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Cold start,my 6.2 "pops" out the exhaust and surges..

diesel4me

diesel4me

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Not sure if this is just "normal" for a cold start on a 6.2 or not..truck didn't do this previously..

When I went to start it up the other day at 22 degrees out,it did start after some cranking,and I heard a "pop-popping" sound like popcorn out of the exhaust--like an exhaust valve may have been sticking...after about 10 seconds it went away...

It almost sounds like it comes from the exhaust manifolds or front pipes,but I have no leaks at those points..

The engine also now surges some at fast idle,until it is warmed up some..not a "skip" or misfire,its more like one cylinder doesn't fire consistently until its been running a few minutes..it accelerates ok and pulls good,not like it has a "dead" cylinder..the engine has always had a somewhat ragged idle and sometimes it'll misfire at idle at a stoplight,but goes away once your driving it above idle..

Any ideas ?...maybe its just getting old and worn out,needs a valve job,injector or injector pump,head gasket maybe ?...if so,that means it's time to really start looking for a gas engine for this truck...:eek:..
 
It does have one dead glow plug I cant get out,but it didn't do this before--but maybe un-burned fuel from that cylinder is getting ignited in the exhaust manifold ,until it runs long enough to start firing on compression alone..?

Far as I know the rest of the glow plugs work,I did put one AC 9G in place of a dead 60G though,but I dont see why that would make any difference..the only thing that may do, is be harder to replace it if it decides to swell up..

I have inspected the fuel lines all the way back to the tank--I plumbed it with 3/8" copper tubing and only used short lengths of rubber hose to connect it to the sending unit and fuel filter..don't see any weeping or leaks anywhere along that run..nor at the line going to the injector pump from the fuel filter..

This truck never had a secondary filter since I owned it,and seeing that I had the fuel filter plug up a few months ago with rust from the inside of the canister and dirt,resulting it it having to be towed--it is possible some may have gotten past the filter and into the injectors and fuel lines to them..

When I replaced the fuel filter,I filled the new one with "Diesel Kleen" instead of fuel,and now I'm wondering if that was a good idea or not--may have loosened some crud up and now its in the injector pump,or the fuel lines and injectors?..
But--once it warms up it runs decent,and I feel it has more power than it ever did...

98% of my driving is local trips,mostly short runs under 5-10 miles,the few times I do take it further than that I use back roads that have speed limits under 40 mph..perhaps it is getting sooted up in the cylinders and the valves are getting crusty...
I'm going to add some more diesel fuel treatment and see if that improves it any..

A friend gave me a used group 75 red top Duralast battery the other day,that was bought in august 2011--it was in daily use in a car,that a customer of his decided to scrap--it seems to be in good condition,so if the batteries in the truck now keep failing to crank it in frigid weather,I'll put that one in,after determining which one of the two existing ones is the "worst" one, as far as passing the load test..if I had deeper pockets I'd just buy two new batteries,but cant,not this month at least..

I think it would start a lot easier if it had 10W-30 oil in it instead of 15W-40 too...or synthetic,but I'm leery of using that in an old engine thats had conventional oil in it "forever"..especially a "loose" old 6.2..!
 
When was the last time you ran it up to the governor? If I don't do that to mine it likes to stick and do weird stuff..
 
I floored it a few times in park after I got pissed off at it a few times a month or so ago,when it had to be jump started..as a rule I never wind it up high enough driving it to redline the govenor--I chug around under 45 mph most of the time..

I also had to use starting fluid to get it to start once when it was below 20 out ,that may have done something internally to it too..when it started it surged up and down like crazy for several seconds,and it took a good minute or so to smooth out somewhat and sound normal again..this is why I hate using starting fluid--but it was either get it started with it,or walk home..
 
Sounds like an air leak to me.. and I figure if it's mechanical it must be exercised occasionally or it'll wear a spot and start to stick?? Not sure if that is true but there being sliding surfaces in the pump it sure seems like that would make some sense.. especially with the uslf diesel now.
 
Mine used to "backfire" out the intake and pop and run rough and smoke out the exhaust too when idling. My high idle solenoid was way out of adjustment. The cold timing advance would activate but the solenoid couldn't bump up idle speed at all so the engine Would start running like crap after a minute or so of idling. If I just fired it up and drove it then it ran fine. I accidently learned of the high idle solenoid and found I had to adjust the plunger way out to get it to actually go to a high idle rpm. Then the smoking and rough running quit.
 
Thanks for the thoughts--any experiences like yours are welcome here and taken note of..

The fast idle works on my engine OK though,it does idle noticeably higher with it activated--I have it manually controlled,the sensor in the right cylinder head decided to pop the plastic part out one day,and the wires caught fire on the hot exhaust manifold!..

I got home from a 4 mile ride one night just after dark,and saw a "light" under the hood as I was walking away from the truck--good thing I opened the hood to see if the under hood lamp I installed had turned itself on somehow--it was the flames off the burning wires I saw,and the rubber fuel lines going to the injector pump and fuel filter were no more than 3" away...bet it would have burnt to the ground,if I didn't bother to investigate!..:eek:..

I'm leaning towards one cylinder thats not firing at low rpms consistently due to a leaky valve ,it sometimes misfires every so often at idle even when fully warmed up now..

It probably has lower compression in one cylinder that it doesn't get hot enough to fire the fuel by compression alone every time...once you rev it up even a bit past idle the "skip" is not noticeable..
I've also noticed the engine seems to be vibrating more than usual,but that might be due to the exhaust pipes hitting the frame or transfer case..harmonic balancer looks ok ..

I have never looked at the injector pump timing,but I'm betting someone advanced it some,because its always been more "rattly" than my other 6.2 in the Suburban and compared to others I've heard..that may be a factor too ?..the engine seems peppier than the "quiet" one in the Burb too..maybe when its cold,the cold start spark advance on top of it being advanced to start with may be letting it fire too early ?..

By the way,if its over 40 degrees,it starts "normally" and doesn't do the misfire or popping,its only when its really cold like 20 degrees,and it hasn't had the block heater plugged in--I hardly ever use it,it doesn't seem to help it start any better--its a tank type that goes in a heater hose,and is only 450 watts...it does work,but seems like it only heats up the heater core more than the engine..waste of electricity...
 
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