79 911sc in deep do do

jerkan · jerkan's Garage

tried starting the car this morning and heard a loud bang coming from the engine compartment. Sounded a little bit like a combustion detonation, typical of 911s when the mixture is off, but was more mettalic in nature. tried starting it a second time and it ran shortly with a rattling noise like a chain rattling on metal and then it stopped completely. I could not get it to turn over at all and the starter would not engage. this sounds like a broken timing chain or chain tensioner to me. I would really appreciate your thoughts and troubleshooting suggestions as I need a place to start.

2.7RACER · 08-13-2005, 07:35 PM

From your description I would expect the worst. Just to confirm things, I would attempt to rotate the engine by hand. If the engine is locked up, I'm afraid an engine drop and disassembly is in your future. At that point you can decide whether you have the time and inclination to tackle this kind of project.
Once the engine is out I would remove the timing covers and check the chains and tensioners. True, this can be done with a partial drop, but any further repair will require the engine to be removed.
I'm afraid your engine has provided you with an opportunity to become familiar with it's inner workings.

felix_browne · 08-13-2005, 08:16 PM

the sound of your walet hittling the floor or your free time being absorbed by your car is a distinct one indeed. if it sounded like a chain being dragged across a metal garbage can that was more noticable at lower rpms and cooler temps then expect the worst. going from there if the car will start and you don't have a stethascope place the blade of a screwdriver against the timing chain covers and listen through it for any scraping sounds (a very usefull technique). if you hear any turn the car off right away. if the chain is jumping teeth you will hear a dull thudding. if you don't hear that, check compression, and if any cylinders way off you should investigate further to see if the valves or pushrods themselves have been bent. if not set the mix and hope for the best (revs too slowly then too lean, wants to stall on decel, too rich - at this age the factory #s likely aren't the best standard).

limble · 08-14-2005, 06:08 AM

You can pull the timing chain covers off without doing even a partial drop.

LakeCleElum · 08-14-2005, 06:56 AM

Timing chain cause by the failure of the tensioners. Probably bent valves at this point.....

jerkan · jerkan's Garage

what is the process for removing the timing chain covers if i do not drop the engine at first. Do you have to remove the muffler and do you need to remove the front sheet metal?

Zeke · 08-14-2005, 04:49 PM

There is a good description of the process in Wayne's book. You can get it most likely at a local book store if you can't wait a day or two for the mail. If you order it from Pelican, get the engine rebuild book too, and you will get a CD as well (if you think you might proceed on this yourself). Ask for shipment by US Priority Mail. Faster.

limble · 08-14-2005, 05:48 PM

Pull the tray out. Maybe 6-8 bolts then you should be able to remove the timing chain covers. Like Zeke wrote buying Waynes book is a good idea.