N108 in the way

Messed up my first IP head seal - pinched at the bottom, of course. Now on the second attempt with the tiniest piece of mirror from the side of an eyeliner box I could see a small piece of the old seal stuck in the groove, preventing the new o ring from snapping into place. After hours on my knees with that mirror and a curved pick I got to it and pushed it deeper under the pump, or maybe it has fallen out. I cannot see all the way under! Cannot verify that the new seal is 100% in the groove all the way around.

The IP is not coming out of the car, and I imagine trying to get the N108 out will be nearly impossible with the IP still in. I even have a boroscope about a 1/4 inch in diameter, and still can't see under there to be able to say that the seal is in with 100% certainty. So frustrating! What is the trick to this?!

There is a pretty good size chamfer on the bore of the pump the head slides in to but I doubt your piece of o-ring is in it.

KLXD said:

There is a pretty good size chamfer on the bore of the pump the head slides in to but I doubt your piece of o-ring is in it.

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that's exactly where it is, i believe. running the pick along the edge blindly, i can feel it stumble over the piece when the pick is at a slight angle. i backed out the head just a little more, and i can now see it with the boroscope. nasty little speck. going to move the backside screw to the top and try to get the pick in from the back. would be a lot easier if i could move the new seal, but it's too late now - i'm afraid i might pierce it trying to pick it up.

And people wonder why I don't use the whole "stretch the o ring around the front of the head" method.

I just take the whole dang pump head out to do the job. It's honestly pretty easy, just have to understand how everything lines up and how to keep the cam plate from flopping out along with the rollers behind it. I do it with the QA removed so I can see what's going on and hold the cam plate in place while removing the whole pump head as an assembly, plunger with plate and springs as one unit...

That sounds better than the what the OP's doing. I would remove the pump but if the belt's relatively new maybe not.

You should mention how you're keeping the thrust washer in place. Vasoline?

KLXD said:

That sounds better than the what the OP's doing. I would remove the pump but if the belt's relatively new maybe not.

You should mention how you're keeping the thrust washer in place. Vasoline?

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I just put it back where it belongs on the back of the plunger and very gingerly maneuver the assembly back in place. Once in awhile one will fall out on me, but you know it when it does that. Just have to take the assembly back out, fish the washer back out and put it back where it belongs. That smidge of surface tension from a little bit of remaining diesel on the back of the plunger is usually sufficient. I angle the plunger upwards a little as I'm putting the head back on, then as I near the cam plate, lower it and line it up carefully.

Prior to removal of the assembly, I rotate the engine over until I can see the opening on the back of the plunger through the QA opening (QA removed) that lines up with the nub on the cam plate that aligns and drives the thing. This puts the cam plate resting back on the rollers as well instead of extending outwards on the apex of the lobes. Makes it a bit easier to keep things in place and I can see exactly where the plunger needs to line up. Plus, should the cam plate flop forward, I know exactly what position it was in to put it back. Not very fun getting the rollers back in place while the pump is on the car, though... But it can be done. I've been known to insert a clean paper towel (I prefer Scott "Shop Towels") into the front of the pump once the head has been removed and set down, then insert a pair of clean pliers in through the QA opening to hold the shop towel back on the cam plate and keep the cam plate in place, freeing both hands up to deal with the pump head, remove the o ring and install the new one the right way without stretching the bajeezus out of it.

Either that or deegingerkid is hanging around as a very handy extra set of hands for that step of the process and I'll have her grab the pump head and install the o ring while I hold the cam plate in place after I've carefully removed the assembly from the pump. I've done several dozen pumps this way over the last several years now. If I'm opening that pump up, I'm replacing all the seals I can with it still bolted to the car. Case pressure relief valve o rings (tap the collar back flush while you're there), shut off solenoid o rings, top and middle cover seal, triangle plug that threads into the pump head (I have seen a number of them leak now--I made my own socket for it) and of course the pump head o ring itself.

Speaking of the case pressure relief valve, I have had cars that set codes for incorrect timing advance. Run a basic setting 04 and notice that the timing doesn't change AT ALL (should vary between EARLY around 8 degrees BTDC and LATE is about 4 degrees BTDC). 75% of the time replacing the o rings on the case pressure relief valve fixes it. Particularly the bottom one further in the pump. I've had those be flattened out and rock hard, allowing fuel pressure to bypass the valve altogether and just go passed the lower o ring. You'd be amazed at how much better one of these runs once the timing advance is working correctly again and it's such a simple fix usually.

But yeah, using a tacky assembly grease like vasoline isn't a terrible idea so long as it doesn't cause problems as it merges with diesel and goes through the fuel system.

It is unfortunate that the N108 can't be removed with the pump still bolted to the engine, but I rarely see them leak fortunately. Whatever chemistry those green o rings use seems to be a fair bit more durable than the normal buna-n stuff.

I did a demonstration on removing the pump head at TDIFest 2012 in Michigan, it was on film too, but I don't think that the film ever got posted. It was also on an early 1Z pump, which has a smaller QA opening and is a little bit more difficult to deal with than the ALH pumps.

Some day I should make another film outlining how I do pump seals and post it... Try to edit it to be short and to the point (unlike some of my posts).

Sounds like a good way to go about it except...

I had to reseal a pump I bought from a feller in the salt belt. When I pulled the head the chamfer on the pump body was badly corroded. Bore was too up to where the o-ring sat. I'd hate to push the new o-ring over that.

With it off the engine I was able to remove the corrosion and polish the surface with the opening downward to keep junk out of the pump then flush it with spray can.

With your method at least you can wipe that area to remove dirt. Without pulling the head out you can't even do that. I cringe at what dirt gets pushed into the pump by the new o-ring when people do it the other way.

Purists will cringe at my approach too I suppose.

Interesting thoughts on the relief valve seals. I've always thought the keeper moving out was a red herring since the piston can't fall out and fuel pressure pushes the piston in during operation.

KLXD said:

Sounds like a good way to go about it except...

I had to reseal a pump I bought from a feller in the salt belt. When I pulled the head the chamfer on the pump body was badly corroded. Bore was too up to where the o-ring sat. I'd hate to push the new o-ring over that.

With it off the engine I was able to remove the corrosion and polish the surface with the opening downward to keep junk out of the pump then flush it with spray can.

With your method at least you can wipe that area to remove dirt. Without pulling the head out you can't even do that. I cringe at what dirt gets pushed into the pump by the new o-ring when people do it the other way.

Purists will cringe at my approach too I suppose.

Interesting thoughts on the relief valve seals. I've always thought the keeper moving out was a red herring since the piston can't fall out and fuel pressure pushes the piston in during operation.

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The keeper moving out or even just backing out some does contribute to losing a little pressure, but it's nowhere near as significant a change as when that lower o ring can simply no longer seal.

I hear you on the rust belt part. When I was still living in Michigan I only did it by removing the pump from the car. Then again, I also hadn't yet developed this method. We're lucky on this coast, the corrosion is at a minimum here. These cars can still stay on the road easily for a long, long time.

when you remove the original o-ring you reassemble it and compare it with the new. When you have a complete o-ring then you know you have all the peices.

But honestly I think a miniature mirror gives me enough access to make sure there is no o-ring left in the groove.

I've pinched a couple and every employee that i've had has pinched a couple but now we have 100% success in doing it without pulling the head.