Help please :) GMC Sierra 1996 C2500 General Maintenance Questions

[Grognak]

We've inherited a truck, (in title) I am a beginner mechanic with knowledge in vehicle electrical systems and some programming so I can do multiple basics. My questions are, what systems should I inspect for condition? What general maintenances or service should I perform as soon as possible to prevent further damage? How might I do some of these things? The truck is 260000 miles, the original owner, grandpa, took good care of the truck and was an experienced tradesman/mechanic , another family member inherited it after my grandpa, drove it maybe 6 thousand miles, and then family members started noticing it wasn't being serviced at all so far as putting gas in the tank and replacing lights. here's where I step in with my new knowledge,

They had an oil change, we topped off the coolant, and now we're checking for parasitic draw because the battery had died twice.


I don't think I hear knocking, unless its light. I can compression test I suppose.

I do see oil leaking around the head and dripping to the bottom of the block

Superficial rust on the frame ( southern states)

Rusty coolant

Certain corroded wires

Decaying rubber

Poor alignment, very wobbly steering

Stiff and very reactive brakes. ( light push makes a tough jerk, and pedal is stiff)dark power steering fluid

I'm really looking for niche advice that beginners are likely to miss, things obvious to experienced mechanics but not to anyone else.

For example short and long term fuel trim, I have no idea what those mean, but I know parameters like those can give you information on the health of your systems, however I don't know what parameters I should be evaluating. Which parameters should I monitor to know the health of my engine and how I can repair the truck?
I don't know if its a good idea to change my transmission oil, or if that's even a good idea (people say don't if your gears are already damaged )


I'm real lost with how to give my truck the proper care it needs and anything will help.

This truck is too beautiful and nostalgic to let die. Thank you.

If a picture of the engine bay or any areas would help I can do that, I am just awake at night right now and wont go bother for the keys.

 

[OBS_Trash]

Welcome! Congrats on your newly inherited truck especially a family owned, hopefully it stays that way.

First off - Disclaimer: You wanted a Mechanic's advise, Well I'm a Self taught 4th degree BlackBelt stage 6 Certified You-Tube Mechanic so disregard every single thing i say. No seriously, i'm not kidding.

The list is pretty standard for the mileage. These engines relatively are "Easy" to work on, all things considered of coarse. With this group, Books, You-tube even greenly skilled people can accomplish many things solo (No shop required)

The oil leak from the heads indicate you possibly need to replace gaskets, this is where you start asking yourself with any repair like this "Since I'm pulling Intake/heads, etc,etc....Since I'm this far in, what else should i replace while im here and have access? Possibly the Fuel Injection Maybe? - Might as well right? or wait till you NEED to?

Flush the Coolant, don't just top off, If Southern Surface rust is something you want to get ahead off consider POR15 or some other Rust Encapsulator (I used POR15 brush on for my 71' restore - looks great, But eastwood has a decent spray can that can get hard to reach places, dosen't look as nice - depends what your reason is

Rubber - If your talking door seals (Exposed to elements), Most that stuff is relatively cheap, look at places like LMC / Rock Auto to compare.

Steering - hahahah, welcome to good ol slosh town. I Replaced all my basic Steering components (Control Arm/Bushings/TieRods/Idler/Pittman) with Moog items you can get from Rock Auto pretty cheap, YouTube will show you how. - Drives way better, no more squeaky And i STILL have that Slosh, some say it will never leave a chevy's soul - You will have to get alignment done at shop after you replace it all.

Corroded wires - Time consuming yes, but spend time replacing them. Buy some good heat shrink sleeves, connectors, Wire Loom and go to town. Check the 3 grounding straps for wear. All this stuff is easy to replace and you said you were good on electronics. Alot of connectors can be bought off Amazon. However some here will burn you at the stake if you do so, I spread my purchases around depending what it is. Some parts, yeah you better spend$$ on the AC Delco or you will regret it, but ive bought many non critical items off amazon and had no issues. You will hear all different type of opinions. that could be your draw issue too.

Put most your effort in your brakes, Ovehaul if you need. To me that's the most important and most overlooked. Inspect closely and replace and worn hoses (Not Metal) that have sign of worn/wear.

Good Luck Man! Now let the real Slim Shady's step in give actual advice!

 

[Das Hatt]

Glad you are here! I am the one who replied you over on reddit, lol. This place is a gold mine for information. Good luck!

 

[movietvet]

Welcome to the forum.

I would get and go thru ANY maintenance and repair work paperwork that grandpa had. If not, then you have a few things that you should do just to get to a baseline.

Compression test. Oil leak may be the valve covers. Rusty coolant-drain all of it and flush as best you can with a flush kit and chemical but remember that the rust in the block is likely coming back. Change thermostat and check for bulging hoses. radiator may already be leaking and if rusty, there will be blockage inside. Age of belts unknown, check for glaze and cracks and replace as needed. Check the lower weep hole at water pump, is likely leaking with the rust that is in the system. Inspect entire steering and suspension and if unknown how to do have a qualified shop do it and let you see. If unknown, replace the cap, rotor, wires, plugs, fuel filter, pcv valve. Remove IAC and inspect and clean as needed and in the port. Flush/change all fluids. Inspect brake system completely. Post pics here of all inspections. There is more but this will keep you busy.

 

[Grognak]

Welcome! Congrats on your newly inherited truck especially a family owned, hopefully it stays that way.

First off - Disclaimer: You wanted a Mechanic's advise, Well I'm a Self taught 4th degree BlackBelt stage 6 Certified You-Tube Mechanic so disregard every single thing i say. No seriously, i'm not kidding.

The list is pretty standard for the mileage. These engines relatively are "Easy" to work on, all things considered of coarse. With this group, Books, You-tube even greenly skilled people can accomplish many things solo (No shop required)

The oil leak from the heads indicate you possibly need to replace gaskets, this is where you start asking yourself with any repair like this "Since I'm pulling Intake/heads, etc,etc....Since I'm this far in, what else should i replace while im here and have access? Possibly the Fuel Injection Maybe? - Might as well right? or wait till you NEED to?

Flush the Coolant, don't just top off, If Southern Surface rust is something you want to get ahead off consider POR15 or some other Rust Encapsulator (I used POR15 brush on for my 71' restore - looks great, But eastwood has a decent spray can that can get hard to reach places, dosen't look as nice - depends what your reason is

Rubber - If your talking door seals (Exposed to elements), Most that stuff is relatively cheap, look at places like LMC / Rock Auto to compare.

Steering - hahahah, welcome to good ol slosh town. I Replaced all my basic Steering components (Control Arm/Bushings/TieRods/Idler/Pittman) with Moog items you can get from Rock Auto pretty cheap, YouTube will show you how. - Drives way better, no more squeaky And i STILL have that Slosh, some say it will never leave a chevy's soul - You will have to get alignment done at shop after you replace it all.

Corroded wires - Time consuming yes, but spend time replacing them. Buy some good heat shrink sleeves, connectors, Wire Loom and go to town. Check the 3 grounding straps for wear. All this stuff is easy to replace and you said you were good on electronics. Alot of connectors can be bought off Amazon. However some here will burn you at the stake if you do so, I spread my purchases around depending what it is. Some parts, yeah you better spend$$ on the AC Delco or you will regret it, but ive bought many non critical items off amazon and had no issues. You will hear all different type of opinions. that could be your draw issue too.

Put most your effort in your brakes, Ovehaul if you need. To me that's the most important and most overlooked. Inspect closely and replace and worn hoses (Not Metal) that have sign of worn/wear.

Good Luck Man! Now let the real Slim Shady's step in give actual advice!

Thank you so much man Im going to study what youve given me and get to it when the budget is right. I appreciate you.

 

[Grognak]

Glad you are here! I am the one who replied you over on reddit, lol. This place is a gold mine for information. Good luck!

Thank you for your help man, so cool you found me here too!

 

[Grognak]

Welcome to the forum.

I would get and go thru ANY maintenance and repair work paperwork that grandpa had. If not, then you have a few things that you should do just to get to a baseline.

Compression test. Oil leak may be the valve covers. Rusty coolant-drain all of it and flush as best you can with a flush kit and chemical but remember that the rust in the block is likely coming back. Change thermostat and check for bulging hoses. radiator may already be leaking and if rusty, there will be blockage inside. Age of belts unknown, check for glaze and cracks and replace as needed. Check the lower weep hole at water pump, is likely leaking with the rust that is in the system. Inspect entire steering and suspension and if unknown how to do have a qualified shop do it and let you see. If unknown, replace the cap, rotor, wires, plugs, fuel filter, pcv valve. Remove IAC and inspect and clean as needed and in the port. Flush/change all fluids. Inspect brake system completely. Post pics here of all inspections. There is more but this will keep you busy.

This definitely will keep me busy, will post inspections, thank you man. <3

 

[Cadillacmak]

Welcome, and please post pictures.