Weepy injection pump

[Ajax MD]

Last week, I found fluid in the engine valley. We've had a lot of rain. The fluid was clear and odorless but seemed viscous for just water.

I mopped up all the fluid. With the hood raised and doghouse removed, I idled the engine in the driveway and carefully watched the IP. No drips for 15 minutes. Everything bone dry.
I took the truck for a 40 minute drive and found a bit of fluid in the valley down by the IP. It seems to be fuel.

If the leak only presents itself under additional pressure from driving, what should I be looking at? Is it just a loose fitting?

I understand that a crow foot wrench is best to snug down fittings on the IP. What size, and how long of an extension is needed?

Thanks.

 

[Barrman]

There are seals on the throttle shaft that are known to start seeping.

Several ways to look at it:

Just keep driving and checking to see if it gets worse. Which a lot of people do but is not the safest idea in the world.

Change the throttle shaft seals with the IP on the engine. People have done it but I really don't see how.

Remove the IP and change the throttle shaft seals and put the IP back on.

Get the IP rebuilt. I think this is the best option if you plan to keep the vehicle. If the seals on the outside are going, so are the ones inside that make your engine run. The IP has a limited lifetime due to all of the seals and is meant to be rebuilt. The engine TM has a great step by step of pulling the IP. It is really very easy. Yes, crow foot wrenches are a must. Many threads here and all the diesel truck forums about high quantity shops all over the country doing rebuilds through the mail. Do a search for any local Stanadyne service places in your area first though. They could be an option local to you.

 

[Retiredwarhorses]

Advance servo plunger seal is the common seal that leak...people say it can be replaced while in the truck, I’ve done hundreds of pumps, I see no easy way to get it replaced. If it were me, I would remove the pump and get it rebuilt.

 

[Ajax MD]

Ok, thanks guys.

I don't think I'm going to torture myself replacing seals "in situ." I like the idea of shipping it off to be rebuilt. I'll cruise the archives and see who's reputable. I'm more concerned about getting the pump back sealed up tight and working correctly than I am about saving every penny.

How long does it typically take? I might wait until this virus nonsense is over with.

 

[Retiredwarhorses]

We have pumps in stock, rebuilt...what model pump do you have?

 

[Ajax MD]

We have pumps in stock, rebuilt...what model pump do you have?

Pffft... beats me. It's a 6.5, that's all I know so far.

 

[Retiredwarhorses]

You need to know what pump yo have..look at the left side of the pump with a flashlight, I’m looking for a number like
2831-5209, or 4523, 4524, 4179.

 

[Ajax MD]

I'm still trying to get in there to get the fuel pump P/N, but my wife drove the truck for an hour.
I checked it out when she got home and the valley was bone-dry.

Maybe I'm hallucinating.

 

[Wire Fox]

Advance servo plunger seal is the common seal that leak...people say it can be replaced while in the truck, I’ve done hundreds of pumps, I see no easy way to get it replaced. If it were me, I would remove the pump and get it rebuilt.

Easy, it sure is not. I did do it once-trying to resolve a fuel leak-before the pump revealed it had worse problems and needed fully rebuilt. You have to modify an offset wrench to be exceedingly thin in order to fit between the pump and valley to get the servo advance cover off. I bought such a wrench, then ground it down until it fit the space correctly. Still was tricky and annoying, but I did replace the seal (and stopped the leak). IIRC, it took about half an hour once I had the completed tool in-hand. A week or so later, the pump just stopped building adequate pressure and needed a professional rebuilt. With how bad my fuel system looked at the time, it was certainly a case of now-flowing fuel dislodging deposits and clogging the pump.

 

[cwc]

Hi Wirefox, thanks for confirming it is possible to change the advance piston seal with the pump in place. I am looking at doing it since I have one dripping here. Do you happen to recall what you took off for access, Intake manifold, coolant crossover or other? It looks like you would have to take the lever off also, how did you drive out the pin given the limited space?

Also, did you find the seal sold individually? Seems like a waste to buy a whole soft parts kit just for that, thanks!

 

[Wire Fox]

Hi Wirefox, thanks for confirming it is possible to change the advance piston seal with the pump in place. I am looking at doing it since I have one dripping here. Do you happen to recall what you took off for access, Intake manifold, coolant crossover or other? It looks like you would have to take the lever off also, how did you drive out the pin given the limited space?

Also, did you find the seal sold individually? Seems like a waste to buy a whole soft parts kit just for that, thanks!

The complete procedure is in TM 9-2320-280-34, Section 4-5 "Servo Advance Seal Replacement". This is the TM most people seem to overlook, because it's sometimes hard to intuitively know what's supposed to be at this higher level of maintenance. You'll need to have the intake manifold removed and the pump stripped to the point of having the kick-down switch removed to begin the procedure.

Appendix C, Figure 18 of the same TM contains instructions on how to modify the appropriate offset box wrench. This should be the only special tool required beyond standard mechanic's tools.

I had purchased the whole seal kit as it was my intention to re-seal my entire pump at a later date (which I tried and failed to successfully complete). There may be the seals individually sold. They would be NSN 5330-01-233-8597 (PN 27163) and NSN 5330-01-233-2778 (PN 27609), if you can find them individually.

 

[Hummermark]

Hi I replaced this seal on one of my Humvee injector pumps a few years back,I kept the GM packing that it came in as a useful reference for part number which is 22530034 I just did a quick search with that part number and found one for $7 might be able to get cheaper if you make a few phone calls.
Other numbers on packet is 3654A8 and G.R. 3.306 seal

 

[cwc]

Thanks Wire Fox and Hummermark, greatly appreciate the info!

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