I've been reading or "lurking here a little while." I currently am driving an 82 Chevy 6.2 3.4 ton. I've had this old truck a while and it has been/ is a work in progrgess. The engine has been excellent until lately. Recently it has developed valve train noise and a plunking sound in the intake. Today while I had the airfilter off I put my fingers into the intake and it is blowing air back into the intake manifold on the passenger side. Do you think it has lost an intake valve? I checked the glow plugs and it has not ingested one of them. I have no idea how many miles. My question is how long can the bottom end last with just rebuilt heads or do I need to look for a donor or plan an overhaul.

Best regards

Kirk

The sound you describe can be caused by blowback through the intake if the gasses can't excape through a valve.

A collapsed lifter, bent pushrod, worn rocker arm, all possible causes of the popping in the intake. Even a chunk of foreign material under a valve can do this. Start with an inspection. Is there excessive crankcase pressure (blowby)? Is the noise on one side? Can you tell by putting your fingers over the intake to isolate the sound?

You may have to pull the valve covers and look for a loose rocker. The '82 should have the bushed, cast iron rockers with springs between them, not the plastic spacers that often fail. Unless someone has changed engines..........

If you find a collapsed lifter, install an external oil pressure gauge and check the pressure, low oil pressure can cause lifters to collapse.

Looks like Fred pretty much covered it for ya so I'll just say :welcome2:

Opps, forgot the :welcome2:, sorry.

The sound you describe can be caused by blowback through the intake if the gasses can't excape through a valve.

A collapsed lifter, bent pushrod, worn rocker arm, all possible causes of the popping in the intake. Even a chunk of foreign material under a valve can do this. Start with an inspection. Is there excessive crankcase pressure (blowby)? Is the noise on one side? Can you tell by putting your fingers over the intake to isolate the sound?

You may have to pull the valve covers and look for a loose rocker. The '82 should have the bushed, cast iron rockers with springs between them, not the plastic spacers that often fail. Unless someone has changed engines..........

If you find a collapsed lifter, install an external oil pressure gauge and check the pressure, low oil pressure can cause lifters to collapse.


First of all thank you for your responses. I believe the engine to be the original. The heads used the 82 injectors when I replaced the IP. I haven't noticed any excessive blowby.

The noise is on one side with substantial compression coming up through the passenger side intake. As for oil pressure I have no idea because my gauge has never worked. Where would you thread in an external gauge if I can get my hands on one.

How long can it run this way without killing itself. Were calving right now and tearing it down could be too much down time. I will inspect as suggested when I can focus on the job at hand. I am really surprised at how well it still gets down the road.

I've seen owners drive them, sounding like you describe for long periods. I would persue it as soon as time allows. If it's original, it could just be normal wear, things are starting to "talk to you" about a rebuild, but a close inspection will tell.

I usually just remove the factory oil pressure sending unit, with a 9/16" wrench, (heated and bent 90 degrees) leaving the brass fitting in the block and threading an external oil pressure gauge, 1/8" pipe thread (with a long hose/line attached), I run it up between the hood and cowl, into the driver's side wind wing to allow me to read the pressure from the driver's seat and road test it if necessary.

Thanks again. I will look for a portable manual pressure gauge.

Just an update. After using seafoam for almost a month in the oil and not having time to tear into it....my ticking and plunking have recently subsided. I am so happy and also thankful to this forum for all the helpful suggestions.

Thanks
Kirk

that last post just probably made Iamdave0887 one happy SOB.

I know it seems unbelievable...I wouldn't have put any faith in it if didn't really happen. A miracle for sure and now I think it runs better than ever.

if you had sticky rings. seafoam can free them up. giving you better compression and oiling in the cylinders. a couple 6.2's i ripped apart had a few stuck rings

What are folks' opinions of sucking seafoam into the intake via the CDR, then letting it settle for a few hours before burning it out? I saw a procedure to do this via the PCV on the 'Vette forum and was thinking of trying it on my truck. Seafoam in the crankcase + the intake = a clean motor, no?

Install a drip system through the top of the air cleaner housing! Bottle goes empty filler up again!