Leak Btwn Cam Towers & Heads (Kinda Long, Sorry)

[Dan in Pasadena]

Finally got around to taking my car into my wrench and putting it on the lift to see if we could find where the oil leak was coming from. Cam tower to head joint is the verdict. Oil leaks onto heat exchangers, mild to moderate smoke at stoplights as the oil burns off, I worry about a heat exchanger fire.

The car is '76 2.7 with 125,000 miles. No Thermal Reactors AND has had an 11 blade fan since early on. Never rebuilt as far as I know. Before I bought it about 1-1/2 year ago the studs were re-torqued by a reputable shop and held. It did not pull the studs as far as I know. I am sort of assuming that is a pertinent factlet to those who may offer some advise.

The discussion quickly became the slippery slope of, "since the cam towers are off you may as well do a valve job, which puts more stress on the rings, if you're gonna consider re-ringing, etc." Leading to a discussion of rebuilding the engine. NO smoke past rings that I can tell. No compression tests yet taken, no cylinder leakage tests yet taken.

I did a quick search in the Engine Rebuilding Forum and saw conflicting discussions of whether re-tightening the cam towers bolts will stop leaks and also a discussion of whether these type leaks are really that or rocker shaft seal leakage. I confess I don't really understand the latter.

Could REALLY use some advice from the pro's - Steve Weiner, Henry Schmidt, John Walker, Grady, and more. The wrench is a good guy but I suspect we may have gotten too serious about a rebuild before considering other options. All advice appreciated.

[afterburn 549]

Bet it is not.....na na ha ha ( just kidding ) but I bet it is rocker shafts. In fact I am so confidant I almost would put in "O" ring seals to prove it for you. Unless you know something that I dont.....( something about the assy. processes that some one did).....these things will disguise themselves as all sorts of leaks. BTDT

[Steve@Rennsport]

Dan:

Retorqueing the cam tower-to-head fasteners rarely changes anything. If it leaks from that juncture, its usually a sealant failure. You can pull the valve covers and gently check the nuts to be sure. I would also use some brake cleaner and a CLEAN, lint-free rag to wipe off the oil residue inside there so you can see where the oil seepage is coming from.

Assuming for the moment that your magnesium valve covers are not warped and leaking,...........run the engine for 10 minutes and pull the valve covers so you can take a look in there at the ends of each rocker shaft to see if its still dry or not.

If its wet, I'd recommend that you pull the rockers and shafts to install the RSR rocker shaft seals and reinstall the rocker arms being especially careful to torque the shafts correctly.

[MBEngineering]

HI could you pinpoint the leak a little more to a cylinder?? as you have the potential for a No of leaks; cam box to head, rocker shafts, cam seal/gasket, oil feed pipe, oil feed pipe union, cam spray bar locater bolt, (at the back of the cam box), and rocker covers. If the engine has had no repair work done on it in the last few years the sealant/gaskets could have failed, a good clean up and look at to locate the leak would be the first thing and then a decision what to do next.

regards mike

[Henry Schmidt]

With a 125K on a 2.7 your mechanic is correct. That kind of mileage is at the high end of how long the engine will live before a rebuild is necessary.
When these engines were new, we were seeing major explosions in the first 60K.
A major failure point was the valve guides. The valve guides are so soft that they were out of spec and more in very low numbers of miles (50-60K)
My advise, do a thorough check to determine the true nature of the leak. As stated look to the rocker shafts, (although if the engine has never been apart) rocker shafts are not likely, cam joint ring seals and gaskets and look at as much as possible on the top of the engine. Oil sender, breather cover and vent hoses can leak and those leaks cause moisture everywhere.
If you determine that the leak is as your mechanic suspects, it's time to evaluate the cars value to you.
2.7 engines have their own idiosyncrasies.
If you pull the heads and just reseal you heads you run the risk the the valve guides are shot and heads must be done. If you look at the rings you will probably find a need for pistons and cylinders. If you assemble the engine without CaseSavers you risk pulling a stud or two and it goes on.
Decide what you're willing to do before you start.
For what's it's worth, at 125K and no major work I would bet it's time for an overhaul. Don't budget for a head reseal only to discover that you really need an overhaul.
Be careful not to chase small problems when a major repair is called for.
Good luck

[Dan in Pasadena]

I knew you guys would have sensible opinions.

Henry, Agree with the "chasing small problems when you need major work" and I tend to agree with your "125k probably needs an overhaul" advice too. But I am also cognizant of my usual tendency to over worry & over think a fix from a few hundred dollars into a full rebuild.

The car is cosmetically excellent and I would hate to sell it. For the $$ discussed with my wrench, my total investment will be over its realistic market value...of course that is irrelevant if I keep it long term but I am uncertain about that lately for other reasons. Oh yeah, oil T-stat Oring, pressure sender switch, breather gasket and breather hose were all done when the clutch and chain tensioners were done a couple of months ago. Oil cooler seals were NOT done and probably should have been. Doesn't appear to be leaking at the return tubes. I would not consider a rebuild without case savers, align boring, balancing, etc. First priority would be long term reliability.

Mike, I gotta admit I don't know these engines well enough to understand all the possible leak sources you mentiuoned but appreciate the info. Will discuss with my wrench.

Steve, The valve covers have been upgraded and are not leaking. Rocker shaft seals - if they are leaking wouldn't the oil be seeping from the ends of the engine - front and rear? My leakage appears to be coming from toward the centers of the cylinder banks, but I could certainly be wrong. Am I misunderstanding where the shafts would leak? Your diagnostic advice is appreciated, I will get those valve covers pulled to see what can be seen. I'll post back later.

[afterburn 549]

Henry has a valid pt. as well as everyone else. I was presuming the eng has been recently apart. You either luv the 2.7 or hate it. going into it have you weapons at hand ( knowledge ) some would say for the $$ put in a newer one ( all aluminum ) so NOW you have ammunition to work with.

[Dan in Pasadena]

Afterburn - I am not a 2.7 basher. I knew what I was buying when I bought it. As has been related many times in many threads, the 2.7's issues are well known by now and so are the fixes - just like with many other (all?) era 911 engines.

Others may disagree but I think the 2.7 is a great engine when the appropriate fixes are applied and they are is a solid state of tune....just like all other 911 engines, now that I think of it!

Besides, if I opted for a used 3.0 I wouldn't KNOW for certain I wasn't buying a different set of problems. If I bought one and rebuilt it...I'd be out more cash than if I just rebuilt mine. If I do end up having to bite the bullet and opt for a full rebuild, then I'll have it done the right way and I'll know for sure just what I have.

[afterburn 549]

I am with ya Dan , have one myself....just wanted to help with 20/20 hind sight.

[john walker's workshop]

find a 3.0. if you open up a 2.7 for anything, it becomes a giant can-o-worms. if the studs aren't pulled now, they surely will when you reinstall the heads, etc, etc. all the mating surfaces are worn, the case needs a line bore, etc, etc. it's a complete rebuild waiting to happen.

[Dan in Pasadena]

JOhn, My wrench and I discussedthat one thing would likely lead to another on my engine. I'm not exactly sure why it WOULDN'T on a 3.0 too. Those engines are pretty long in the tooth now too. Having said that, what is the price on a good used 3.0 however you would define that? Mileage? Leak down numbers? Seems the only way to get all that unless I happen to find someone with a good one that is upgrading to a 3.6 for example is to go to someplace like Oklahoma Foreign or Parts Heaven and then I pay a retail premium. Your advice IF I decide to go the 3.0 direction. Remember, I'm in California so passing smog isan issue.

[john walker's workshop]

a shop up here has a '83 for around $5K with harness and brain. mileage in the 80s, studs checked. not too bad moneywise, but they can go for a tad less if you get lucky. no smog issues.

[Dan in Pasadena]

Wonder if a 3.0 would even pass visual here in California?

[Steve@Rennsport]

Hi Dan:

JW offers some really sound advice based on sheer economics.

I agree with you, a PROPERLY prepared & built 2.7 (2.8) is an excellent engine provided that it has a good oil cooler to maintain temps between 180 and 200. The only issue is the extensive machine work (read: expensive) required to make these a solid, reliable, and leak-free motor. In most cases, it simply doesn't make any sense unless one wants to maintain a period looking powerplant.

An SC engine looks almost the same as the 2.7 to the uninitiated so that should pass a visual without a problem. Only a Porsche expert will spot the color differences between the magnesium and aluminum engine parts and the fan shroud. One could even install the green shroud on the 3.0 to make look authentic if that was important.

[Dan in Pasadena]

Thanks Steve. The things I remember talking about with my mechanic were align boring, decking the cam towers, of course installing case savers. He said but I can't remember the term for machining the spigots to make them round again. He was clear that the 2.7's get all out of shape and frequently require extensive machining to make them right. His recommendation was ARP studs over using Raceware for a street car like mine and over using stock early steel studs for the relatively minor cost difference. Let's see? Refurbish the rods, they get magnafluxed or dye penetrant examined, new bushings, of course all new bearings, balancing...I can't remember more.
Interesting side note, my 125k car has NO external oil cooler. So I suppose that I got that far is good. Its got me thinking about what Henry said, that valve guides in these cars frequently went at low, low miles. Mine does NOT smoke so I gotta wonder if the guides were done?, which of course leads to the question of whether the PO that may have done them went down the same slippery slope and did the valves, other things? If so, then....I really wonder if the RSR seals "might" be the only things needed? Probably too much to hope for, of course!

I haven't gone back to Wayne's book lately but I seem to remember there is more machining (than what I related) recommended. You're the experts Steve, John, Henry...are there other "MUST do's" your experience says to do...particualrly with 2.7's?