Oil leak question. Cam cases !

[pjv911]

I have a few oil leaks that I will be repairing next week. They include rear main seal (clutch side),cam cases (both sides) and the oil cooler that is mounted on the motor appears to leak at the case.
My questions are as follows,

Could i have the cam cases machined true by a normal engine machine shop or is there a reason for caution.
Does the oil cooler(engine mounted) have a o-ring or a gasket?
And one more question Should I do the wheel centers in blue or leave them black ?

[jabb]

The oil cooler has large O rings between the cooler and block.

Why do you think the cam towers are warped. Could be the Rocker shafts that are leaking. I would check those before doing any machine work.

[pjv911]

I allready checked the rockers. The leaks are under 2 valve spring pockets. I did seal them with silicon allready but want to fix it right now that the cold weather has come.

[CamB]

Blue wheels - I think the original RSs has wheels coded to the "Carrera" colour

[Early_S_Man]

The sealant used in the '70s between the heads and camshaft housing is a known problem and primary cause of most older 911 oil leaks on otherwise healthy engines, such as mine!

Get a tube of Loctite 518 and the spray 'primer/activator' at a NAPA store ... you won't be sorry!!! Loctite says the 518 has better adhesion to aluminum than 574, and is the FAA-approved replacement for 574, which has been officially discontinued for more than a year!!!

Plan on pulling the chain cases while you have the engine apart, and use the Loctite 518 to 'prep' the paper gaskets for the chain cases, per the Loctite instructions.

Blue centers and caps to match the decals, just like all of the Grand Prix White RS's were originally sold!

[ChrisBennet]

What a gorgeous car!

I agree that the cam towers are not likely the cause. They are pretty rigid pieces. I've been using 518 to seal the cam towers to the heads without the primer/activator and it works great. I didn't know about the primer until Warren mentioned it (thanks Warren!). According to Loctite, the primer changes the gap fill from .01" to .05" which is a considerable improvement.

I can think of 4 possible causes for your "oil cooler leak":
1. Leaky thermostat or oil pressure switch leaking over to run down outside of cooler.
2. Leaky oil cooler seals.
3. Leak in case behind cooler. There is a pressed-in tube that has a "window" in the case right behind the cooler (see picture). A mechanic friend of mine told me these often leak in older cases.
4. Leaking oil cooler.

#3 requires complete teardown to weld so try to eliminate the other causes if you can. If you have the engine on the stand, rotate it so the cooler is on the bottom when you remove the cooler. Otherwise the oil that leaks out when you remove the cooler will destroy the evidence of the leaking seam. I'm told you can see it leaking using a boroscope while the engine is running. (My boroscope is too big to get in there.)
If you actually have a leaking cooler be very careful of used ones as it seems a high percentage of these leak as well when tested.
-Chris

[pjv911]

You guys are the best. Soon I will be able to answer these questions as I continue to get more hands on experiance with these cars. I wish someone would ask a question about an everday car so I could contribute with all the great help offered here. Come on someone ask a tech qustion about them nissans, chevys, etc .
I KNOW YOU DRIVE THEM TOO.

[ChrisBennet]

Originally posted by pjv911
...Come on some ask about there nissan, chevy, etc .
I KNOW YOU DRIVE THEM TOO.

I don't - my "other" car is a Porsche.

[RoninLB]

pjv911- Why did my purchased new '69 'Vette 427 390 hp rod bearings look/were beat after 50,000 miles. I changed oil every 1000 miles and only raced from a slow roll and never over reved it? Why did same eng break a piston ring when decelerating from a highway to an off ramp at medium high speed?? What is best way to drive a mean machine quick on highway and not get tagged? What is best fuel filter to use on carbed engines if standard filters clean to 10 microns and that is not good enough?

[ChrisBennet]

Originally posted by RoninLB
pjv911- Why did my purchased new '69 'Vette 427 390 hp rod bearings look/were beat after 50,000 miles. I changed oil every 1000 miles and only raced from a slow roll and never over reved it? Why did same eng break a piston ring when decelerating from a highway to an off ramp at medium high speed?? What is best way to drive a mean machine quick on highway and not get tagged? What is best fuel filter to use on carbed engines if standard filters clean to 10 microns and that is not good enough?

I'm no pjv911 but... If you're experiencing detonation/pinging it would beat your rod bearings and break your rings.

[Roland Kunz]

Hello

Reguarding 3.)

This is well known problem and Porsche used to seal those areas on new cases and recomend to seal them on all used/rebuild cases as well. I think this came in the mid 80´s.

I used the same sealer like on the chain housing cases ( Sika Chemie )

Grüsse

[RoninLB]

Chris--educated guess, very good, but not good enough. Pinging was obvious in those engines, so that is not it. I know answers and want to see a reply. Around this board, IMHO, humilty is power. There is more brains around here than at Harvard U. I assume everyone has something to offer. With the support of this board there is no doubt in my brain [what's left of it ] that the best way out is always through. No other man-made device can fulfill my ego like a 911.

[Superman]

Pjv, I'm having another problem with my '73 Datsun (with '74 1.8L engine), but if you know abotu these things, there is a question I'd like answered. The darned thing runs very lean. Cleaning and rebuilding the carb did not change that. The jets are correct for the 1.8 L engine. What's making it run so lean? Someone suggested the dash pot or the decel valve should be replaced.

[pjv911]

Superman your car is almost as old as me so i cant say i have much personal experiance with that particular datsun. I am assuming you have the L-18 motor. My first suggestion would have been a leaking egr valve diaphram but they got those in 76`. I think the carbs on those are mounted to a plate which is bolted to the manifold. If so make sure the gasket is good. I would check engine vaccum at idle and 3000 rpm. Look for rapid fluctuation on the vaccum gauge. If you do check your valve adjustment to make sure there not to tight. A decel valve would definetely cause the problem. A dashpot only holds up your idle speed as you decelerate to help with emmisions. I should not have to ask if you checked for vaccum leaks so i am assuming you checked. But from what i get by your description you are even lean at full throttle as well. Hope that helps some

[pjv911]

Ronin those motors were never known to last long but if you want a guess i would say your oil was contaminated with raw fuel causing the oil to break down regardless of how clean it was. As a result your rings were overheating because of the fuel being washed past them(lack of lubrication). Eventually the ring lands widened and on deceleration they will fluter more severly causing the damage you describe.

[RoninLB]

pjv911----" never known to last long"... Yes it was a dilemma. You wanted the power of a big block but they blew up much sooner than small blocks. Bearings took a pounding. There was a sharp contrast between a Chevy 396 and a Chevy 454 in engine life. They ate up spark plugs sometimes in one weekend of big action. It was worth it. Cops didn't have radar. It was territorial. If an unknown machine came into your neighbor hood, well, what's he doing here. It was a carb eat carb fuel world. Big blocks didn't last long. On the broken ring when comming off of highway it was a blocked "pcv" valve. It caused a high pressure in crank case when decelerating that rings couldn't live with. Only broke one ring and made it home without much wall damage. I honed it out and back on the street it went. Thank you for reply.