Replacing mechanical lift pump

[Doug Towne]

Hello, I'm in the process of changing the lift pump on my 83 Sub. 2WD 6.2 with a Banks turbo.

There is not very much room to work up there with the cross over pipe in the way. I managed to get the old pump off with some cramped fingers and a few choice words.

My question is, will the pump bolt up correctly if the pump arm is not properly engaged with the rod?

I can fit the tip of my finger between the the rod and the backing plate. Is that enough room to slip the pump arm in, or will I need to remove the plate and use grease on the rod?

Thanks

[DmaxMaverick]

You have to get the push rod up or the pump arm won't engage it properly. The pump will install with the arm along side it, making it worthless.

Rotate the crank to be sure you are working with the rod on the low side of the push rod lobe, just like a valve push rod. If you are TDC, it should be clear.

Heavy grease, like wheel bearing grease, is the best way to do it on the vehicle. You don't really have enough room in there to do it any way else. If you have enough room to work with you can use a fealer gage slipped between the turbo adapter and block. You will have to bend the fealer gage inward to hold the rod in place. Be careful to protect the gasket.

If all else fails, and I mean all other options, there is one other way. Loosely wad up a small piece of construction paper and place it in the hole to hold the rod up. Use no more paper than necessary, and make sure it is coarse construction paper. The paper will break down over time, is non-abrasive, and hurt nothing. It will probably never leave the hole. There is, however, a slight chance that a large enough piece could get out and plug a small hole. I've used this trick several times in urgency with no problems. Attempt at your own risk.

[arveetek]

Here are some step by step instructions I wrote a long time ago that might come in handy for you:


Hard starting can often be attributed to a failing fuel lift pump. This mechanical pump is mounted down on the lower, front passenger side of the engine block, in the same place as on the gasser blocks.

I have changed several pumps, and through trial and error, have come up with the following tips for changing this pump out. When you remove the pump, you allow air into the system, and if you don't follow these steps, you can end up with an air-locked diesel engine, which can be rather frustrating to start.

These steps apply to 84 and up 6.2L diesel equipped trucks with the Model 80 square fuel filter mounted on the firewall. For 82-83 trucks with the round, spin-on style filters, read the note at the bottom.

First, drain the fuel filter. On the very bottom right side of the fuel filter assy. is a little plastic valve. Right under this valve should be a barbed hose fitting pointing straight down....it will be hard to see, you can feel it though. There might already be a length of hose attached to this fitting. If not, get a length of hose to help drain the fuel away from the truck and into a pan or something. You don't have to, but it will make a much cleaner job.

On top of the fuel filter assy. is another small plastic valve directly above a smaller barbed fuel fitting pointing straight out on the left side. This is the air bleed valve. Open this valve, and then open the drain valve on the bottom. This will let the fuel drain out of the filter, down the hose, and into a pan. This will prevent fuel from spilling all over you when you remove the pump.

After the fuel has drained, start removing the pump by disconnecting the fuel lines. The suction side will have a rubber hose and clamp, the pressure side will have a steel line screwed into the pump. Use a 9/16" line wrench if you can to avoid stripping this fitting. When you remove the suction hose, it may continue to dribble fuel out. If so, shove a 3/8" bolt into that hose to stop it up.

Next, remove the two mounting bolts holding the pump on. IIRC, you need a 1/2" socket for this. The bolt on the back side of the pump is hard to get to. You can try getting to it from the top side of the motor or from the bottom. I think the top side is just a bit easier.

Remove the pump.

Now remove the plunger rod cover by removing the two remaining bolts at the bottom. IIRC, these require a 7/16" socket. You have to remove this plate in order to remove the plunger rod. When you removed the pump, the rod probably fell down. Now you can't get the rod to stay up in place. (This rod rides against the camshaft, which in turn rides against the pump plunger.) Once you remove the cover, slide the rod out. Cover it with thick grease, and shove it back up in the hole. The grease will help hold it in place. There is a chance that the motor shut off in a place where the camshaft lobe is holding the rod out in the extended position. If this happened, it will be next to impossible to install the pump. I suggest you rotate the engine by putting a large socket on one of the front pulley bolts. You can tell when the rod is retracted all the way because it goes way up in there out of the way.

Clean up the surfaces on the rod cover and the engine block. I like to use Ultra Copper silicone sealant on these parts. Reinstall the cover.

The pump should come with a gasket. I typically install the gasket along with Indian Head gasket Shellac.

Install the pump.

Reconnect the fuel lines.

Now you have to bleed the fuel system. First, if you haven't recently replaced the fuel filter, go ahead and install a new one. Just undo the clasps and pull straight out on the filter. Put a little oil on the o-rings of the new one when you go to install it. The new just pushes back on.

Close the drain valve on the bottom of the fuel filter assy, but leave the air valve on top open. Next, disconnect the fuel cut-off solenoid on the injection pump. This is the pink wire right on top of the pump itself. We want to avoid pumping any air into the injection lines when we start cranking the motor, and by removing this wire, the air can't get into them.

To save battery power and the glow plugs, disconnect all 8 wires going to the glow plugs. (that is if you have an automatic glow system...if yours is manual, then just don't glow!)

If you can, install a piece of clear tubing over the small barb on the top left of the fuel filter assy. I usually run this clear hose into a container sitting on the cowl of the vehicle so I can see it from the driver's seat.

Start cranking the motor over. We're not trying to start it, we're just priming the system. What you're doing is pumping fuel from the tank, into the pump, up to the filter, and back through the return lines. Since the injection pump is disconnected, it won't get any air in it and get air-locked.

Only crank the motor for no more than 30 seconds. I have personally burned up a starter by cranking too long. Let the starter cool for 2 minutes before cranking again.

When you see clean diesel fuel coming out the hose at the top of the fuel filter, shut the air bleed valve off, disconnect the clear hose, reconnect the pink wire to the injection pump, reconnect the glow plugs, and start it up. I guarantee it start up on the first try with this technique (as long as the injection lines didn't have air in them to start with).

I know this seems like a lot of steps, but you should be able to get this all done in under 2 hours. I can do it now in under one hour. Using these steps makes it very easy to change the pump and bleed the fuel system.

BTW...you can use these same steps to change the fuel filter. Just skip the part about changing the pump!

Good luck!

NOTE: Since the 82-83 trucks use spin-on fuel filters with no air-bleed valves, the only way to bleed the system is to fill the filters up with clean diesel fuel, install them, and then crank the engine over for a while with the pink wire disconnected from the injection pump. It's hard to know when the air is purged, but I have found that two 30 second cranking sessions should be plenty. Then reconnect the pink wire, and start the engine. Keep the motor revved up a bit until it seems to be running smoothly.

Casey

[britannic]

If you don't want to take the turbo and manifold off, I recommend unbolting the pass. engine mount through bolt and lifting the engine as much you can to provide better access to the lift pump bolts.

It's a royal pain, but definitely doable with great patience and nimble fingers. It really helps to use gear wrenches if you have them. I've changed the lift pump twice using this method.

[Dieselboy]

After the turbo, that corner of the engine has become what I call a "high rent district." I went ahead and put on a new pump at the time of the project, and I don't look forward to replacing it. Let me know what tricks you employed to get it done. ;)

[Doug Towne]

Well, I got the new pump bolted up. Yes, nimble fingers, swivel sockets and various extentions did the trick.

The problem I'm battling now is get the hard line to the pump started. Unfortunately the turbo oil return line is right up against the hard line making it very difficult to get things lined up.

My breaks over, back to the cold concrete.

Thanks for the replys.

[Quack_Addict]

Just curious, can you run an electric fuel-pump in place of the lift pump? I don't see why it wouldn't work (lift pump pretty much describes it's function)... unless Diesel is too viscous for such a pump to handle.

[britannic]

Originally posted by Quack_Addict:
Just curious, can you run an electric fuel-pump in place of the lift pump? I don't see why it wouldn't work (lift pump pretty much describes it's function)... unless Diesel is too viscous for such a pump to handle. Yes you can and in fact I have a brand new inline electric OEM GM 6.5LTD pump if you're interested.

[Doug Towne]

I'm sure most of you have experienced this before. You've got a problem that giving you fits. You reluctantly take a break to calm down and get a shot of your favorite beverage. You then return to the problem and everything threads,slips and falls into place just like it's suppose to.

As you've probably guessed, the pump is in and the beast is running. The leaking fuel pump is solved but unfortunately the other problem I thought would be associated was not.

The engine starts to "lay down" and miss in the higher rpm ranges. I don't have a tach, so I can't tell at what rpm this starts to occur. I'll deal with this another day.

As for changing the pump, I wish I could offer some great tips that haven't already been given, but the truth is, it's just a difficult job given the very cramped quarters. Although, small hands and forearms would be a plus.

Thanks again for the excellent tips.

[britannic]

Originally posted by Doug Towne:
Well, I got the new pump bolted up. Yes, nimble fingers, swivel sockets and various extentions did the trick.

The problem I'm battling now is get the hard line to the pump started. Unfortunately the turbo oil return line is right up against the hard line making it very difficult to get things lined up.

My breaks over, back to the cold concrete.

Thanks for the replys. To get the hard line started, I found it easier to loosen the line's clips, get the nut going on the pump and then tighten the clips back up.

[Quack_Addict]

I'm sure most of you have experienced this before. You've got a problem that giving you fits. You reluctantly take a break to calm down and get a shot of your favorite beverage. You then return to the problem and everything threads,slips and falls into place just like it's suppose to.
Nope... my experience has been that everything seems to go together pretty easy; when 90% complete I realize I forgot to put that one little washer, clip, hair-pin or other seemingly near insignificant component in and have to tear everything back down to put it in. Then, nothing wants to go back together properly on reassembly and that is what gives me fits and has me swearing like a sailor. ;)

[Quack_Addict]

Brit -

I appreciate the offer but I'm not in need of a new lift pump at this time - I just put a new one on my rig last fall. Just curious if it would work.

[CleviteKid]

Not only will an electric lift pump work (that is what all the 6.5LTD trucks have) but it will work WITH the mechanical lift pump. Take a look at LIFT PUMP AND FILTER (http://www.thedieselpage.com/features/leefilt.htm) for more information.

Dr. Lee :cool:

[JACK ROBERTS]

I've been there and done this, the mechanical pump replacement is UGLY. I am a believer in changing to electric pump, it's easy and makes replacing filters much easier. My 2 cents. Jack

[mirage]

I've got to agree with Jack, replacing the mechanical lift pump with an electric one is one of the better things I have done to my truck :)

Mirage

[RaptorMan555]

I've been using the electric lift pump on the firewall for quite a few years now and have one on my new project truck, never had the first problem and the mechanical pump is still on the engine. Seems the crossover pipe shortens their life from the heat. I tried heat shields and all but the electric pump is trouble free for me!

[jcomp]

I think the banks instructions should include a paragraph suggesting an upgrade to an electric pump. I made the mistake of not following the instructions exactly in order when I installed my banks kit and ended up installing the lift pump after the exhaust manifold. That was bad enough.

Now that my engine's out of the truck, it's getting a nice low maintenance block-off plate instead of a mechanical lift pump. :cool: