# 2001 Bobcat 753 F series (fresh air) cab heater, blows cold



## Kubota 8540 (Sep 25, 2009)

I just replaced the radiator, both hoses, clamps, thermostat, water pump, all heater hoses and flushed the heater core. The core had a small amount of goo but runs clear water in/out. Blower blows fine, temperature selector valve is clear and moves freely. Heater core fins are not plugged and were lightly dusty when I blew them out.

Thermostat seems to open right about 179-180 ish according to the temp on the outside of the water neck housing. The heater hose lines going toward the heater core start off about 125-140 but just before the "H" bypass, but at the cab entry point are only 75-80 degrees. I checked for kinks when cab is closed/down, but they are fine. Heater core is simply room temp.

What am I missing?


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## xgiovannix12 (Dec 8, 2012)

mine in my 763 never gets that hot either it blows warm thats about it


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## Kubota 8540 (Sep 25, 2009)

When this machine was new it would roast me out of the cab until the outside temp got down below zero. It slowly would put out less and less heat over the past 3 years. Which wasn't really noticeable because we have had real mild winters. This winter, absolutely nothing for heat, just cold air. Now that everything has been replaced or flushed, no heat, WHY?


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## Kubota 8540 (Sep 25, 2009)

A couple diagrams


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## Kubota 8540 (Sep 25, 2009)

I have installed heaters from scratch before in skidsteers, but this time this makes no sense. It seems like all the flow of anti-freeze is flowing thru the "H" bypass and nothing thru the heater core. But I can blow air thru the heater hoses/core, I can run the garden hose thru the heater hoses/core (both directions). Stumped.


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## Kubota 8540 (Sep 25, 2009)

Can someone answer why a bypass "H" is needed in the heater hoses? It's always been in there but getting real tempted to eliminate it.


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## Aerospace Eng (Mar 3, 2015)

Assuming the heater core is in parallel with the radiator, the only reason for a bypass on it would be to control the amount of heat by controlling the flow through the core.

I wouldn’t eliminate it, just put a ball or needle valve in there so you can vary the amount of heat independent of how much air you are blowing.


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## On a Call (Jan 14, 2015)

What if you installed a valve to slow the bypass ? This would cause more fluid to travel through the core and allow more heat? 

I am no mechanic....but it makes sense to me. And I did not stay at a Red Roof lodge either.

Good luck...nothing like having heat when it is cold outside.


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## rjigto4oje (Oct 27, 2010)

Tstat or flow problem


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## xgiovannix12 (Dec 8, 2012)

i was thinking of doing this to my machine and seeing if it got better the valve


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## Kubota 8540 (Sep 25, 2009)

On a Call said:


> What if you installed a valve to slow the bypass ? This would cause more fluid to travel through the core and allow more heat?
> 
> I am no mechanic....but it makes sense to me. And I did not stay at a Red Roof lodge either.
> 
> Good luck...nothing like having heat when it is cold outside.


Nothing like not having heat for 7 hours when the temp outside was -10F. Following night it was still snowing and the cab glass kept fogging up so I had to run the cab fan.....again with no heat.


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## Kubota 8540 (Sep 25, 2009)

rjigto4oje said:


> Tstat or flow problem


 Definitely not a tstat problem. Checked and tstat open and closes fine


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## Kubota 8540 (Sep 25, 2009)

xgiovannix12 said:


> i was thinking of doing this to my machine and seeing if it got better the valve


Just got back from chasing all over creation for 5/8" hose barbs to install a ball valve in the bypass. Thats next to try.


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## xgiovannix12 (Dec 8, 2012)

Kubota 8540 said:


> Just got back from chasing all over creation for 5/8" hose barbs to install a ball valve in the bypass. Thats next to try.


let me know how it works... My heat is warm thats about it when my door fogs I crack the window


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## Kubota 8540 (Sep 25, 2009)

Question. Do diesel engines after they have a couple thousand hours on them tend to run cooler? Compared to when they are new? This open "H" bypass has been on there since new and always had PLENTY of heat. Again the heater core is not clogged or restricted. It flows fluid freely with a small flow from a garden hose forwards and backwards.


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## rjigto4oje (Oct 27, 2010)

Try covering the radiator and see what happens I do that on my diesel truck and it helps not saying that secure all but to see if it does help


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## Kubota 8540 (Sep 25, 2009)

Before I replaced the water pump, belt, Tstat, hoses and radiator. I did do that, it raised my temp a little on the gauge but not in the heater core. With all the new parts, nothing is raising the heater core temp either. I now have middle of the green engine temp on the gauge.

Before the Tstat change I only could get into 25% of the green on the gauge.


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## Kubota 8540 (Sep 25, 2009)

Just seems the flow is using the bypass and not the heater core. But its not blocked. Going now to try and see if it could be air locked in the heater core and then install a ball valve in the bypass.


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## Aerospace Eng (Mar 3, 2015)

Kubota 8540 said:


> Question. Do diesel engines after they have a couple thousand hours on them tend to run cooler? Compared to when they are new? This open "H" bypass has been on there since new and always had PLENTY of heat. Again the heater core is not clogged or restricted. It flows fluid freely with a small flow from a garden hose forwards and backwards.


No.
You basically have three circuits in parallel, correct?
The radiator, the bypass, and the heater core.
You have a single water pump.
The amount of liquid pumped will be a function of the resistance of the three in parallel.
There has to be a valve to shut off the heater, otherwise you would roast in the summer. Have you checked it?
The temperature of the water going to the heater core should be the same as the temperature of the water going to the radiator. So the supply hose should be at the same temperature as the radiator hoses (which will be a bit lower than the actual fluid temperature).
The drop off in temperature along the hose indicates you have a flow problem.

It's possible the bypass is there because Kubota wanted a bit more flow when the thermostat was closed than the hole in the thermostat would provide.


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## Kubota 8540 (Sep 25, 2009)

Aerospace Eng said:


> No.
> You basically have three circuits in parallel, correct?
> The radiator, the bypass, and the heater core.
> You have a single water pump.
> ...


Glad you answered my diesel engine question, I was about to come back and answer it myself.

Yes, there is a shut off valve on the incoming heater hose. I removed it, checked it, it was clean and worked properly even at the end of a garden hose.

Yes, it is a flow problem. Checked that by putting a ball valve in the bypass. I closed it approx 1/2 way. I then run the engine a little over idle for 10-15 minutes and checked the temp at the ducts in the cab. There is up to 125F at the ducts. With the temp gauge 3/8 of the way into the green safe zone. I now have heat like it used to be. But

But now I want to know 2 things.
1) Why do I now need a ball valve in the bypass. Never was one before?
2) What temp should the heat coming out of the vent ducts be?


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## Kubota 8540 (Sep 25, 2009)

On a Call said:


> I am no mechanic....but it makes sense to me. And I did not stay at a Red Roof lodge either.


They may have left the light on for you but it wasn't a Holiday Inn Express!


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## Aerospace Eng (Mar 3, 2015)

If it worked in temperatures as cold as this before, if shouldn't be different (assuming your cab isn't leakier).

A garden hose will show a complete plug, but remember that it is pressurized much more significantly than a water pump provides.

One way to check that is to feel/measure the heat at the face of the outlet side of the heater core. Is one area warm and the other cold? If so, you have a partial plug.
​As to how hot, that depends on how much air you are blowing through it. The more air, the more the total heat, but the cooler the duct will be.

Just as a SWAG, I would aim for a 30 degree or so delta T (duct temperature versus ambient cabin air temperature) with the fan wicked up to max.


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## John_DeereGreen (Jan 2, 2011)

Is the temperature control valve mechaniclly controlled or electronically controlled?


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## Kubota 8540 (Sep 25, 2009)

John_DeereGreen said:


> Is the temperature control valve mechaniclly controlled or electronically controlled?


Manual, direct no cable or linkages


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## Aerospace Eng (Mar 3, 2015)

John_DeereGreen said:


> Is the temperature control valve mechaniclly controlled or electronically controlled?


Good thought. It didn't occur to me that there might be an air temperature measurement and an electronically controlled valve. 
All my machines are too old for that technology


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## Kubota 8540 (Sep 25, 2009)

Aerospace Eng said:


> If it worked in temperatures as cold as this before, if shouldn't be different (assuming your cab isn't leakier).
> 
> A garden hose will show a complete plug, but remember that it is pressurized much more significantly than a water pump provides.
> 
> ...


Thats the same idea I had. I think possibly over time the heater core has developed a build up inside. Probably should be removed and cleaned on the inside or replaced with new.

A real pain to get at. Cab up, unbolt and remove seat, and unbolt back of heater cover. Cab down, remove all ducts, then take out all screws around heater core, disconnect electrical.

Flow from water pump thru the heater hose can be shut of with my thumb over the end of it. Not sure of its psi, but Garden hose, no way.


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## Aerospace Eng (Mar 3, 2015)

Partially closing the bypass won't hurt anything right now. I'd go with that and leave the disassembly until spring.


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## Kubota 8540 (Sep 25, 2009)

As the heater slowly failed I tried everything except digging in to find the real problem. Plugged every hole and crack I could find or feel. I know it certainly gets pricey to try to get it right. Radiator, hoses, clamps, thermostat, gasket, water pump, heater hoses and clamps, and anti-freeze. Bobcat thinks their parts are gold. Sitting out there for 7 hours with no heat I was surprised how easily my wallet opened up for a $1K project.

This will be a temporary solution, until I can get this heater core cleaned out or a new heater core. Definitely a low pressure water pump and system.


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## Kubota 8540 (Sep 25, 2009)

Thanks everybody for your input. Was starting to drive me a little crazy. Making me question myself. Hope this will help some others with similar issues.


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## John_DeereGreen (Jan 2, 2011)

Aerospace Eng said:


> Good thought. It didn't occur to me that there might be an air temperature measurement and an electronically controlled valve.
> All my machines are too old for that technology


Our toolcat is a 2004 and the fancy electric controller thingamajgig decided to lay an egg and leave the operator with the temperature stuck on "deep freeze" mode. We pulled that controller out, set it manually and he's been nice and toasty since. It can be fixed in the spring.


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## xgiovannix12 (Dec 8, 2012)

so how big of a valve did ya get and im curious if the machine temp will change


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## Kubota 8540 (Sep 25, 2009)

I haven't worked the Bobcat yet, only run it in the shop at 1/4-1/3 throttle. It put out plenty of heat and the temp gauge was not quite have way in the green safe area. But I will keep a close eye on the temp of both the heater and the engine temp, then adjust the bypass valve accordingly. This will only be a temporary solution to removing and cleaning the heater core or replacing it come better weather and less use.







The valve is a 1/2" as well as the tees. The hose barbs were 1/2" toward the water pump and 5/8 toward the heater.


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## Kubota 8540 (Sep 25, 2009)

There are very few things you just can't find on the internet. Even find things you don't want to find. The heater core part # 6670140 is lost in the vast barren internet waste land. Finally after many many searches, rewordings I found one hit. $229 But seems shady to buy from. Looks like the dealership has got me on this one.


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## Kubota 8540 (Sep 25, 2009)

I don't mind paying a little more for parts from the dealership but the water pump in this project they wanted $241 + some shipping and would take 5-7 days to get to the dealer. I found the water pump for $40 + $20 fuel and had in hand in 2.5 hours. Both New.


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## Kubota 8540 (Sep 25, 2009)

It's rather hard to believe that the heater core is so sensitive that all it took to get heat again was a little more flow by closing the bypass a little. Look at the positioning of the bypass valve in the picture above. That is making 125-130 degree heat at the vents in the cab.


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## John_DeereGreen (Jan 2, 2011)

Kubota 8540 said:


> It's rather hard to believe that the heater core is so sensitive that all it took to get heat again was a little more flow by closing the bypass a little. Look at the positioning of the bypass valve in the picture above. That is making 125-130 degree heat at the vents in the cab.


That is amazing...


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## stodds12 (Oct 20, 2013)

You’re more patient than I was. I flipped the Oem heater for a princess auto jobby (which works surprising well). 

1 freezing cold night moving snow around was 1 too many for this guy haha


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## zlssefi (Dec 29, 2011)

Heater cores are very sensitive to blockage. I know you have been through the ringer with this machine. I have a 74 h90E international that i bought with a snowplowing business back in 2002. When i bought the business the machine operators asked me to check the heat in the loader as icicles were hanging inside the machine during storms. Guys had to wear snowsuits to operate an enclosed cab loader. Heater hoses were fine, but i insulated them. Then checking the heater core i found no temp drop across the core. I pulled the core and was able to get garden hose water through it. Same problem when i reinstalled. I took it out again and took it to a radiator shop who boiled it in a hot tank. Holy **** did that make heat. After that i had a 50 degree drop across the core.


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## Kubota 8540 (Sep 25, 2009)

Well I thought of disconnecting the heater hoses and dumping a CLR solution into them and letting it soak a few days. But the core being about 16 years old, Maybe the krud is all that is keeping it from leaking? LOL. I think I can limp by until spring then do just what you mentioned or break out the big wallet and buy a new core IF I can find one.


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## zlssefi (Dec 29, 2011)

hmm. the core in this loader was already 30 years old, and ive put another 16 yrs on it...i should probably stop talking about it...lol did bobcat say what the core was worth? On ebay right now theres a complete factory heater kit, core, motor, blower, valves, vents etc for 1300 bucks. https://www.ebay.com/itm/bobcat-cab-heater-kit/152852368367?hash=item2396b60bef:g:iMcAAOSwevlaTVoF


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## Kubota 8540 (Sep 25, 2009)

I haven't had very good luck with the local northern IL Bobcat dealerships. When I call for parts, no one ever answers the phone. I leave a message and maybe 4-6 hours later they call back. So this time I tried the online parts request, well it's been 2 days. But hey great news, they acknowledged that I emailed them. But still no info or price on the heater core. No more Bobcats for me. Changing Brands.

Excuse me, it isnt 2 days, it is 4 days. They were emailed Saturday morning at 9 AM.

It took 2 days to acknowledge that I emailed them.


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## Kubota 8540 (Sep 25, 2009)

Just received a heater core parts quote from WHEREVER? If purchased it will take 4-5 weeks to USA?









Haven't heard from any Bobcat parts dealer as of yet.

I'm not much of a solderer, but in 4-5 weeks I think I could fabricate one from scratch.


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## zlssefi (Dec 29, 2011)

this is insane. my bobcat dealer picks up the phone every single time. never had to leave a msg


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## Kubota 8540 (Sep 25, 2009)

zlssefi said:


> this is insane. my bobcat dealer picks up the phone every single time. never had to leave a msg


Yes thats sounds like a great way to do business. LOL


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## Kubota 8540 (Sep 25, 2009)

Just did ANOTHER parts request from another Bobcat dealer, I instantly received an email acknowledgement, of my request. We will see if I actually get a pricing response. Too bad they can't use their automated system to do the pricing and availability.


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## Kubota 8540 (Sep 25, 2009)

Bobcat dealer.

Got a response !!!!! $190 + tax + shipping, drop shipment.


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## xgiovannix12 (Dec 8, 2012)

bobcat always done me good.. I just called them for parts like an hour ago and ordered what I needed should be here by monday


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## zlssefi (Dec 29, 2011)

not to hijack or anything, but i had to call bobcat for protech pusher parts today. polymer trip spring assembly and two 7 foot cutting edges......2100.00 Plus tax...what in the F***


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## Kubota 8540 (Sep 25, 2009)

Well one thing is for certain, Bobcat is not afraid or shy about charging for parts.

This is a screenshot from a popular website. Bobcat wanted $241+tax+shipping + would take 5-7 days. This website usually has whatever to my door in 2 days even if its a Sunday.









I spent a little more than this and had it in 2.5 hours.

I have a Bobcat, not because it's a Bobcat, but because it has a Kubota Diesel. Bobcat has some licensing deal on its part numbers. I couldn't get a Kubota dealer 10 minutes from my house to tell me what the Kubota part number was for the water pump. I did try an online cross reference and found it. Not in stock.


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## Kubota 8540 (Sep 25, 2009)

I don't mean to seem negative about Bobcat. I have had a basically trouble free 2001 skidsteer and have owned since new, with simple basic maintenance.


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## Kubota 8540 (Sep 25, 2009)

My point is.......The above seller is selling this part for $29.95 which includes free shipping. They are not selling these at a loss.


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## John_DeereGreen (Jan 2, 2011)

Yes, one thing is certain. Bobcat is very proud of their parts and they are not scared of making a sizeable profit on said parts.


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## Jackets (Jan 4, 2015)

Possibly a Kubota SSV65 in your future? Local company has one and loves it. I'm not a fan of the foot controls myself i prefer Pilot. Loved Running the SVL75-2 Freaking beast compared to rubber for dirtwork.


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## Kubota 8540 (Sep 25, 2009)

Jackets said:


> Possibly a Kubota SSV65 in your future? Local company has one and loves it. I'm not a fan of the foot controls myself i prefer Pilot. Loved Running the SVL75-2 Freaking beast compared to rubber for dirtwork.


I think thats a very good match to what I use the Bobcat for. I have operated via hand controls, but all I have owned is hand and foot control, which is fine with me. I'm on gravel and concrete a lot so tracks are not in my future.


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## Kubota 8540 (Sep 25, 2009)

No kidding, just tonight got a quote from another Bobcat dealer. $199+tax+shipping for the heater core.


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