options for 17mm acorn nut removal 1991 560SEL - input requested

[HuskyMan]

Still working on removing the outter 17mm acorn nut from the right of the rear fuel pump (17mm acorn nut on the end of metal fuel line connecting both fuel pumps). After talking with a couple of friends, three suggestions were made:

1. Heat up the 17mm acorn nut using a propane or an oxygen acetylene torch. After the nut expands it should be easy to remove.

2. Use a metal cutting head on a dremel tool to cut off the nut. I'm concerned I might cut too deep damaging the threads. In addition, I would have to purchase another acorn nut from the dealership.

3. Use an electric impact wrench to bust the nut loose.

I did get an epiphany this morning and tried a tire lug wrench which has a 17mm end. Had a friend hold the backing nut using a 17mm open end wrench. Also placed a jack stand under the rear most fuel pump to steady it. Still no joy. Tried a regular lug wrench because I could hold the point of pivot better. Still no joy. SOMEONE HAS USED A HEAVY DUTY IMPACT WRENCH ON THIS NUT BECAUSE IT IS STUCK STUCK STUCK!

So.......of the above three options, which idea might work best?

[pmckechnie]

First I would never talk to, see, associate with, etc who ever recommended you use a torch of any kind around a fuel pump or fuel tank. Your life is worth much more than the car.

Now, I may try a heat gun (no flame) or hair drier. You could also try putting as much pressure on it with wrenches as you can and hit the end of the nut with a hammer, not a big one, just a tapping hammer.

PaulM

[Hirnbeiss]

I read somewhere where someone took the line off with the pump and then worked on that stuck nut. Is that an option in your case?

[liquiddog]

I assume your already tried pb blaster.

What usually works for me is putting a section of black steel pipe over the socket wrench to make it a little longer.

If there's not enough room sharp solid taps on a box of end wrench from "little stubby" usually does the trick.

[HuskyMan]

I used PB blaster repeatedly, no joy. Then tried Boshield T9 bicycle lubricant repeatedly, still no joy. One of my friends has suggested using a 50/50 mix of acetone and Dexron III transmission fluid mixed in a small bottle to lubricate the acorn nut.

I am using a set of hose clamps from NAPA which seems to be cutting off fuel from the assembly fairly well though it is still S-L-O-W-L-Y dripping gas into a pan I placed on the floor. So, I'm unsure whether it would be safe to remove the fuel pump/filter assembly from the car without risking fuel spillage.

What wattage rating would you recommend for purchasing a heat gun? I found this one:

http://www.homedepot.com/p/Wagner-HT3500-1500-Watt-Digital-Heat-Gun-0503040/203474822

[Hit Man X]

My vote is to simply cut off and replace. From what I remember it just hooks to the check valve at the end of the pump. Either way, you need to remove the assembly from the vehicle for ease of work.

If you are concerned about fuel loss, why not just drain the tank?

OR

Buy a pair of hose barbs from your hardware store. Plug one end with some epoxy, then install each on the fuel lines from the tank to the pumps. They will then be like a plug.

If I was you (and this is what I did), you should probably go ahead and replace the rest of the soft lines back there as they are typically partially split due to age.

[liquiddog]

I replaced my main fuel line due to a bulge in it. Draining the tank is not a big deal. I did it outside the garage.

Sharp jabbing whacks are what are going to get this thing to let go. It may snap the hollow bolt, but that's going to be how you get this thing off...

Have you tried a stubby 8 oz ball pen hammer with a taught box end wrench? Good solid whacks. Imagine your target beyond the strike point. Go Mr. Miagi on this thing. Solid sharp blows. Quality better than quantity.

[HuskyMan]

Update. I purchased the heat gun from home depot and tried it out today. Man does it get HOT HOT HOT!!! I turned it on highest temp setting and went to work on the stuck 17mm acorn bolt. I set a time for five minutes to limit the time I heated it up.

Not only did the acorn bolt heat up, but the banjo fitting and copper crush washers heated up as well. then, fuel began to leak from the area around the copper crush washers and the banjo bolt began to smoke! YIKES! I shut the heat gun down PRONTO! I was afraid I might start a fire which would not have been fun; a fire is the last thing I needed.

I'm thinking of using Hylomar to seal the area around the copper crush washers. After running the car out of gas I would be more confident in attempting this repair. Input or thoughts are appreciated........

this

http://shop.advanceautoparts.com/p/permatex-hylomar-universal-blue-racing-formula-gasket-dressing-flange-sealant-85249/7740008-P?searchTerm=hylomar#fragment-3

or this

http://www.amazon.com/Hylomar-Universal-Regular-Temperature-Sealant/dp/B00HLSUXYC/ref=sr_1_2?ie=UTF8&qid=1422321036&sr=8-2&keywords=Hylomar#customerReviews.

[HuskyMan]

here is another possibility:

Changing the fuel filter - YotaTech Forums

he used this damaged bolt remover from sears with success:

Craftsman 10 pc. Impact Grade Bolt-Out™ Damaged Bolt/Nut Remover - Tools - Hand Tools - Tap & Dies & Sets

[liquiddog]

When I did a fuel pump on my 190e I just removed one end of main supply line and let it drain into a gas can. I was also replacing that line anyway since it had developed a large bulge in the middle of the line, and looked like it was ready to pop.

[HuskyMan]

Update. Unfortunately the Hylomar did not stop the fuel leak. I placed three coats with eight hours dry time between each on the copper washer/banjo fitting area....so, tried some Permatex #2 gasket sealent which also did not work. I'm going to drain the tank and remove the pump and filter assembly for bench repair.

I'm thinking of buying one of these super siphon hoses for draining the fuel tank:

http://www.northerntool.com/shop/tools/product_200603938_200603938

http://www.northerntool.com/shop/tools/product_200639248_200639248

[liquiddog]

I got a bicycle pump style fluid evacuator and never could get even the smallest hose to make it down into the tank.

I ended up backing up onto some wheel ramps and draining the main line into a gas tank. Of course I clamped the line before removing it.

[HuskyMan]

Which one of the following would you recommend for siphoning the fuel from the 1991 560SEL?? Obviously, the ten dollar option looks better but I want something that WORKS.

http://www.amazon.com/Portable-Transfer-Gasoline-Case-Adapter/dp/B00QDC31VO/ref=lh_di_t_dup?ie=UTF8&psc=1&smid=A1CP71A0ML4NK8

or

http://www.northerntool.com/shop/tools/product_200603938_200603938

[Hit Man X]

Originally Posted by liquiddog

...I ended up backing up onto some wheel ramps and draining the main line into a gas tank. Of course I clamped the line before removing it.

This is exactly what I recommend too.

Why spend the money for a siphon rig if you do not need it?

[HuskyMan]

I have six five gallon gas tanks and there is a full tank (23.5 gallons) of gas in the car. This means I'll have to stop the draining with a hose clamp and then place another empty five gallon container under the car. Isn't there a chance this could be messy (accidentally overfill the five gallon container)??