What am I doing wrong with my fuel filter??

gbonifie · 04-16-2005, 01:57 PM

Figured I would tackle an easy project today and replace my fuel filter -- or so I thought. The original came off the car with no problems and then I installed the new filter from our host. The car started right up after the fuel system pressurized and ran great. A quick check for leaks and I'm out on the road for a sunny Saturday afternoon drive. Uh-oh. There were a couple of drops of gas on the inlet fitting on the bottom of the filter. I grabbed my wrench and checked the fitting and it was snug. Gas was still leaking and now there was a small puddle under the car. I shut the car off and started cleaning up the mess thinking maybe I damaged the fitting, even though I had spun it onto the inlet by hand before tightening it up.

Took the filter off and checked the threads and fitting and they looked fine. Spun the filter back on by hand and tightened up the fittings and decided to try again. This time I just turned the engine over a few times and checked the fitting and it was leaking just like the first time. Removed the filter and cleaned up the mess (much smaller since I didn't start the car).

Car is an '87 and the filter is part # 928 110 253 06 which appears to be correct. This particular filter is unbranded and just says "made in Italy" on the label. I'm not sure what to do at this point other than try a new filter. If you guys have any ideas of what I'm doing wrong, let me know.

I made it through the tune up, valve adjustment, new bilstiens, soft-brake lines, brake bleed and now this simple thing hangs me up. Go figure!

darkbeer · 04-16-2005, 02:41 PM

with dry, clean hands/fingers....gently feel around & up the sides of the filter to see if you can find the actual spot the leak is coming from...this info should help you determine what is wrong. You could also re-install the old filter to rule out any of the lines being at fault.

Grady Clay · 04-16-2005, 03:02 PM

Reinstall the old filter asap, don't burn the car down.

Best,
Grady

kqw · 04-16-2005, 03:44 PM

You are using two wrenches right? Do the bottom first and then the top. By the way, they have to be really tight. Sounds like you are not tightening them enough.

DonMo · DonMo's Garage

I always add a little liquid telflon thread sealer when I change filters, never leaks.

TerryH · TerryH's Garage

Mahle filters have fittings already installed onto the filter to adapt to the fittings on our fuel lines. Are these fittings tight on your Italian filter?

You also need to snug your fuel lines pretty well while using a backup wrench to hold the mating nut.

gbonifie · 04-16-2005, 05:14 PM

Thanks for the input guys. I took a break and took the wife out to dinner. It was her first day off in three weeks and here I go making a big mess working on the car.

There was no crush washer with the new filter, and I don't remember seeing one on the old filter. Can someone confirm if a crush washer should be used? Of course, feeling overconfident, I took the old filter and gas soaked paper towels to a toxic dropoff before I started the 911 and checked the new filter for leaks. I am using two wrenches, one to hold the mating nut and one to turn the fitting on the fuel line. While the filter was on and leaking, I dried the inlet fitting with a paper towel and the gas reappeared on the last couple of threads on the fuel line fitting. So it appears it's leaking out of the filter inlet. Perhaps in fear of overtightening the fitting, I'm not tightening it enough?

DonMo · DonMo's Garage

No crush ring on mine today KN-21 I think, they are flared fittings.

gbonifie · 04-16-2005, 05:32 PM

Thanks DonMo -- that's what I thought.

kqw · 05:57 PM

No crush ring...

It's got to be tight. I know the fear of over tightening but it has to pretty snug in order not to leak.

michigan · 04-17-2005, 01:52 AM

You probably have a bad threaded filter. I would try that next.

gbonifie · 04-17-2005, 05:38 AM

Michigan -- I think you nailed it. I looked at the inlet on the filter and the last couple of threads are not completely formed. I'll pick up a new filter Monday morning.

gbonifie · 04-18-2005, 12:15 PM

Picked up a new Mahle filter this morning and installed it and no more leaks! The inlet on the Mahle filter had clean threads all the way to the end. The threads on the other filter didn't go all the way in and the last couple were not completly formed. Not sure what the odds of this are, but it's something I will check next time.

Grady -- your concern was duly noted. I will definitely be more careful next time.