2020 toolcat code E001076-16

[laurencen]

So, your -26c equals a -15F (for us down here) so it is plenty cold for fuel gelling. Brrr Are you testing the old valve or new one? A call to Bobcat may be needed. It would be nice to know EXACTLY how this bypass is suppose to work. Especially if you live WAY up there! :cold:

this is the old one, still waiting on the new one, I would have expected it to open when I placed it in the freezer but no, left it outside last night at -26C I expected it to open, service were not familiar how this valve works just that its a bypass valve and the warm fuel gets circulated thro the filter however how warm is this fuel? will it not warm the diverter causing it to close?

by January we will see the -40C or lower, just maybe it will open then

 

[ruffdog]

Diesel fuel gelling happens when the paraffin usually present in diesel starts to solidify when the temperature drops. At 32 degrees F, the wax in liquid form will crystallize and leave the fuel tank clouded. At 10-15 degrees F, it will finally start to gel and clog the tank and fuel filters. I would like to think that the valve would be open at 32F (0C)....please check new valve when it comes. Being that the Doosan's run a 2 micron filter, you can't have any gelling going on.

 

[laurencen]

definitely will try the new one when it arrives prior to installing, I would have figured open at around -5C, would be curious how much warmer the return fuel gets and how quickly the valve closes after opening

 

[laurencen]

well here is the update, the new valve arrived today, at room temp the white inlet is open to the T lines so acting like a Tee, in the freezer at _20C no change to the way its sitting, all 3 ends are free flowing, at 40C hot water no change all 3 ends are free flowing, what exactly does this valve do? the old one with the broken Tee end is closed at _20C, its closed at room temp and closed at 40C so my question tomorrow is what and when does this valve do anything

it was my understanding it would open at cold temperatures and close when warm return diesel flows, clearly out of two samples I see no change at any temperature, the dealer was going to look into how this valve works I will check tomorrow, at this stage the 50 cent Tee works as good as the 60 dollar valve

 

[ruffdog]

Thanks for the update. "Diesel fuel is a mixture of hydrocarbons—with boiling points in the range of 150 to 380°C—which are obtained from petroleum." Maybe it closes at a even hotter temp than you are testing at. This is a important thread for people that are having gelling problems at cold temps though. I'd be cutting the old one apart to see how it works....just the way I am.

 

[laurencen]

ruffdog, I am not sure the temperature the diesel fuel returns from the pump but I would expect the valve to be open at cold temperatures so warmer fuel comes from the pump and circulates back into the filter

clearly on the day mine gelled it was cold and the valve was closed so no bypass of fuel, this new one is open any temperature cold or hot so it bypasses regardless of the temperature, I could try putting it in close to boiling water say 95C but is that realistic for return fuel from the pump, either way looks like my original was defective from day one

have another call into the service to better understand how this valve should operate, when a motor is running the water is likely closer to the 90C so possibly it takes that to close the new valve, I will see tonight

 

[laurencen]

given the fact engines run at temperatures to the 90C heated up the new valve to 95C for 10 mins, still wide open and the old one stays closed, neither of the bypass valves seem to do anything regardless of how cold or hot they get, for the application neither would do anything for cold weather operation

for anyone with this valve on there machine one wonders if they are open or closed and if they are working as intended, have another on order and maybe it will work as designed though no one seems to know when and how this valve functions

 

[ruffdog]

If a person had a quality T fitting in place of the valve, it seems like it would be fine for cold weather operation. For HOT weather, you could install a simple on/off fuel valve in the return line coming from the engine. It would have to be between the normal return line T and the T that replaced the bypass valve. So, in hot weather you could shut the valve so the return fuel goes directly to the cooler. Then, as the weather cools in the Fall, open your valve again.

 

[ruffdog]

given the fact engines run at temperatures to the 90C heated up the new valve to 95C for 10 mins, still wide open and the old one stays closed, neither of the bypass valves seem to do anything regardless of how cold or hot they get, for the application neither would do anything for cold weather operation

for anyone with this valve on there machine one wonders if they are open or closed and if they are working as intended, have another on order and maybe it will work as designed though no one seems to know when and how this valve functions

Maybe this is why the part numbers changed????:confused3: If the old PN valve would not open when it should, maybe the new PN valve is open ALL the time. If the engineers found out that the fuel never gets too hot in the incoming filter, why not run it open all the time? Hmmm....interesting.

 

[laurencen]

you have a point though best I can see inside the new valve it has the same internal metal assembly, I was advised not to use the T during summer but pinch the line from the injector block, like the shut off on the line for summer you still have to remove the cover its not hard just a feature not expected on a new machine

you are likely correct why the number changed, my original one is not opening so it never cycles warmer fuel thro the filter or return line to the tank

 

[laurencen]

further to the idea Bobcat changed the part number possibly to just a T I looked at both parts old and new, they both have the new part number molded in the housing

 

[laurencen]

just got the scoop on this nifty little valve, it functions as a T in the system during cold and normal day temperatures, when the fuel return gets around 120F it closes the return line which then sends fuel around the cooler and back to tank so its open at cold temperatures.

this being said I have the original valve stuck closed and the new valve stuck open, a replacement part is on order and will check it on arrival

have a great weekend all

 

[ruffdog]

Thanks for the update......:thumbsup:

 

[laurencen]

have a final update, working with the service dept it appears the new valve is functioning correctly the original was defective

how this valve works is during normal and cold temperatures it functions as a Tee, when the fuel coming into the Tee is warmed to 120 +/- the white connection of the Tee acts as a check valve and allows flow coming into the Tee but not out this is the white end of the Tee only, the other two ends from tank and to primer/filter can flow any direction when needed.

Looking at the plumbing diagram in the service manual I still have not figured how it interacts in the system, the white end goes to the one side of the pump and the cooler via a Y fitting,

anyone now knowing how the Tee functions have a better understanding how the flow diagram would look for cold and hot? no flow diagram in my service manual, now to install it back into the Toolcat this weekend

 

[ruffdog]

When open, the return fuel from the injection can flow through the valve and into the pre-filter supply hose. This will help warm the incoming fuel and filter. When the valve closes during hot conditions, the return fuel from the injection pump must flow to the cooler, then the tank. It does this through a T that is between the valve and injection pump in the return hose.

 

[laurencen]

when hot the flow from the Tee to the Y you mention is cut off, it acts like a check valve so fuel from the Y can flow thro the Tee but not from the Tee in my mind its working opposite to how I would have thought, have to draw the flow diagram over the weekend