1st928

Well, the inevitable has happened - I've discovered my fuel tank has a 1/4 in.
layer of sludge on the bottom (might have something to do with the in-tank
pump siezed solid - and yes... I did try the reverse polarity drill..no go ! )

This '79 has sat for 8 years so its no big surprise I need to clean the entire fuel system - but for now - the tank issue.

My question - what is a good cleaner to dissolve the waxy looking crud in there
without compromising the plastic tank ? I've never seen "Berrymans" here in Canada as some recommend and wonder if "Gunk parts cleaner" would be safe
to use. Their Product Info says not safe on rubber, gaskets, and plastic. I'm
wondering.....all plastics ?

Anyone with a BTDT ? I'm sure this will be one of many querys that are sure to come as I accept the joy of 928 ownership .Appreciate any help you may offer. BTW - the tank is out. Thanks Ben K

dr bob

The "parts cleaner" that I've seen isn't appropriate for all the other stuff that the fuel system is made of, although the tank itself can --probably-- take it. If the tank is out and all the plumbing is removed from the tank to the point where the parts cleanet might be tried, you're already 90+ percent of the way to getting the tank cleaned without such a harsh chemical.

If the tank is out, start off with a decent detergent and hot water bath for the insides. Laundry detergent would be a good way to start. This will get most of the stuff out of there. If you have access to a pressure washer, use that through the fuel pump hole to blow as much of the slime as possible.

Next step is a soak with mineral spirits/paint thinner. This should take everything else out. Soak overnight, then another detergent/hot water bath. If there are still deposits or varnish that won't come out, try some acetone. Do this one outside, away from everything. Let the acetone soak for a bit, but be aware that it will evaporate quickly. If it evaporates, all the stuff you dissolve will end up redeposited in the tank. Flush the tank with detergent/hot water to get any remaining stuff out, before you dump the last acetone out of the tank.

The acetone and to a lesser extent the paint thinner require a lot of care when handling. Avoid skin contace for sure, avoid breathing the fumes, etc. Flammability is a big issue with the acetone.

Good luck!

1st928

Thanks dr. bob for the walkthrough. I intend to pressure blast it the get the main "ka - ka"
out and then go from there. Is there anything high pressure would damage by going through the "gauge sender" hole ?
Would "laquer thinner" work instead of "acetone" ? I'm also unsure how long I leave this stuff in there without my tank turning to jelly before my eyes - yet still do what it's suppose to ?
Not decided what I'm gonna do about the rest - some kinda pressure flush of ??? and blow it all
out the fuel rail I'm thinking. And the injectors...well maybe, I get lucky and won"t have to go that far!

But I'm expecting an uphill battle all the way by what I had to fight - just to get the pump out........

Sharks

I removed the sender and let the tank sit overnight with mineral spirits in it as stated above. My hand and arm are small enough to fit (very tight) through the sender hole on top and was able to get a small fingernail brush inside and scrubbed the tank out.

I found that my tank was missing the plastic screen at the bottom that stops particles from entering the fuel pump. I think the small pieces of plastic that I found were the remains of the screen that has disintegrated over the years. One of those pieces stopped my fuel pump 200 miles from home.

I ordered a new tank outlet (seal and screen included), a new gasket for the sender, new fuel filter, new check valve, and rubber hoses from our friends at 928 Specialists. I have not had any fuel related problems since.

ROG100

Ditto what Sharks did.
I used a high pressure washer wand to get in there and blast the crud out.
The tank is designed in such a way that there is containment of crud in the bottom around the side of the deep recess where the pump screen sits.
Even if you had some crud in there it would sit in this area and not overflow to the screen filter.
Then there is the screen filter. So crud would have to be pretty persistent to get to the pump.
The filter in the 84 was cracked though still holding together.
The filter needs changing as a maintainance item - probably worth doing every three of four years.

Brett Matthews

And then, if you want to be certain everything is flushed out well, If you have access to a competent radiator shop, have them flush the tank out.

I didn't like putting water in my tank, nor do I know the elasticity point of the tank's plastic, against any of the chemicals mentioned. the tank may be impervious to all of them, I have no idea...
So, I took the only choice for me. I knew of such a competent radiator shop, so drained and dropped my tank, took it to them, and had it back a couple days later, dry, defunked, and clean. Installed my new filter screen, and installed the tank back up into the cavity. Piece of mind, MY mind anyway, for the long run.

1st928

Thanks guys - looks like its not as bad as I thought - the mung is mainly in the well area with lots of it sticking to the pump itself. I'm telling you - I had to wind the pump out for 15 min. just to shear the stuff off inside the tank. Only good thing - the pump was seized - cause I destroyed it in the
lengthy battle though a good soaking might have saved it ; as there was very little debris in the screen. Oh well......I want to do this only once (I'm referring to the screen on the end of the pump.)

I don't seem to have a filter screen in the tank . Should I be able to see it through the pump inlet ?
From the top I see a raised (3 - 4 Inch) flange where the gauge sender goes through and the screen on the pump.

Am I missing this part ? How hard to install it ?

Thanks for everyones response

Ben K

Normy

I seem to remember looking into this for my car once. I was told that most shops send tanks out to companies that do this professionally- and they actually "boil" the tank in hot water and detergent!

N!

1st928

thanks Normy
That probably would be the safest way to clean it right........but I'm going to try the pres.wash/solvent
route- - quick and cheap - ) and a little bit 'livin on the edge'.......

Ben K