Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 924/944/968 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
Unhappy snapped head bolts, pissed off and x-posted all over

ok,

problem:
3 rocker cover bolts are now snapped into the cylinder head, one has a snapped stud extractor tool !
have re-fitted all, awaiting some action, (loads of HYLOMAR!).
Have some theories, can I have some GOOD eductaed guess's or real experience.

TIME LINE:
1> originally removed bolts (they were really tight)
2> when refitting I torqued them all up, Now I possibly Over tignedten them but were all ok, ran engine up to get her hot, then tigten them again, switched engine off, done another check and one bolt snapped
3> car ran with no drippage at all for at least 1 month
4> today (with some help) we tried to remove the original bolt, but then snapped a stud extractor into the hole.
5> decided to leave dogs lie and put back together
6> on refitting old bolts (with a new torque wrnech set to 15lbs) seemed a problem , so turned down to 8lbs, snapped another one, then while hand tigteneging, stnapped the third

ok, theory is, that step 1 & step 2, had stressed/streched them , so now they were really weak, so questions (considerening there are 13 bolts, 9 long ones (25 each, 4 small ones 5 each)

1> the bolts are Allen keyd, and are a weird shape ie not a not bolt, but contoured, going to do some manufacturing using standard bolts and collers etc.

2> was considering bolts from a breakers but, if these soft alloy bolts are stressed are they prone to snapping ?

3> HOW DO YALL tiugtened them up, with an allen key, hand tight ? or how

4> ANY OF YALL had similar problems ?

5> replacing the 4 short ones are not a problem , but if I have to shell out 25 quid for 9 !

6> going to drill out the old bolts carefully and if the thread strips (it looks like there are inserts) are they available, or dealer fit, other option is to fit a heli-coil, which cuts a thread inside the insert so the orginal bolts will fit.


ideas, suggestions, shoulder to cry on

((((((((((((((((((((((((


Ad
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-11-2003, 03:24 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
ppl are reading this thread but no suggestions

pls
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-11-2003, 05:43 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
vott does ziss do?
 
ronin's Avatar
 
Join Date: May 2003
Location: Seattle
Posts: 6,677
I haven't done porsche heads before and don't know, but is the procedure of re-tightening the bolts while the engine is hot porsche prescribed or endorsed? it seems to me that the rapid heating and cooling of the head would create enough torque on the heads to be able to break the bolts if you tighten them while the engine is changing temps. anyone else?
__________________

Last edited by ronin; 10-11-2003 at 06:11 PM..
Old 10-11-2003, 06:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Roger Hall's Avatar
 
Join Date: Dec 2001
Location: Cordova, TN
Posts: 1,222
I dont think you are actually talking about head bolts they are torqued much higher than 15 lbs. Are you talking about the valve cover bolts?

I cant imagine 8 lbs snaping a bolt. You are probably not reading the torque wrench properly. I dont mean to be rude the same thing happened to me I was reading the Nm scale instead of the In lb and snaped one on my daughters Mazda. If you use a punch to start a drill in the center and the right size drill bit and tap you should not need to helicoil. Helicoils are more commonly used for striped threads. The broken extractor is a problem they are made out of some really hard steel. Just be carefull and take your time.
__________________
Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.

Last edited by Roger Hall; 10-11-2003 at 06:42 PM..
Old 10-11-2003, 06:09 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
speed's Avatar
 
Join Date: Jan 2003
Location: Los Angeles, CA
Posts: 55
Install the cam housing bolts (M8). A small amount of grease in the head of the Allen bolt or on the tip of the Allen head socket will hold the bolt on the socket while installing inside the cam housing. Remember to install the coolant return pipe when installing the cam housing bolts. There is no specified tightening sequence for the cam housing bolts. However, they should be tightened so that the cam housing is pulled down evenly onto the alignment pins. Once the housing is fully seated on the head, torque the cam housing bolts to 20 Nm (14 ft-lbs).
__________________
1985.1 944n/a
Old 10-11-2003, 06:27 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
speed's Avatar
 
Join Date: Jan 2003
Location: Los Angeles, CA
Posts: 55
could you have put a long bolt in a short hole, causing the bolt to bottom out, then twisting the head off?
__________________
1985.1 944n/a
Old 10-11-2003, 06:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
hi guys !

ok, from replies here we go

1> I screwed up with the engine hot thing, (got my wires crossed)
2> The CD manual (I just read) the cover bolts are 8 ft/lbs, I thought they were supposed to be 15ft lbs, again from somewhere, so I doubled the torque on them !

cheers for the replies all,

sittng at home at 3:35am, and not feeling as crap as I was earlier on this evening.

Roger, I'm hoping the helicoil is the last chaance, my mate is doing the drilling, again the bloody stud extractor is going to be a *****

A
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-11-2003, 06:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Roger Hall's Avatar
 
Join Date: Dec 2001
Location: Cordova, TN
Posts: 1,222
I will probably get alot of greif for this but I am not that much of fan when it comes to torque wrenchs. I would always use one on the head gasket, intake/exhaust manifolds, internal engine parts, drive train parts, and when mating alumium to steel, but for items like valve covers I never use torque wrench's. Just snung them down evenly with a socket set.
__________________
Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-11-2003, 06:55 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
vott does ziss do?
 
ronin's Avatar
 
Join Date: May 2003
Location: Seattle
Posts: 6,677
Quote:
Originally posted by adrian jaye

1> I screwed up with the engine hot thing, (got my wires crossed)
thought so

Quote:
sittng at home at 3:35am, and not feeling as crap as I was earlier on this evening.
cool. always good to take a step back and reasess the situation. usually brings things back into focus and lets you start fresh. that's what I usually do (once the wrenches start flying )
__________________
Old 10-11-2003, 06:58 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
speed's Avatar
 
Join Date: Jan 2003
Location: Los Angeles, CA
Posts: 55
just looked up four sources and they range from 14-15 lbs, or 20 Nm...I know that the last guy who did the overhaul on my 944 just tightened the daylight out of the bolts, enough to split the gasket and cause an oil leak, man was i sweating not to strip the bolts, they were that tight...but I will tighten them to 8, then step it up to 15lbs, see how it goes, thanks for the heads up.
__________________
1985.1 944n/a
Old 10-11-2003, 07:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
Hey Speed, Ronin, Roger, all....

cheers for the help, just woken up, going to start the day afresh (10am)

still annoyed with myself. but feeling a bit better,
re torque wrenches (YEP good idea, Rog)
Speed, the 944 haynes (n/a usa, states 15ft/lbs, 6 volume .pdf files on CD says 8 !)
I think either would have been ok, but the screws are kancked so they were very weak. though will only do up by hand !

one last question,
is there any way I can check, that I havent killed the threads in the head, can I flush them out etc ? when putting new bolts in should I put them in clean and dry, a bit of engine oil, WD-40 etc ?

cheers

A
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-12-2003, 01:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Let's go shooting.
 
Dark Skies's Avatar
 
Join Date: Feb 2003
Location: United Kingdom.
Posts: 1,200
I don't think you should lube the threads when you replace the screws - it'll throw out the accuracy of your torque wrench and you could maybe end up where you are now again.

I'm not sure the you will be able to drill out that stud extractor too easily either - they're made from carbon steel and have a very hard surface. You may need to use a cobalt or diamond tipped drill bit to avoid skidding all over the place and damaging the edges of the thread. I wondered if you might have more joy getting it spark eroded out.

As for checking the condition of the threads ... if the threaded hole is blind you could try using a syringe filled with meths to flush them out and follow this up with chasing the threads with a bronze brush - If there's a gun shop in your area you could get a bore brush for a .38/ .380 / 9mm calibre. Some machine shops stock them. I know that Paynes in Eynshem (near Witney Oxfordshire) stock them. If you can get the car to them they can tackle the damaged threads / broken extractor in situ. too,

Shining a decent penlight into the holes ought to reveal if the threads have taken a beating. Look for good sharp edges on the threads signs of flattening / wider threads suggest some stripping has occured - sometimes you can dress these up with a finishing tap. If some have gone you might still be okay providing it's superficial. By the way - you could probably get a rifle bore inspection torch at the shop. The one I have has a long glass M6 tube for a lens which would allow you to get right in there to get a good look.

If the blade of a thread pitch guage will fit in the hole and it sits in the threaded section nice and square then you have got away with it.
__________________
1983 944 Lux (manual) 2.5 litre 8 valve na and no pas

1991 944 (automatic) 2.7 litre 16 valve na and pas

"I have only five words for you: From my cold, dead hands."

Last edited by Dark Skies; 10-12-2003 at 03:46 AM..
Old 10-12-2003, 03:32 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
cheers

A
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-12-2003, 09:30 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Join Date: Aug 2001
Location: Brighton UK since 11/2012
Posts: 3,170
This is a 944S2 not a NA. The valve cover bolts are a different design. These bolts are notorious for snapping off in the head. Yes, you should replace them all. No, they only have to be tightened once and you should replace the rubber seals. The bolts don't have to be really tight, 15-18nm should be enough. Make sure you se some sealant at the corners of the cover or it will leak. As the bolts have broken off, I would strongly suggest you get a workshop to drill out the bolts.
__________________
From November 2012; Precision Porsche Specialist
Sussex UK, +44 (0)1825-721-205
2001-2012 Gerber Motorsport Inc. 206-352-6911
07.15.06 1996 Ducati 900SP. Suprisingly enough, it's red
08.16.09 1999 Kawasaki ZRX1100. Green.
Old 10-12-2003, 12:39 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Roger Hall's Avatar
 
Join Date: Dec 2001
Location: Cordova, TN
Posts: 1,222
If you can eaisly start the new bolts in then the threads are ok. If the bolt will not eaisly start then you can clean up the threads with a tap.
__________________
Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 10-12-2003, 05:00 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
well, the makis helped me (a very long evening) to remove 2 of the snapped studs with some deft drilling, WITHOUT damage to the threads

now all I need is to dig out the original snapped bolt with the stud extractor snapped in ti as well (gulp)
roll on Saturday !
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-13-2003, 02:22 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
adrian jaye's Avatar
 
Join Date: Sep 2001
Location: berkshire uk
Posts: 1,697
well, good news

the makster good me good again,

the 3 bolts that were snapped
top one, we drilled out enough to reomve the bolt (was'nt torqued in too hard) so new bolt went in ok
Middle one: drilled out, lost some of the top thread but the lower half saved,
Bottom one, maganed to get out stud extractor, fitted a Helicoil, new bolt

with loads of drilles, chisels, fabricated bits and bobs, all is now well. need to monitor the bolts, changed out all the bolts with new ones (ouch) !, save to say around 200 job parts all told

also changed out the tensioner, pad on the camshaft chain, easy job.

bled brakes

so now MOT and a well deserved 24k service at AFN's

whew !!!!!!!!!!!!!!!!!
__________________
-----------------------------------------------------------
The fear of God is the begining of wisdom <><

NotJustPorsche
Subscribe: notjustporsche-subscribe@yahoogroups.com
Old 10-18-2003, 11:27 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:38 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.