Top end only, or split the case...?

[thetorch]

I have a 1969 911T with an '82 SC 3.0 case and an '87 3.2 top end. I do not know the exact pistons and rods, but it was claimed to be a 3.2SS. The cam towers and cams appear to be stock 3.2 (unless the cams were reground -- I have no reason to think that).

The engine runs terrific. I went from PMOs to a Motec ITB setup. It's a great street car, plenty of power for me, excellent all-around driver.

Issues:
1. Both sides I have small but constant oil leaks between the cam towers and the heads. I have investigated this over and over, and it's definitely NOT rocker arms, valve covers, nor oil return tubes. Several times I have carefully cleaned everything, checked with fluorescent dye in the oil. Leaks appear near cylinders #3 and #6. Only drips while running, but over the course of a couple of months, it starts to bake oil on my SSIs, and flings back onto the muffler and bakes on there.

2. I occasionally get a "mosquito fog" of blue smoke when idling. Not on start up, not often, but if the rear end is parked lower than the front, after starting I get a giant cloud of smoke at the first stoplight or two. Or if working on a warm idle in the driveway. Doesn't happen often. Suspect worn valve guides, though I don't get any smoke on a downhill decel test. Pictures of #4 oil fouled plug (about 1,000 miles on it) and exhaust valve #4. Exhaust valves are showing seepage around the valve guides, #4 particularly bad. At least one intake valve looking oily (can't recall which one). See pics below

3. I do have some oil leaking from the case parting line. Not a lot, but a few drops overnight. Annoying.

Leakdown:
1: 3%
2: 2%
3: 2%
4: 3%
5: 2%
6: 2%

Compression:
1: 175
2: 175
3: 180
4: 175
5: 180
6: 175

Oil consumption: have not been carefully tracking. Estimate about 1qt / 1,000 miles.

I would love to clean up the oil leaks. At some point, the heads look like they need to be rebuilt, with new valve guides, etc.

I know splitting the case is a lot more work, but feels like sooner or later I will want to fix the leaks at the case line.

Just in the planning phase, but trying to think ahead to the fall and winter. I will do most of the (non-machining) work myself, with help from a friend who has built a number of Porsche engines, from 356s to 2.2s to 3.0s to 3.2s.


So my questions are:
Valve guides appear to be a problem, yes?
Do it all at once (top and bottom end), or am I asking for trouble splitting the case?

Constructive advice welcome.

[thetorch]

a few more pics. exhaust valves...





someone tried putting rtv near cylinder #6 to redirect oil off the heat exhangers. didn't work.

[colingreene]

If you do have leaking from the case and it annoys you. As you have said it does I would split the case.

Obviously if your power level is about where you want it to be I would not suggest going ape.
However about 9:1 and a bit of a cam upgrade wont do you wrong at all.

What's your budget look? like things can get big fast.

[winders]

That plug tells me the plug is either too cold or you are running too rich. What lambda did you tune to?

[thetorch]

Originally Posted by winders

That plug tells me the plug is either too cold or you are running too rich. What lambda did you tune to?

It's the only plug that looks like that. What the best way to show the lambdas -- scatter of tps vs lambda, or histogram?

[Rusty911]

Do you know how many miles on the bottom end already since last rebuild? If motor had a full rebuild last time with new bearings etc, you might just need top end. If you don’t know history from po then you might consider split it.

[thetorch]

Originally Posted by Rusty911

Do you know how many miles on the bottom end already since last rebuild? If motor had a full rebuild last time with new bearings etc, you might just need top end. If you don’t know history from po then you might consider split it.

Unknown. Believe it's been over a decade since it was built from 3.0 to 3.2.

[Zuffenwerker]

Some factors to consider:
Oil pressure - if it’s sub par split! Refresh mains and send out oil pump.
How are the threads in the case for the head studs? If no bueno there’s a good reason to split it.
Is your intermediate gear or distributor drive gear worn? If so … split! Im gear will knock when worn. You can peak at both to get a good look.
If you don’t split… doesn’t mean you can’t at least refresh con rod bearings. A lot of ppl forget this.
Check for gold in your oil .,, too much gold and you may want some new main bearings.

Daniel

[stownsen914]

Your puff of smoke at stoplights could be from many things. Classic sign of worn valve guides is smoke on overrun (coasting in gear, throttle closed).

Oil can pool in the muffler after sitting, as oil level rises in the engine sump, especially as you note, when parked for extended periods with rear lower than front. You’ll get smoke for a period of time as it burns off.

[al lkosmal]

Top end for sure, but I would check the triangle of death for oil leaks.....leaks there can migrate under the fiberglass shroud and easily look to be coming from #3 & #6 cylinders.....

[thetorch]

Originally Posted by al lkosmal

Top end for sure, but I would check the triangle of death for oil leaks.....leaks there can migrate under the fiberglass shroud and easily look to be coming from #3 & #6 cylinders.....

I should have said before: not coming from triangle. dry.

[Flat6pac]

It’s $60+ for the bottom gasket set. Opening the bottom gives you access to knowledge and a reseal.
Intermediate shaft bearings,
Chain rails
Look at the mains. The mains get oil before the rods. If mains are clear of scratches,
That’s what you can expect inside the rod bearings so why open the rods.
You get a chance to power wash the case, who wants to rebuild a crusty case?
Then, you know what you own…
Bruce

[gsxrken]

Originally Posted by Flat6pac

It’s $60+ for the bottom gasket set. Opening the bottom gives you access to knowledge and a reseal.
Intermediate shaft bearings,
Chain rails
Look at the mains. The mains get oil before the rods. If mains are clear of scratches,
That’s what you can expect inside the rod bearings so why open the rods.
You get a chance to power wash the case, who wants to rebuild a crusty case?
Then, you know what you own…
Bruce

+100 to this.

I rebuilt mine mostly due to oil leaks. From a performance standpoint I could have lived with it indefinitely, but the leaks and the fumes and the occasional puffs annoyed the eff out of me and why should my hobby car annoy me? It’s nice to know it’s all good for many years again, and dry. For now anyway. 😀

[thetorch]

Originally Posted by Flat6pac

It’s $60+ for the bottom gasket set. Opening the bottom gives you access to knowledge and a reseal.
Intermediate shaft bearings,
Chain rails
Look at the mains. The mains get oil before the rods. If mains are clear of scratches,
That’s what you can expect inside the rod bearings so why open the rods.
You get a chance to power wash the case, who wants to rebuild a crusty case?
Then, you know what you own…
Bruce

Agreed. I don't see myself doing the top end and not doing the bottom case. Thanks for the tip about the mains and rods. Very helpful.

[thetorch]

Originally Posted by gsxrken

+100 to this.

I rebuilt mine mostly due to oil leaks. From a performance standpoint I could have lived with it indefinitely, but the leaks and the fumes and the occasional puffs annoyed the eff out of me and why should my hobby car annoy me? It’s nice to know it’s all good for many years again, and dry. For now anyway. 😀

same sentiment. i think of it as an only child, and i'm enjoying spoiling it.

[Alan L]

You are 3/4 of the way there by the time you have torn the top end down. Engine out and top end teardown. A few hrs extra work to get to the bottom of the engine. As said previously.
I think the 3.2s had guide issues?
The cam box/heads is a critical seal area. May not have been done quite right.
While the heads are being done you can split the case and have it back together by the time the heads come back. Otherwise you can sit and twiddle your fingers with the case unsplit , still waiting for the heads to come back. And save $60 on gaskets.
Alan

[stownsen914]

I see comments above about taking apart the bottom end and looking at the main bearings but not the rod bearings. That would seem an odd choice.

[prschmn]

I agree with splitting the case for sure. And feel it also wise to check the rod bearings.
The mains may be fine but I've seen more than once worn rod bearings despite that.
And you have the added advantage of replacing the rod bolts-never know if there's been an overrev!

[dannobee]

I've seen a lot more worn out intermediate shaft bearings than rods and mains. It seems like every one has bearings down to the copper. And as mentioned above, the knocking noise that some don't even notice until it's fixed.

Bruce is speaking words of wisdom. Fix ALL of the leaks while you're this far into it. Order the Wrightwood gasket set, and for gawd's sake, use modern sealant on the case halves and cam housings.

[thetorch]

Update:

I do not, in fact, have a short stroke 3.2, but a regular stroke (74.4) 3.2. This is news to me.

What I found:
Case: 1982 Carrera 3.0 (date mark 82 41)
Pistons: Mahle 3.2 (marked 95P36++)
Cylinders: Mahle 95mm (marked Mahle 95ZN1++).
Carrera 3.2 crankshaft (marked 930 014 09)
Connecting Rods: 3.2 (marked 930.103.121.2 R)
Heads: 3.2 (marked K1926R dated 7-87)
Cam Towers and cams: stock Carrera 3.2 (Left cam marked: 930 14710)
Oil pump: SC part (911.107.105.1R)

Overall condition is very good. Bearings look unmarred, crank looks excellent. I haven't pulled the rods off the crank so I haven't measured any rod journals yet. Oil pump looks like new. Upper head studs are steel, lower studs were replaced with newer porsche steel studs at some point. They look like new.

My friend thinks I should go to 98mm P&Cs to get to (about) 3.4L. My understanding is that I can have the cylinders bored out to 98 without a problem, and get some 98mm pistons with 9.5 or 9.8 compression. This should all bolt right in, correct? The whole setup is 3.2 from the crank to the cam towers (other than the SC distributor gear on the crankshaft, and the case of course).

Open to (constructive) thoughts on my 3.0 -> 3.2 -> 3.4 idea.