99 K2500 Burb Adventure/Camping/Hunting Rig

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1952Chevy

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Purchased the truck 8 May 2021, $1200

99 K2500 Suburban, L29, Auto T-Case, GT5(410 open diff), 210k Miles

No Rust anywhere on the truck

Interior needs work such as:
- Seats Replace/covered
- Misc switches replaced
- Misc interior pieces replaced
- A REALLY good cleaning

Exterior
- Needs Tires
- No leaks of any kind
- Minor scratches and dings
- Exterior Door handles cracked
- Passenger Mirror cracked
- Windshield Cracked

Engine
- Possible Rod knock
- Drained ~12qt of oil from the motor
- Came with a bunch of new sensors I have to look up part numbers to determine what they are. Also has new plug wires/cap/rotor in a box in the cab.

At idle the oil press read about 60-70 which seems high. Need to verify if its reading correctly or if it's off.
Drained the oil, checked for metal only found 1 or 2 flakes, no signs of shavings in the oil. (possible hint of gas smell in the oil)
Replaced with fresh oil still making sounds(possible 5/7 rod knock).
Determined the sound may be coming from the flex-plate/torque converter.
Attempted to remove inspection cover, exhaust is in the way.

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1952Chevy

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Haven't been able to remove the exhaust yet, and therefore can't remove the flex plate cover.

I did use a stethoscope to try and locate the sounds. You can hear it throughout the block, but it gets louder the closer you get to the bell housing area. Leading me to believe it may actually be a cracked flex plate or loose converter bolt.

I also looked up part number for all the sensors/parts still in the cab.
- Cam position sensor
- Ignition module
- Ignition coil
- EGR Valve
- Idle air control valve

Talked to the previous owner he still has more parts for it and he will be getting those to me. He isn't sure what exactly but for sure has a leveling kit.
 

1952Chevy

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Today I cut the exhaust section out cleanly, to be able to weld/clamp back in place. Flexplate and torque converter/bolts all look fine, nothing loose. Of course with the exhaust removed it's now louder and harder to hear the knock.

Still can't pinpoint the sound, but it's in the block somewhere. I attempted to pull plug wires one at a time, on the drivers side cylinders, no change. Haven't done the passenger side yet. Next step is passenger side, and cutting open the oil filter.

After that I'll drop the oil pan and inspect the rods/bearings.
 

Erik the Awful

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Drained the oil, checked for metal only found 1 or 2 flakes, no signs of shavings in the oil. (possible hint of gas smell in the oil)
Replaced with fresh oil still making sounds(possible 5/7 rod knock).
"1 or 2 flakes" isn't much, but it's still indicative of internal engine damage. I wouldn't beat around the bush with trying to isolate the problem externally. Tear it down and rebuild.
 

1952Chevy

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It's been a while since I've been able to work on the truck. Finally got some time yesterday. I finished pulling each plug wire individually and there were not noticeable changes in the knock sounds. I decided to pull the plugs, cylinders 5 and 7 are both completely carbon fouled and have a strong gas smell to them. The rest of the plugs are a little dirty, but not near as bad. I'm probably going to pull the injectors, as well as valve covers and check everything out on the top end.

I've heard leaking injectors can cause a sound similar to rod knock. So here it goes.
 

1952Chevy

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So I got the upper plenum off, and jumped the fuel pump relay. Instantly the 5 and 7 injectors started leaking.

So I ordered a set of Bosch style 4 hole injectors. I decided to try Precision Auto Injectors instead of Five 0 simply due to price. They were 183ish for a set of 8. So I'm going to install those, change out the cap and rotor while the upper plenum is off. Then oil change again. Then we'll see what happens.

Mind you this picture was taken about 5 seconds after jumping the relay. By the time I removed the jumper wire it was even worse.

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I also bought some wheel and tires. Got a deal on some H2 wheels with BFG K02's 285/70R17s. Just need to get some center caps and new lugs. Got the set for 420 tires have somewhere around 1/3 to 1/2 tread left. Only 1 wheel has any damage, and its minor curb rash. Can easily be touched up.
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1952Chevy

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Nice looking 'Burb! I don't know if you have watched Lawrence Tolman, but he's got a build going on not too far from you.

Looks like you are on track to find that sound. Hopefully not as serious as it sounds...
At the time, I had not. However I recently found his videos, and then noticed your comment as I was going back through the thread! He has a lot of in depth info on his projects. I really like his videos.
 

1952Chevy

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So I forgot to update after working on the truck(had to leave town for work).

So I replaced the injectors. While I had the upper plenum off I replaced the oil pressure switch, plugs, wires, cap and rotor, and EGR valve.

Fired it up, and seems to be making the same noise, hard to tell though because either some of the wires/plugs are bad(I doubt) or my timing is off. Its running pretty rough, and throwing a code that I need to read and figure out.

One of the screws for the cap broke and I was unable to remove the screw. I attempted to hold the cap in place with some epoxy. I believe it may not be quite right. I am going to redo that, and double check connections on all the plugs and wires make sure everything is fully seated where it should be. Check timing and go from there. New injectors were nice and easy to install. I didn't even break any of the pegs on the fuel rail! I was happy about that. Unfortunately it's too early to tell if this was a fix or not.

Of note not engine related.
I discovered a torn boot on the passenger side CV shaft.
I also put on a flex pipe to quiet the exhaust while listening for the knock sound. Once I have everything resolved I'm going to weld the original section of pipe back in where it belongs.
 

1965truckrod

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Just a quick tidbit about oil pressure on L29. Stock oil pump is massive, flows a high amount of volume. High pressure usually indicates a higher viscosity oil. I run Delo 15w40 diesel oil and Lucas oil additive. At idle I'm right around 58 to 62psi and up to 80 if I'm hauling ass. Before the thicker oil and Lucas additive I noted a few rather noisy lifters. That disappeared with the good oil. Might be what you're hearing. The bottom end of these motors are nearly all forged parts so a rod knock would be unusual unless it was run without oil or overheated. If you have done any running logs I'll be happy to look them over for you. My L29 has about 160k most of which was towing a boat or long trips. It was our travel/ tow rig so every system was used regularly including the electric 4WD system. Never had to replace and drivetrain sensors but I also run high end oil and additives in my cases.
 
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