineering specs leaving no room for errors. This is how I resolved my tractor.
Derehl engine oil cooler kit, no fan, sandwich plate ran to filter. Boom simple fix. I can run bush hog all day in west Texas Heat, Temp stays at 180 tops.

RTV engineering is bad, they have cooler plates at hydraulics, then dumping them back into the engine. radiator and filter is small, and screen sits at angle where dust clogs it up after 30 min chocking it off.
I'm working on this fix at the moment,
engine oil cooler with dual fan, with manual switch. And I'm installing
second oil cooler for hydraulics.

I will report back after this is installed.

Good Luck
GM

 

[Phil P]

Hi

This will be my last post on this subject.

I have contacted Kubota several time and they finally told me not to call back they do not support their equipment except thru a dealer.

That was the last straw.

This unit was purchased with the idea that we could use off road diesel fuel at a savings over the gasoline we use in the 15 Hondas we have.

The upper management has now sent a memo to all management personnel not to consider purchasing any Kubota equipment regardless of what it is. They site Kubota’s refusal to supper this equipment as the reason.

Phil P

 

[lugbolt]

There's more to it.

I know......

Kubota themselves do not offer technical assistance directly to the public. Never have, well in ONE circumstance they have, but that was a one-time deal in the central division. For technical assistance, all correspondence is done between the dealer and Kubota's technical support center--that is ASSuming that the dealer can't figure the issue out on their own. The TSC is invaluable, however we (as dealer techs) try not to use it all that much because there's only a few guys in the TSC to support the entire United States' dealer network. I consider the TSC to be a second-to-last resort.

Here's where I see issues. There are MULTIPLE causes for overheating. You're looking at the major components but what about the other stuff? How about usage? How is it used? What I see commonly with RTV's is that they're used for tractors, and they are NOT tractors, they're utility vehicles. When I say they're used for tractors, I see people pulling discs, mowers, using them for log skidders, bulldozers, pushing airplanes, pulling trucks out of the mud, you know--tractor stuff. That kind of usage--high load, low-to medium RPM and in too high of a gear WILL get the engine hot.

Engineering. Kubota engineers them to run at operating temperature for "most" designed usage. Some folks use them differently. So why not put a larger radiator in it? It won't warm up, particularly in colder climates (Northern states/Canada/Alaska/etc). Keep in mind that since they're mass produced, they have to meet "most" applications demands. They simply can't build low temp units and hot climate units. That would be stupid from an engineering-and marketing-standpoint.

I've been around-and used plenty of them. So long as the radiator is clean externally, the block & head are clean (no scale), no cracks or anything to affect the cooling system pressure (head gasket, block or head crack, etc), and the water pump is actually working, they run fine and won't get overheated under most usages that they're designed for. Therein lies the problems with "them".

What I have seen some of are pump impellers loose on the pump shaft. Head gaskets leaking due to improperly machined, warped, or improperly CLEANED head and cylinder block surface. Belts loose. Wrong belts (too narrow, slips). block and or head coolant passages plugged (seen that quite a few times). Radiators plugged internally. And no you can't see it from the top, it's got to have the tanks removed and the core physically cleaned. Or better yet replace the darn thing, it's not that expensive. Fan broken in a couple of cases. Thermosensors and thermoswitches failing/failed (temp probe and fan switch respectively). Dirty/restricted air filter/intake system. Dirty/restricted muffler. Low oil level. Dirty trans coolers on the ones that have them. Remember the transmission has a heat exchanger, a sandwich type, that circulates coolant through it so if the trans oil is hot, it's going to heat the coolant too. "Bad" wiring. Fan circuit issues, dirty fuse blocks, dirty connections, etc. Warped/failed filler necks (VERY common...if it's been overheated ONCE, they warp/fail). A combination of one or more of the above.

Without laying my hands on it, there's no way to know what's actually wrong. But it sounds like you've (or your company) has given up.