Hamilton Felix
01-31-2005, 03:23 AM
I've got one here that's baffling: :confused:
This particular problem is happening on a Chevrolet, but I don't think it is brand specific. Whatever this is, I think it could happen on a Ford, Chev, Dodge, etc. I just want answers.
1993 Chevy half ton with 4.3 V6 and 4L60E automatic ---
Drove me nuts to work on this half metric, half U.S. abortion. :mad: The trick engine-to-trans bolts were worst, with 3/8-16 thread going into the engine, a 9/16 wrench sized "head," then more bolt extending past that, in 8mm x 1.25 thread to take a nut that uses a 13mm wrench. I want my OLD trucks!
Engine pulled for rebuild after it puked a mainseal. Sent out to commercial rebuilder.
Engine came back from rebuilder, sat on my engine stand in my shop for about nine months. Finally got put back into the truck.
Truck would barely start, would not idle at all, would die if put into gear - even at high rpm. We figured Idle Air Control on the Throttle Body Injection. Knowing it needed better timing and a few other checks, we trailered it to Mr. Goodwrench.
Local GMC dealership at first thought IAC and a locked torque converter, but got into it and found the only problem was late valve timing. The rebuild shop had put timing chain and camshaft together wrong. That was fixed, and cost a pile of labor dollars. They assured us the incorrect cam/valve timing was the only problem.
The truck was driven maybe a mile, over the Louis Auto Glass for a windshield, then back the the dealership, then Karen and Joel picked it up the next day, and Joel drove it the 50 miles back to Marblemount.
Joel said it had good power when he left the dealership and got out onto the freeway. He noticed it downshifted twice on a hill about 9 miles short of Marblemount, though he hadn't really changed throttle position. Maybe it was getting weak. He got to my Rental One, a mile above Marblemount, and the truck would not restart. The exhaust manifolds and exhaust system back to the catalytic converter showed red hot.
Joel let the rig cool, beat on the catalytic converter a bit, then drove it the five miles to my shop. We figured plugged catalyst was the only answer.
Last night, I removed the converter, went through three layers of metal, and emptied out the contents. Tonight, I welded our little "door" closed again (two layers, top side of converter), then put the converter back on the truck(hey, it was screwed anyway; I can always go buy a good one if we end up somewhere that they test emissions on a '93 pickup). . Joel and Karen took it for a test drive. I could see some exhaust leak from the bad muffler behind the converter, but nothing seemed obstructed.
They came back soon, Joel saying we had a problem and asking me to come outside and look. I walked out, and I could still see some glow on the right exhaust manifold. I had Karen restart briefly. Exhaust seemed to be coming out of the tailpipe, but it sure seemed hot. Oil pressure is good, and coolant temp has not jumped (and this thing has a ridiculously small radiator, so it wouldn't handle much extra heat). And now there's a pretty good knock that seems to be coming from the right bank.
Now this is professionally rebuilt engine, assembled by a reputable builder. How many things can be screwed up??? Mr. Goodwrench wasn't too surprised about the cam mis-timing, because there was a run of timing chains that was mismarked. Just following the factory manual directions will get you a mis-timed camshaft.
What the H--- can we have that's turning the exhaust manifolds into afterburners? And where did we pick up that knock?
I'm baffled. This thing does not have the AIR system with pump (like my '77 F250), though I believe it does have EGR. Again, it's a '93 with TBI, just rebuilt. I'm open to suggestion here.
I think I just heard someone suggest I enjoy an excellent imported dark beer, then to go bed. :beer: :D I've had enough for one night.
This particular problem is happening on a Chevrolet, but I don't think it is brand specific. Whatever this is, I think it could happen on a Ford, Chev, Dodge, etc. I just want answers.
1993 Chevy half ton with 4.3 V6 and 4L60E automatic ---
Drove me nuts to work on this half metric, half U.S. abortion. :mad: The trick engine-to-trans bolts were worst, with 3/8-16 thread going into the engine, a 9/16 wrench sized "head," then more bolt extending past that, in 8mm x 1.25 thread to take a nut that uses a 13mm wrench. I want my OLD trucks!
Engine pulled for rebuild after it puked a mainseal. Sent out to commercial rebuilder.
Engine came back from rebuilder, sat on my engine stand in my shop for about nine months. Finally got put back into the truck.
Truck would barely start, would not idle at all, would die if put into gear - even at high rpm. We figured Idle Air Control on the Throttle Body Injection. Knowing it needed better timing and a few other checks, we trailered it to Mr. Goodwrench.
Local GMC dealership at first thought IAC and a locked torque converter, but got into it and found the only problem was late valve timing. The rebuild shop had put timing chain and camshaft together wrong. That was fixed, and cost a pile of labor dollars. They assured us the incorrect cam/valve timing was the only problem.
The truck was driven maybe a mile, over the Louis Auto Glass for a windshield, then back the the dealership, then Karen and Joel picked it up the next day, and Joel drove it the 50 miles back to Marblemount.
Joel said it had good power when he left the dealership and got out onto the freeway. He noticed it downshifted twice on a hill about 9 miles short of Marblemount, though he hadn't really changed throttle position. Maybe it was getting weak. He got to my Rental One, a mile above Marblemount, and the truck would not restart. The exhaust manifolds and exhaust system back to the catalytic converter showed red hot.
Joel let the rig cool, beat on the catalytic converter a bit, then drove it the five miles to my shop. We figured plugged catalyst was the only answer.
Last night, I removed the converter, went through three layers of metal, and emptied out the contents. Tonight, I welded our little "door" closed again (two layers, top side of converter), then put the converter back on the truck(hey, it was screwed anyway; I can always go buy a good one if we end up somewhere that they test emissions on a '93 pickup). . Joel and Karen took it for a test drive. I could see some exhaust leak from the bad muffler behind the converter, but nothing seemed obstructed.
They came back soon, Joel saying we had a problem and asking me to come outside and look. I walked out, and I could still see some glow on the right exhaust manifold. I had Karen restart briefly. Exhaust seemed to be coming out of the tailpipe, but it sure seemed hot. Oil pressure is good, and coolant temp has not jumped (and this thing has a ridiculously small radiator, so it wouldn't handle much extra heat). And now there's a pretty good knock that seems to be coming from the right bank.
Now this is professionally rebuilt engine, assembled by a reputable builder. How many things can be screwed up??? Mr. Goodwrench wasn't too surprised about the cam mis-timing, because there was a run of timing chains that was mismarked. Just following the factory manual directions will get you a mis-timed camshaft.
What the H--- can we have that's turning the exhaust manifolds into afterburners? And where did we pick up that knock?
I'm baffled. This thing does not have the AIR system with pump (like my '77 F250), though I believe it does have EGR. Again, it's a '93 with TBI, just rebuilt. I'm open to suggestion here.
I think I just heard someone suggest I enjoy an excellent imported dark beer, then to go bed. :beer: :D I've had enough for one night.