Stupid question about Overflow Valve

[FATCAT]

How does one remove the overflow valve? Over the weekend I figured I would replace my old valve (120,000 miles on it) and proceeded to spend some 45 minutes trying to remove the thing. It appears that the clearance between the top of the pump and the notch cutout of the engine is not enought room to remove the valve. After loosening the valve all the way with the head touching the engine it appears that there is still 1/8" of bolt thread left in the pump. No matter what way I tried to angle the valve, it would not come out ... clearance was not enough.

So, how have you folks removed the valve ... or do I have something wrong with my pump/engine? Should they be this close together or could something be bent or mis-aligned?

 

[CumminsPower98]

Valve removal

FATCAT, mine is really close too but it does come out, I have to bend the fuel line a tiny bit to get it out. If you just can't get it you may have to remove the screw on the top (7/16" head). If you do this, be very careful not to loose the VERY small parts inside (place a rag under where you are working). This should give you enough room to remove the main body of the valve. Hope this helps.

 

[Piers]

Just take a halfmoon file and remove some of the head casting, doesn't take very much filing to get enough clearance.

 

[FATCAT]

Piers, I like that idea best. I just didn't think we would have to do something like this to remove a valve ... you would have thought that this would have been a better designed for such a simple part.

Bending the fuel like gets me nervous, especially with my luck, I would probably kink or snap the line in half.



Thanks.

 

[Deezul1]

I unscrewed the valve completly from the pump and then pulled the line with the valve in the line towards me a little and it came out ok.

 

[illflem]

I've done it many times on different trucks the same way Deezul describes with 100% success. It does make it a little harder to reinstall while bending the tubing back while turning the valve at the same time. Think I'll try Piers trick next time just to see, but I'll use a die grinder.

 

[Piers]

I guess I should have kept typing for an extra line or two. You still have to bend the line a little to get the valve out, but some heads seem to have a little tighter fit than others and you need to remove some of the head casting via file or die grinder to be able to unthread the valve completely. Seems the 94-95 heads have this problem more than the 96 and newer.

 

[jimk]

clearance for overflow valve

I did as Piers suggested and used a file to gain some clearance a year ago. At first I was a little hesitant, but after a while I this is a crock and I filed the housing and it worked fine.

 

[swamp rat]

A light grazing with a dremel works wonders, and it smooths out the rough burrs nicely. Just don't get crazy and lay into too hard. One or two gentle passes is all it takes.

 

[FATCAT]

Filing the head casting did the trick

Piers,

thank you very much for your idea, just a few passes with the file and I had the clearence I needed to remove the valve. Your new valve works great, I feel the "snap" of the engine now. She was getting a little sluggish before and I guess 120K+ miles is good enough for the original overflow valve.

 

[RJ2]

At 60K would I want to change out the valve ?Haven't done a pressure test, still looking for a must have deal on a electronic fuel pressure guage in a single pod.

 

[Fish On]

After getting out the old overflow valve does the one piers sells just screw back in it's place? Someone told me that the one you get from piers doesn't require filing becasue it looks nothing like the stock one? Is this true, I'm sure if piers is selling the overflow valve it would work fine.

 

[Cooker]

The overflow valve I got from Piers looks exactly like the OEM unit. It is a Bosch part and, as far as I know, it is the exact same part Cummins sells.



-Ryan

 

[Dave Remillard]

I'm joining FATCAT, because I to have a question that may sound stupid to most of you. I have over 100K on my rig without any new parts to the pump at all. It runs fine, but it sounds like those of you that know these engines and pumps think its a good idea to replace the valve. Should I be thinking of doing this and can someone explain to me its function. I looked in the manual and found the procedure to replace, but no explanation of its purpose. The bombing will begin soon, and I would like to have everything in as good of working order as I can before starting with plates, exhaust, DDT C VB ect. Thanks

 

[Joe G.]

The basic function of the valve is to keep a pressurized head of fuel in the pump so the plungers fill correctly for each stroke. As long as it does that and does not stick closed no need to replace it. A fuel pressure gauge is a nice thing to have so you can get a warning about low pressure.

 

[Cooker]

Replace the valve only if it is bad. There is no need to replace it at a set number of miles. Testing your fuel pressure is the best way to determine if the valve is functioning properly.



I'm with Joe G, a fuel pressure gauge is a nice thing to have.



-Ryan

 

[illflem]

A mechcanical oil pressure gauge setup will cost less than a $50 overflow valve from Piers. Do a search on fuel pressure gauge to find much info. Remember that a gauge for a 12 valve is a different animal than one for a 24.

 

[-Alex-]

Whats is the minimum pressure for a 12 V with a p7100?

 

[Joe G.]

Some trucks have less than 20 PSI but that is kind of a mark to start checking to see if you have something wrong. Pressure gauges are a bit of a problem on these things because of pressure spikes from the mechanical lift pump. I have a snubber on my pressure gauge line. It was not enuff to damp the spikes to a reasonable level so I added a needle valve. If the spikes are not damped they will beat the gauge to pieces. I seldom have less than 25 PSI except in hot weather. Then sometimes I will see as low as 15.

 

[illflem]

Found some new snubbers and needle valves from Grainger, very cheap -

http://www.grainger.com/images/catalog/1421.GIF lower left corner



Don't know what's going on with that link, it worked fine while it was loading but when it finished it shrunk down to unreadable. Maybe one of you computer wizes can figure it out.