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roketenginer 04-24-2021 08:12 PM

Onan 10HDKCA Overheating
 
Hey everyone.


So I have a few questions regarding my Onan generator.
The unit is a Onan (Kubota engine) 10HDKCA.

I have had this thing running on and off. Sometimes it will run 4 hrs no issues...other times it will run 15 minutes and throw a 3-6 code.

I've went through and verified the fuel pump is pumping. It has a little shake/vibration to it. Both while priming and running.

I've also looked at fuel flow before and after the diesel filter...it fills up a solo cup in like 15 seconds. It's fresh diesel (no black slime and looked at my coalescing filter in the engine run bay...no water so I feel confident my diesel is good). I also added some diesel additive to the tank when I bought 90 gallons the other day. I also re-bled fuel at the injectors. I'm pretty comfortable around diesels. Pretty simple...air...fuel...compression. BOOM!

I've cleaned the air cleaner element. So that shouldn't be an issue. Plus it's new. Only ~20 hrs on it. Bought it direct from Kubota.

The belt is connected to the main crank and water pump (my model doesn't have a tensioner). It feels loose for my liking (~.5" of deflection if I push) but when the crank spins, it spins the pump. No squeaking. No rubber smell. I've also taken the belt off and spin the pump pulley... It spins.

Fast forward to me diagnosing this mess. I took all the panels off and it ran smooth for ~10 minutes then shut off with a high temperature (one blink) code. This is a fresh surprise considering I've been getting 3-6 codes. So it's welcome...sorta. What it tells me is that my temperature sensor is working!!! So that's freaking awesome to know.

However, I've been reading that these engines need the cowling installed for adequate cooling? Is this a real reason for it to throw a high temperature code? AFTER throwing 3-6 codes about 4 seperate times after runtimes between 30 minutes and 4 hrs.

Back to diagnosing....

I've squeezed the intake and exit coolant hoses...when I squeeze one hose the other pushes back (engine off; coolant cool). Making me think that the radiator isn't clogged, and furthermore the thermostat is open? But could it still be clogged? Enough to throw a temp code. Keep in mind I had been getting 3-6 codes for a random engine stall/quit and this is my first time getting a temp code; allbeit with the cowling off.

I've also sqeazed the hoses when the engine is running (cowl off) and the hoses are hard (both sides) making me think the water pump is pushing coolant but the radiator is causing a restriction?

Do any of y'all think it could be the thermostat? Maybe my squeezing was a result of the coolant moving through the bypass hoses...?

Can I (potentially) remove the thermostat and run it to see if it still overheats? At least be safe enough to get my stuff charged to get on the road?

Any help would be great. Honestly I'm in the weeds here...I've done so much to diagnose.. also we do have an AutoGen Start system and it's disabled right now...so that shouldn't be messing with anything related to the genny.

Right now I'm at Talladega running the bus engine to recharge every 5 or 6 hrs at a time.

My plan (after I limp home) is to start tearing this down to the radiator.. looking for abrasions on hoses, etc.

Replacing: water pump belt, thermostat, water pump, and cleaning the radiator with something?

Again, any help is appreciated.

Ray,IN 04-24-2021 08:31 PM

Have you contacted Kubota sales yet? I would expect them to be helpful for a genset with 20 hrs on the meter.

roketenginer 04-24-2021 08:52 PM

Quote:

Originally Posted by Ray,IN (Post 5725761)
Have you contacted Kubota sales yet? I would expect them to be helpful for a genset with 20 hrs on the meter.

No...the generator has 2k hours. The air filter has 20 hrs..

Ray,IN 04-24-2021 11:13 PM

Quote:

Originally Posted by roketenginer (Post 5725784)
No...the generator has 2k hours. The air filter has 20 hrs..

My bad, speed reading got me again.

groveln 04-25-2021 04:40 PM

When is the last time you've changed the coolant system roketenginer? These units need the coolant changed out every 3 years to keep them in tiptop running shape..I learned this the hard way & it was very expensive to have Cummins do something I'm capable of doing. I just did mine yesterday with a flushout too.

shootist 04-25-2021 08:47 PM

Thermostat first, your time to overheat is all over the place. If that's due to load on the gen being different then I would lean towards a bad radiator. A radiator can be clean and still be deteriorated to the point it won't cool. The overheating is gradual and may not overheat while under a light load.

roketenginer 04-25-2021 10:11 PM

Quote:

Originally Posted by groveln (Post 5726797)
When is the last time you've changed the coolant system roketenginer? These units need the coolant changed out every 3 years to keep them in tiptop running shape..I learned this the hard way & it was very expensive to have Cummins do something I'm capable of doing. I just did mine yesterday with a flushout too.

I haven't. Just oil, oil filer, fuel filter, air cleaner. I'll be doing a flush and replacing the thermostat, inspecting the lines for holes (sucking in air maybe), and boiling the radiator to clean it out.

I checked the airflow with the cowling on. It sucks air up from the bottom at the radiator. So the fan is developing a vacuum and moving air through the cowling.

THenne1713 04-26-2021 01:00 AM

If pump working, not leaking thru weep hole, fluid level good/ full and fan/ fan clutch (if equipped) good, most likely THERMOSTAT; they can go bad suddenly, either stick shut, stick up, even had one snap in half suddenly

roketenginer 04-26-2021 11:11 AM

Copy, I'm gonna plan on doing a full coolant flush of the coolant as well as thermostat replacement and inspection of the water pump. The RV is a 07 Monaco Dynasty 43' tag axle and the mx records are a little lacking from the previous owner. I'm an airline pilot so records of mx are essential where I'm from.

Question, do you know of anyone putting a coolant temp gauge on the generator? Like with an actual AutoMeter gauge? I'd rather know the problem could be developing rather than be surprised. I do a lot of RVing over-the-road w/ the generator on (at least with my former Bounder I did) and I'd like to know the condition of the generator going down the road if at all possible from the driver's seat. And maybe an oil PSI/temp gauge as well? I looked on the generator and there are a few sensor bungs that have wires leading off it I could steal those signals for some gauges? There's no such thing as too much data!

groveln 04-26-2021 07:17 PM

Genie coolant change out
 
There's a great video on YouTube on hoe to change out & flush your genie







Quote:

Originally Posted by roketenginer (Post 5727278)
I haven't. Just oil, oil filer, fuel filter, air cleaner. I'll be doing a flush and replacing the thermostat, inspecting the lines for holes (sucking in air maybe), and boiling the radiator to clean it out.

I checked the airflow with the cowling on. It sucks air up from the bottom at the radiator. So the fan is developing a vacuum and moving air through the cowling.


nbluesky 04-26-2021 07:34 PM

Before getting too crazy with coolant system (although it sounds like service is due) I would want to know the temp switch is not failing. It's a cheap easy to replace part or I'm sure you can look up how to ohm test it. If it's sending faulty signals it could be shutting it down. I also would love a temp gauge on the genny. I'm sure there is a way to wire one in.

roketenginer 04-27-2021 03:29 PM

I checked the sensor it showed 1 ohm cold.

Is there a way to 'test' a radiator? Can I blow low psi compressed air through it? Or should I just leave it be and use prestone cleaner to get the scaling out?

roketenginer 04-27-2021 05:50 PM

I ordered a pressure fill cap, temperature sensor, and thermostat. I will refill with some quality fluid after.

I tested flow of the radiator, it flows very well. If I still get overheating issues I will know THAT is where my problem is.

nbluesky 04-28-2021 06:54 AM

Quote:

Originally Posted by roketenginer (Post 5729490)
I ordered a pressure fill cap, temperature sensor, and thermostat. I will refill with some quality fluid after.

I tested flow of the radiator, it flows very well. If I still get overheating issues I will know THAT is where my problem is.


You could also pick up one of those cheap thermometer laser guns. You could know actual temp of coolant in different parts of the system as it runs. Would prob be able to tell if there is a blockage in the the radiator and for sure see if the thermostat is stuck closed.

Amazon Thermometer Gun

Corc 04-28-2021 06:59 PM

The generator already has a temp sensor on it, feeding information to the control. Seems you could tap into it and add a standard resistance gage, if you knew the sensor value. Otherwise you could tee in an additional sensor pretty easy.

The Onan techs can read actual coolant temp with electronic service tool, inPower. Control uses temp to determine things like glow plug burn time. Do not know anyway for customer to access or display control data.

HarryStone 04-30-2021 04:26 PM

Quote:

Originally Posted by Corc (Post 5730780)
The generator already has a temp sensor on it, feeding information to the control. Seems you could tap into it and add a standard resistance gage, if you knew the sensor value. Otherwise you could tee in an additional sensor pretty easy.

The Onan techs can read actual coolant temp with electronic service tool, inPower. Control uses temp to determine things like glow plug burn time. Do not know anyway for customer to access or display control data.

It's likely the temp sensor is a preset switch. Closed until it hits a preset temp, then it opens. I doubt the gen set would need a sophisticated sensor like cars have.

roketenginer 05-14-2021 08:20 PM

Thought I'd give a quick update on this deal.

So I bought the pressure cap, thermostat (71 degree C), and temperature sensor. I also installed gauges for the generator at the drivers station (water temp, oil pressure, chassis battery voltage) these gauges only work when the generator is on. Pretty slick set up if you ask me. The temp and oil sensors are electric on this gauge set-up so its really easy to wire up.

So after refilling coolant with Prestone, burping the air I let the engine run for about 2 hours no issues. I used my Flir infrared camera to see where the heat was soaking into the radiator. The incoming side of the radiator was ~150-160 and exiting was ~100-110. So the radiator is working, the cowling is pulling a vacuum and drawing air through the radiator.

The engine then cut out after 4 hours. Throwing a 3-6 code. So I let the engine cool, I checked the oil level and it was maybe 2 mm above the full line so I siphoned some out. Interesting note, before I siphoned the oil my gauge was reading ~30PSI... I thought this was a manufacturing defect. After I took out some oil my pressure went up to ~42PSI. Coincidence? I think not.

I think the random shut down 3-6 code can also be triggered by fuel, or other factors... Like crankcase pressure. As it turns out oil level in diesel engines can create wild amounts of crankcase pressure. I think this might have been my issue.

If y'all want a write up on my gauge installation I can create a new thread and do it there.... SUPER straight forward if you know which side of the wrench is up.

nbluesky 05-15-2021 09:56 AM

Thanks for posting a follow up! I'm curious if you run it now for extended time does it indeed stay running? 30 psi does not seem low enough to trigger a shutdown but I'm not sure what the threshold would be.

Yes of course would love to see some pics of the new setup!

roketenginer 05-15-2021 01:55 PM

Ok, so it ran for about 1.5 hrs and .4 both times before throwing a 3-6 code twice. I bled the injectors, checked the fuel rail; clean. I'm now going to order a fuel pump. My guess is that this pump gets lazy when it gets warm. My understanding of electronics says that's a reasonable assumption. So now on the chopping block is the fuel pump. Looking at the old records the previous 2 owners didn't replace much so this may be an original part. When you hold down the stop switch you hear (and can feel) the pump pumping.

If the new pump doesn't work I'll replace the rubber fuel lines, and if that doesn't work I'll assume at that point the computer might be tripping out.

The fuel filter is new (~20 hrs). I'm considering putting one of those FleetGuard cannister filters at the tank just for good measure... But maybe after I can get this thing running for more than 2 hrs at a time.

Ok, I'll get on that post for yall about the gauges!!

roketenginer 05-15-2021 04:10 PM

Quote:

Originally Posted by nbluesky (Post 5752214)
Thanks for posting a follow up! I'm curious if you run it now for extended time does it indeed stay running? 30 psi does not seem low enough to trigger a shutdown but I'm not sure what the threshold would be.

Yes of course would love to see some pics of the new setup!

https://www.irv2.com/forums/f258/add...or-536969.html

nbluesky 05-15-2021 08:25 PM

Quote:

Originally Posted by roketenginer (Post 5752407)
I'm now going to order a fuel pump. My guess is that this pump gets lazy when it gets warm. My understanding of electronics says that's a reasonable assumption.


Hmm. Do you have a way of checking fuel pressure and watching to see if it drops as the pump gets warm? Seems unlikely to me that that would be the problem. EDIT: After reading several post of folks saying a new fuel pump fixed their problem I understand your thinking.

Also have you confirmed that it is not shutting down due to coolant temp? I assume so now that you have the new gauges installed.

Found this comment on another post, worth checking out:

"... after chasing stuff around like the fuel filter,etc, , I found it to be a bad 12v battery power connection to the genset"

I always try to troubleshoot and test things to find the source of the problem before throwing parts at it. I have had better luck in the past doing that. Sometimes it can be really frustrating finding the problem but in the end it feels really good knowing you diagnosed the issue and fixed the source of the problem with one fix. Just my way of doing things but to each their own!

roketenginer 05-22-2021 09:01 PM

So I replaced the fuel pump and I'm not sure if I made the issue better or worse. It's still shutting down and throwing a 36 code.

I primed the engine with the rocker switch as the manual says for about 1 minute and then again for another minute. Started up and ran for ~0.7 hours.

I tried to restart and it wouldn't run longer than 1 second. So I'd try to reprime and I couldn't hear the fuel pump pumping... It is hooked up because it did work the first two times initially.

At this point I'm thinking maybe the computer is bad. I'm going to look alittle closer at the fuel shutoff governor, bleed the lines at the injectors, and recheck the fuel lines for cracks where it might be sucking water.... I think I'm also going to blow compressed air through the fuel line that goes to the tank.

More on this later...

THenne1713 05-22-2021 10:40 PM

Is there a fuel solenoid, or solenoid that operates a manual valve, or something that a loose wire/ bad coil would shut down fuel? Never seen this engine, nor studied their manuals... but know those control boards are $$$ and loose wires/ bad solenoids are cheap to fix. Corroded connections or rodent damage are very common w/ RVs

shootist 05-22-2021 11:06 PM

To reset the board you have to disconnect the 12v cables coming in the back of the gen. Mine would crank and not start, then would not even crank nor turn on the fuel pump. I had shut it down under load one time that caused it. Disconnection of 12v to the gen fixed it. It was throwing governor codes.

Mile Marker 42 05-22-2021 11:13 PM

Crazy question, but have you disconnected power to the generator underneath for 30 mins and wire brushed any corrosion from the cable terminal ends and mounting studs? I had an issue recently with my 7500QD and this actually fixed my issue. An aviation mechanic suggested this to me as he said this is how they clear codes on planes.

roketenginer 05-23-2021 09:20 AM

Quote:

Originally Posted by THenne1713 (Post 5762003)
Is there a fuel solenoid, or solenoid that operates a manual valve, or something that a loose wire/ bad coil would shut down fuel? Never seen this engine, nor studied their manuals... but know those control boards are $$$ and loose wires/ bad solenoids are cheap to fix. Corroded connections or rodent damage are very common w/ RVs

I'm going to check the solenoid next; I found the service manual thanks to the files page here.... LIFE SAVER.

I'm also going to look a little deeper into the injection pump to ensure nothing is jammed.

I'm going to do the 12v power off for an hour to see if this remedies anything to reset the computer; I'm also going to check for frayed wires.

roketenginer 05-23-2021 09:21 AM

Quote:

Originally Posted by Mile Marker 42 (Post 5762023)
Crazy question, but have you disconnected power to the generator underneath for 30 mins and wire brushed any corrosion from the cable terminal ends and mounting studs? I had an issue recently with my 7500QD and this actually fixed my issue. An aviation mechanic suggested this to me as he said this is how they clear codes on planes.

I did that when I cleaned the terminals on the back of the gen... I'm going to check for continuity here next.

roketenginer 05-23-2021 12:47 PM

Ok, so I went through the service manual and checked all of the applicable areas. I checked the fuel fittings, I checked for cracks, etc. All good.

I when through and tested fuel flow through the filter. Good again. The service manual wants 8oz in <1 minute. Mine did 8oz in ~20 seconds.

I removed the governor actuator and tested it for the 2-4ohms AND I put 12v to it and the plunger retracted. So thats good.

The last thing on the list is control board replacement followed by 'service the engine'. My best guess is, when this engine runs it runs extremely well. I'm no stranger to Kubota engines and have a tractor, skid steer, and UTV all kubota, all ~20 years old.

My personal thought is the control board. I've read where some handy guy wired a relay to bypass the fuel pump control to just turn the fuel pump on whenever the engine is running. I may go that route in the interm if I can't find a control board (with a warranty...).

I'm grasping at straws here. Fuel filter, fuel pump, air cleaner, oil filter, oil level are all good. Its not overheating and it has nominal oil pressure.

If anyone doesn't have any ideas... lol

THenne1713 05-23-2021 11:32 PM

ONE of biggest problems for Gas or Diesel is the LOW PRESSURE FUEL PUMP Because THE LITTLE SLIDING Piston pump fools you by being INTERMITTENT, and when first failing, maybe not until 90-120-minutes run...(often with a variety or other symptoms such as SURGING) many owners with (some brands of RV) blame OVERHEAT/ VAPOR LOCK, which (may/may not) be an influence on (some) but not all, but it is currently a $30+/- part in (most cases) or OEM= $100+/-?. MY suspicion after disassembing my 20yo/ 200-hour pump was fuel contamination, (had white putty like substance on piston & bore wall, that I NOW suspect (right/wrong?) is maybe TEFLON dope pipe sealant from station fuel tank/ hose fitting/ piping?) Diesel LP pump gets fuel to HIGH Pressure pump for Injectors; not much read// found on problems w/ diesel HP pump? BUT LP pump similar/ same on gas and diesel, with similar failures? and ONAN TEST is "greater than x-PSI", which Most owners cannot do, (NOT "pulled line loose and it flowed fuel" as many onwer/ troubleshooters do), so easier/ cheaper and FASTER to change pump. and new pumps seem to have low fail rate? (Have read of one new fail, but... ?) I do KNOW Diesel HARD to stop if it is getting fuel and shutoff METHOD is always STOP FUEL FLOW, and Code 36 says "controls did NOT shut off engine"? LUCK

THenne1713 05-23-2021 11:35 PM

p.s tale/ TIP: When I first bought Rv TS/ BRAKE Light problem, checked fuses x3 times and then spent a week chasing wires, only to recheck and FIND blown fuse that I had checked x3 times... so ROKETENGINER, are U getting my drift? Yeah, I know I am getting old, and used to be better in my youth.. :-)

roketenginer 05-24-2021 03:36 PM

Quote:

Originally Posted by THenne1713 (Post 5763315)
p.s tale/ TIP: When I first bought Rv TS/ BRAKE Light problem, checked fuses x3 times and then spent a week chasing wires, only to recheck and FIND blown fuse that I had checked x3 times... so ROKETENGINER, are U getting my drift? Yeah, I know I am getting old, and used to be better in my youth.. :-)

I don't mean to be rude, but no I don't understand what you are getting at.

Are you saying vaporlock is the majority cause of these things?

Or the lift pump getting too hot?

Or there being FOD in the diesel fuel?

THenne1713 05-24-2021 10:48 PM

OK, so (you said) you had "checked" A, B, C ... (including fuel pump) and (I said) "only to recheck and FIND blown fuse that I had checked x3 times... a week earlier" BET YOU did not check fuel pump PRESSURE? BUT (I would) spend $30 and replace FP anyway... suspect that diesel board is NOT just $30? (Believe someone said $1500 recently, but maybe wrong) and yeah, board may have a RELAY that is intermittent that controls FPUMP, but start w/ cheap items FIRST? Hope this helps? p.s. Oh, and I guess it doesn't matter WHY, if old worked for a period, and a new one will make the problem go away?

PanJH 05-25-2021 06:18 AM

Quote:

Originally Posted by Mile Marker 42 (Post 5762023)
Crazy question, but have you disconnected power to the generator underneath for 30 mins and wire brushed any corrosion from the cable terminal ends and mounting studs? I had an issue recently with my 7500QD and this actually fixed my issue. An aviation mechanic suggested this to me as he said this is how they clear codes on planes.

Similar situation when I was getting a 36 code on my 10hdkca I was going bonkers trying to figure it out. To net out a very long story, it was the power cable from the chassis batteries that runs for some 40+ ft to the genset. It was failing internally and would result in shutting down the electric fuel pump throwing the 36 code.

nbluesky 05-25-2021 06:41 AM

If you do end up replacing the board make sure you call Flight Systems first. Their replacement boards are a fraction of the price of Cummins.

https://www.flightsystems.com/standb...-controls.html

roketenginer 05-25-2021 09:43 AM

Quote:

Originally Posted by THenne1713 (Post 5764630)
OK, so (you said) you had "checked" A, B, C ... (including fuel pump) and (I said) "only to recheck and FIND blown fuse that I had checked x3 times... a week earlier" BET YOU did not check fuel pump PRESSURE? BUT (I would) spend $30 and replace FP anyway... suspect that diesel board is NOT just $30? (Believe someone said $1500 recently, but maybe wrong) and yeah, board may have a RELAY that is intermittent that controls FPUMP, but start w/ cheap items FIRST? Hope this helps? p.s. Oh, and I guess it doesn't matter WHY, if old worked for a period, and a new one will make the problem go away?

Gotcha! Yeah they are around $600-$900, not cheap.

Right now I've ordered some relays to replace the K1, K2, K3 relays. I'm going to check for proper voltage at the generator, then I'm going to straight up wire the fuel pump to a relay and if it runs longer than 15 hrs I know its the PCB controller.

I had to wire my old onan like that (7kw; 1993 model marquis) to the hobbs meter with a relay to turn on the fuel pump.... NEVER had an issue after that. It had ~6,000 hours on it when I sold the old Bounder.

F4Gary 05-25-2021 12:53 PM

Quote:

Originally Posted by THenne1713 (Post 5764630)
OK, so (you said) you had "checked" A, B, C ... (including fuel pump) and (I said) "only to recheck and FIND blown fuse that I had checked x3 times... a week earlier" BET YOU did not check fuel pump PRESSURE? BUT (I would) spend $30 and replace FP anyway... suspect that diesel board is NOT just $30? (Believe someone said $1500 recently, but maybe wrong) and yeah, board may have a RELAY that is intermittent that controls FPUMP, but start w/ cheap items FIRST? Hope this helps? p.s. Oh, and I guess it doesn't matter WHY, if old worked for a period, and a new one will make the problem go away?

He replaced the fuel pump in post #22.

roketenginer 05-26-2021 08:01 PM

Ok, everyone. I'll close this thread out here.

I replaced the K1, K2, K3 relays with some SPDT relays. Didn't solve my problem of my fuel pump NOT priming when I try to prime it. So now I'm about 99% sure the problem is in the computer/PCB/controller.

THIS is what I did.

Using the schematic in the service manual for the HDKCA I found a 12v power source off the 'Status Indicator' LED. This light will illuminate when 1) priming 2) when generator is running 3) when starting. I tapped off that line and Tee'd a wire into it that I ran to the (+) side of the fuel pump. I soldered it and used a wire that can handle 15a of current. I also verified the wire wasn't overheating with my infrared camera.

So far this new set up has been running ~2.5 hours with the a/c's and other components pulling ~45amps. Which is more than a half load. No overheating, no surging, EGT: ~300F, Coolant: ~165F, Oil PSI: ~44PSI. I've also noticed that there's less vibration (maybe because I put in alot of seafoam and its been cleaning the injectors?). Overall, Kubota engines are bulletproof as I've always known.

My assumption is this. The 36 code is when the generator drops below 1000rpm for more than .5 seconds. My guess is the generator would run fine on a light load WITHOUT the lift pump working (because the computer told it to stop?), but as soon as the a/c compressor/coffee maker/etc. clicked on the amp draw was enough to lug the generator down, making it unable to keep up with less than optimal fuel draw and the engine would plum quit.

I can 100% say that the computer is bad and I'm going to be ordering the flight systems one here shortly. It sucks something so expensive has to go bad, but this is RVing.

In conclusion, simple & cheap first, find a service manual, common sense. And ask questions; can't forget that.

Y'all have a good one!


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