[David E. Clark]

I saved this from one of Grady Clay's posts on this forum several years ago. The man was a Porsche repair genius. Ignore his advice at your peril! You should also look at the two links in my signature block for loads of information about MFI.

Putting your 911 back in service.

Put in new hot plugs. I would use BP5ES but some recommend hot recessed-tip plugs (like some race plugs) to prevent fowling. You want to do everything possible to have the engine fire and run properly on the first try.
Treat it lust like a brand new engine. It will need careful break-in.

Oil the cylinders, cams, etc. and turn over the engine with a wrench on the crank pulley. Turn two or more revolutions and make sure there isn’t hydraulic lock.

Install fresh fuel high octane fuel with some 2-stroke oil in it.

Make sure the fuel system is working properly.

Make sure the ignition system is working properly.

Some use a spare muffler and cat bypass for start-up as it will get oiled.

Start and run at as low RPM possible for 15 seconds. Let sit for 15 minutes. Repeat, extending the running time but keep RPM low. Gradually bring up to normal running.

Never run the engine at high RPM.

For first drive you want to give it some power but not run it longer than a couple of minutes without a “rest.” Again, extend the running time with increasing high power (not high RPM.)

The theory here is that there are localized high friction areas that get hot during this re-break-in process. You don’t want anything to get too high temperature and induce failure or have exceedingly high ware. When under power, the rings seal (mostly) from cylinder pressure. You want them to re-seal asap but not get overheated. High RPM will overheat the rings in a flash and the high friction can over stress the ring lands in the pistons. Some of the other areas are the cam-to-rocker surfaces, chain links, rocker-to-shaft, chain idler sprockets, and more.

This situation is far more delicate than a new engine brake-in procedure. Treat this just like a fresh engine but extend the break-in and be even more careful.

What to do with a 911 that wasn’t preserved for storage?

Drain the fuel from the drain port in the tank. Don’t run the fuel pump. If necessary (probably) clean the tank and outlet filter screen.

Buy a new battery.

Change the oil and filter, clean sump plate.

Remove the sparkplugs and inspect with a light or bore scope. If the cylinders are rusty don’t turn the engine, go to Plan B.

Remove the intake valve covers and inspect for rust. If the cam is rusty, go to Plan B.

If you suspect there is corrosion in the oil sump tank, remove it and clean or replace it. Those rust flakes go directly to your bearings without a filter.
If everything appears OK, proceed as above but even more carefully.






Plan B and what to do with a 911 that has been stored for several (many) years?


Don’t try and start it! You may do far more damage to it in one minute than 100K mi. of driving.

In most cases it is best to just remove the engine and trans and do a maintenance overhaul.

Often the brake master cylinder has failed (or will after a few applications of the brakes.)

Old tires should be replaced with new.

Get the old battery out asap.

Electrical connections may be an issue and need to be cleaned.

Fuel and ignition system components will need cleaning or replacement.

Chain tensioners that sit for long are an issue for any engine.




What to do after your 911 is back in service.

Nice extended calm tours will get everything friendly with adjacent parts.

Change oil regularly. Check the sump screen for anything unusual.

Use higher than necessary octane fuel until the rings are fully seated.

Keep an eye on brake fluid level and possible fluid in the pedal assembly.

Inspect for any signs of tire failure, inboard and out.

As things change, bring them back into spec. If something fails (wheel bearing, CV, door latch, window regulator, hood lift, etc. – fix it. You want to keep your 911 in top form.

If it ever seems to loose power under acceleration – STOP. Find out why. You never want to have a rod bearing failure turn into a rod failure, broken case, and worse.