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engine overhaul/maintenance

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Hi, i have a 1978 911sc 3 litre. The car has done 140,000 miles it has had regular servicing from previous owners and i have been doing some maintenance work on it myself. recently i've noticed a bit of a chattering sound from the left bank of cylinders at higher RPM. i believe this to be either slightly leaking valves or a leaking head gasket. i have decided to do a bit of an engine overhaul as i believe this is due. i don't believe it is the timing chain as this has been replaced recently, with the tensioner modification done. i was wondering if people could recommend parts companies and what i should change out, or the possible problem.

regards

alastair
 
Hi Alastair, it's really hard to diagnose this without hearing it, but 'chattering' as opposed to a rattle might indicate a gasket problem, could be a head stud issue, valve adjustment is easily checked and done, (on a stone cold engine). There is no such thing as a 'bit of an engine overhaul' if you are lookin at the top end you could check the bottom end while you are at it, also if you have to rebuild perhaps a little performance increase in the way of larger cylinders and pistons might suit , there are loads of options and things you should attend to if ou are to do this properly. I doubt a timing chain has been replaced without the engine being stripped in which case the problem you have now shouldn't be happening, most likely the chain tensioners were replaced, if only one was done it might be time to inspect the other, buy and read
'How to Rebuild and Modify
Your Porsche 911 Engine'
(1965-1989)
Wayne Dempsey
http://www.101projects.com/911-Rebuild/index.htm
Find reputable specialists and get second and third opinions before doing anything major if you start stripping it thinking you can do a 'bit of a job' this will turn out to be more expensive than you think.
 
Hi Alister,
This may be bad news. last year I had a rattling noise from my car. It sounded like some metal parts knocking together (like exhaust, or oil pipes) and came on under medium to hard acceleration above 3000rpm. This was diagnosed as a broken head stud. Some of the exhaust studs are visable with the lower cam cover removed, if a stud is broken it will be loose or missing, worth a look. I'm just getting my car back together after removing the engine last August. Best piece of advice I can offer for a rebuild is to put the engine onto a trolley, I made one from a chipboard floorboard and castors from Machine Mart..
 
What engine stand and mount did you use Paul and Alastair a seized solid exhaust stud can be drilled and helicoiled with the engine in situ if you use a jig. Hope it's exhaust and not head.
 
Hi Bones,
I did all the work with the engine on the trolley (I didn't seperate the crank case). It was the head studs on the exhaust side that I meant. Even with the engine down to the crank case I couldn't get the studs out. I took the whole lot to a local Aston Martin specialist who warmed the whole crank case by putting it in a box and blasting with a gas powered space heater, then removed the studs with a stud extractor. It took them several go's! I did at least replace all the studs. See photos.

EA6D1C6CD4F9435AACB95BCB59D8F47B.jpg
 
Thanks for posting the pics Paul always nice to see what pweople get up to in their spare time! [:D] Those studs can be a real swine to get out out even with real serious heat, Chris Turner roasted one of my exhaust studs for about ten mins and the bugger still wouldn't shift in the end it was drilled out and time-certed.
 
The last one I rebuilt had three bottom studs sheared off level with the crankcase (well a little spike sticking up like a stump was all that remained on one). I dropped the cases off with CES Power Ltd in Buckingham and they did a sterling job of spark eroding the bits out of the cases.

My recommendation when fitting new bolts is to use the later versions as fitted to the 993 engines. You can easily tell these from the earlier type - gloss black with thread running the length of the bolt. Apparently these are made from a different material and are not prone to failure.
 
early studs will do the job just as well but whatever you use avoid dilavar studs, fitted as standard.
 
Hi Alister,
I have just looked at your question again and you asked about suppliers. I have used Type 911 who advertise in Porsche Post, their web site is very good and they send parts out same day for next day delivery. They also do a "service kit" for the SC with all parts required (except oil). I have also used PCT (Autobarn) in Coventry who diagnosed my problem at an open day last year.
Good luck,
Paul.
 
thanks for all your tips and advice. i think i will invest in the book and see where i go from there. i will inform you of how it all goes.

regards

Alastair
 
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