Fuel Injector Replacement- stuck fuel line nut on Injector

[Mike K]

I’m in the process of replacing my fuel injectors. I spent a great deal of time trying to clean them, they’re still dripping and leaking fuel. So decided to take the plunge and ordered 6 new Bosch fuel injectors.

I’ve managed to unbolt all the fuel injector line nuts off the injectors and loosened the injectors, except for the no. 4 cylinder.
As I try to unbolt the fuel line nut off the injector, the injector is loose in the block and turns with the fuel line nut, with the danger of twisting and breaking the fuel line. I’ve run the engine to heat it all up and sprayed WD40 on the top of the nut, it still wont budge.

I have both the 19mm Hazet wrench for the injector and the 17mm wrench for the fuel line nut. There’s not enough room to fit the 19mm on the injector and then the 17mm on the fuel line nut in order to hold the injector in place and then counter-rotate them.

I’ve now ordered a Hazet insert flare nut wrench (1st pic), which I hope will work, so that I can get this in place under the fuel line nut and onto the injector to hold it and stop it turning, and then try to unfasten the fuel line nut with the 17mm Hazet wrench.

I guess loosening the no. 4 fuel line all the way back to the injector pump and separating that line out should help?

In the worst case scenario, and that I do end up snapping the fuel line, does anyone know where I can get a replacement fuel line? I’ve checked all the usual suspects SLS etc. = not available....

Any other thoughts or input would be greatly appreciated.

Many thanks and best,

Mike

[Larry & Norma]

If you remove the valve cover you can get a spanner on to the injector.

[Mike K]

Thanks Larry!
It didn't even occur to me.

Best,

Mike

[wwheeler]

There's always one! Murphy's Law says so.

Take the cover off and use a wrench on the injector as well to keep it from turning. Frequently the fuel line nut corrodes on the line it self making the injector spin before the nut. I always put a tiny amount of anti-seize where the nut and the fuel line interface when installing. And use a torque wrench to insure the injector is tighter than the nut. The injector should be around 21 Ft. Lbs. but check the specs for sure.

[Mike K]

Thanks for the input Wallace.  Yep, every time I undertake work on the car, I know it's going to take 2 or 3 times longer than originally planned.
Clearly someone over-tightened the fuel line nut and not enough torque on the injector itself.

Best,
Mike

[Benz Dr.]

I've had to use heat right on the gland nut to get badly seized ones apart. If you're careful, there's little chance of damaging anything.

[lurtch]

Another Larry says:

Knock'er-loose is a much better penetrant than WD-40.

https://www.youtube.com/watch?v=6VM7NxPXRDY

Larry in CA

[Mike K]

Thanks for the input gentlemen, much appreciated.

On the subject of penetrants, I've read that a homemade mixture of 100% Acetone & ATF mixed in equal proportions is most effective at freeing up seized bolts. It is suggested that you mix only as much as you need and shake well as the 2 liquids are like oil and water.

Here's another brew with Acetone & vegetable oil:
http://www.engineeringforchange.org/how-to-make-penetrating-oil/

"Penetrating oils ........... Average torque load to loosen

No Oil used ................... 516 pounds
WD-40 ..................... ... 238 pounds
PB Blaster .................... 214 pounds
Liquid Wrench ...............127 pounds
Kano Kroil .................... 106 pounds
*ATF-Acetone mix............53 pounds

*The ATF-Acetone mix is a "home brew" mix of 50 - 50 automatic transmission fluid and acetone. Note this "home brew" released bolts better than any commercial product in this one particular test.
ATF-Acetone mix is best, but you can also use ATF and lacquer thinner in a 50-50 mix."


Anyone tried this?

Best,
Mike

[jameshoward]

Naj introduced me to Plus Gas. I've got to say that I can't see how anything could be better than that stuff. It was utterly invaluable when changing over the rear diff a few years ago. I'd just about given up on some parts when I found a can of the stuff and it just blew me away.

Did you mange to get it off?

[Benz Dr.]

I've used heat and then I melted a wax candle into the heated area. It doesn't work in every case but then it doesn't work badly either.

[Mike K]

Naj introduced me to Plus Gas. I've got to say that I can't see how anything could be better than that stuff. It was utterly invaluable when changing over the rear diff a few years ago. I'd just about given up on some parts when I found a can of the stuff and it just blew me away.

Did you mange to get it off?

I'm away for a couple of days and will have a go at No.4 again later in the week.....I'll post an update on how it goes.

Best,

Mike

[Mike K]

Following all the advice received here, I managed to loosen the No.4 injector line from the injector, without breaking the fuel line.
 
I firstly made a home brew of 50% Acetone & 50% ATF fluid as a penetrant, ran the engine to heat up and dripped the brew onto the fuel line nut.
Removed the valve cover & had space to get a spanner onto the injector and another spanner onto the fuel line nut above. With a fair amount of force I was able to loosen the nut from the injector.

While I had the cover off, took the opportunity to also check the torque on the engine head bolts and when things cooled down also checked the valve clearances.

P.S. Just in case anyone thinks I've been neglecting the oil (based on the oil colour in the pics), I did an oil change about 100 miles ago and then added Liqui Moly MOS2 Oil Additive which gives the oil that dark grey sludgy colour.

Thanks to everyone for their input and advice, always greatly appreciated!

Best,

Mike

[wwheeler]

Yea! Good job and a wonderful feeling when it is done.

You can use a socket to torque the injector before the valve cover goes on.

[tel76]

Mike,
The slipper on your timing chain is fitted incorrectly, it should be fitted with the long section downwards.

[Mike K]

Thanks for pointing out Eric, I wasn't aware of this. Here's a close up pic.
Never done this before, is it a big deal to reinstall?

Best,

Mike

[wwheeler]

Mike,
The slipper on your timing chain is fitted incorrectly, it should be fitted with the long section downwards.

Are you sure? Just for reference, I looked at the valve adjustment tour. There is an old aluminum one that is long side up. The reason I am aware of this is because on my old 220SE engine, I had severe wear and was trying to decide which way it is positioned. The wear was from an unrelated problem that is now fixed. But it was long side up when I took it off and the new one is now long side up.  

[Benz Dr.]

I install them long end down. Any slack in the chain will happen further away from the gear.

 Installing everything the way it came apart is a good adage until you find out it was done wrong before you had it apart. I see this sort of thing more than you might imagine.

 Which leads me to the three great truths after age 60:

1) never pass up a chance to visit the washroom
2) never waste an erection
3) never trust a fart


   

[reggie]

 

[mbzse]

Are you sure?:::/...

This is from M-B workshop literature. Eric is right (as usual)
/Hans in Sweden
.

[wwheeler]

Fantastic information and thank you. Like the Dr., I would have thought down was correct because of the slack after the cog. But I was too chicken to reverse it. The diagram pretty much tells it the way it should be. I wonder how many are installed incorrectly?

Easy to change. Just remove the two allen head bolts that hold the bracket. Take bracket off engine and then pry guide off the pins carefully. There is a wire spring that holds the guide to the bracket pins. A tip: Put rags on the head below the bracket to catch the bracket bolts if they get loose. You DO NOT want them to go into the oil pan.

Dr., Those are great truths to always live by.