1995 GMC K2500

[DerekTheGreat]

Okay... So a couple new problems... The idler pulley i installed a month ago already has wobble in it... So i need to replace that. One of my spark plugs looks like it has oil leaking around it. I don't know if it is on the threads and causing misfire. My guess is it is. Speaking of spark plugs. I bought some MSD iridium performance spark plugs, but the gap is different than what is manufacturer recommended; however, every site i checked said they were compatible with my truck. Should I have just gone with OEM spark plugs?

Also, the truck has started to sputter with light throttle application. It doesn't matter if it is at 55 mph and just trying to maintain speed or if I'm just lightly pulling out of the driveway. I think I need to replace the fuel injectors, but if I have to replace those I'm going to replace the fuel filter as well. I'm learning a lot, but with all the little things that keep popping up I just want to replace everything. Just start ripping stuff out and putting new stuff in and hope everything gets resolved. But that's kinda out of my budget right now... oh well. I guess with the oil in the spark plug I should replace the valve cover gaskets.

One more thing. I noticed some white smoke at cold start this morning coming out the tail pipe... It only lasted about 30 seconds and then was gone. I'm thinking valve stem seal. But I wasn't planning on opening up the engine this year... Oh well. Guess I'll add that to the list... Or would it be okay to just wait until next spring when I change out the cylinder heads?

Take those iridium plugs back and get yourself regular old copper core plugs, CR043TS. The stock ignition system doesn't like those fancy plugs and I wouldn't be surprised if it runs worse with those plugs you have. If you haven't checked your existing plugs, time to pull them all. Will give you a baseline of how the engine has been running if they've been in there for a few thousand miles. Look online for spark plug charts, but if there is fluffy brown stuff all over the electrode and such she's definitely an oil burner. I'm not an expert but I've read that oily threads can be caused by oil getting past the rings.

I wouldn't do anything with the fuel injectors until you've straightened out the ignition components and verified that the injectors are spraying correctly and the truck maintains base idle when hot just fine. I'd change the fuel filter though. It's never a bad idea to change all fluids & filters when acquiring a new vehicle, least not IMO.

 

[PlayingWithTBI]

Now... to just get rid of that rough idle... well and a few other things. When the truck is in gear and idling, the muffler rattles against the frame (not heat shield).

Some times a rattling exhaust pipe will make the PCM (Knock Sensor) pull timing and can cause a rough idle and/or acceleration. If you put a good scanner on it you can see what's going on.

 

[Trevor Floyd]

Take those iridium plugs back and get yourself regular old copper core plugs, CR043TS. The stock ignition system doesn't like those fancy plugs and I wouldn't be surprised if it runs worse with those plugs you have. If you haven't checked your existing plugs, time to pull them all. Will give you a baseline of how the engine has been running if they've been in there for a few thousand miles. Look online for spark plug charts, but if there is fluffy brown stuff all over the electrode and such she's definitely an oil burner. I'm not an expert but I've read that oily threads can be caused by oil getting past the rings.

I wouldn't do anything with the fuel injectors until you've straightened out the ignition components and verified that the injectors are spraying correctly and the truck maintains base idle when hot just fine. I'd change the fuel filter though. It's never a bad idea to change all fluids & filters when acquiring a new vehicle, least not IMO.

Okay... so I replaced the valve cover gaskets and the park plugs with AC Delco copper core. After I replaced the first gasket my idle was high in park and neutral.... 1500 rpms... I replaced the second gasket and my idle shot up to 2400 rpms in park and neutral and 1100 in gear. The valve cover gaskets are mahle’s. I double check the part number between autozone and summitracing.

I look for vaccum leaks and I found two. One on the pcv to intake connector. I need to replace that whole line. And another one that I had extra vacuum line around. That one was a 1/4” line with almost a full break. I fixed it and the idle didn’t go down at all.... not sure what happened. I double checked the gasket orientation and made sure it didn’t roll during installation

 

[Trevor Floyd]

Alright I fixed the high idle. It was the throttle cable and vacuum leaks. I still have the tail pipe rattle but I still don’t have a rear shock on that side. The shock mount will be here Tuesday. I’m hoping that fixes it

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[Trevor Floyd]

So I finally got that final shock installed. I pulled the bed off, removed the old shock mount/bracket, drilled out the last rivet, installed the new shock mount/bracket and the new skyjacker blackmax shock.

It was quite the effort for one shock. To get the bed off I wrangled together 5 boys from around the neighborhood that I know. They're all pretty scrawny 14 or 15 year olds that I work with at church.

By the time I was ready to put the bed back on it was dark out. So I called my Father in law and he came up with his two sons and we put the bed back on and everything back together in about 30 minutes. Having the truck come back together that fast was pretty cool to see. I finished putting my tools away around 10:00pm.

I'm going to take the bed off again this weekend or next to remove all that rust and coat the frame. Should be fun!....

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[Trevor Floyd]

Alright... So I think I have a bad rear differential. My daughter opened up the rear window last night while driving and I noticed a whining/howling sound coming from the rear of my truck. The sound would disappear when I came to a stop and start up again when accelerating. On or off the gas pedal the sound was there. Also, there is a whirring.. almost grinding noise from the rear at really low speeds....forward and reverse. Question for you guys.....

Should I take the truck into the shop to have them diagnose the rear diff? I'm pretty positive it is the rear differential. Is there a another way to tell if the rear differential is going out? Will changing the gear oil help much? Is it typically worth it to rebuild the rear differential or just replace the rear axle?

Maybe I'll head down to the local pic a part and see if I can find a rear axle to throw on and replace my current one.

 

[Trevor Floyd]

I took the bed off again... I was trying get the rust off the frame. I was using a grinder, wire wheel, sander and rust dissolver.. 2 hours in my father in law tells me he has a sand blaster....... it was amazing. I ran out of time and had to get the bed back on. But now that I know I have access to a sand blaster I’m going to blast the whole frame and cross members

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[Trevor Floyd]

Alright guys.. I'm back at it.. kind of. A few weeks ago, the charge on my battery was extremely unstable while driving. It fluctuated from 11V to 14.5V all while driving. Throttle didn't didn't matter. It would randomly jump up to 14V at times and then suddenly drop back down to 11V. I figured it had to be something with my alternator connection. I noticed the crimp on the alternator wire was loose... So I recrimped the alternator cable. It helped a little bit, meaning I could coast down the hill from my house to work without too much worry about my battery dying and I could hit the throttle right before I turned my car off... usually, to give it a little extra charged so that I didn't need a jump every time I went to start the car.

I decided to check the crimp again after a week of just hoping I can get from point A to point B. I noticed my alternator bolt was loose. So I disconnected the battery (both positive and negative), removed the alternator cable from the alternator and I torqed the crap out of that bolt so that it would never come loose again. It's the freaking sword in the stone. I reattached the alternator cable. Connected the negative terminal on the battery........ and as I begin to screw back in the positive terminal.... hissing and smoke ensue... lots of smoke. Crap... I caught my truck on fire.

Turns out my alternator cable arced about six inches from my batter. Blew a hole through the alternator cable insulation and arced somewhere to the truck.. I've only been able to find the flash-point. Luckily, nothing else was damaged. I put in a $20 alternator from the junkyard, installed a new 6 gauge cable with a 200 amp fuse terminal between the alternator and battery to prevent this from happening again. Works great now. Except I think the alternator I grabbed is a little undersized. If I have headlights on, radio and heat going the voltage drops when I'm off the throttle. So I'll probably buy a 140 amp alternator here pretty soon.

I still have the wire that arced. Keepsake for one of the more exciting moments I've had under the hood. Also, when I replaced the alternator cable I added a throttle body spacer (TBI). I might have some more lower end torque... a little, but my idle is noticeably smoother. Since I was forced to go under the hood, I've now caught the bug and need to do more! I was planning on waiting till spring, but I don't think that's going to happen. I'll upload some pictures of my wire routing and my blown out cable. The wiring was a piece of cake.

 

[White96k2500]

Alright... So I think I have a bad rear differential. My daughter opened up the rear window last night while driving and I noticed a whining/howling sound coming from the rear of my truck. The sound would disappear when I came to a stop and start up again when accelerating. On or off the gas pedal the sound was there. Also, there is a whirring.. almost grinding noise from the rear at really low speeds....forward and reverse. Question for you guys.....

Should I take the truck into the shop to have them diagnose the rear diff? I'm pretty positive it is the rear differential. Is there a another way to tell if the rear differential is going out? Will changing the gear oil help much? Is it typically worth it to rebuild the rear differential or just replace the rear axle?

Maybe I'll head down to the local pic a part and see if I can find a rear axle to throw on and replace my current one.

Probably just low fluid and you may need to add a friction modifier to the rear diff fluid depending on if you have the g80 locker in the truck (you can tell by the “g codes” in the glovebox on the sticker

 

[Trevor Floyd]

Probably just low fluid and you may need to add a friction modifier to the rear diff fluid depending on if you have the g80 locker in the truck (you can tell by the “g codes” in the glovebox on the sticker

That sounds like some good advice to me. I'll probably just replace all the fluid. Also, I'll check to see if I need the g80 locker in the truck. Thanks for the help. Much appreciated!