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jiggity76

Best way to clean out gas tank.

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rich_e777

I might have to do this to but not on a W body. Would a about a gallon of seafoam sloshed around in there take care of everything? Looks like its been seal from the pump but is there alot of rust in it?

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jiggity76
22 minutes ago, rich_e777 said:

I might have to do this to but not on a W body. Would a about a gallon of seafoam sloshed around in there take care of everything? Looks like its been seal from the pump but is there alot of rust in it?

I've been talking to NCTyphoonKid and I think I'm just going to flush it with clean fresh gas.  The tank is beautiful inside as I don't see any rust thru the pump opening.  

Hey, since your available here right now, I've been looking thru some threads.  Do you know what this is?  It has silicone around it and was wondering if I need to do any preventative maintenance on it.  I don't want oil leaks.  I'm replacing the intake gaskets right now.

 

20200606_100912[1].jpg

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rich_e777

Honestly surprised you dont know as much as your into these cars. Thats the infamous oil pump drive shaft that in order to change the oring seal on the LQ1 requires the head to be pulled to remove. It loves to leak oil.

If its leaking you might be able to lift it slightly and pick the old seal out. Then as you rotate the shaft squeeze some RTV under the lip all the way around. Looks like that was done before at some point. IIRC one member ground the head down to get the shaft out without removing the head.

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jiggity76

This is new territory for me so I'm learning!  Whatever I learn here will be applied to the STE as well.

I thought it might be the oil pump but wasn't 100% sure.  Yes, I've heard the stories.  

That sounds like a good plan.  Might give it a shot.  Just want to make sure it's not leaking.

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rich_e777

Its part of the oil pump, Schurkey has a nice pic of the drive shaft completely removed but would yell at me for posting it again. That shaft rotates a hex connection rod that spins the oil pump on the bottom of the engine. I dont know why the engine designers left a weak point for that drive shaft to leak on the top of the engine, it doesnt make sense to me why it would be there.

 

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Schurkey

 

On 6/5/2020 at 8:32 PM, jiggity76 said:

I want to reuse my original gas tank.  What's the best method to clean it out?

BEST way to clean-out a gas tank is to haul it to a radiator shop, and let them "boil it out" in their radiator-cleaning tank.

 

Lumina_Oil_Pump_Drive_01.JPG

 

DO NOT blort a bunch of RTV under the flange of the oil pump drive.  RTV that doesn't get squeezed between two clamped parts does nothing for sealing.  Get a distributor gasket, cut a split in it, coat the gasket with sealer, (Permatex "hardening" sealer works for me) work the gasket into place.  This will likely reduce the leak by 90+ percent, the only leakage would be at the split in the gasket.  Even with the split, you might get lucky and have zero leakage.  If you take the entire drive plug out, install a new O-ring...and the gasket for added protection.

This thing exists because otherwise there'd be nothing to drive the oil pump; or it wouldn't be removable.  this is all that remains of the distributor that the engine family was designed to have.  Once the engine went to distributorless ignition, only the oil pump drive was needed.  The only reason this thing is a pain in the ass is because you have to take the head off to remove it.  If you could pull it out easily, a new O-ring every ten years would be no big deal.

Edited by Schurkey

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jiggity76
35 minutes ago, Schurkey said:

 

BEST way to clean-out a gas tank is to haul it to a radiator shop, and let them "boil it out" in their radiator-cleaning tank.

 

Lumina_Oil_Pump_Drive_01.JPG

 

DO NOT blort a bunch of RTV under the flange of the oil pump drive.  RTV that doesn't get squeezed between two clamped parts does nothing for sealing.  Get a distributor gasket, cut a split in it, coat the gasket with sealer, (Permatex "hardening" sealer works for me) work the gasket into place.  This will likely reduce the leak by 90+ percent, the only leakage would be at the split in the gasket.  Even with the split, you might get lucky and have zero leakage.  If you take the entire drive plug out, install a new O-ring...and the gasket for added protection.

This thing exists because otherwise there'd be nothing to drive the oil pump; or it wouldn't be removable.  this is all that remains of the distributor that the engine family was designed to have.  Once the engine went to distributorless ignition, only the oil pump drive was needed.  The only reason this thing is a pain in the ass is because you have to take the head off to remove it.  If you could pull it out easily, a new O-ring every ten years would be no big deal.

Oh that's awesome info, thanks so much!

I don't have the skills to pull the head so your saying to use BOTH the O-ring and paper gasket.  Just use the hardener and NO RTV sealant?

And...love the idea of boiling out the gas tank, I would have never thought of that!

Edited by jiggity76

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Schurkey

Unless you remove the head, the drive plug comes up about a quarter-inch, more-or-less.

The existing O-ring is junk.  It'll be hard as a rock, brittle, and not sealing any more.  But you can't get it out, and you can't put a new one in there.  All you have left to do is to cut and wrap a gasket coated in sealer under the flange,  Clamp it back down, and hope for the best.

AFTER you get the head removed, the drive plug comes all the way out, and at that point you can break the old O-ring, stretch a new one back in, and theoretically that's all you need.  The new O-ring is (supposedly) improved.  When it was me, I put a new, uncut gasket in there for a "second" seal.

https://www.amazon.com/Permatex-80007-Hardening-Gasket-Sealant/dp/B002YLVLY2/ref=sr_1_2?dchild=1&keywords=Permatex+%231&qid=1591581753&sr=8-2

Edited by Schurkey

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jiggity76

Thanks for the link.  I just ordered it.  I think I need to do this since I'm in there anyways.  Not sure if it's leaking but going to do my damnest to prevent leaks, or slow it down.  Same for my LQ1 STE, I'm sure if it will need it too.

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1987 GMC Jimmy

Hey, bud! Yeah, rad shops will “rod” them out for you, but you can try putting some CLR/Zep in them to get rid of the rust. Mine sat for 15 years so that wasn’t an option for me. I can’t remember if the pump baffling on these is metal, but if it’s plastic, it may succumb to the highly acidic stuff you soak the tank with. If the tank was all metal on the inside, I’d feel perfectly fine trying that. You just have to be patient with it. 

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