1976 Cadillac RWD replace fuel filter troubles-experience needed

[Scot Minesinger]

Working on a 1976 Cadillac Fleetwood and it although it runs smooth, when you hit the gas it bogs down like it is going to stall you let up and it comes back to life, you have to accelerate slowly.

The spark plugs and wires have been replaced and the car runs extremely even and smooth, starts good and all, just on a call for power it starts to die.  I'm thinking fuel.  The fuel filter looks to have never been changed in 39 years and 45k miles, so no matter what the problem is this should be done.

I have my own tool for the 1" nut at carb, but I cannot seem to break loose the 5/8" compression nut on fuel line.  When I put the wrenches on it, you can tell they are going to round the nut if I put more force on it.  It is soaking in penetrating oil, as I write this.  I have a hardened 5/8" impact deep socket that worked great on my transmission lines, but even that you can feel will round the nut if I put more force on it.  Pictures show the tools I'm working with.  Not opposed to buying more tool, as this comes up from time to time.

It is understood the fuel line can be cut as a last resort and then replaced, but hate to go that way, as it will cost another couple hours and $50.

Any ideas?  I can't be the first to try and remove a never been removed compression nut on this set up, as this was made in over one million Cadillacs.

["Cadillac Kid" Greg Surfas 15364]

Scott,
It sounds like you are going to get a lesson in Quadrajets.  Be sure the secondary air valve spring is correctly adjusted, the secondary jet rot cam has not broken, the secondary and primary pull-offs are working and by the way, use a tubing wrench to get the filter nut off.
Greg Surfas

[bcroe]

The recommended tubing wrench is a must; its a specially designed 6 point tool for the
job.  I also tried making my own once, but it wasn't up to the job.  Bruce Roe

[chrisntam]

Scot, I had an issue taking the my transmission cooler lines off the radiator.  I found that the line itself had become permanently connected to the flare nut.  I could see the nut was loose (the threads), but the line itself was twisting.  I used WD-40, PB Blaster and no luck.  I heard later there is a home made concoction of a 50/50 mix of acetone and ATF that does really well as a penetrant.

If the 5/8" flare nut is about to round off I think you're sol.  What about cutting the line on a nice straight section, use a deep 6 point socket to loosen the nut?  If you round it off, then maybe even a 6 point may not work.  If you are able to cut the line and get the nut off, just use a short section of 3/8" fuel hose to join the two section.  If you end up replacing the line, I'd lean towards getting a steel replacement (as opposed to stainless steel).  I got a ss fuel line and had difficulty getting it to seal at the fuel pump.  I hear this is a common issue with ss.

It appears you have the right tools for the job, it's just the fact that time (and possibly other mechanics) have taken a toll on the flare nut prior to you getting to it.

Let us know how it turns out.

I had a fuel filter clog on my '75 delta (due to debris in the tank), had the same symptom as what you describe.

Best of luck to you, it blows when things don't go as planned.

chris.

[chrisntam]

Hey Scot,

I just took another look at the pic you posted. You're using the 1" line wrench to hold the carb nut and the cut out deep socket looking thing on the flare nut?  What about getting 6 point metric in an equivalent size (or just a bit smaller) for a tighter fit?  Sorry can't be of more help.........

[76eldo]

With the 1" wrench holding the large nut and a proper line wrench on the fitting it should break loose.

How do you have a socket on there?  How does it go o Ed the fuel line ?

Brian

[Gene Beaird]

Scott,

I'm a firm believer in Sears Craftsman tools.  My Dad got me started with them, and my tool boxes are full of them.  There are a few tools I do upgrade, though, and flare wrenches are one class of tool I have upgraded, because I kept rounding flare nuts off with the Craftsman tools.  I broke down and spent the cash on a set of Snap-On flare wrenches, both SAE and Metric.  They were about 3X the price of the Craftsman, but I feel it was money well-spent.  I'd really recommend flagging down a Snap-On dealer, or going online, and purchasing at least this size flare nut wrench from them.  They are a lot stouter than the Craftsman analogs.

With that tool in hand, as others have mentioned, do hit the threads with some penetrating oil, and let it set overnight.  The next day, try to remove the nut.  Take your 1" for the filter housing nut and put it on the filter housing nut as if you would be removing the filter housing.  Use that to stabilize that nut so it doesn't move while you try to remove the tubing nut.  Put the flare wrench on the tubing nut orienting the nut in a way so you can get to it with a hammer.  With the hammer, try to jar the nut loose with a couple of good whacks with that hammer.  That has worked for me when nothing else would, even on nuts that have started to round off.

If the nut has, or starts to round off, try to dress it back up with a file.  If it's already rounded beyond use, you may want to try clamping a pair of vise-grip pliers on it nice and tight and rapping that with a hammer. 

Failing that, as the others have said, you may have to just cut the tube off and remove the nut with a deep socket.  I hope you don't get to that point, though.  Go back together with some anti-seize after you get the filter replaced.

[76eldo]

Try tightening it first.  The hex will grab better in that direction. The key is just getting it to move at all. Sometimes going a hair tighter will allow you to break the grip and then loosen it.

If all else fails just cut it.  May get a decent line from a parts car or see of a company like inline tube makes it.  Marketing it run right is the object. I get the preservation aspect but you can only do so much.

By the way it sounds like an accellerator pump issue.

Brian

[Scot Minesinger]

Guys,

Thanks for this advice.  Another club member sent me a private message of another technique that seems the most promising.  I did not take great care in my photo, but just for clarity, I am using a high quality 5/8" six point flare wrench.  As all open ended wrenches do, this one starts to open when I put force on it and I can tell the nut will round.  This fuel filter is original.  At least the fuel flare nut looked like it had never been touched in 39 years.  Even if replacing it does not solve the problem it sure seems a good place to start. 

The six point deep hardened socket wrench is slotted by me with a grinder and fits over the fuel line, and this worked on trans lines without opening when the flare nut wrench was going to fail me, however I used a hose clamp to really keep it from opening so maybe will try that too.

If I have to cut the fuel line I will.  Not so interested in authenticity, just want to save the time (my labor and waiting for in-line tube to send one) and money.

On the carb work, not sure I will be tackling that.  The education process and time is not in my schedule right now.  Work responsibilities are crushing me now, unless Greg is traveling to DC in the near future to help me.

Will post results when cured.

Thanks,

Scot

["Cadillac Kid" Greg Surfas 15364]

Just missed me Scott.  We just came back (last week) from a couple of weeks at Massanutten. Hah
Seriously, what I( have had to do on more than one occasion is use vice grips on the tubing nut> You can get a pretty large pair of vise grips on the nut and with a tubing wrench on the carb, tap the vice grips.  I don't recall this method failing.
Greg Surfas

[TJ Hopland]

I have had em were after cutting the line and removing the filter housing it was still a bugger to remove.   I have no idea what makes those stick so bad, its not like the brake lines that get exposed to road salt and brake fluid.  Must be people that are use to working on diesel injection lines that run at 3500psi that changed the filter last time. 

Be careful not to damage the carb end of things while fighting with this thing.


So you think this carb has not been touched in 38 years?

[Roadmaster75]

Those fittings on my 78 Eldorado exhibited similar reluctance to move. 

We used a 1 inch open end to hold the big one firmly & the "high quality" 6 point
line wrench as stated previously.  Only after careful, repeated persuasion in both directions
did she break loose.  Imperative to keep those wrenches absolutely square on their
targets to avoid the rounding off syndrome.

Also, once you get it loose ensure that you retain the spring and thin gasket
found inside the housing.  Have a replacement handy, as these are very easily
distorted once your new filter is installed and tightened.  If it gets crooked and distorts
inside the housing it WILL leak like a sieve despite the tightness of the fittings.

BTW, you've already found that
It's really hard trying to reach all the way to the center of an Eldorado engine bay to wield
your wrenches effectively!!

You'll get 'em off…….!

mike

[mgbeda]

Sounds like you're doing everything right.

Try the 50/50 ATF/acetone penetrating oil - it really is all that.  And hitting the wrench with a hammer is always better than steady force.  I agree on trying to tighten it first.

The first time I changed Bessie's fuel filter (back in the 80's) the nut was so tight that when I got it to move it actually twisted the fuel line!

-mB

[Bob Hoffmann CLC#96]

Guys,
Hate to say this, but...  the fuel filter is in the fuel pump!! Yeah, there may be a little screen or some other filter looking thing in the carb. It does very little.
HTH, Bob

["Cadillac Kid" Greg Surfas 15364]

Not on a 76 Bob
Greg Surfas

[Coupe Deville]

The first time I changed Bessie's fuel filter (back in the 80's) the nut was so tight that when I got it to move it actually twisted the fuel line!

Been there on my 472..did this about a year ago. I started to strip the line nut while using a line wrench. I resorted to a crows foot wrench/socket? Not sure of the official name but it loosened the nut right off, and mine had never been removed before.

I will post a picture of the tool. Put a 3/8ths extension on it and a ratchet on that and you should be fine I think.

Best of luck

-Gavin   

[Scot Minesinger]

OK, broke the nut loose without messing anything up - yes!

Thanks to all:

Bought the extreme high quality wrench (had to hemmer it on because nut started to round, and the rehearsed no-wimp sledge hammer blow, did on first try after soaking it with 50/50 acetone/trans fluid mixture.   After I bought the wrench, broke the nut and now it is time for dinner, fuel filter change will have to wait until after.

If I suffer further problems, will start another post.

It is written in the shop manual that the filter is in the carb inlet.  The fuel pump has a 5/8" flare nut only (so it cannot be at the pump), no 1-1/4" nut to remove for fuel filter like on my 1970 Cadillac where it is at the pump.

Thanks again!  This really was great.

[Bob Hoffmann CLC#96]

Not on a 76 Bob
Greg Surfas

I stand corrected.

[The Tassie Devil(le)]

There is a Sintered Bronze Filter in the Carby inlet, and a paper one in the pump.

Bruce.

[bill06447]

I usually have luck with Vise Grip pliers on these types of flare nuts-especially brake line.

On every Quadrajet I encounter I will replace the small filter in the carb then add an inline filter somewhere between the fuel pump and the carburetor, this way the in-carb filter can sit there and do nothing while the inline one catches all the dirt (and is easier to replace).

Bill