IMO glow plugs that are not self regulating are a ticking time bomb! Even when somewhat new a controller problem can turn them into engine damage debris. Been there done that with a "Late Model at the time" 1988 6.2L NA that ate it's glow plugs in like 1990. There isn't a set life for glow plugs...
I would suspect in this order:
Align the truck ... wait: you confirmed problem with a wheel bearing failure. This may resolve the MPG problem alone.
Look for fuel leaks. Diesel fuel will evaporate off the exhaust manifold. The return lines can be a real PIA to deal with and leak especially if...
An INOP parking brake has killed people. Got run over by your own truck is a bad way to go out or be crippled for life. They gave it back to you in this condition. :eek: Then missed a common wheel bearing failure... Sounds like they specialize in gross negligence thus a place that you shouldn't...
Word: Pictures. Video.
A video of the engine cranking can let us hear if one hole has low compression. Knock sounds may be known to us.
It smokes,,, What Color and when esp. if the color is different?
Black is too much fuel or not enough air.
Check the simple things like the air filter and...
How do you go about changing the timing set on a Gen V 454? The timing cover... It's 10 bolts. No bolts from the oil pan go into the timing cover like the older 454's.
Or is it 10 bolts and Drop The Oil Pan!? After all it's a 1 piece oil pan gasket that goes through the bottom of this timing...
I DO NOT TRUST Amazon for filters or anything else critical as it may be a knock-off and they don't GAF. Even Rock Auto has proven to be trouble to get warranty on items damaged from a part failure. If what you buy takes out your engine, ask @Will L. , think of how it's not covered.
Local...
Have you had any luck checking the TPS and brake switch as mentioned above? A combo of the TPS being out of adjustment and/or bad brake switch could be hard shifting. At the minimum pull codes.
If this hasn't been fixed I would suggest you get them to the shop I recommended in Phoenix. I would...
Well maybe it was (or a knock-off).
Watching O2 sensor cross counts ... Only light throttle would there be any. Heavier throttle it went "lean" and stayed there. Spark plugs read lean. So a fuel problem.
Timing light check of the injector spray pattern showed noting unusual.
Listening to...
You haven't mentioned rings. If you haven't looked into a gapless 2nd ring set now is the time. Results in my thread below. Reminder it may be...
https://www.thetruckstop.us/forum/threads/total-seal-gapless-rings.29135/
It comes as an assembly with the hose. We are not replacing just the pump, but, the entire module with level sensor, sock etc. The old hose was also 'loose' so yeah don't think much of the clamps. They only got to last longer than the in-tank pump/motor lifetime warranty, err um, vehicle gets...
Found the problem. Cracked fuel hose on the fuel pump assembly in the tank. (Not an AC Delco Part.) Runs like it should now. Further no more idle speed hunting. We followed the advice to use a 1996 Vortec pump that isn't maxed out by the stock power level on the 1993 454.
Reference...
Where are you, pickup, located?
Call a GM dealer parts department and get price and availability of a transmission, including core cost, via your VIN.
You spent $7K and either get results or fight for a refund including taking them to court. Breach of warranty and loss of use: present them...
If you are in Arizona look up Allstate Transmission in Phoenix. Jeff bought the place from his dad and they took care of a few 4L80E's behind my 6.5TD's.
https://allstatetransmission.net/
As to shifting hard or not staying in 4th. The Service Engine Soon light is a present for a bulb check...
To reach a large audience you can try say eBay and someone who wants it bad enough will even pay to ship it. Set your reserve at the local offer you got or slightly higher. Because it's supposedly a fuel miser it has more value. It's also 27 years old and a historic/classic vehicle...
There is fuel listed on the sample, but, my advice is for a properly done sample.
Bluntly this contaminated and "wrong" oil sample just about sent you down an expensive rabbit hole. Either do the oil samples properly or don't do them at all!
Not sure you have any action needed as the sample...
Cracked head on Patch didn't show up in the oil samples.
Odds are very good your pulling out a Zombie.
WTF for that lab? The engine oil has failed! They should have called you with "take it out of service, change engine oil immediately, and fix it". It's out of viscosity range (critical) ...
Don't bother unless you need a reason to rebuild this engine. They will either be visually FUBAR from loss of oil or look like normal wear. Seeing copper backing color is worn out of course. Bearings only when the valves, cylinders, and rings have a lifetime or two on them... IMO a visual for...
Guess what thread you win this year! 🤪
I would have guessed a clogged oil filter, esp with seafoam cleaner, and been right... Yeah, but some other issues before you go through a bunch of them silly small oil filters. Wait, I will upgrade that to problem.
Oil Sludge is still a thing.
Take a...
In these modern times you are best to leave the emissions alone. Shops that sell anything to rework em have gone away with the EPA crackdown. So you will be hard pressed to find parts to mess with it anymore. If you ever sell it, after it's modified, the buyer can force you to put it back to...