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Replaced injector nozzles then problems

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anhipps

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Just finished changing out the injector nozzles, started up fine, let it idle for a while while I took stuff out of the bed, then took it for a test drive. Was running good initially. Then I did a medium acceleration run with it(3000 rpm), ok at first, then saw blue smoke after shift to 3rd. Slowed down, sped up, ok.

Slowed down, then accelerated mildly through the gears, blue smoke as it shifted into higher gears. Slowed to turn around, running rough. Took it back home. As I slowed for a corner running not too bad, came to another corner running rougher(missing) blue smoke even when driving slow to the house.

Shut it down and did a visual, no leaks, no spewing, but... (edit: found the coolant to be a little dark. That settled out later). I have searched both here and at the "Place" couldn't find anything about oil in coolant(disregard, no oil in coolant)(I may not know how to do the most effective search, but I tried what I know).

I'm a self employed carpenter and this is my bread and butter truck. I'm going to pull the glow plugs to see if I can isolate the affected cylinder(s). I'm hoping its just a head gasket. Whatever input you foks can throw my way would be appreciated.

1993 GMC 3500. Stock except, 3" down pipe, 3" straight exhaust. 215,000 miles. Injectors were original as far as I know.
 
Last edited:
An update to the above post.

Pulled the glow plugs on the passenger side, the third cylinder back is wet. others are dry with some soot. I'll check the other side make sure I dont have a problem over there as well. At least it may be only on the "easy" side.

I suppose I'll need to pull the head, get it checked out(?) and hope its only the gasket.

My thinking...... New nozzles, increased cylinder pressure, pressure pushes past aged gasket seal.

Well, half the morning shot, I've got to transfer my tools to my old truck and get to work. Now I guess I'm glad I kept the old gasser just in case. Again, thanks for any help or pointers to applicable threads. I'll be checking back after the days work.
 
Well, I decided to keep checking the truck out.

I was incorrect in my first post, there is NO oil in the coolant. The darkness might be some soot and that settled out after a couple of hours.

I pulled the injector to test it and it pops good. Put the injector back in and then started up the engine and cracked the lines at each of the passenger side injectors to see how the engine responded. At the suspect cylinder, no change, at the other three cylinders, engine stumbled more. I will crack the lines on the other side to eliminate everything except the one wet cylinder.
 
The truck was running fine before rebuilding the injectors. It was starting a little slower and lukewarm starts(too warm for glow plugs but too cool too start without extended cranking). Even with a bad cylinder, it is starting faster.

By the way, I changed all the glow plugs to Bosch duraterms when I did the injectors.

I would like to do a compression test, but I need to find out what it should be and get a hold of the proper tool.

Tonight after work, I fired it up to check to see if there wereany bubbles in the coolant(none) or if there was extra crankcase pressure(seemed ok).

It would seem that I have good fuel at the cylinder but not enough compression to light it off. Even if I do a compression test, won't I still need to pull the head to identify the problem?
The possibilities seem to be:
head gasket
valve
hole in piston
bent rod(?)

Anything else? Again any help would be great, in the meantime, I'll keep searching the archives and checking what I can.
 
I would swap the injector in the dead hole to see if that is the problem. You said it did not have this issue until you did the work, and it ran fine initially. My bet is the nozzle is doo-doo.
 
I swapped injectors with the front cylinder, the problem did not follow the injector. I also hooked up the injector to the line outside the head, and cranked the engine. Injector gave a good puff at each cycle.

Then I decided to check the compression with my conventional compression tester gauge(320 psi). Used a grease gun hose to hokk it into the glow glug hole. With the engine cranking, the needle on the gauge did not move at all, nothing. I gave the gauge a puff from my air compressor to make sure it would move with some pressure applied and the gauge is good.

So it would appear that I have no significant compression on that cylinder. I would have figured that if it was the head gasket, there would be some compression.

Now I think I might try to get that cylinder to TDC and apply air to it to see If I can hear where the air might be leaking to. But even if that gives me some indication of the problem, it looks like I have no choice but to pull the head.
 
anhipps said:
I swapped injectors with the front cylinder, the problem did not follow the injector. I also hooked up the injector to the line outside the head, and cranked the engine. Injector gave a good puff at each cycle.

Then I decided to check the compression with my conventional compression tester gauge(320 psi). Used a grease gun hose to hokk it into the glow glug hole. With the engine cranking, the needle on the gauge did not move at all, nothing. I gave the gauge a puff from my air compressor to make sure it would move with some pressure applied and the gauge is good.

So it would appear that I have no significant compression on that cylinder. I would have figured that if it was the head gasket, there would be some compression.

Now I think I might try to get that cylinder to TDC and apply air to it to see If I can hear where the air might be leaking to. But even if that gives me some indication of the problem, it looks like I have no choice but to pull the head.
Click to expand...

Eventhough it doesn't look like it has compression it could be the guage even w/ the air you blew into it. I would try it on one of the other cylinders just to be sure.
 
I did use the gauge on another cylinder and the needle swung past 250 on each compression stroke.
 
"Now I think I might try to get that cylinder to TDC and apply air to it to see If I can hear where the air might be leaking to. But even if that gives me some indication of the problem, it looks like I have no choice but to pull the head."

If you do this and you hear air leaking at either the exhaust or intake, I would make sure that the valves aren't stuck or a broken spring. Take a close look at them when you remove the valve cover. It bothers me that you lost compression after changing injector nozzles. Doesn't make sense. Maybe someone else can shed a little light here. Good luck...
 
If you pull your valve covers and find a rocker button busted and a rocker off center holding a valve open, I have 16 new buttons left over from my 6.5. PM me as I don't get in the 6.5 section much if you need them. I was fixing to gather up old parts and put things on ebay this weekend. Many a folk had replaced the plastic with a bolt and metal washer setup, search for it if it turns out to be your problem. Good luck!
 
I was able to get to work on the truck this evening. Pulled the driver's side valve cover to see what I could find.

Found broken exhaust valve spring on the #5 cylinder. It could be a lot worse and I hope that is the only problem. I'm still not sure why it would have occured with the nozzle change, maybe it was ready to go and the higher rpm of the test run pushed it over the edge.

Anyway, now I need to get a new spring, and change it out. I'll need to bring that cylinder to TDC. Can you see the piston through the injector hole if you look at the right angle? Or is there another way to tell when the piston is all the way up? I guess its time to go searchin' for info.

If anyone out there has some words of instruction, I'm all ears.
 
make up a fitting to go from air line to glow or injector hole and put it at TDC...hook up air and put around a 100psi in to hold up valves and change the spring...go to autozone(or some other parts store that rents tools) and get a valve spring compressor...
 
Pull off rocker arm shaft and put compressed air into the cylinder. Probably thru glow hole. you may have to rig up a fitting to make do. No need for TDC. Air will hold valves shut. Compress spring and remove keeper. Install new spring and re-install keeper and rocker shaft. I thought the problem was on the passenger side?
 
Thanks for the input. I incorrectly wrote "passenger side" in an earlier post. The broken spring is on the driver's side.

Now I have to get a new spring and then find some time.
 
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