Outer Limits 4x4 Board

Wondering if anyone out there can help me with my problem

I have a chevy with block hugger headers and the bolts that bolt the bottom of the headers to the collector boxes, keep coming loose - 4 on each side. I have welded M8 nuts onto the bottom of the headers so I dont need to hold them with a spanner when tightening the bolts from below.

On a trip on Sat I was left with one on one side and two on the other. So it was sucking air in, the oxygen sensors were saying it needs more fuel to compensate the extra air, so the computer would act accordingly.

I have tried locking washers, Locktite 623 on clean treads, startype washers, but I think with the heat expanding together with the vibration it makes them come loose.

There is not a lot of room down there to do much but ant helpful ideas would be great

I had a car that a flange kept coming loose no matter what, used some muffler putty like a threadlock, worked a treat

thanks Zookie, thats a good product I never thought about.

I have emailed Loctite to ask them what temp it will with stand. Their product sheet does not give a rating, rather it says it with stands heat(how much?) and sets like a weld

Thanks again

I was thinking similar. My old WB panelvan used to do the same thing till I used high heat silicon(red stuff that smells like vinegar) like locktight and double nutted them.

put two nuts on like lock nuts or try a tack weld on each nut once there tight

460cixy wrote:put two nuts on like lock nuts or try a tack weld on each nut once there tight

Or locknut them and tack the two locknuts together. I think the sealant idea with locknuts is safer for later though.

With out distroying the thread could you drill a small hole thru it and they lock wire the nuts on

I have the same trouble with my block huggers. I went to the exhaust shop and they said the flange itself may be slightly warped causing the gasket to blow out, thus allowing the bolts to come loose.
Carl.

Hi temp silocone

apply to both gasket surfaces/ flanges, and on the bolt threads !

Also use nylock nuts the plastic in the nylock nut will melt onto the thread and will then 'bake dry' ........ you'll have hells own trouble getting em off tho !

Oh ...... weld the BOLT in not the nut ! .... heat distrotion to the bolt head from welding wont effect the thread on either the bolt or the nut, however by welding a nut you weaken it considerably and the thread cut can be dammaged causing a less than desirable 'fit' to the bolt ..... hence the loosening !

For extream conditions I've fitted a brass nut then used a nylock nut as a 'locking nut' ....... works a treat


The other major contributing factor may well be in the zorst system itself, a poorly fitted engine pipe can 'pull' on the extractor flange ( usually to one side ), this in turn leaves enough space for the gasket to work itself 'free' ( for want of a better word).
Once the gasket can move its a simple operation to blow it out and then the whole lot comes loose real quick. A re-tentioning of the bolts can overcome this after an inital warm up but its a drama that will unfold in the future again. Better to cut and reweld the engine pipe around 750mm from the extractor flange joint to relive any twist tha may be built into the system.

Kingy

Try centre punching the thread above the nut, but only in one or two spots. The thread will be corrupted enough to stop the nut coming loose of its own accord, but not enough to stop it coming undone with a spanner.