I have always been frustrated trying to remove those rock-hard fuel return lines that are on the injectors. You can tug on them, and often they break. You can try to carefully use a blade, but then you risk nicking the barb and will have leaks.

Tonight I used a heat gun (got mine from Harbor Freight for $9.99) to heat the hose at the nipple. I put the nozzle of the gun just 2-3 inches away from the nipple area, and just applied heat for about 5-10 seconds on the high setting. Without waiting more than a few sconds, I grabbed my needle noze pliers, grabbed the hose just above the nipple, and they would pop right off. I tried one without heat and couldn't get it off, applied the heat, and it immediately came off with very little force. I had all hoses off in about 3-4 minutes, versus the one time I spent 20 minutes on one hose!!

Please be careful, as I suppose it is possible to apply too much heat and ruin something or start a fire! Just enough to heat the rubber and cause it to soften a bit. You might have the same effect if you just tried to remove them right after driving the car, but then you have the issue of working on a hot engine, which has its own hazards.

Maybe this will help someone and curious if others out there already used this method.

Which lines are you talking about, the ones underneath near the tank, or the ones in the engine compartment?

Ive never had a problem, if they were too stiff, I just cut them off beyond the nipple with a hose cutter, then cut down the side of the hose with a blade, and remove whats left on the nipple. If they are that stiff, they are not worth keeping.

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This post brought to you by Carl's Jr.

These are the fuel return lines that are on the injectors. They are definitely not worth saving after they are hard. The problem with using a blade is that you just need to be careful not to nick the barb on the injector as some have had leaks after doing this. Heat allows you to just pull up and off they come. Much quicker in my experience.

What I have always done is grab them about 1 inch above the Nipple with a Pliers pull on the gently while I used a small Screwdriver below the Hose to push up on it. 95% of the time the whole hose comes off and I have never damaged a Nipple.

Below is the only pic I could find fast of a small Nail Puller. There is a much smaller one available at cheapie tool places that could be bent into more of a hook shape on then end.
To use it would be similar to what I said before. You grab the hose with the Pliers and get it under some gentle tension and you would use the Nail Puller tool to pull up on the underside of the Hose that is on the Nipples.
The cheapie tools are made of soft Steel and you would have to work hard to damage a Nipple with one.

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84 300D, 82 Volvo 244Gl Diesel

ahhhh, ok! Good idea for that. I usually just carefully yank the injector return lines off and if the break on the nipple, pull the rest off with a needle nose plier. Never damaged any either, but it is annoying to have 2 or 3 break per 10 or 8 attachments.

I will have to try the heat gun idea, I though you were waving it around down by the fuel tank!
Must be localized heat that does it, they still break pretty easy on a hot engine thats been running.

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This post brought to you by Carl's Jr.

on the 15 or so cars I've worked on, I've never had an issue. I take needle nose pliers and grip along the side of the nipple section of the hose. squeeze tight, and they split around the nipple. never had a single one that would not come off this way. never even touched the nipple with the pliers.

I mostly have to agree with vstech.
At the worst I have had a few hoses Break off and stay on the Nipples; never had a problem with the hose stuck.
I surely would have removed the old Hoses and installed the new Hoses in the same time it would take me to find and drag out my Heat Gun and an Extension Cord.

Also I am inclined to pull my Injectors every few years and test them. If the Hose is still good I reuse it until it leaks so I am careful when I pull them off.

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84 300D, 82 Volvo 244Gl Diesel

For the average DIY its probably a smart suggestion. If ever I take the lines off I always shorten them by 1/2" or so on each end so that when they are put back they have fresh hose on the Nipple. when they get too short, just put new hose on.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Fuel return line is what- a quarter a foot retail? Who would save that stuff unless you fail to plan and buy three feet before working on your car?

I've been using GATE 1/4 Inch (3.4mm) fuel line working well thus far. Time will tell. Looks good and doesn't leak or seep. When I remove my old lines I give them a twist and pull they come off with out a hitch. I did have one stubborn one that I didn't grab low enough and it broke. Just grabbed it lower with pliers and twist and pull. Came off.

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92 300D 2.5L OM602 OBK #59

I like the idea. Good thinking.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13