Hello, My '78 245 runs a little rough, even after the standard tune-up stuff. I tried a few different test for the injector o-rings, and they all failed. I decided to pull the injectors, soak them in Techron over night to clean them up a bit, and then install them with the new o-rings. All of the plastic injector holder/insulators were in terrible shape, so I ordered a new set. I'm left with two questions though.
The first of which is how do you get the holders off the injectors? The injector turns around freely in the holder but it does not slide out.
The second is where do the o-rings go? It seems like the larger one goes on the injector holder, but I seen no place for the smaller one. This car's previous owners seem to have taken very poor care of it (I've seen some very stupid mistakes all over the car), so I am beginning to wonder if they even had the smaller rings in there.
Do you mean that all the tests indicated bad o-rings?
The real test of a properly functioning injector is the spray pattern. The spray pattern is affected by the cleanliness of the injector inside as well as outside. Many properly equipped Volvo shops have a tool that can force a cleaner through the injectors whilst off the car and can observe the spray pattern of liquid from the injectors. Soaking the injectors in Techron may not clear a dirty injector if it is dirty inside. Running with Techron additive in the tank could help clean the intectors inside, but the real verification is cleaning and spray pattern inspection.
Install the injector holders back onto the head with the injectors inserted. Use a small prybar between the bottom of the injector and the screw that holds the injector holder onto the head to pry out the injector. Then remove the injector holder.
This is a pretty good indication of a worn o-ring between the injector and the inside of the injector holder, which will suck air and lean out the mixture, mostly at idle.
The smaller one is on the injector inside the injector holder and is what is holding the injector in place inside the holder. Its purpose is to form an airtight seal between the injector and the inside of the injector holder. The larger o-ring forms an airtight seal between the holder and the head. Both are important.
If the smaller o-rints were missing, you would be able to easily remove the injectors from the holder because there would be nothing to keep the injector in the holder. When you pry the injector out of the holder, you are compressing this o-ring to get the injector out.
The fat oring is holding the injector and holder together. They will pull out, but since you have new holders, you can just break your old ones. The skinny orings go in the slot on the outside of the holder to seal the holder to the head.
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