DBG Roosa Master Fuel Bypass Line Elimination

I’m resealing my DBG Stanadyne pump off my 2510 and was wondering if I can eliminate the bypass line that goes from the fuel line inlet to the body of the pump on the back side? I had another pump rebuilt a few years ago and it came back without that line. Do I need to do something different inside the pump or was it realized that it was not needed and can be blinded off? The pump tech manual has no info on this. Thanks for any response.

Is this the line you're referring to in photo? If so it can be eliminated as long as fuel return line back is intact

I would not simply remove it. It's there to keep a small amount of internal pressure inside the pump housing - via that little spring and check ball. Some have it mounted like your's and newer pumps have it built into the pumps return-fuel fitting. They all have either a check-ball-regulator or a vent-wire somewhere. What you could do to is remove the one you've got an install a newer "fitting" type regulator valve like newer pumps have.

According to parts catalog the 2510 has same return line fitting(parts key #5 R35352) that tractors without the tube have. Plus back when I worked for a dealer I knew of several tractors that ran many hrs with check ball removed from inj pump return line fitting.

I have removed many of the glass check balls,when they plug up.Never had any issues with that on the Roosa and Standadine.I dont think i would eliminate the line completely.

(quoted from post at 10:54:01 02/16/14) I dont think i would eliminate the line completely.

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Which line are you referring to? Parts key #18 in 1st photo?

The symptoms for removing the glass ball was the tractor would start and run for a few minutes, then just shutdown, let it sit for a few and it would run. Pressure built up in the return side and would seize the pump enough to kill the engine. Remove the ball and never look back. Or sometimes just cleaning it up and freeing the check valve would fix it as well.

The IP doesn't "seize" with the return line restricted, the pumping plungers are simply held inward by the increased housing pressure so they cannot move outward and take in a charge of fuel, so no fuel injection occurs. And the engine stalls.

As said, the pump does NOT sieze and then "remove the glass ball and NEVER? look back". When the flex ring breaks apart and you remove to glass ball so the flex debris doesn't plug the fitting, the governor weight retainer has metal on metal wear. When the tabs get worn off the, governor no longer works causing the engine to run away. Locally had a governor fail and killed the farmers son from flying shrapnel. Your never look back, comes at the risk of someone dying!

Well...30 years of doing this with tractors I"ve never killed or blown anyone or anything up.

Most of these rumors start by what people think they know vs actually doing it and having no understanding of really is going on...thus the comments.

Bob says there is pressure built up in the head causing the pistons not to move...that"s a seize...I bet if you spell Bob"s name backwards you still get Bob. How many of these pumps have either one of you torn down and rebuilt? How many service calls have you actually gone out on and fixed the problem by removing the ball and got the customer going? How many of those have you followed up on? How many have you run on a test stand and verified this "blow up" you speak of? I"d say not many with the comments made.

I have deleted this line on 2510's before and all went well, that was several years ago with no problems...

I'm with you gpower,, I have tossed more than my share of check balls, and yes even though it don't fix the actual problem it gets the tractor back in the field working till it can be o/H'ed I have deleted this line on 2510's before with no problem,, and I think I have only seen this line set-up on 2510's,,I don't know why they did it in the first place???

(quoted from post at 15:59:48 02/16/14) I'm with you gpower,, I have tossed more than my share of check balls, and yes even though it don't fix the actual problem it gets the tractor back in the field working till it can be o/H'ed I have deleted this line on 2510's before with no problem,, and I think I have only seen this line set-up on 2510's,,I don't know why they did it in the first place???

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Thanks to you & Gpower I rest my case!!!

The pump does NOT sieze up stopping the engine, the internal pressure causes the pumping plungers to not be filled with fuel thus not pump fuel. I have worked on these tractors for the last 40 years and taking the glass ball out usually has no consequence but ignoring the reason the fitting plugs as in flex ring failure will lead to governor failure at some point.

I can't speak for others - but I've gone out on many service calls where a pump crapped out. Many times I've torn the pump off, tore it apart on site, fixed it and stuck it back on. In regard to the "ball" . . technically it is a "housing pressure regulator." It is there to maintain slight internal pressure -around 2-4 PSI. If if plugs - the internal housing pressure raises to a level where it's as high as the incoming transfer-pump pressure. When that happens, all feed flow of low pressure fuel stops. Subsequently - the pump "starves" for fuel because the fuel charge/transfer pump stops working. There is nothing getting seized. The high-pressure pump plungers in the head starve for fuel. They do not get stuck. The two blades in the rotary part of the pump are what makes the charge fuel. They are hooked to a pressure regulator that is set around 60 PSI. When the "ball" gets stuck and internal pressure raises to 60 PSI - all flow stops.

Thanks for the all responses. Yes it is #18 in the parts book. What’s confusing is why the 2510’s had this line and most others didn’t? There was no check ball in the return fitting but a vent wire. I have had this tractor for the last 8 years and it has always been one of the best starting diesels I own to the point I was reluctant to tackle this job. But it all started because it was leaking fuel from what I thought was the hose where it goes into the timing window on the back side. It turns out it was leaking out of the throttle shaft instead. In order to put new seals on the shaft the pump has to come off, so since it has to be removed why not replace the flex ring too right? When we took the pump apart the flex ring was gone with no evidence of any pieces anywhere. One rivet was starting to get loose too. I'm replacing the flex ring with the solid weight retainer as it was only $30 more than the flex ring weight retainer.
Unfortunately that is the least of my problems now as the cam advance screw broke when putting back together so I have a big problem now. Lesson learned is to get the right tools for the job. I only had the Bristol tool or modified T45 Torx bit and not the cam support bushing. I know people have had success with the tool only but the bushing minimizes side load on the screw when you’re reefing on it. The tech repair book also says to always replace the pin as I'm sure it got cracked during removal. It took two whacks with a drift pin to get it to budge.

Seems to be some disagreement about the ball and spring and also several misunderstandings on how the pump actually works. The Roosamaster/Stanadyne DBG pump is two pumps in one. It has a rotary bladed vane pump that sits in the back. It is a charge/feed pump that delivers low pressure diesel fuel to the other end where high pressure pumping takes place. That high pressure is done by two small pistons. So a low pressure rotary pump is feeding a high pressure piston pump. The low pressure feed pump has a pressure regulator set at 60 PSI. The ball and spring you mention is a "housing pressure regulator" set at 4-6 PSI. One pressure works against the other. If that ball gets stuck closed - the internal pressure will rise until it gets to the same PSI as the charge pressure. When that happens with 60 PSI against 60 PSI - all flow stops. Then the pump starves for fuel and the engine will not run.

To anyone who says they removed the ball and all was fine? Did you recheck the timing advance curve after removal (if equipped)? Just because the engine still runs does not mean it's right. Let's say a typical Deere is set to have the timing advanced by 14 degrees when the charge-pump reaches 60 PSI. If you remove that ball - it lowers the housing pressure by 4-6 PSI. This works the same as raising the charge pressure by 4-6 PSI and the result is the timing advances too much, too soon. That if the pump has a hydraulic timing advance. On older pumps that do not - removing the ball just drops the housing pressure to zero which does not affect much in regard to running. I think Stanadyne wants some internal pump housing pressure to eliminate dirt intrusion. I.e. slight pressure on the inside pushing out.

Having nothing left to read I dropped in on this Deere site and find the discussion on the bypass on the Roosa Master pump very interesting. IH went to that bypass on the 7 & 806 tractors shortly after their switching to Roosa pumps on 806 tractors. The reason given was to lengthen the life of the fuel filters as a large share of the fuel would then be bypassed through innards of pump housing and back to the primary pump instead of to tank and back through filters. When we started having the elastocast governor ring failures they said take it off to help lower the internal pump temperature and increase life of governor ring. Pumps with bypass had the ball check valve in the bypass along with orfice wire in return fitting on pump. When you took off the bypass you discard the wire orfice and use the new fitting with check ball. The check ball was not a total check so to speak as it had a slight groove in the seat which allowed some flow. The ball did regulate the pressure inside the pump housing and of course affects the automatic advance as well as the charge of the pumping plungers. The 806 primary pressures were set to about 85 psi at rated high idle and I never did check pressure in the case . I don't remember what they claimed the pressure would run but it was under 10psi with every thing working properly. I also repaired a lot of those Roosa Masters in my day.

There is one additional function of the check-ball "housing pressure regulator valve." It only applies to farm tractors with fuel tanks lower then the engine and the valve mounted at the exit of the pump. It's to prevent fuel drain-back and difficult cold starting. It was a big issue on Ford and GM cars and trucks late 70s and early 80s with DB2 pumps.

That makes sense JD,, but I always wondered why they put that rear line on the 2510's,,and never on any of the other Deere's...

As to "calling jd and I out" as to how many pumps we've torn down and repaired and how many service calls we've been on to see the "coffee grounds in the return fitting" problem, you are picking on the wrong two guys!

Also, you wrote "Bob says there is pressure built up in the head causing the pistons not to move...that"s a seize".

IMHO, the plungers not being able to take on a charge of fuel because the pressure is nearly equal on both sides of them hardly qualifies as a "seize!