Undercarriage cleaning advice...

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dkraven

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Portland, OR
First Name
David
Truck Year
1977
Truck Model
c25 Sierra Grande
Engine Size
350
Getting a 1977 Sierra Grand up and running that was gifted to me. It spent plenty of time sitting in weeds and its undercarriage is grimy, oily, caked on dirt, I'm sure you've all seen what I'm talking about. Eventually I'll do a thorough job of it, but what would you all do first? Just go at it with a pressure washer and see what's what? Truck runs surprisingly well, brakes and suspension don't feel all that bad. To be honest I'm a little worried what I'll find once I start blasting grease off it.
 

PrairieDrifter

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Mason
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84,79,77,76,70,48
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Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
If you're lucky it's in the dry and crusty phase. Then it's pretty easy to scrape off, then degrease and pressure wash the rest. If it's still slimy, degreaser and a hot pressure washer is your best friend, other than getting filthy yourself lol.
 

JACK34

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OTR TRUCKER
First Name
JACK
Truck Year
1978
Truck Model
C10
Engine Size
250
I did my entire frame on my 94 1500 I had the box off so it was much easier. Anyway my frame was pretty bad crusty rust had to use a needler and replace all the mounts and springs. Luckily there was no rubber undercoating. Pressure washed the crap out of it and used SPI"s wax and grease remover and then put 4 or 5 coats of Epoxy primer on it. Not sure how much grease or oil is on your frame or why but, you won't find any rust where there is a oil leak flinging oil all over the bottom side. Good luck!!
 

85 red GMC

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Bradley
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Have you considered dry ice (dryce) methods for underbody cleaning
 

leverhead

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Location
az
First Name
Steve
Truck Year
1975
Truck Model
blazer
Engine Size
350
I had what I thought to be the crustiest 1975 k5 blazer undercarriage on the planet.
Here is what I did:

Pump bottle spray super clean on everything for a few days...keep letting it soak in and loosen things up. Then pressure clean...I used a turbo nozzle.

Rinse and repeat until satisfied.

Stubborn areas got scraped...then spray and wipe off. Rinse and repeat.

Do this outside...lay plastic down if so inclined. I wore goggles and a white paint suit and gloves.

This was a couple Years ago. UndercarriGe is restored/rebuilt and looks like a new car under there now...you would never know it.

Hope this helps
 

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