how to clean off old gasket material / goop from valve cover engine interface
06-23-2008, 10:13 PM
#16
Instructor
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My original leak
http://spfhs68.com/porsche/leak/
now after carefull cleaning with soft abrasive pad in my die grinder, and installation of a plain green German gasket I have a leak at the other end top (rear of engine) on the same valve cover.So the the original leak is gone, I await the silicon gaskets and new lock-nuts (6 ft-lbs) as the final solution.
I actually removed the valve cover studs to be sure that I got the engine surface clean. If this does not do it then possibly it is coming from the top intake gasket but I so doubt it.
http://spfhs68.com/porsche/leak/
now after carefull cleaning with soft abrasive pad in my die grinder, and installation of a plain green German gasket I have a leak at the other end top (rear of engine) on the same valve cover.So the the original leak is gone, I await the silicon gaskets and new lock-nuts (6 ft-lbs) as the final solution.
I actually removed the valve cover studs to be sure that I got the engine surface clean. If this does not do it then possibly it is coming from the top intake gasket but I so doubt it.
06-27-2008, 02:57 AM
#17
Three Wheelin'
6 ft-lbs is not tight enough for an 8MM (thread size) nut. The proper torque is 18 ft-lbs for an 8x1.25MM thread. I was wondering where you guys keep coming up with the 6 ft-lbs figure, so I broke out my Bentley manual and there it was! Not everything is correct in those. To be honest, I don't even bother with a torque wrench on 911 valve cover nuts anymore since I have done so many I know how tight to make them so there are no leaks, but no overtightening either. However, anyone who hasn't done this too much should use a torque wrench, and of course tighten in the correct pattern. Also tighten them evenly in several stages. Remember the nut needs to be tight enough to slightly crush the aluminum washer so that oil can't seep past the threads; 6 ft-lbs may not be enough for that, or to provide clamping force on the valve cover/gasket. The 6MM studs for the valve covers on 4 valve/cyl 944/968/928 and BMWs and also the 6MM bolts on 993 valve covers call for 7 ft-lbs, so that tells you that Bentley is off.
06-27-2008, 04:14 AM
#18
Burning Brakes
Chris, There's a recent thread on Pelican where Pete Z. concurs with you regarding 18 ft/lbs instead of the 6 ft/lbs that the Bentley manual (and also everything I've ever read on these forums) states as being the correct torque values for the valve covers. I just checked the factory manuals, and could not find a clarification. I'm a novice compared to many, but that's what I've used (6 ft/lbs) and have never leaked a drop around the valve covers. I don't want to continue to pass along bogus information, but before Pete (and now you), I've always read 6 ft/lbs, with admonishments against going too tight on those nuts, so now I'm really confused. I realize too that many "experienced" hands simply use a box wrench but I'm not one. I know that the Bentleys sometimes contain errors, but 8 nm (5.9 ft/lbs) is also the spec listed in Wayne Dempsey's Rebuilding Porsche 911 engines book, and also in his 101 Projects. You (and Pete) are suggesting a value that is 3x every spec that I've seen. I've seen many times where "experts" disagree on an issue (and I'm CERTAINLY not one of those 
). I just know that 6 ft/lbs works for me and I use a torque wrench to get them exactly that and have never had a leak. I'd sure like to hear what some others (who've done lots of valve adjustments) have to say. Thank you for your input...I'm not arguing with you, just continuing to "learn as I go", and I'll be the first to admit if I'm wrong.
Keith
'88 CE coupe
ps: Here's a quote from Dempsey's book: "The valve covers are notorious for being overtightened. The nuts should only be tightened to 8 nm (5.9 ft/lbs). If you overtighten them, then you have the potential of warping and deforming them. This may cause leaks later on. Tighten them down to the specified torque. If you find that they are leaking later on, you can always tighten them up a bit more."
Everyone should use their own judgement imo...I just know what works for me.
). I just know that 6 ft/lbs works for me and I use a torque wrench to get them exactly that and have never had a leak. I'd sure like to hear what some others (who've done lots of valve adjustments) have to say. Thank you for your input...I'm not arguing with you, just continuing to "learn as I go", and I'll be the first to admit if I'm wrong. Keith
'88 CE coupe
ps: Here's a quote from Dempsey's book: "The valve covers are notorious for being overtightened. The nuts should only be tightened to 8 nm (5.9 ft/lbs). If you overtighten them, then you have the potential of warping and deforming them. This may cause leaks later on. Tighten them down to the specified torque. If you find that they are leaking later on, you can always tighten them up a bit more."
Everyone should use their own judgement imo...I just know what works for me.
06-27-2008, 07:12 PM
#19
Rennlist Member
This is a very interesting discussion, and I, too, am enthralled with it. (longing for the decisive answer). I mentioned (to Pete) in that thread, that I would propose that what was so important was to evenly apply these torques...torque aside....
I'm like KC911,.................we're talking a factor of 3X,..(one doesn't see that variance on putting an engine case together, do they?) Probably a non-issue in the VC world (with a gasket)...some guys do well at the lower setting, others (SHOPS?) do well at the higher torque on over 100,00 911's (and WTF would argue with that?)........I'd like to hear all of the experts here chime in (guys that work on 'em, day in, day out,..such as Pete {{{{{{{well,..he used to}}}}}}}}}} {{{same thing}}},
I checked mine last night with a techwrench digital that goes (only) to 20 foot/lbs....[[[[[so she can read the 6 foot/lbs accurately]]]],...on VC nuts set up on the last valve adjustment by MY P-wrench,...and found them at ~ 6 ft/lbs.........
...surely you pros would understand us neophytes, upon seeing a leak at the VC, simply tightening (with proper sequencing0 the VC nylocks from their present 6 to the higher torque setting.
There's no question in my mind that the higher torque setting WILL NOT bend the valve covers (due, simply, to torque),...those such as Pete attest to this at over 100,000 911's +.
Howabout the other big boys chiming in here,..let's slam this thing home.
Best to all,
Doyle
I'm like KC911,.................we're talking a factor of 3X,..(one doesn't see that variance on putting an engine case together, do they?) Probably a non-issue in the VC world (with a gasket)...some guys do well at the lower setting, others (SHOPS?) do well at the higher torque on over 100,00 911's (and WTF would argue with that?)........I'd like to hear all of the experts here chime in (guys that work on 'em, day in, day out,..such as Pete {{{{{{{well,..he used to}}}}}}}}}} {{{same thing}}},
I checked mine last night with a techwrench digital that goes (only) to 20 foot/lbs....[[[[[so she can read the 6 foot/lbs accurately]]]],...on VC nuts set up on the last valve adjustment by MY P-wrench,...and found them at ~ 6 ft/lbs.........
...surely you pros would understand us neophytes, upon seeing a leak at the VC, simply tightening (with proper sequencing0 the VC nylocks from their present 6 to the higher torque setting.
There's no question in my mind that the higher torque setting WILL NOT bend the valve covers (due, simply, to torque),...those such as Pete attest to this at over 100,000 911's +.
Howabout the other big boys chiming in here,..let's slam this thing home.
Best to all,
Doyle
Last edited by dshepp806; 06-27-2008 at 07:13 PM. Reason: spelling
06-28-2008, 12:29 AM
#20
Three Wheelin'
OK, I did a search back to a previous thread where Pete mentioned that the 6 ft-lb figure is actually an error from the original factory manual which has been subsequently re-printed in everything else, check Pete's post #98:
https://rennlist.com/forums/showthre...lve+adjustment
Now, if you guys have been torquing the nuts to 6 ft-lbs all this time and have never had leaks, then by all means keep doing it. But I will still argue that the "correct" torque for any normal 8x1.25 MM thread is 18 ft-lbs. There is nothing special about the valve cover studs or nuts on a 911 engine that would make it any different. Anything else that thread size/pitch in any Porsche manual hat is not hardened is 18, no reason valve covers would be different. I think the novice overtightening that is mentioned is way more than even 18 ft lbs, which would be easy to do. Thing is, even though 18 is 3x6, it is not THAT much tighter overall since the numbers are still small. Torque an 8 mm nut down to 6, then 18, and you'll see what I mean, it doesn't take that much more force.
https://rennlist.com/forums/showthre...lve+adjustment
Now, if you guys have been torquing the nuts to 6 ft-lbs all this time and have never had leaks, then by all means keep doing it. But I will still argue that the "correct" torque for any normal 8x1.25 MM thread is 18 ft-lbs. There is nothing special about the valve cover studs or nuts on a 911 engine that would make it any different. Anything else that thread size/pitch in any Porsche manual hat is not hardened is 18, no reason valve covers would be different. I think the novice overtightening that is mentioned is way more than even 18 ft lbs, which would be easy to do. Thing is, even though 18 is 3x6, it is not THAT much tighter overall since the numbers are still small. Torque an 8 mm nut down to 6, then 18, and you'll see what I mean, it doesn't take that much more force.
06-28-2008, 01:43 AM
#21
Droops,
Very enlightening. Pete says that 6 ft/lbs "is just flat wrong". That's good enough for me. Despite my flat sanding of the valve covers, I still get rare drips that made my new SSI's look not so new. Next oil change for me is 1000 miles and I will give 18 ft/lbs a go.
Thanks!
Very enlightening. Pete says that 6 ft/lbs "is just flat wrong". That's good enough for me. Despite my flat sanding of the valve covers, I still get rare drips that made my new SSI's look not so new. Next oil change for me is 1000 miles and I will give 18 ft/lbs a go.
Thanks!
