Overflow Valve

[Jeff in OKC]

My truck idles rough and I have had the injectors checked and valves have been adjusted... I have heard alot about the overflow valve being a problem with rough idle and general missing... Can anyone explain in detail how to fix the overflow valve problem, how to take it apart and what I am looking for, and how to fix it. . ???

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Jeff Pilnicki, '94 Dodge Ram 2500, Auto transmission, Mostly stock, Chrome Brush guard, modifying exhaust to straight 4" pipe w/5" tip

 

[Joe G.]

Jeff,

Any fix to the overflow valve is temporary. You can stretch the spring a little and help the situation but that weakens the string. It's not long before the problem returns. I made a little shim about 1/16" thick for mine to increase the sping pressure. That's still working after 10K miles or so, but I don't expect it to last. As far as I know there are no repair parts for this valve. The valve is easy to take off the pump. It's on the side of the pump toward the engine and in line with the forward delivery valve. It looks something like a banjo fitting. Before you take it out cram some rags between the pump and the engine to catch any dropped flat washers. It's easy to take apart.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

[Rock Fish]

Jeff
Try this before you spend a lot of money.
While your truck is at an idle, take a wrench and loosen the injector line to the injectors one at a time, when you open the line the injector will star missing, do this to all of the injectors one at a time.
If this makes a differnce in the idle rpm it is not a problem with your injectors.
Most truck with bad overflow valve are hard to start.
John

 

[Deezul1]

My overflow valve was bad but no misses or hard starting only power loss above 60mph with RV in tow and not as responsive to throttle at higher speeds when empty. Remove the valve and stretch the spring to. 550 and reinstall. A new one is supposed to be . 500. I did mine 8 months ago and it still is working fine. My local injection shop wants about $60. 00 for a new Bosch valve assembly and Cummins and Dodge are more.
Good Luck

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96 SLT Laramie CC 5spd, 3. 54, no muff, no cat, 5"turn down tip
. Member NRA/USPSA

 

[HEMI®Dart]

Jeff,

Does your truck tend to miss & idle rough when its HOT? This is when the overflow valve usally acts up.

You may be confused if you look at your overflow valve. The OE one on my '94 was a sealed unit. It had a steel ball pressed into the top of it. No way was it coming out without destroying the valve. The newer ones the guys area taking about have a hex nut on the top of the valve. This can be unscrewed and the spring removed and streched.

If yours has a 'ball' like a ball bearing pressed into the top of the oveflow valve, get a new one. #ad


I wish I had a scanner to show you guys, I have the old OE valve in my hand.

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Bill R
94 2500 SLT 4x4 5 Speed, 3. 54 LS, JRE 4" exhaust, Autometer Pyro, Boost & Water temp gauges, Bosch 215 HP injectors, Timing @ 14. 7º, JRE Stage III #4 plate 270/675, AFC spring kit, Scotty Air, Bully Dog Propane Injection, Roadmaster Active Suspension, Optima Red Tops, Geno's Exhaust Blanket, Espar Heater (won it!), Synthetic lubes throughout.



[This message has been edited by HEMI®Dart (edited 01-15-2001). ]

 

[DOWG]

Installed new 215 injectors right before Thanksgiving. My truck just started the "rough idle/miss" when hot deal. It has been 5,000 miles so my guess (after reading the above posts) is the overflow valve. Just bought one at Cummins today for $81 and there is a new part number: 3932096.

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1998 Driftwood Extended Cab,Short Box,12 Valve,4X4,Auto,Dunrite TC,3. 54,Banks Plate,AFC Spring Kit,Isspro EGT,Rickson 19. 5's,Abbott EPRA, Rancho Shocks,Heim Trackbar,Mag-Hytec transmission Pan & Pumpkin Cover,Amzoil Synthetic's,Ranchhand Bull Nose Front Bumper, Headache Rack,Tool Chest,Side Steps,Rear Bumper and 100% Stock Airconditioning.

[This message has been edited by DOWG (edited 02-02-2001). ]

 

[DieselB59]

Trucks with bad overflow valve are hard to start? Fixing of overflow valve a temporary fix? Wrong on both counts. For a truck with a bad overflow valve to be hard to start, it would have to be almost hung wide open. The problems begin when the spring loses its rate and the pressure falls below 20 psi. This causes the rough idle. Replacing the valve instead of repairing it is the cure. Go to a dealer and get a new one and you'll have to also loosen the 10mm hold down bolt for the steel return line that it is attached to so that once you loosen and remove the valve, you can pivot the line upward and remove it from the banjo fitting. A hard to start diagnosis is that of the fuel system losing its prime, as in a cracked or rotted fuel return line, which takes on air.

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Chris Timochko
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s.
*******************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission.

 

[Jeff in OKC]

Originally posted by DieselB59:
Trucks with bad overflow valve are hard to start? Fixing of overflow valve a temporary fix? Wrong on both counts. For a truck with a bad overflow valve to be hard to start, it would have to be almost hung wide open. The problems begin when the spring loses its rate and the pressure falls below 20 psi. This causes the rough idle. Replacing the valve instead of repairing it is the cure. Go to a dealer and get a new one and you'll have to also loosen the 10mm hold down bolt for the steel return line that it is attached to so that once you loosen and remove the valve, you can pivot the line upward and remove it from the banjo fitting. A hard to start diagnosis is that of the fuel system losing its prime, as in a cracked or rotted fuel return line, which takes on air.

 

[DOWG]

On Saturday my mechanical mentor and I went about the business of replacing the overflow valve due to rough idle and engine miss at operating tempertature. I changed the fuel filter first to remove that potential problem from the loop. Then we checked the fuel pressure (prefilter) and got 20 psi. The overflow valve was changed and we then had 28 psi. I was pleased to see the lift pump is healthy at 67,500 miles. The problem is gone; an easy diagnosis and fix with the help of this forum. Got questions? TDR's got answers!

[This message has been edited by DOWG (edited 02-05-2001). ]

 

[Andy Redmond]

I changed on on Saturday with similiar circumstances. Their is a Bosch TSB out on FIP valves that end in bosch number 086. DC paid for mine. Call their 800 # and send the claim in. .

The Bosch TSB is DSD SL 96-08, may 28, 1996, replacement of part # 2 417 413 086 with 2 417 413 093.

The one I changed ended in 093 (early 98 12 valve); however, the miss went away and the fuel psi post filter was 29 psi at idle no load. BTW the filter was changed as well.


Another surprise, DC was three bucks less than Cummins, go figure.
Good luck, Andy

 

[DOWG]

Hey Andy, YOU are my mechanical mentor and the overflow valve you changed on saturday was mine... ... ..... Thanks!