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6.2 turbocharged popping

imiceman44

imiceman44

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So I put the third transmission on my 84 suburban and took it for a test drive, made one loop around the block, everything going good then I get a big bang, and it starts to sputter, I pushed it a little and it pops, continuous popping as long as I have my foot in it and it's smoking big time.
I thought a bad injector so I ran some purge through it and it felt like it smoothed out a little bit and it didn't smoke at idle but driving it around it was still smoking and popping.
I loosened the injector lines one by one and couldn't find an injector that is the culprit.
I hear the popping at idle through the intake and out the tailpipe.
Any thoughts.
One thought is burnt valve but I didn't drive it enough to burn, literally one mile loop.
Could it be timing, skipped a tooth on the chain or something?
I can live with the popping but the white cloud that follows me will attract the cops and hate from everyone
 
I had a 6.2 with timing gears that were one tooth off, started and ran fine but excessive white smoke.

Real mosquito fogger.

88815092-D8BC-4AF8-818F-5BE235977F63.jpeg
 
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No idea...

Had a Harley that did something similar, but wasn't rideable.

Turned out to be the valves were sticking in the guides.
 
imiceman44 said:
So I put the third transmission on my 84 suburban and took it for a test drive, made one loop around the block, everything going good then I get a big bang, and it starts to sputter, I pushed it a little and it pops, continuous popping as long as I have my foot in it and it's smoking big time.
I thought a bad injector so I ran some purge through it and it felt like it smoothed out a little bit and it didn't smoke at idle but driving it around it was still smoking and popping.
I loosened the injector lines one by one and couldn't find an injector that is the culprit.
I hear the popping at idle through the intake and out the tailpipe.
Any thoughts.
One thought is burnt valve but I didn't drive it enough to burn, literally one mile loop.
Could it be timing, skipped a tooth on the chain or something?
I can live with the popping but the white cloud that follows me will attract the cops and hate from everyone
Click to expand...

Is it hard to start?

Ignoring the noise, does it produce good power when it's running?

Are you getting normal or diminished amounts of boost?

My first thought is timing chain skipped a tooth, but that should have affected these items. If so, you will be able to compensate somewhat by adjusting the IP timing. If that solves your issue, you'll have good confidence it's a timing issue. Could also be the IP suddenly getting loose, as that would also throw off the timing.

Any idea how worn the timing set is? Is the chain loose?
 
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Head gasket, cracked head or block. Just a random thought.
More so wanted to reply to find out what the actual problem is.
 
campfire said:
Is it hard to start?

Ignoring the noise, does it produce good power when it's running?

Are you getting normal or diminished amounts of boost?

My first thought is timing chain skipped a tooth, but that should have affected these items. If so, you will be able to compensate somewhat by adjusting the IP timing. If that solves your issue, you'll have good confidence it's a timing issue. Could also be the IP suddenly getting loose, as that would also throw off the timing.

Any idea how worn the timing set is? Is the chain loose?
Click to expand...
It starts pretty easily, but maybe a couple of revolutions more than before but it's also colder now.
Boost is still the same at 8psi
It feels a little weaker but otherwise runs decent other than the plume of smoke trailing and the popping continuous.
I have it trapped now so I can't drive it but I will take a video to show the smoke and the sound.
 
bigblock454 said:
Another possibility is a rockerarm button. Compression test is fairly easy on those.
Click to expand...
Tell me more about this.
I have the compression tester for diesel somewhere so I could do that but what do you think happened?
The button popped or twisted or what?
It is steel if I remember correctly right?
 
imiceman44 said:
Tell me more about this.
Click to expand...

There is a nylon button that holds both the intake and exhaust rockers in place. Those are known to get brittle over time and break off allowing the rocker to slip off the valve.

Assuming your IP is tight and hasn't shifted a compression test is probably the next easiest thing, and might tell you which side to tear into first. A slipped timing tooth I guess is possible but i'd think that much of a shift would really be noticeable in starting/performance.
 
Not a diesel but I have had popping out the intake. Been a while, 15 years ago probably. I had wiped out a lobe on the cam. I think it was an exhaust lobe. When the intake valve would open the extra pressure would "pop" back out the carb. It would start right up and drive around the block ok, popping the whole way. Pulled the cam and 1 lobe was round. I had messed up the valve lash during a previous adjustment, went too tight trying to quiet down the valvetrain. If you have popping out the intake it sounds like a timing or valve issue to me.
 
bigblock454 said:
There is a nylon button that holds both the intake and exhaust rockers in place. Those are known to get brittle over time and break off allowing the rocker to slip off the valve.

Assuming your IP is tight and hasn't shifted a compression test is probably the next easiest thing, and might tell you which side to tear into first. A slipped timing tooth I guess is possible but i'd think that much of a shift would really be noticeable in starting/performance.
Click to expand...
This might be the most possible explanation.
It happened suddenly and I had only warmed it up and drove around a one mile loop and it popped with a bang and that's all she wrote
 
bigblock454 said:
There is a nylon button that holds both the intake and exhaust rockers in place. Those are known to get brittle over time and break off allowing the rocker to slip off the valve.

Assuming your IP is tight and hasn't shifted a compression test is probably the next easiest thing, and might tell you which side to tear into first. A slipped timing tooth I guess is possible but i'd think that much of a shift would really be noticeable in starting/performance.
Click to expand...
I guess I will be checking my other heads for those parts then possibly checking for new buttons.
 
bigblock454 said:
There is a nylon button that holds both the intake and exhaust rockers in place. Those are known to get brittle over time and break off allowing the rocker to slip off the valve.

Assuming your IP is tight and hasn't shifted a compression test is probably the next easiest thing, and might tell you which side to tear into first. A slipped timing tooth I guess is possible but i'd think that much of a shift would really be noticeable in starting/performance.
Click to expand...
So I finally pulled the intake off and ran the engine and it is cylinder # 4 that has exhaust popping out of.
I pulled the valve cover on that side and I can't find anything wrong.
Push rods are not bent, rockers are tight.
Only thing I can think of is maybe broken ring?
I guess a compression check will show me that?
It could be a flat lobe on the cam or a burnt valve but it happened instantly, those happen gradually.
 
1984 6.2 has the rocker arms on a roller shaft so no buttons to break.

What turbo set up do you have? To get 8 psi out of my Banks turbo I have to be climbing a hill with the throttle to the floor, rpm above 2500 and rolling along above 50 mph. I’m just curious.

What color is the smoke? Puffy white is coolant. Dirty white is cold engine with fuel but no combustion. Blue is oil and normally means rings or valve seals.

My thought is head gasket. Pull all the glow plugs and do compression checks. 2 cylinders next to each other with low numbers would point to the gasket bad. My GEP engine came from the military with that exact fault.

I don’t have a video of a popping 6.2. But, my signature below is my YouTube channel. I have a video of my M35A2 popping. It has a bad head gasket that I need to replace.
 
Barrman said:
1984 6.2 has the rocker arms on a roller shaft so no buttons to break.

What turbo set up do you have? To get 8 psi out of my Banks turbo I have to be climbing a hill with the throttle to the floor, rpm above 2500 and rolling along above 50 mph. I’m just curious.

What color is the smoke? Puffy white is coolant. Dirty white is cold engine with fuel but no combustion. Blue is oil and normally means rings or valve seals.

My thought is head gasket. Pull all the glow plugs and do compression checks. 2 cylinders next to each other with low numbers would point to the gasket bad. My GEP engine came from the military with that exact fault.

I don’t have a video of a popping 6.2. But, my signature below is my YouTube channel. I have a video of my M35A2 popping. It has a bad head gasket that I need to replace.
Click to expand...
That would make sense, I already had a bad head gasket failure and I cheaped out and got the stock gasket and TTY bolts, should have gone with the thicker gasket and ARP studs.
And I have the ATS turbo.
I get 5psi most times but if I push it hard, I reach 8psi max
 
Barrman said:
1984 6.2 has the rocker arms on a roller shaft so no buttons to break.

What turbo set up do you have? To get 8 psi out of my Banks turbo I have to be climbing a hill with the throttle to the floor, rpm above 2500 and rolling along above 50 mph. I’m just curious.

What color is the smoke? Puffy white is coolant. Dirty white is cold engine with fuel but no combustion. Blue is oil and normally means rings or valve seals.

My thought is head gasket. Pull all the glow plugs and do compression checks. 2 cylinders next to each other with low numbers would point to the gasket bad. My GEP engine came from the military with that exact fault.

I don’t have a video of a popping 6.2. But, my signature below is my YouTube channel. I have a video of my M35A2 popping. It has a bad head gasket that I need to replace.
Click to expand...
Well knowing I had trouble with the head gaskets before I assumed that was most likely the culprit.
I pulled the head off and sure enough a chunk is missing between 4 and 2, and the rings are blown towards 2.
Also the ring between 4 and 6 is starting to deform towards 6.
I pulled the other head and there was some evidence of future problems as well with deformed rings.
Talking to my parts guy at napa who also builds turbo engines all the time and decided to go with 6.5 TD head gaskets 10 over and stock head bolts.
Here are some pictures.
First is blown side (passenger side)
20230119_123019.jpg20230119_123024.jpg
Tomorrow I will torque the heads and then finish putting it together.
Hopefully this is the last time in this motor for while
 
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