1988 Carrera 3.2 Top End Overhaul

[dkirk]

Gentlemen,

My first post. I did search the archives on these questions but couldn't find an answer that exactly addressed them. Here they are:

1) Will 3.6L 964 factory camshafts fit and function in the 3.2L engine? By "fit", I mean a drop-in. I'm thinking about doing a top end overhaul this spring as my engine now has 110,000 miles and blows blue smoke after idling for several minutes (converter removed). It would be a good time to upgrade to a little higher performance cam grind but I don't want to install aftermarket regrinds.

2) Would you recommend installing new piston rings while the heads are off? I haven't done a compression nor leak-down test, but the engine runs very strong and compression sounds even when cranking on the starter. If so, what bore surface treatment is required or recommended for breaking in a new set of rings?

3) I'm electing not to split the case and replace all bearings as the engine exhibits the correct oil pressure when hot and there's no unusual sounds indicating excessive clearances. Engine oil remains clean and there's virtually no metal on the drain plugs noticed during oil changes. Is not to replace bearings at this point, a good decision?

This is my first 911 engine job, but I've read all the most popular books on the subject and feel confident that I can successfully tackle it. I'd greatly appreciate the experience of those on this forum in answering my questions as I don't have lots of experience with this air-cooled masterpiece.

Thank you in advance for anything you would be so kind as to contribute.

Dave

[Flat6pac]

1) 964 are a slip in, no work needed.
2} No, because it will make the top too strong with the valve job and the bottom might not be able to hold.
3) I open the bottom because I want to see the main bearings and replace the intermediate shafts bearings. Accept if the main bearings are clear of defect so should the rods be too. The case gets a complete cleaning. You then invest several hours into the bottom and then you know. I label each main that I take out for exact re placement. The center case sealants are replaced as with the cross bolt seals.

[88911coupe]

I ended up going all the way in since once you've got the p/c's off you are really just about 85% done from a time perspective and the peace of mind was priceless. Of course I like takning stuff apart! Mine was in great shape but you may end up kicking yourself 20k miles down the road. The parts to do all the internals are small potatoes in the sheme of things. I just like knowing I'd had the crank out and measured. You don't mention miles but I guess if it's really low you may not need to bother...you call oviously. Good luck whatever you decide.

[dkirk]

Thanks guys - your comments noted and appreciated.

Dave

[AlfonsoR]

Originally Posted by Flat6pac

3) I open the bottom because I want to see the main bearings and replace the intermediate shafts bearings. Accept if the main bearings are clear of defect so should the rods be too. The case gets a complete cleaning. You then invest several hours into the bottom and then you know. I label each main that I take out for exact re placement. The center case sealants are replaced as with the cross bolt seals.

I agree with Flat6, at 100 k miles, it would be a good preventative thing to open it up and refresh everything. You get into a bit more expense and more time, but most people would agree it's worth it. Most would also recommend ARP fasteners for the rod bolts. The slope can easily get steep, but buy your parts from a site sponsor, i.e. Steve Wiener, and not only will he give you competitive pricing, but he can give you endless tips on what to do and what not to do.

The intermediate shaft bearings are known to be showing copper by this mileage, on some engines, although there are many 3.0s and 3.2s that see 200 k miles plus with no bottom end rebuild, but how do you know which one you have?? If you are undecided, you can do an oil analysis. High metals, i.e. copper, would be the nod to opening the bottom end.

[dkirk]

AlfonsoR,

Thank you for some excellent advice. The oil analysis is a great idea and will be performed.

Dave

[AlfonsoR]

Dave you are welcome on the advise. I am fairly new to 911s though. I don't have the experience so my advise will tend to be toward the conservative side most of the time.

I have started a thread with questions concerning the Intermediate shaft.
Intermediate shaft questions

At least one well seasoned flat 6 veteran is recommending not to split the case "just to check the IS bearings".

There are some things that even the pro's don't agree on, like head studs, so sometimes you will get conflicting opinions. All that to say, tread carefully. Ask a lot of questions, think your decisions through thoroughly, and make the right decision for you.

Good luck,
Alfonso

[dkirk]

Thanks again Alfonso,

I read the thread you started and the advice is somewhat conflicting. I will do an oil analysis before starting the overhaul, and this should reveal if any lower end problems are occurring in my engine.

Seems that we have similar vintage 911's with about the same mileage. My engine doesn't leak any oil as I replaced the oil drainback tubes last year, which was a source of "spotting" on the garage floor. The valve guide and stem seal situation is what I'm most concerned about with my engine as it will begin to blow a bit of blue smoke out the exhaust after prolonged idling or creeping in heavy traffic. This is a bit embarrasing...a Porsche shouldn't do this!

The 3.2 Carrera is my favorite vintage of 911, and I was very fortunate to pick up this very pristine example. The engine is such a work of art - first class German engineering! I really enjoy driving this automobile, but the next best thing (to me) is wrenching on it. The engine overhaul is something I'm really looking forward to.

Dave

[AlfonsoR]

Yeah, i hate oil leaks but love 911s. I don't have a deep bank account, but i love fine machines and parts, like Pankl rods.... I must be a masochist?

make sure you post your questions, if you have any, on your head rebuild. There are a lot of good, knowledgeable folks that give great advise.

[lindemans]

My 1989 3.2 was done recently.
Valves and rings were main reason for the rebuild (oil consumption).

Most parts looked in decent shape after 150.000 mls BUT one rod bearing (big end) had worn pretty much through its surface layer and really needed replacement as well. Main bearings looked good.

I would take the trouble to at least also check rod bearings, can be done without splitting the case.

[AlfonsoR]

^^^ That's interesting that only one rod bearing showed appreciable wear. Which one was it? Did you figure out why only one?

[lindemans]

@Alfonso:

I should have been more accurate. Actually on several bearing halves, the layer below the bearing wear surface was becoming visible, at the surface area that gets the full mechanical load when demanding engine power.
On cilinder 4 this was most visible, but not unproportionally worse than the others.

According to the shop expert probably a combination of heavy loads for extensive time and old oil. It could also relate to slight surface corrosion as the engine had been unused during a 2 year period (2007-2009).
Furhermore, worn bearings are not uncommon after 150kmiles.
He also claimed he could read consistent high RPMs from the wear on the valve spring ends.

Must be from a previous owner, I do not recognise my driving behaviour in this. He could confirm that from the good condition of the clutch that I have ran for 40kmiles since new and is still in great shape.

It should also be noted that the engine ran its first 110kmiles in Germany, so it must have been driven the way it was meant to be ...

[ChrisBennet]

The right hand 964 camshaft extends out the "back" end of the camshaft carrier. (The power steering pump is powered from it on a 964.) To use it in your 3.2 you can either get an expensive cap (~$90 last time I looked) or cut off the part that extends out the back. For a 3.6 motor I did once, I just cut it off.
I think most people just have their 3.2 camshafts reground to 964 specs.
-Chris