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Fuel Filter Pre-Heater Delete by vanbcguy on 21 Oct, 2011 07:50
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So I know I've suggested it to folks before, but I finally got rid of the "pre-heated" fuel filter on Jezzie yesterday.
Just for reference, this is the "correct" filter for my application - it has the mounting location for the "recirculator" valve:
Jezzie has had some persistent bubbles that come and go. Generally if I fire her up after she's been sitting I get a few, and I'd always suspected they were coming from the "recirculator" on the return line to the filter. Of course the "fun" thing with that is that any air in your system just keeps getting circulated around back through the filter and in to the engine again until the fuel is finally warm enough to close the valve. It makes purging air from your pump a complete PITA.
Anyhow, not all cars had the circulator valve, so I did some poking around. If you search by application, '1985 Jetta Diesel' comes back with a filter that doesn't have the spot for the valve on top (AND it's a $10 cheaper filter!!)
It's trivially easy to just connect the two return lines together, and then presto no more air getting in to your filter!!
Whenever I've changed the filter in the past it's always been a pain to purge the air out - you have to mess around for a while before you're not getting any more air bubbles in the supply line. After the change it was basically instantly bubble-free fuel. Sooooo much easier.
If you live somewhere cold enough that you have fuel gelling issues, I'd recommend an actual heated filter instead (like one with a 12V connection). If not (and with today's diesel unless you're somewhere REALLY cold you should be fine) then ditch the stupid "air-in-to-my-filter" valve and get the filter that doesn't need it! -
#1 by rabbitman on 21 Oct, 2011 11:14
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Maybe this is the problem with my golf, I can't get it to start very often. If I mash the gas, pul the CS handle and crank away it'll fire right away but I can't keep it running and then it won't start again. Could be that it's just getting a gulp of air and can't get straight fuel fast enough to keep running.
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#2 by ORCoaster on 21 Oct, 2011 12:29
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Yesterday I was cursing the air bubbles in the inlet line, again, and I pulled the filter and did the suggested blow air down to the tank thing and it was fine. So not getting a vacuum from the tank side. I cleaned the copper washers, again, and reinstalled. Also drained for water. Two tiny drops in 1 oz of fuel.
I put it all back together and arrrrgggghh them bubbles at all speeds. Not just Idle. I didn't remove the inlet line from the top so just for S and Giggles did that and watched a bunch of air race into the pump at idle. I just reefed on the 19 mm wrench in anger and boop instant solid fuel. What the heck? Going to have to see how long it holds. I have tweaked this bolt so many times in the past I don't know if it needs fatter newer washers or what.
Anyone find new washers to be the golden fix rather than heating and sanding them in 600 sandpaper in a figure eight motion?
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#3 by 8v-of-fury on 21 Oct, 2011 13:53
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Anyone find new washers to be the golden fix rather than heating and sanding them in 600 sandpaper in a figure eight motion?
weird I've never even had to do that, on the dozen cars/pumps I've worked on. -
#4 by the caveman on 21 Oct, 2011 16:17
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After I had done a couple of WVO conversions I started deleting the valve by running the return directly and making a loop from one side of the valve to the other. Having VO return into the diesel filter would cause the filter to freeze and cause a no start or stalling problems when below -5 Co and lower. Never noticed any cold running issues with the valve deleted- and it gets cold enough here to make a difference. Since then I just use the older non valve filter
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#5 by vanbcguy on 22 Oct, 2011 01:03
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Maybe this is the problem with my golf, I can't get it to start very often. If I mash the gas, pul the CS handle and crank away it'll fire right away but I can't keep it running and then it won't start again. Could be that it's just getting a gulp of air and can't get straight fuel fast enough to keep running.
Do you have clear lines on your Golf? That makes the biggest difference when trying to diagnose fuel problems - suddenly you can see what's going on!
I've run Jezzie basically out of fuel about twice now (both times knowing I had a jug in the trunk) - the way the car acts is totally different from a gasser, she'll get lower and lower on power till eventually you almost have to hold the pedal to the floor to keep her running. First time I ever did it I had no idea what was going on, but popping the hood and seeing the air in the lines was an instant "aha!". At the time I was trying out a wax blend and had managed to plug my filler neck. Ooops. If there's enough air in the lines it definitely gets hard to keep an idle let alone actually do any "work" with the engine.