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Old 11-12-2001, 07:06 PM
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RunningTooHot RunningTooHot is offline
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Lightbulb El-Cheapo diesel compression adapter

I hope that maybe this will come in handy for some of you out there.

Instead of buying a whole new set of compression gauges specifically made for diesels, here is an alternative solution for those of you that already have a compression tester for gasoline engines.

Obtain the following items:

1. An old injector.
2. A 2” inch section of quarter inch galvanized pipe.
3. A barbed fitting with an appropriately threaded (spark plug sized threads) female end connection (sized so that the barbed end can be inserted into the galvanized pipe)
4. A small diameter drinking straw
5. JB weld (that is what I used, as it is stronger than most typical two-part epoxy mixes)
6. Some old leftover plastic film from a shrink-wrapped item (Polyethelene). Saran Wrap may work(?).
7. An air pressure gauge that reads to at least 400 PSI. Graingers is a good source.
8 A rubber o-ring sized for the compression gauge threads. (Again, spark plug thread sized diameter).

Take the old injector and unscrew the two halves. Toss the top half and all the innards. Thoroughly clean the bottom half with carburetor cleaner/brake cleaner. Thoroughly clean and de-grease the galvanized pipe. On a flat level surface place the injector in an upright position with the bottom opening on the plastic film. Insert the galvanized pipe into the injector so that it is centered & one end of the pipe is also resting on the plastic film (Coaxial placement) Mix up a batch of JB weld and dribble it into the injector from the top, surrounding the galvanized pipe & filling the injector body completely. The JB weld will not stick to the plastic film. Let it harden overnight.

Peel off the plastic film from the injector body. Mix up a batch of JB weld. Using a toothpick, smear the inside walls of the galvanized pipe with some of the mixture. Butter up the barbed end of the fitting with the mixture & insert it into the galvanized pipe. Turn the injector upside down and place it on a flat level surface. Take the drinking straw and insert it through the galvanized pipe & barbed fitting. Carefully fill up the galvanized pipe with more of the mixture -- this takes a bit of patience to do properly because of the straw in the center, but you want to make sure that there are no air bubbles and that the barbed fitting is completely enveloped with the JB weld. (Helpful hint: you can use the straw advantageously by pulling it towards the top while it is smeared with the mixture, pulling the goop up inside of the galvanized pipe.) Take a pair of scissors and cut the straw flush with the top of the threaded section of the barbed fitting so that it can rest in this upside down position overnight. Once it is hard, take an appropriately sized drill bit & using the tube/tunnel formed by the straw as a guide, drill out the opening to the same diameter as the internal diameter of the barbed fitting & remove the rest of the straw.

You will be able to use your injector socket on this new adapter. Change out the gauge on your compression tester to the new one. Use a rubber o-ring to seal the compression tester when screwing it into the female end of the barbed fitting – don’t rely on the threads to seal against the pressure – then it’s bomb’s away….

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