I coat the thread with silicone, slows the loosening down a bit.
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I coat the thread with silicone, slows the loosening down a bit.
My son is a Diesel Fitter for Cummins. If I used a threadlock substance on manifold bolts or exhaust bolts, he would kick my a** (behind).
What they use is Loctite silver grade anti seize (grease) and torque tight to the the bolts to the recommended values as specified. With a bit of heat this stuff works well. I nor Cummins have never had a bolt come loose.
All of my manifold bolts and exhausts bolts and nuts are 8.8 stainless steel (so too are the terminal bolts on my batteries as well). You can always get them undone.
Another tip is, dip the bolts in oil, wipe off the excess and install them. With a bit of heat the oil burns around the bolt and locks it, but with a bit of tension you can get it undone. It will be about 1 1/4 time the tension you used to do it up with. Try it.
One other tip my son does, if the bolt appears to be tight or not wanting to go the full depth of the threaded hole, get a tap threader (or an old bolt with two cuts longways in it) and run it down the hole and clean out all the muck at the bottom. What muck? Muck like old silicon or excess thread lock that has been compressed, cooked and gone hard.
My son works on diesel engines from the normal truck variety to engines that are larger than your average bedroom, out of haulpacks or power generators. I have a photo of him standing on a step ladder fitting instrument senders or sensor, (and I am talking about him being at least two and a half metres off the ground), to start dyno running it.
Thats nice Miles , but none of the Cummins/Cat/Detroit/MTU engines I know of have aluminium heads ! or alloy blocks .They also run segemented exhaust manifolds and some are even water cooled (semi marinised) . Dont think id use stainless in a alloy thread. Woudnt be using a SS bolt where a bit of Tensile stength is required .
The problem in my case Miles is to keep the manifold to head bolts tight, not to loosen them,
Cheers Charlie
spring and external star washers are your friend.
Hi AllQuote:
Originally Posted by miles
Maybe Miles it is the way you wrote it in your reply, but was meaning to say this.
I would not use a stainless steel thread in Aluminium without using a good quality anti-seize compound.
The powery mess that occurs from electrolysis between the unprotected stainless and aluminium would bind the two metals together, breakage of the bolts or studs then does occur when trying to dismantle those parts.
Cheers Arthur
Gee I really started something here!
What I did was as follows
I have fitted teh manifolds without gaskets using Permatex "Copper" high temp silicone good for 371C or 600F.
I fitted the LH without any lubrication in chased threads to a little above the 20Ft lbs.
On the RH I covered the bolts /washers with moly/graphite assembly lube to see if the lowered torque requirement would mean they are tighter,in chased threads.
Theory is that the oil will evaporate as above and leave a moly coating.And now I will check them when I think of it.
Regards Philip A