Need some help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BLOWN72 · 04-20-2012, 12:48 PM

I finally got the truck in running order, brakes fixed and all the good stuff. The only problem I got now is the gas in the tank is old. What is the best way to clean it out?

shelbert · 04-20-2012, 02:49 PM

I guess it depends on the age and condition of the gas in there. If its just old gas but has not varnished up badly I would just remove the tank, flush it well with some new gas and prob go with that. Just make sure you at least blow the lines out as well as replace any filters and such.

I had one that was so badly varnished up and I used a mixture of simple green and water and it sat over a weekend and was like new. If you do use any water based cleaners make sure as soon as you drain it out you dry it completely , I usually stick a hair dryer into the sending unit hole for a few yours.

Do not use any type of acid like muratic unless you are going to dry and coat is as soon as you have it drained or you will create a flash rust nightmare. and filling it with gas will not stop it dispite what alot of people say.

If its very rusty my advice is just replace it, The headaches you will get from that rust getting into your carbs are worth 2 times the cost of replacing it. And dont think a filter is going to stop the rust because it will not. They are not really any more expansive for a aftermarket tank than having a shop boil it out and coat it.

There are do it yourself coatings and I have had mixed results with them lasting, and I think it would be a pain to get it coated properly.

After many years of messing with these mistreated vintage cars/trucks there are 2 things I usually just replace at the 1st signs of a problem. The gas tanks and radiators.

68gmsee · 04-20-2012, 03:08 PM

^ agree with above. If you check towards the bottom and see small areas where gas may have leaked or if you smell heavy gas aroma it's time to replace it or have it professionally leaned and sealed.

I bought a Spectra GM49A for my 68 GMC and it's one of the things I did. Great tank made in Canada and fit was right on.

You can order them now from local auto parts.

04-20-2012, 12:48 PM	#1
BLOWN72 Registered User Join Date: Oct 2011 Location: Normal, IL Posts: 82	Need some help I finally got the truck in running order, brakes fixed and all the good stuff. The only problem I got now is the gas in the tank is old. What is the best way to clean it out? __________________ 1972 C10 SHORT BED, BLACK ON BLACK, ZZ3 CRATE MOTOR WITH B&M 250 SUPERCHARGER, HEADERS, 350TURBO TRANS, BOOST RETARD, POSI, 373 GEARS 1966 MUSTANG COUPLE, 289 HIPO MOTOR, CAM, 650 HOLLEY CARB, FULL LENGTH HEADERS, 2.5" FLOWMASTER EXHAUST, HURST SHIFTER, 373 GEARS POSI 2006 MONTE CARLO, FLOWMASTER MUFFLERS, K&N INTAKE, EXTERIOR MODS

04-20-2012, 02:49 PM	#2
shelbert Registered User Join Date: Jan 2012 Location: Nashville, TN Posts: 27	Re: Need some help I guess it depends on the age and condition of the gas in there. If its just old gas but has not varnished up badly I would just remove the tank, flush it well with some new gas and prob go with that. Just make sure you at least blow the lines out as well as replace any filters and such. I had one that was so badly varnished up and I used a mixture of simple green and water and it sat over a weekend and was like new. If you do use any water based cleaners make sure as soon as you drain it out you dry it completely , I usually stick a hair dryer into the sending unit hole for a few yours. Do not use any type of acid like muratic unless you are going to dry and coat is as soon as you have it drained or you will create a flash rust nightmare. and filling it with gas will not stop it dispite what alot of people say. If its very rusty my advice is just replace it, The headaches you will get from that rust getting into your carbs are worth 2 times the cost of replacing it. And dont think a filter is going to stop the rust because it will not. They are not really any more expansive for a aftermarket tank than having a shop boil it out and coat it. There are do it yourself coatings and I have had mixed results with them lasting, and I think it would be a pain to get it coated properly. After many years of messing with these mistreated vintage cars/trucks there are 2 things I usually just replace at the 1st signs of a problem. The gas tanks and radiators.

04-20-2012, 03:08 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Need some help ^ agree with above. If you check towards the bottom and see small areas where gas may have leaked or if you smell heavy gas aroma it's time to replace it or have it professionally leaned and sealed. I bought a Spectra GM49A for my 68 GMC and it's one of the things I did. Great tank made in Canada and fit was right on. You can order them now from local auto parts.



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