Injector Joy

[Astrogoth]

Well I changed the drivers side set today. A lot more effort than I thought. They were in very tightly. So tight they squeeked for several revolutions during removal. I sent away for a Snap-On-Tool 6.2L GM Injector Socket ($40!) and I'm glad I did. The normal 30MM's are too wide to get in there. It's a 1/2 inch drive socket so have a large wrench to stick it on. An extension bar to add length to the wrench's handle for extra torque is a must. You'll need it.
The new injectors went in easely. Finger tightened up untill the final 1/2 revolution. Don't forget the copper washer they need. Have to get some small hose and clamps tomorrow and I'll be finished.

All I can say is this had beter cure the white smoke problem.

[Action]

I went to the local GM dealer to get a few of those clamps for the injector vent line hoses. They were about $3 each! I am glad I only needed two of them.
Jason

[JoeB]

Jason:
You can get an entire kit with new injector vent line hoses and all clamps, enough to do all eight injectors for about $25 from Diesel Injection Service. They advertise on the 6.5 Diesel web site.
Joe

[Astrogoth]

Injector service finished today. The rears were easy from the inside of the cab with the engine cover off.

Results: The white smoke on acceleration and just a whiff at idle is still there unchanged. The engine seems a bit smoother but that could be my pride talking after working on it for three days and waiting for three weeks due to weather. No improvement at all.

I'm now thinking valves or, gods forbid, a small hole in a piston. It's not a gasket due to the water level not droping and the oil not being contaminated by water. Both those scenarios can't be fixed in my driveway here so I have to look for a good mechanic nearby. Anyone know one? San Bernardino area.

Yea, I know it's a hobby but boy am I pissed. All that work for zip.

[dilvoy]

Does it still smoke when the engine is fully warm?

[Astrogoth]

Yup. I let it warm up to 200 in my drive around the block.

I think my truck was made by the Russians to bankrupt its yankee capitalist owner. Either that or it's cursed by Satan. Or I am. I'm tired.

[battlebuggy]

The smoke can come from injector pump problems and timing also. I would not be thinking valves/seats or holed pistons. Many people do not realize that timing is very critical to diesels and miss the correct setting by a small amount. That is all it takes to get incomplete combustion. You can positively eliminate those scenarios by a compression test that you can run in your driveway. Also I have never seen a dead cyl problem where it would not cause the engine to run rough, especially under any load. You can feel it. An old shade tree method you can try to locate dead cylinder issues is to have the engine idling and while noting the RPM loosen the fuel line on the supply side of the injector. Wrap a rag around it to catch the fuel. This will kill the cylinder. If the engine slows or stumbles a little then that cylinder is OK. As a further test listen to the engine speed increase as you tighten the line again. Do that with all cylinders and if you find one that does not cause a change then I would suspect it and move to the compression test of the engine. You can do the comp test with any good mechanic tester or the STE-ICE adapter.
Glenn
MVPA
MTANJ

[Astrogoth]

Time for an STE-ICE tester I think. Thanks.

[dilvoy]

I had a CUCV start putting out white smoke and loose power very quickly. It was running fine, then the next day it barely made enough power to get out of the driveway. I had to put it into low range to get out. My problem was with the fitting at the top of the injector pump where the fuel return line, that brings return fuel from the injectors back into the pump, attaches to. This fitting has a small glass plunger inside with a small coil springbehind it. In my case the plunger got stuck in the almost closed position. According to a shop manual, timing advance is affected by the pressure of the return fuel into the injector pump. I removed the fitting and tried to blow through it and i could not. I broke the glass part out and removed the spring, all with a paper clip on the side of the freeway, with a paper clip. To my relief everything was back to normal. I think the glass plunger and spring are there to even out pressure pulses of the return fuel, so timing advance does not pulse and give an uneven idle, for smooth operation. The truck though still had just as smooth idle without the plunger. If you break out the plunger, be sure to remove the spring and any broken glass, so nothing gets into the injector pump. George

[Astrogoth]

Well, after a long inspection I've come to this: Humvee's do not have a lift pump. Mine doesn't. Hummers do. NAPA has replacements for $76.00. Anyway my Humvee has a gasoline engine type fuel pump on the lower block. The mysetry deepens.

[Guest]

That is the lift pump. Fed Regs made the civ trucks use an electric which would shut down in an accident via electric circuit. Your mil truck simply uses an AC mechanical pump which is much better anyway.

[dilvoy]

Guest is correct on the lift pump issue. The mechanical one that is in the normal Chevy gas engine fuel pump position and can be weak and not providing enough volume for the Injector pump to have enough fuel to operate properly. I pride myself in not being a parts changer to fix problems, but you might change the lift pump. It is pretty exposed on a Humvee as compared to most Civilian vehicles and should ge easy to do. If yours is the original one to the vehicle it has served it's time. My guess is that it won't fix your problem, but they only cost about $40 or so. Too cheap no to try.

[Astrogoth]

Good point. Easy to get at. Only $40. Already ordered from Kascar. We will see. Is there any trick to replacing one?


Extra set of (slightly) used injectors for trade. Since replacing them didn't help the smoke issue I can safely say they are in good shape. Anything uncommon and Humvee related considdered. Price not a factor.

[dilvoy]

Astrogoth, There are two bolts that hold the pump against the plate that is attached to the block. That plate is there, because there is a steel shaft that runs on an excentric that is on the cambshaft. It brings the motion down to where the lever on the fuel pump can get to it. That shaft will want to slide down against the metal plate and not allow the pump to be installed. The lever of the pump needs to be under the shaft, so don't try and force the pump on with the bolts, if the pump is cocked sideways. Depending on what position the excentric is on the camshaft the shaft sticks out more or less. Less is easier. You can rotate the engine to get it to the best position. I have installed pumps with the shaft in the farthest out " worst position" though. The pump will be kicked out at the bottom while you tighten up the bolts. In this case the spring pressure of the pump lever arm needs to be overcome to bolt the pump into place. With the bolts partially in place you should be able to use your hands to over come the spring and have the pump line up, if not the shaft has slipped down to the side of the lever. I have used brake cleaner to clean off the shaft of oil and then used grease to keep it up. it still slides down though. I now use a dab of engine sealant and let it set for a few minutes. I had another thought sometimes a clogger fuel filter can cause white smoke in diesels, but there is usually a loss of power too.

[Astrogoth]

Thanks dilvoy. One of the first things I did when I got this beast was to change the fuel filter. As far as a loss of power... I've never driven a Humvee that had much power! Still mine seems worse than the others. We'll see about that. I know there's a filter screen *in* the fuel tank for large dirt. If that's clogged blowing compressed air backwards through the fuel line when the pump's off may fix it. I'll remember to remove the fuel cap first!


The pump R&R sounds easy. I just wondered if there was anything unforseen involved. You cleared that up. Now I have to wait for the parts. That's okay. Rain predicted for next two days.