Dan12valve
Newbie
I figured I'd follow up on an old thread I made over a year ago, and add some new things. Maybe it will help someone in the future with these old trucks. Goes over a/c, idle, and ignition issues.
http://www.gmt400.com/threads/so-i-blew-my-muffler-up.34756/
TLDR: ignition module issues caused a muffler to blow up and cat fouling
1. I replaced the ignition module about 5 times in 15,000 or so miles. Truck has scared me a bit dying in weird places, but after a cool down period (5-15 min) it would start and run for another 5 miles or so and would either die completely and not restart or loose power and then die. Seemed to depend on outside temp (I didn't realize that till the last fix) and load/driving style (fast driving meant faster dying). Some times the ICM would last longer than others making me suspect other things(coil, ECM, distributor, fuel pump,ect).
I finally bought an Ac Delco unit off rockauto and that seems to have fixed the issue. I am currently at 245,000 miles and haven't had any major issues since 235,000. The issue was two fold, heat and cheap auto store brand electronics. On my original distributor the base where the ICM and cap mount was corroded to the point it broke the bolts that hold down the cap and the ICM which is why I replaced it. Its made of aluminium and after the bolt in the ICM I had enough. The bolt broke on the way out and I needed a way to securely mount my new delco ICM. I had to have it then so I drove to the local auto store.
I now believe the ICM's went out because the distributor plate wasn't taking enough heat away due to corrosion and burning up the ICM. I also think the delco ICM is far better quality. I did buy an autozone branded distributor and have been happy with it. Its thicker aluminium on the base where the cap mounts and it resembles an MSD. I chucked the az brand ICM included.
No more dying, no more backfires, and no more being stranded. I once idled for 3 hours in summer for a/c and no issues.
2. I notice the truck has a very hard 1-2 shift at part throttle, didn't think much of it. 10-20% throttle will break both rears loose in the rain. I replaced the Throttle Position Sensor on a whim thinking it may fix the idle my next issue (it tested good in voltage range,but on second look it had some jumpy spots). In turn I fix a problem that I thought was just the way it was.
3. I've also been hunting a slightly rough idle. I attributed this to the ignition as well as other things. I tried looking for air leaks with carb cleaner. Rebuilt the throttle body. Replaced fuel pump thinking pressure.... also a delco unit. Looked at compression and leakdown(all holes 160-170). All to no avail. I finally bought a borescope on a whim and took a peak down the intake with the throttle body removed only to see oil starting where the head meets the intake. Once upon a time, this engine got hot and slightly warped the intake and caused an air/oil/water leak. The water was leaking out the top and pooled on the intake and ran down by the heads. Replacing the intake gaskets fixed all the idle issues and the surging in parking lots. Issue was on the 1 and 2 where the where the coolant jacket runs parallel to the intake runners.
Replaced plugs and wires at this time.
The intake runner on cyl #2. Notice wet valve and runner.
Gasket between head and intake.
Left to Right. 8-6-4-2
Notice the glazing on 2.
L-R. 1-3-5-7
Notice slightly wet #1.
4. Finally, I have a truck that drives like I think it should. So I decide on a little treat.
I reinstalled air conditioning myself. New Delco compressor, new condenser, and new dryer. Original compressor had seals go bad and leaked out rather than seizing. Rented a vac pump and made a day of it. The air even on heat had always felt very anemic out of the vents leading me to thinking it was clogged.
At least my dodge was clogged. The air handling box under the dash was actually the issue. Someone in the past took it apart (most likely my grandfather when it was his), and lost some screws as well as warped the case. It no longer sealed and most of the air regardless of temperature was blown out under the dash.
I figured doing it myself I would see things shops didn't, and it was my first A/C job. I also knew a shop wouldn't go in the dash for any reasonable sum. I thought I would blow it TBH.
Dash pulled enough to get the box out, completely disassembled. The rubbish on the ground was all that came out of the box.
http://www.gmt400.com/threads/so-i-blew-my-muffler-up.34756/
TLDR: ignition module issues caused a muffler to blow up and cat fouling
1. I replaced the ignition module about 5 times in 15,000 or so miles. Truck has scared me a bit dying in weird places, but after a cool down period (5-15 min) it would start and run for another 5 miles or so and would either die completely and not restart or loose power and then die. Seemed to depend on outside temp (I didn't realize that till the last fix) and load/driving style (fast driving meant faster dying). Some times the ICM would last longer than others making me suspect other things(coil, ECM, distributor, fuel pump,ect).
I finally bought an Ac Delco unit off rockauto and that seems to have fixed the issue. I am currently at 245,000 miles and haven't had any major issues since 235,000. The issue was two fold, heat and cheap auto store brand electronics. On my original distributor the base where the ICM and cap mount was corroded to the point it broke the bolts that hold down the cap and the ICM which is why I replaced it. Its made of aluminium and after the bolt in the ICM I had enough. The bolt broke on the way out and I needed a way to securely mount my new delco ICM. I had to have it then so I drove to the local auto store.
I now believe the ICM's went out because the distributor plate wasn't taking enough heat away due to corrosion and burning up the ICM. I also think the delco ICM is far better quality. I did buy an autozone branded distributor and have been happy with it. Its thicker aluminium on the base where the cap mounts and it resembles an MSD. I chucked the az brand ICM included.
No more dying, no more backfires, and no more being stranded. I once idled for 3 hours in summer for a/c and no issues.
2. I notice the truck has a very hard 1-2 shift at part throttle, didn't think much of it. 10-20% throttle will break both rears loose in the rain. I replaced the Throttle Position Sensor on a whim thinking it may fix the idle my next issue (it tested good in voltage range,but on second look it had some jumpy spots). In turn I fix a problem that I thought was just the way it was.
3. I've also been hunting a slightly rough idle. I attributed this to the ignition as well as other things. I tried looking for air leaks with carb cleaner. Rebuilt the throttle body. Replaced fuel pump thinking pressure.... also a delco unit. Looked at compression and leakdown(all holes 160-170). All to no avail. I finally bought a borescope on a whim and took a peak down the intake with the throttle body removed only to see oil starting where the head meets the intake. Once upon a time, this engine got hot and slightly warped the intake and caused an air/oil/water leak. The water was leaking out the top and pooled on the intake and ran down by the heads. Replacing the intake gaskets fixed all the idle issues and the surging in parking lots. Issue was on the 1 and 2 where the where the coolant jacket runs parallel to the intake runners.
Replaced plugs and wires at this time.
You must be registered for see images attach
The intake runner on cyl #2. Notice wet valve and runner.
You must be registered for see images attach
Gasket between head and intake.
You must be registered for see images attach
Left to Right. 8-6-4-2
Notice the glazing on 2.
You must be registered for see images attach
L-R. 1-3-5-7
Notice slightly wet #1.
4. Finally, I have a truck that drives like I think it should. So I decide on a little treat.
I reinstalled air conditioning myself. New Delco compressor, new condenser, and new dryer. Original compressor had seals go bad and leaked out rather than seizing. Rented a vac pump and made a day of it. The air even on heat had always felt very anemic out of the vents leading me to thinking it was clogged.
At least my dodge was clogged. The air handling box under the dash was actually the issue. Someone in the past took it apart (most likely my grandfather when it was his), and lost some screws as well as warped the case. It no longer sealed and most of the air regardless of temperature was blown out under the dash.
I figured doing it myself I would see things shops didn't, and it was my first A/C job. I also knew a shop wouldn't go in the dash for any reasonable sum. I thought I would blow it TBH.
You must be registered for see images attach
Dash pulled enough to get the box out, completely disassembled. The rubbish on the ground was all that came out of the box.
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