OP
jedjoe
Silver Member
I just looked it up on this small valve. Opening pressure is 0.5 Kilopascal or 0.0725 psi
TC35 fuel filter problem SOLVED!
- Thread starter jedjoe
- Start date
OP
jedjoe
Silver Member
Opening pressure for the 1/4" inline check valve is 0.5 Kpa or 0.0725 psi.
OP
jedjoe
Silver Member
the check valve has an opening pressure of 0.5 kPa or 0.0725 psi
OP
jedjoe
Silver Member
0.5 kpa or 0.0725 psi
thclimer
Platinum Member
That's a very small amount of pressure, I'd install it to give it a try.
OP
jedjoe
Silver Member
Here is an update that will have you all scratching your heads....
Please examine the attached photo as you read this post.
So, I ran the tractor for a few days leaving the hemostat crimping the return line section that connects to the filter bowl. The tractor ran perfectly, with no symptoms and no loss of power even when throttled up for most of that time. Probably 4-5 hours of full use and there was no drop in the level of the filter bowl...it stayed full. Excellent.
Today the 1/4" check valves arrived. I removed the hemostat, returning that one section of return line (from the "T" connector to the filter assembly)to use. I added the check valve on the part of the return line that travels from the "T" connector back to the tank. Based upon past conversations with others (and with my agreeing with them), that check valve (which has a VERY LOW opening pressure) SHOULD have stopped any air from being sucked down the line (and yes, I tripled checked the valve to ensure it was operating properly and I had installed it with the correct direction of flow (flow allowing fuel back to the tank but not allowing air from the tank).
Guess what? The problem RETURNED! Within 15 minutes of use, the bowl was only 1/2 full.
Anticipating the questions of all of these smart tractor minds, let me say this: 1) The filter bowl assembly itself is fully intact, without any cracks or damaged "o" ring; 2) the return line from the injectors to the "T" connector is brand new, as is the line I crimped for my previous experiment.
As far as I can understand this, the problem is stopped when I shut down the hose from the "T" connector to the top of the filter assembly. The problem returns when I unclamped that small run of return hose. The "T" connector is brand new, so the air is not coming from that connector. The air CAN'T be coming from the main return line to the tank, as there is now a check valve that works perfectly, stopping any air from being suctioned from the return line. So....what's left? Unless I am dementing, the ONLY place left for that air to enter is somewhere along the line from where it exits the injectors but before it reaches the "T" connector. Right? Or am I missing something??? This weekend, I will remove the fiberglas panel that blocks access to where that line connects to the injector exit. Maybe when I replaced that line I didn't tighten it sufficiently.
For those of you much wiser than me about fuel injection systems, is it possible that air is leaving the injectors along with the excess fuel? And if so, why is it ending up in the filter assembly rather than being pushed back to the tank?
Please examine the attached photo as you read this post.
So, I ran the tractor for a few days leaving the hemostat crimping the return line section that connects to the filter bowl. The tractor ran perfectly, with no symptoms and no loss of power even when throttled up for most of that time. Probably 4-5 hours of full use and there was no drop in the level of the filter bowl...it stayed full. Excellent.
Today the 1/4" check valves arrived. I removed the hemostat, returning that one section of return line (from the "T" connector to the filter assembly)to use. I added the check valve on the part of the return line that travels from the "T" connector back to the tank. Based upon past conversations with others (and with my agreeing with them), that check valve (which has a VERY LOW opening pressure) SHOULD have stopped any air from being sucked down the line (and yes, I tripled checked the valve to ensure it was operating properly and I had installed it with the correct direction of flow (flow allowing fuel back to the tank but not allowing air from the tank).
Guess what? The problem RETURNED! Within 15 minutes of use, the bowl was only 1/2 full.
Anticipating the questions of all of these smart tractor minds, let me say this: 1) The filter bowl assembly itself is fully intact, without any cracks or damaged "o" ring; 2) the return line from the injectors to the "T" connector is brand new, as is the line I crimped for my previous experiment.
As far as I can understand this, the problem is stopped when I shut down the hose from the "T" connector to the top of the filter assembly. The problem returns when I unclamped that small run of return hose. The "T" connector is brand new, so the air is not coming from that connector. The air CAN'T be coming from the main return line to the tank, as there is now a check valve that works perfectly, stopping any air from being suctioned from the return line. So....what's left? Unless I am dementing, the ONLY place left for that air to enter is somewhere along the line from where it exits the injectors but before it reaches the "T" connector. Right? Or am I missing something??? This weekend, I will remove the fiberglas panel that blocks access to where that line connects to the injector exit. Maybe when I replaced that line I didn't tighten it sufficiently.
For those of you much wiser than me about fuel injection systems, is it possible that air is leaving the injectors along with the excess fuel? And if so, why is it ending up in the filter assembly rather than being pushed back to the tank?
Harry in Ky
Veteran Member
No, you're not the only TC owner to experience this, and for what it's worth, there are Kubotas out there doing the same thing. Probably other brands as well. That return line connection is not a "new Holland only" concept. Your "heating the fuel" theory may hold some water, but I see many newer tractors, at least those with common rail systems now have a fuel cooler in the mix. Fuel is sent up front and through a small cooler placed near hydraulic coolers, A/C condenser, etc, before going to the filters and the engine. I guess no added heat needed there.
OP
jedjoe
Silver Member
So I believe I have solved this ongoing problem to my satisfaction. After checking to ensure that the return line from the injectors was not loose (and therefore not a source of air), I did a bit more research on diesel fuel injections systems. It seems that well over half of the available diagrams of such systems don't even include the return line that runs back to the fuel filter assembly, the excess fuel instead simply returning to the tank directly. When I did see that extra line, the orifice on top of the fuel filter assembly was typically identified as an "overflow". This led me to believe that if fuel is moving along that one small line, it's more likely exiting the assembly, NOT entering it. So....I installed one more check valve, this time on that line and oriented so that fuel can leave the assembly but nothing can enter it (fuel or air) from the return line. See attached image.
I then ran the tractor at high throttle for about 2-3 hours today (end of year field mowing). NO DROP IN THE FILTER ASSEMBLY! Just as important, there was no loss of power nor any signs that pressure was building anywhere in the system (no leaks, no popped connections, nothing).
What I learned from this process (beside now really understanding the fuel delivery system) was that the source of the air into the filter bowl was DEFINITELY coming from the return line orifice at the top of the assembly. Adding the first check valve (preventing air from being suctioned down the return line from the tank) DID NOT FIX the problem. Surprising, as that seemed the logical source of the air. Adding the second check valve (on the short section of the return line that runs directly into the filter assembly) DID FIX the problem. Moreover, preventing fuel movement back toward the filter assembly via that return line has (so far) created no problem at all. If that top orifice is really an "overflow", then my check valve will still permit such overflow, as the opening pressure on the check valve is very small (0.07 psi).
I think I can live with this solution and move on. The check valves are cheap, so I'd encourage anyone else with this same problem on a TC to try this solution if nothing else has worked to date.
Thanks all!
I then ran the tractor at high throttle for about 2-3 hours today (end of year field mowing). NO DROP IN THE FILTER ASSEMBLY! Just as important, there was no loss of power nor any signs that pressure was building anywhere in the system (no leaks, no popped connections, nothing).
What I learned from this process (beside now really understanding the fuel delivery system) was that the source of the air into the filter bowl was DEFINITELY coming from the return line orifice at the top of the assembly. Adding the first check valve (preventing air from being suctioned down the return line from the tank) DID NOT FIX the problem. Surprising, as that seemed the logical source of the air. Adding the second check valve (on the short section of the return line that runs directly into the filter assembly) DID FIX the problem. Moreover, preventing fuel movement back toward the filter assembly via that return line has (so far) created no problem at all. If that top orifice is really an "overflow", then my check valve will still permit such overflow, as the opening pressure on the check valve is very small (0.07 psi).
I think I can live with this solution and move on. The check valves are cheap, so I'd encourage anyone else with this same problem on a TC to try this solution if nothing else has worked to date.
Thanks all!
thclimer
Platinum Member
Wow, what saga, thanks for sharing your progress and documenting your modifications with pictures. I hope you have many hours of running now without a loss of fuel in the filter housing.
dieselscout80
Veteran Member
Where dI’d you get the check valves and what part number are they?