jrb964

I currently have my engine out of the car doing a clutch job along with a rebuild of the tranny. It is the first time the engine has been out of the car - pretty amazing after 22 years the clutch needed to be replaced. Consequently there is 22 years of oil and grease build on the engine. (What a mess.....)

I'm trying to do as much as possible with the engine out. I am currently having trouble getting at the top of the engine because of the CIS system. Bently's book seems to imply that the CIS system can be removed with simply removing the tweleve (12) nuts that hold the six trumpets on, and disconnect a couple of electrical wires. IS IT REALLY THAT SIMPLE TO REMOVE THE CIS SYSTEM???

If so it would seem that this is the simplest way to go, it would require new gaskets, but that's a simple fix to cleaning the engine/

Would appreciate any feedback.

Bill Gregory

There's an article on tech.rennlist.com under 911 engines, that talks about replacing a blown CIS airbox - that may help answer some questions.

Chuck Harmon

The Bently manual is on the money, it is that simple !... be sure to stuff rags or tape up the holes and do not use a very high pressure spray.
Mutiple applications of Gunk works for me.

Jim Sims

There is a bit more to it that just undoing 12 nuts and washers and lifting off the CIS but not too much more. There are a couple of supports for the air box, the throttle linkage and some emissions items (EGR valve, auxilliary air valve, etc.) to also remove. To clean a 22 year old engine well you'll need to also remove the fan, alternator, fiberglass shroud and the engine wiring harness. Mark all the wiring connections prior to removal; several of the connectors can be mixed up if not labeled. I would also recommend removing the ignition wires (leave spark plugs in place) and distributor. Then plug all the openings into the engine (I use rubber corks, rubber chair leg tips and fitted metal plates with cork gaskets for the intake runners). Some of the openings plugged: distributor hole, all 6 intake ports, breather nozzle, hard oil line and oil intake line under engine mounted oil cooler. Then after using a degreaser I suggest pressure washing the engine. After external cleaning I would suggest removing and cleaning the engine mounted oil cooler, replacing the other known oil leakers and adjusting the valves while the engine is easy to access. Typical other oil leakers: engine mounted thermostat o-ring, oil pressure switch (enhance it's sealing with a bit of epoxy around its crimped seam, engine mounted oil cooler seals (there are three), breather cover gasket, new valve cover gaskets, and hose from breather to oil tank. This is also the time to inspect and likely replace the short sections of rubber hose that connect the intake runners to the air box and other rubber hoses that are ducting air/vacuum through the CIS system. Clean and look over the engine wiring harness and repair any damaged insulation. Clean intake runner/head sealing surfaces of all remaining old gasket and reseal with new gaskets; take care to not drop nuts and washers into the engine. I did all this to my '76 last spring and it runs cool and well and doesn't have a single oil leak. Good luck. Cheers, Jim