911 2.2 engine trouble

redbull760 · 07-27-2004, 02:16 PM

Help my 1970 2.2 smokes a bit more than it should on tick over and smokes loads when you take your foot off the gas pedal i.e. coming up to roundabout.

It clears when you pull away again. It’s a white/grey smoke and you can smell it. It does not seem to affect performance and the engine starts runs and drives great.

I have twin exhausts and as you look the car from the back the left side is the one that’s smoking. The spark plugs seem to be all ok and look the right colour.

A friend has said it could be a valve seal?

If it is this what parts would I require and is it a fairly easy or time consuming job??

Any help would be appreciated.

jpnovak · 07-27-2004, 02:25 PM

Welcome to the board

Sounds like you need to have a valve job done. The smoke is oil leaking past your valve guides throught the valve stem seals. Not typically a DIY job but it can be done. The engine will need to be disassembled to change them out.

yes, this is an expensive rebuild

Joeaksa · 02:38 PM

RedBull (what is your name pls?)

In addition to what Jamie said above, it also sounds like your valve guides themself or rings may be needing some attention. The seals help to keep oil from being sucked down the valve guide when you lift your foot off the gas and a higher vacuum is created in the manifold.

If it smokes at idle then its either the valve guide seal is totally gone on one or more cylinders or one or more of the valve guide(s) are worn or a possible problem with the piston rings.

Anytime you pull a 911 engine apart its best to be prepared for the worst and if it does not happen then you are happy. I would drive it until: (1) You cannot put up with the smoke any longer, (2) The oil consumption is more than is recommended by Porsche, (3) it starts sounding any worse.

You could go to a maintenance facility and have them do a leakdown test. This would help pinpoint where the problems lie. They cannot show a worn valve guide or bad valve seal but can tell you how your valves are seating or how your piston rings are sealing.

If you are worried about your valve guides its also a good time to pull a valve cover while having the leakdown check preformed and have them check the valve guide for wear. Better to have this done and be secure than have a guide wear too much without your knowing it and then have the valve come apart in the cylinder while you are driving and ruin a descent engine. It would get a lot more expensive then!

JoeA

redbull760 · 07-27-2004, 02:35 PM

That’s the bad news I feared.

What parts would I need to order for this rebuild?

Are they all available new?

While the engine is apart is there anything else it would make sense to change/update?

In an ideal world I would like to take the car off the road at the end of September its not a daily driver but would like to take it to shows and a few events about 1500 miles of driving before rebuild.

Will this damage the engine of just carry on smoking of get worse?

Sorry for all the questions, again any help appreciated.

Joeaksa · 07-27-2004, 02:47 PM

Red (name pls?)

Driving it another 1500 miles is a subjective question! Personally I would try to find a good Porsche mechanic and get them to inspect the valve guides for wear. They pull the valve covers off and see if they can get the valve stem to wiggle around or not. If not or a little you could probably drive it another year but I would not tempt it that long.

Are you trained in doing something like this and do you have a facility where you can take the engine apart? I am an aircraft mechanic and for me its not that difficult but for the average mechanic its still a challenge. I lived in Europe for many years and garage space is sometimes difficult to come by, and you will need room to work with the engine and gearbox once you have it out of the car.

A good start would be to get our benefactors (Pelican parts) book on overhauling a 911 engine. It has loads of information in it as well as details the parts and more important, special tools needed to work on the engine.

Your living in the UK and taking the car off of the road in the fall would work perfectly. You could pull the engine and take the top half off. After inspecting the bits you then would still have a long time until spring arrives and you will want the car driving again.

I would take a very good look at either planning on putting a new set of cylinders and pistons on the engine along with a complete valve job or you might also look into buying a good, low mileage 2.4, 2.7 or 3.0 litre engine to transplant into the car. All the parts you need are still being produced as are a wealth of upgrade parts in case you might just want to go a bit faster!

The price for a descent used engine might be less than that of a top end overhaul, but I would do it only from a good shop or someone who can give you a guarantee that you are not buying more problems.

JoeA

redbull760 · 07-27-2004, 02:49 PM

sorry forgot to say my names Stuart.

Joeaksa · 07-27-2004, 02:58 PM

Stuart,

Thanks and here are some links for you:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/ (the Pelican engine overhaul forum)

Technical newbie taking the leap... ( guy doing his first overhaul)

http://www.101projects.com/911-Rebuild/index.htm (911 overhaul book!) (no, I do not work for Pelican, they have helped me a lot with my car!)

optimisation (a recent 2.2 thread on the overhaul forum)

Hope this helps!

Joe

redbull760 · 07-27-2004, 03:00 PM

I could not do the work myself, however one of my friends is a proper mechanic. He has never rebuilt a Porsche engine. He has worked on other performance engines mainly big American V8s and builds a lot of hot rods.

Another friend has a 73 2.4 engine which we believe was running ok about 18 months ago. He just has the block. We were told it had been bored to 2.7. Would my manual fuel injection fit on this engine as I believe this was supplied with carbs?

Joeaksa · 07-27-2004, 03:05 PM

If you have the manual fuel injection system then I believe that it would have to be changed to properly meter enough fuel for a 2.7 engine.

If you have a good friend who you trust with the engine and were to get a good book (like Wayne's) then there is no reason not to give it a try. American motors are big lumbering beasts and the 911 is a work of art. Lots of differences in the two "lumps" but if he is good with one then he should be descent on the other with proper assistance.

Joe

CliffBrown · 07-27-2004, 04:13 PM

Stuart

If you continue to drive with worn valve guides you run the risk of overheating a valve and suffering the consequences (don't ask). The exhaust valve especially, is cooled via it's contact with the valve guide, if this fit becomes loose the valve will overheat and lead to a premature failure. If the seals are leaking it's an entirely different matter. Make sure your mechanic knows the diference and checks. Good Luck.