Sponsored by HUMAN Speakers New Injectorz! RETURN

This file is supposed to help you change your injectors - I suppose it is also a handy reference for simply changing seals as well.

This file provided by: Huw Powell, on or about 2/8/2000.

Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

Start with a set of new injectors and seals.

There are also plastic inserts screwed into the head (intake manifold on the 87.5 Coupe GT) that the injector with its seal(s) pops into, and these have their own little seal at their base. The injectors shown in my picture are the early, unshrouded type. The later style have little metal hats on the tips, where a second, smaller seal is located. I had already replaced my plastic seats, and the seals on my old injectors are fairly new. You're supposed to try to get the green "Viton" seals cause they last longer, especially for the tip seal in turbocharged applications.

The ends of the fuel lines on my car were 12 mm and the injectors 14mm. It is a good idea to use hydraulic fiting wrenches here - they grip four of the six faces of the hex and are supposed to cause less damage to the (unreplaceable!) faces.

There is a $20 VW tool available that gets a nice grip on the them so you can pry with a screwdriver and have your force go in the right direction.

A small dentists pick tool can be useful for removing recalcitrant seals.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

To prepare to do this work a few precautions need to be taken. You are working on the fuel system of the vehicle, and gasoline is a very dangerous substance. Ideally you should work outside. You should at least have very good ventilation. Wear goggles! Do not smoke!

I did two things to make this job easier. One was to remove the Idle Stabiliser Valve, which sits right over the number five injector on CIS-E cars, pretty much blocking access to it, and the other was to remove the remaining fuel pressure in the lines by powering the Cold Start Valve manually. The first item is fairly generic - anything in the way of your injectors, you might want to remove to make the work easier.

Releasing the residual fuel line pressure is handy because the injection system will usually have an ounce or two of fuel at about 50 psi stored in the lines and fuel distributor. This will come spraying out in the worst directions when you open up the first injector fitting if you do not bleed it off. I had the crack pot idea of using the Cold Start Valve to do this. The CSV is the sixth injector like thing, bolted to the intake manifold with an electrical connection going to it. Remove the electrical connector, and simply power up the CSV with a couple of jumper wires (polarity doesn't even matter, it is a simple solenoid) and dump the fuel into the intake manifold! I left the wire off until I was done, because it was one more item that crosses in the way of the injectors.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

Now we are ready to actually start working. If your car has an injector retaining rail, remove it first. Mine was bolted in with two Allen head bolts, the front one was easy to get to, the rear one was a bit tougher.

I started at the front so that the job would get progressively more difficult as I worked.

All you have to do to remove an injector is pull it out of the head (or manifold). This is quite easy if the seals are in good shape - I pulled the first three out completely by hand, pulling gently on the fuel line exactly along the axis of the injector. I used the tool on numbers four and five due to lack of room for my hand.

It is recommended to use the injector removal tool for all the injectors, especially if you have not worked on this assembly before. The tool grabs the injector/fuel line joint at a place where force can be applied without damaging anything. Yanking on the fuel line when the seals have fossilised may result in broken fuel line ends, and cost you a lot more in time, money, and aggravation.

Put the short leg of the tool under the injectors protruding end, catching the skinny part in the tool. Then use a screwdriver to engage one of the slots in the long leg of the tool, and use the cam cover as a fulcrum to apply pressure to the tool. It will pull in the correct direction, exactly in line with the axis of the fuel injector and if you are lucky it will pop right out, with the seal still on it. Wrestle the injector and its line up out of the cave in which it lives into the light where you can get tools at it.

If the seal stays stuck in the seat, use a pick to get it out.

If you are replacing the seats as well (you should), now is the time to carefully remove the old seats and their little gaskets, clean the area nicely, and install the new ones.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

Now with the old injector still attached to the line, but laid out on top of the cam cover, prepare the new injector for installation. take off the nifty plastic caps. Lubricate the new seal(s) with gasoline and slide/roll them onto the new injector. Bring this prepared injector over to the car and place it on a clean rag within reach of the fuel lines.

Remove the old seal from the old injector if it is still there. Using your hydraulic fitting wrenches, loosen the old injector. One of my pictures shows this being done hidden under a rag, over a small container, just in case there was still residual fuel pressure in the line. There wasn't.

Now undo the old injector by hand until it comes out of the female fitting. I tried to move quickly and carefully at this point to avoid getting any crud into the center area of the female fitting, where it would get forced intot he new injectors. Grab the conveniently placed, properly prepared new injector and seal(s), and screw it into the fuel line fitting till it is snug.

Then raise the fuel line a little to make sure there is no strain on the fitting, and using the two wrenches tighten the injector into the fitting. (I had to use a regular 14mm on the injector because the new seal was in the way of sliding the hydraulic fitting wrench on. Oh well.) The torque is pretty light, about 18 foot pounds I think.

Wrestle the fuel line and new injector back into the grimy cave in which they live, trying not to get any of that grime on the new seal(s) or on the new injector. Position them over the seat and push gently. The injector and seal should pop with moderate ease into the plastic seat.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

When you have fought your way through doing the fifth, and most difficult, injector, you are ready to start reassembling. Reinstall the injector retaining rail if there was one. Replace any hoses or components you removed in order to gain access.

Clean as you go! Wipe off dirt and grime if you can. Electrical connections should always be improved with contact cleaner and sealed with silicone dielectric grease when you have the opportunity.

Make sure everything is in its proper place, and that there are no stray tools in the engine compartment. If you are indoors, open all the doors even if it is cold out. My suggestion would be to crank the car for a moment - whether it catches or not, turn it off immediately and have a good sniff around the engine compartment for gasoline leaks. If there are none, start it again (it may take a moment as all the fuel pressure was bled off) and if it is inside, drive it outside. With the car running (and the exhaust not pointing into the house!) check again in the engine bay for fuel leaks and any other bad things.

Test drive.

Put the old injectors in a plastic bag, mark it, and keep it. Someday they will be worth a small fortune, and you will be able to retire to an island in the South Pacific because you saved them.

If you have any gasoline soaked or stained rags dispose of them properly! Do not place them in a trash container indoors as they can spontaneously combust and you might die. They should be kept in an open, metal container outside, until they can be turned over to the Federal Oil Rag Department for proper disposal.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

I was very pleased with the results of this job. My engine drives smoother at any given RPM, and the power band is also smoother as the car accelerates. I don't know if I will see any effect on fuel economy, it is certainly possible. The middle of a New England winter is a difficult time to observe the fuel economy effects of car repairs unless they are drastic.


Supplies - Cautions - Removal - Install - Assemble, Test - Evaluate - Photos

New Parts - Five pretty new Bosch injectors and shiny black seals

Removal - Pulling by hand and using the special tool

Swapping Injectors - Tool set up, gas precautions, new injector in place.