jackb_ms Posted January 18, 2005 Share Posted January 18, 2005 I’m changing from bolts to studs, to attach the exhaust manifold to the block , because there is one thread damaged, the end one at the end of the engine near cylinder number 4. The damage to the tread is such that I can feel it slipped when I trying to tighten it to the same setting as the 4 other one (hand tight). To solve this problem I was going to use some threadlocker, Loctite 270, which is vibration proof, to lock the studs in place. Before doing so I had the idea of checking the technical spec of it and it says it will withstand temperature up to 250C. So my questions are: What temperature the block goes up too? Does a high temperature threadlocker exist? What are my other option? (will have to be done by me) Thank for your help Jack Edited by - jackb_ms on 18 Jan 2005 13:49:48 Link to comment Share on other sites More sharing options...
Sheds Moderator Posted January 18, 2005 Share Posted January 18, 2005 The block will not exceed 110- 120C, if it does the head gasket is dead. Remember it has a water jacket. Near the exhaust it will heat up fastest but it won't reach 250C. Use the standard thread locker, that's what it's made for. You could fix it in with Araldite which will withstand anything but a direct hit from a Scud missile, but this will fix it for ever and is reserved for nasty bodgeit artists, and that's not us, is it? Link to comment Share on other sites More sharing options...
jackb_ms Posted January 18, 2005 Author Share Posted January 18, 2005 😬Thank a lot batteredoldsupersport I'm a much happier man now Jack Emily, The Very Yellow 21 Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 18, 2005 Share Posted January 18, 2005 Considering the header pipes can glow in the dark, I would imagine that the pipework can exceed 250'C. Then you have the conduction through the manifold flanges to the studs. Although there is a water jacket, it must be some distance into the block and the thermal profile would indicate that temperature at the flange/head interface will be greater than the water temperature. As an alternative, why not use exhaust paste: TECHNICAL DATA SHEET FOR 7M91 EXHAUST PASTE & Hi Temp Cement DESCRIPTION SCI is a One Part Dual Heat and Air Cure system based on a modified Silicate Cement. It will Air Cure fast but can be accelerated with Heat. APPLICATIONS The product is designed to do many Sealing jobs where high Temperatures exist as a feature of the system. Typical applications are in Exhaust System sealing, however the use of the product is not limited to this area only. For example, Gas Fumes can be sealed inside of Boiler/Heater Units, Pipework connections can be sealed, Encapsulation of Sensitive Components is possible to extend life/reduce direct exposure to Temperatures up to 1500°C. Flange and Gasket Sealing at high temperature can be achieved also using SCI Paste. SCI can Gap Fill and is possible to use in non moving Joints such as wood, Metal, Brickwork acting as a Fire Stop. The use of SCI with fibre absorbent products allows for large Gap Filling, Netting, Glass Fibre and Metal Cloth are suitable packing/reinforcing items. USEFUL HINTS/NOTES As SCI is an Air Drying/Heat Cure System, avoid leaving containers open to air and store away from heat. This product is Water Soluble in uncured state allowing easy tooling. Water wetting of components also aids adhesion. PROPERTIES Air Drying - No Heat Required. Heat Activated, Exhaust Gas Temp will increase the Cure Rate Significantly. Skin Time: 2 minutes (Ambient 20°C). Joint Drying Time (200°C) - 2 minutes. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
jackb_ms Posted January 18, 2005 Author Share Posted January 18, 2005 Graham thank you for the information I have been reading the technical spec of the 7M91 EXHAUST PASTE & Hi Temp Cement with great care. The worry I have is that the stud will breack loose if I use the 7M91. Have you used this product in a similar application? I'll try to contact Holdtite tomorow Jack Emily, The Very Yellow 21 Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 19, 2005 Share Posted January 19, 2005 I have not used exhaust paste like this, but as the original bolts would not have been loctited in place, I cannot see too much of an issue with spreading some paste on the stud and screwing it home. When you then mount the exhaust manifold and secure with nuts this then come under tension (as it would with bolts) and not come loose. As you say that the original thread in the head may be damaged slightly, would it make sense to increase to the next thread size up (maybe moving to a metric thread?) so that the stud is secured firmly but still fits the flange on the manifold? This would be a better long term solution. Another possibility would be to increase to the next thread size and use a helicoil so that you can use the original size bolt again. These bolts are not tightened very much and if a helicoil can be used for spark plugs, I can see no reason why they could not be used here. The one caveat to the last two options is that there is sufficient spare material around the existing hole to take the next thread size up - but I cannot imagine Ford working to that fine a tolerance back in the 1970s. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Sheds Moderator Posted January 19, 2005 Share Posted January 19, 2005 Graham, I think Jack has a 21 K series... It's probably an M6 or 8. I agree with you that if a drop of thread lock doesn't fix it then it's Helicoil time or drill and tap next up. Link to comment Share on other sites More sharing options...
MorganMan Posted January 19, 2005 Share Posted January 19, 2005 Do it right, buy a helicoil kit. The helicoil is a preformed thread in high quality stell that will outperform the original threads. All other suggestions above are bodges. Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 19, 2005 Share Posted January 19, 2005 See Namrick catalogue for details. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
jackb_ms Posted January 19, 2005 Author Share Posted January 19, 2005 Thank gentlemen for your advice I've been talking to Clive from Aryliam and he is going to drill it out and fit an helicoil kit. Thank again Jack Emily, The Very Yellow 21 Link to comment Share on other sites More sharing options...
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