Hybrid_From_Hell Posted July 5, 2009 Share Posted July 5, 2009 OK I have had an issue with some of the V8s exhaust 'manifold' to exhaust 'port out' head bolts coming loose Being I have the JED Dakar Big Bore special heads / Matching Manifolds these heads have to have the 12 point type bolts fitted to I think P38s some of which have lossened as time has gone by, even tho dogged up good and tight. Having spoken to a few people this is not unknown, but I would like to sort this, so was thinking about redoing with new gaskets and then shoving some threadlock on the threads to ensure they stay put but be able to remove should the need arise without then the use of helicoils However, normal 242 etc threadlock I don't think will take temp of the exhaust area, so what is the stuff thats used, would be grateful for those who know to answer rather than the 'no idea - but heres my wild vague guesses' group Nige Quote Link to comment Share on other sites More sharing options...
steve_d Posted July 5, 2009 Share Posted July 5, 2009 I think you will find they are loose because the gasket is compressing over time. Just keep nipping them up until they arrive at full compression of the gasket. To replace the gaskets now will just start the process over again. Steve Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted July 5, 2009 Author Share Posted July 5, 2009 ^^ Steve, Possible, but I am unsure. 2 extra things 1st - these are not the "Tin Type" gaskets, they are a grey aspestosey looking gasket (obviously not aspestos but same look ) and I didn;t think / wasn't aware that these did the compression bit, but you may be right ? 2nd is that on a few bolts they were not just loose, but finger tight, yet doged up 1 weekend ago so hence me thoughts of "Locking" in ? I have to replace, as where a few have got loose the port exit pressure has split and blown out part of the gasket , so its reit time but I am serioulsy hacked off that they are doing what they do, I have considered dunking the 90 into ice cold 3-4 foot lakes making everyhting contract as it cools may possibly have something to do with this issue Nige Quote Link to comment Share on other sites More sharing options...
Les Henson Posted July 5, 2009 Share Posted July 5, 2009 I've used loctite 270 on manifold bolts/nuts with no problems. It's safe to use over 100deg C http://secure.silmid.com/external/commerce...iles/LOC270.pdf Les. Quote Link to comment Share on other sites More sharing options...
will_warne Posted July 5, 2009 Share Posted July 5, 2009 ^^Steve, Possible, but I am unsure. 2 extra things 1st - these are not the "Tin Type" gaskets, they are a grey aspestosey looking gasket (obviously not aspestos but same look ) and I didn;t think / wasn't aware that these did the compression bit, but you may be right ? 2nd is that on a few bolts they were not just loose, but finger tight, yet doged up 1 weekend ago so hence me thoughts of "Locking" in ? I have to replace, as where a few have got loose the port exit pressure has split and blown out part of the gasket , so its reit time but I am serioulsy hacked off that they are doing what they do, I have considered dunking the 90 into ice cold 3-4 foot lakes making everyhting contract as it cools may possibly have something to do with this issue Nige Would these be of any help? I'd have thought you'd struggle with a thread locking compound as I've never come across one that survives heat! Quote Link to comment Share on other sites More sharing options...
steve_d Posted July 6, 2009 Share Posted July 6, 2009 ^^Steve, Possible, but I am unsure. 2 extra things 1st - these are not the "Tin Type" gaskets, they are a grey aspestosey looking gasket (obviously not aspestos but same look ) and I didn;t think / wasn't aware that these did the compression bit, but you may be right ? 2nd is that on a few bolts they were not just loose, but finger tight, yet doged up 1 weekend ago so hence me thoughts of "Locking" in ? I have to replace, as where a few have got loose the port exit pressure has split and blown out part of the gasket , so its reit time but I am serioulsy hacked off that they are doing what they do, I have considered dunking the 90 into ice cold 3-4 foot lakes making everyhting contract as it cools may possibly have something to do with this issue Nige Those gaskets do compress. When they do they release the load on the bolt which can then spin loose. Similar gaskets on my Chevy engine did the same thing and were tightened three times to bed them in and have stayed there for 5 years now. Steve Quote Link to comment Share on other sites More sharing options...
V8 90 JON Posted July 6, 2009 Share Posted July 6, 2009 Hi Nige, i also have the same exhaust gaskets and have retightend them at least 3 times , the trick is to catch them before the blow damages the gasket!! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 6, 2009 Share Posted July 6, 2009 Nige - just phone Loctite's tech helpline, they're very helpful and should be able to tell you in seconds the right thing for the job. Quote Link to comment Share on other sites More sharing options...
Pete Attryde Posted July 6, 2009 Share Posted July 6, 2009 Both Loctite 266 and 272 are listed as being high temperature (232C/ 450F). Info from here and here . Pete. edit to add. 246 is also high temp. here Pete Quote Link to comment Share on other sites More sharing options...
streaky Posted July 6, 2009 Share Posted July 6, 2009 We used to drill them and use locking wire on the Saluki. I know those bolts are quite hard but with patience it can be done. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted July 6, 2009 Author Share Posted July 6, 2009 Hmmmm Thanks for all the info above I 'aint drilling them yet did that years ago on Bikes and that was bad enough Re threadlocking / needing to retighten regaularly maybe 3x now wondering that if I do use threadlock and then retighten etc if the threadlock will actually then be a bad thing and work against me ? Never had this problem with the Bl**dy tin albiet small ports gaskets so you learn something every day LR wise Thoughts re threadlock and 2 / 3 tighens ? Nige Quote Link to comment Share on other sites More sharing options...
steve_d Posted July 6, 2009 Share Posted July 6, 2009 If you tighten after thread locking the lock is broken. Afraid its one or the other. As said before the gaskets will compress so if it were me I would forgo the thread lock and just tighten them from time to time until they bed down. Don't forget the bolt which will resist bedding down the longest is the one most difficult to get at. Steve Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted July 6, 2009 Author Share Posted July 6, 2009 Hmmmm Twas my thoughts too And does the panel equally agree that the gaskets should go on "Dry" rather than with a smigen of exhaust paste on each side ? I've always worked on dry gaskets but again just seeing if theres a better option ? Ta all Nige Quote Link to comment Share on other sites More sharing options...
V8 90 JON Posted July 6, 2009 Share Posted July 6, 2009 mine were dry fitted,and after three "re-tightens" and a few "dips in water" they dont blow no more! Quote Link to comment Share on other sites More sharing options...
steve_d Posted July 6, 2009 Share Posted July 6, 2009 I use paste. Steve Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 6, 2009 Share Posted July 6, 2009 Depends what threadlock you use - some of it is permanent, some of it just gives a bit of extra grip and can be re-tightened / removed & re-done without reapplication. As I said, phone Loctite and they'll tell you the right thing for the job. Quote Link to comment Share on other sites More sharing options...
Lara Posted July 7, 2009 Share Posted July 7, 2009 Go buy some "K" nuts http://www.merlinmotorsport.co.uk/index.php?cPath=191 All modern race and rally cars use them for everything! Will not come loose on exhausts either!! Lara Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 7, 2009 Share Posted July 7, 2009 I use paste.Steve Ditto, only way I have found to truly seal them properly long term. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted July 7, 2009 Share Posted July 7, 2009 If it is a gasket compressing, then perhaps a simple old spring washer would help? It would maintain load on the nut over a reasonable range of movement? Quote Link to comment Share on other sites More sharing options...
rusty_wingnut Posted July 7, 2009 Share Posted July 7, 2009 what about a lock nut if it's a stud? Quote Link to comment Share on other sites More sharing options...
andy2986 Posted July 7, 2009 Share Posted July 7, 2009 If there studs, how about 2 sets of nuts on each one tightened against each other ?? Andy Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted July 7, 2009 Author Share Posted July 7, 2009 If there studs, how about 2 sets of nuts on each one tightened against each other ??Andy Nope, not studs PITFA P38 12 sided bolts as they only just clear the manifold being the castings bigger I had studs yonks ago on a racer engine, horrible to try to get the manifold on and off tricky enough anyway Hmmmm gloop or not gloop, springs washers or threadlock....call to Loctite next methinks Nige Quote Link to comment Share on other sites More sharing options...
taz90 Posted July 7, 2009 Share Posted July 7, 2009 have you tried Belleville washers http://en.wikipedia.org/wiki/Belleville_washer ive got some m8 washers you can try Quote Link to comment Share on other sites More sharing options...
pat_pending Posted July 7, 2009 Share Posted July 7, 2009 Use bellevilles as suggested, or two flat washers per bolt, both work. The heat can take the temper out of spring washers. I wouldn't bother with thread lock. Blather the gaskets in copperslip, the grease burns off but leaves a copper residue that stops the gaskets sticking to the head or manifold. This stops them from tearing and then blowing due to the different rates of thermal expansion between the two components. Run the engine up to temp', allow to cool and re tighten. The original 3.5 V8s didn't use gaskets and had lock tabs on the bolts, sometimes the joints wouldn't seal after being disturbed. We used silicone RTV between the manifold and head faces, this works if you allow it to cure first and then warm the engine up slowly. Quote Link to comment Share on other sites More sharing options...
q-rover Posted July 9, 2009 Share Posted July 9, 2009 Have a look at these Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.