Valve Issue?

[motormayhem]

My truck sat for about 4 months without being driven while I was away. When I went to start it up again I thought it would be a good idea to lube up the top end of the motor before starting it so I disconnected the cutoff wire from the IP and cranked it over for about 10 seconds without it starting. Then I hooked up the primary again and it fired right up. I let it sit and idle while I finished putting stuff away and closing hood,etc. Anyway it idled great for about 2-3min and then all of a sudden it started bucking and shuttering (like it was running on 7 cylinders which I think it was). I opened the hood and took the air filter off and it was making a weird ticking/slurping noise out of the intake and more smoke than usual out the exhaust. I shut it down right away and went inside thinking it broke a rocker or something, but when I went out again it fired right up and ran like a top. I then drove it for the next 4 days and it ran normal except for doing it once as soon as it started after being parked for about 2 hours. This time I just drove it and it was gone before I got out of the parking lot. The truck then sat again for another month before I drove it again. It again ran normally except for 2 times over the course of a month where it did it right after starting and only till I drove about 300 ft. I haven't done anything yet to try and figure it out, but wanted to see what other people thought it was. I was thinking maybe a sticky valve? I threw a bottle of marvel mystery oil into the crankcase to clean everything out but it was only in there for a day before I had to leave again so I wont get to drive it a little and then change the oil and see what happens for a few months.

 

[motormayhem]

Nobody

 

[Hasdrubal]

"started bucking and shuttering" sounds like fuel starvation, not just one cylinder firing improperly. When was the last time you changed the fuel filter?

 

[motormayhem]

I think it is valve related as it makes a very loud tick out of only the drivers side of the intake with the air filter out

 

[V8Astro]

Could be injector(s) stuck open. The compression forced back into the injector line will make a loud ticking/clacking noise

 

[scottladdy]

Two words, compression test.

 

[motormayhem]

Two words, compression test.

Thats very true...ill have to do that next time im back there. Hopefully the intermittent nature of it wont just give me false good numbers on a compression test. I also hadn't ever head of compression being forced up the injectors.

 

[patracy]

Valve contact I can assure you isn't intermittent in a diesel. You'll hear a sound, followed by worse sounds, until the engine shuts off or locks. I vote fuel system related.

 

[motormayhem]

I was thinking more along the lines of the valve not opening or sticking part of the way open and not hitting the piston. The whole truck only has 58,000miles on it so I would hope its not a bad lifter. It has a 1.5 year old injection pump, but it could be an injector I guess. Oh and the fuel filter is like 8 months old and a better higher flow one than stock so I think I can rule that out, I know what it feels like when the fuel filter chokes it and it doesn't feel like that.

 

[patracy]

I was thinking more along the lines of the valve not opening or sticking part of the way open and not hitting the piston. The whole truck only has 58,000miles on it so I would hope its not a bad lifter. It has a 1.5 year old injection pump, but it could be an injector I guess. Oh and the fuel filter is like 8 months old and a better higher flow one than stock so I think I can rule that out, I know what it feels like when the fuel filter chokes it and it doesn't feel like that.

There is no "sticking part of the way open and not hitting the piston" in a diesel engine. The clearance you have between the head surface and piston crown is only your HG thickness and deck height combined. There is no "combustion chamber" like that of a typical gas engine. These engines are "interference" engines. Meaning, if the cam stops (Timing set failure) or a valve drops, piston will contact the valves and damage will incur.

 

[motormayhem]

There is no "sticking part of the way open and not hitting the piston" in a diesel engine. The clearance you have between the head surface and piston crown is only your HG thickness and deck height combined. There is no "combustion chamber" like that of a typical gas engine. These engines are "interference" engines. Meaning, if the cam stops (Timing set failure) or a valve drops, piston will contact the valves and damage will incur.

Gotcha, I guess I should have realized that since its is 21.5:1 compression. If it helps any it also seems to have more black/grey smoke out the drivers pipe when it does it.

 

[scottladdy]

Old Diesel, Injection Pumps and Injectors

It has a 1.5 year old injection pump, but it could be an injector I guess.

FYI, Diesel fuel degrades over time. It loses lubricity, or it's ability to provide lubrication.

The IP and Injectors in our trucks depend on the lubricity of the fuel. When the fuel degrades, scoring and wear will occur.

Trucks this old with very low mileage probably had very stale fuel at least once in their "careers".

If you replaced the IP, and didn't replace the injectors at the same time ... well, you can see where this is going.

http://www.chevronwithtechron.com/products/documents/diesel_fuel_tech_review.pdf

I would still perform the compression test. It is fairly easy to do, will give you peace of mind (if all is well), and will provide a baseline for future use.