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Join Date: Oct 2003
Location: Jackson, Ms
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3.0 CIS system cleaning - refurb questions

I have completed my long block.. WHEW!!!!!

I am now on to the CIS system. Looking at the unit, it is nice and dirty. I have a difficult time imagining installing the CIS unit on top of my perfect long block.... Okay...

Should I remove the metal intake/injector manifolds and bead blast 'em or hand clean 'em?

Should I replace the injectors?

I will replace the gaskets for the intake manifolds, What about the rubber boots on the other end? I did notice before the re-build, that my idle was slightly inconsistant. I've heard that leaks in the CIS system can cause this to happen. Replace them all?

Are there any other "best practices" that may help me and others out when re-installing a CIS system that has been setting up for over 6 months?

Any pointers, ideas or helpful hints will be much appreciated!
Old 10-20-2004, 07:07 AM
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Hi Groovy,

Having just completed mine, let me start off the deluge of responses sure to weigh in.

1. No need to remove the intake manifols, since they are made of nice shiny aluminum that should clean up with Simple Green (but get it rinsed off quickly). However, if the rubber boots holding everything together are hardened by age and heat, then replace them. I didn't and so far okay. If you replace them all while you have the engine apart, then you'll not have to replace them later with the engine in. New ones should last 20 years.

2. The injectors don't need replacing unless they test bad. To test, remove the injectors from the feed tubes (either metal or flexible), and fill them with carb cleaner, then blow them out with compressed air. If the spray pattern of the carb cleaner exiting the injectors is conical, then you're fine, and you have just tested and cleaner them by this process. If the pattern is not conical, then you have gummed-up injectors or a particle blocking the pittle, and you need to continue blowing carb cleaner until the pattern shows conical.

3. Try not to sotre the CIS Unit in any other position than correct-side up. The flapper valve can get damaged if you turn the Unit upside down. Other than that, also be careful to store the Unit on something soft, as the injectors protrude below the intake, and if you store on hard concrete, you could damage the injectors.

4. Finally, make sure that you have labelled eveything (hoses, wires, etc.) before you take anything off the Unit, as it is so much easier to re-connect everything when labelled. But be aware if you use labels with a sticky side, any cleaner will dissolve the glue and the labels could fall off.

Questions?
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Old 10-20-2004, 07:26 AM
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Hi Andras!

I have stored the unit in the correct position in a plastic bag. I am now worried about the injectors as I have it sitting on a shelf.

The rubber boots are original, so I'll replace those just to be consistant with the re-build.

I'll clean the injectors this evening and test them as well. I'm sure once I get into the CIS system I'll have many questions.

Thanks again!
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Old 10-20-2004, 07:44 AM
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There is at least one rubber o-ring (not in the fuel distributor!) on the cold start valve? and an air box gasket that are inexpensive and easy to replace at this stage. It is also a good time to replace all the fuel and vacuum lines (typically fabric covered rubber hose) that are secured with hose clamps. The larger hoses carrying air about the CIS system should also be checked for cracks or breaks or excessive hardness due to aging and replaced if required. Jim
Old 10-22-2004, 06:44 AM
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Ok, this is my experience with my fresh rebuild and my CIS system. I replaced all the injectors, all the rubber boots, the cold start valve, all the vacuum lines and hoses..especially the stuff that you won't have easy access to once the engine is in the car. I still had a butt load of CIS issues after all that but at least I had a baseline of what was new and could be ruled out as I began to work the bugs out of the system. In the end I replaced the accumulator, the decel valve, and the WUR. Still have a nagging issue or two but all and all things are great. I think you need to step back a remember that the system is 26 years old ( in my case). I spared no expense with the long block, kinda silly to cut corners with the CIS.
Peace, Ron
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Old 10-29-2004, 08:40 AM
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Replace what looks worn and craked.
The foam gasket that sticks to the air housing is probably crumbly. It's underneath the metering housing/fuel distributor. It's a cushion. If it shot- the metering piston wears out.
I replaced al of my injectors and found that it was a big waste of time since the test spray patterns still weren't perfectly conical under all of the sensor plate lifting heights . You get new inj. seals with the engine

Rubber and fuel lines(if plastic) need a thorough inspection. I had a leak in the return line. Small but deadly.

That's just the simple stuff.
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Old 10-29-2004, 09:48 AM
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