Really ?well i just replied above to a post in this thread, and the post has gone
Fnarr...If the threads are a bit iffy then just wind a bit extra ptfe tape on it to make it tighter going in.
well i just replied above to a post in this thread, and the post has gone
A lot of modern HP diesel fuel pumps have PTFE 'bearings' because the mechanical needle or roller type have too much play in them for a pump that is manufactured to molecular level tolerances. That is why they should never be run dry and engine management systems will shut off the fuel injectors if the fuel tank level becomes low enough that there is a risk of no fuel in the HP pump.Interesting, I was told by a time served mechanic who taught me engine rebuilds, it's not compatible with diesel and engine oil.
ok thanks but they was right, they do suffer from bad oil pressure switches.Just had a look and the person posting it decided to delete it.
Thats the stripping down and the cost, having the car of the road for however long i am trying to ovoid, i know its the right way to have it done, the irritating thing is it never leaked after i had done the chain and put it back in, having to take it out to do that hose then back in, now the threads have gone wasnt even cross threaded when put it back in, or atleast it never felt like it.If it's gone tight then loose, it'll probably leak by virtue of being blown out by the oil pressure, time to look at rethreading.
good shout, thanks, i may try that, if the bodge with the tape i have just done dont workPossibly overtightened at some point? take it out and see if there are clean threads a bit further in, if there are, then you might be able to use something like a oil pressure gauge tee piece if it has a longer male thread - or possibly the other pressure switch you mentioned that goes tight after a few turns with some PTFE or threadlock on it... It's all going to be a bodge until you can sort out a proper thread repair.
You could put a thread insert in it in situ, take the switch out and put a bit of rag in the hole...when your drilling and cutting the new thread for the insert use grease on the drill and tap, this catchers and holds all the swarf to the drill bit and tap. To snap the tang off the insert use very small needle nose pliers so it does not get lost. remove the bit of rag with the same needle nose and away you go. This is all assuming access is not an issue of course .
Has that switch got a flat washer underneath it - if so it actually seals on that washer, and not on the taped threads, though putting tape on the threads always makes it easier to get the switch out in future.
Re PTFE tape, there are definitely two grades available; some cheap stuff, which I suspect is not pure PTFE, which is OK for most domestic plumbing - and the more expensive stuff which is pure PTFE and is good for gases at higher pressure. For the good stuff, I tend to buy from RS components.
So do I - but it's a thread sealant, not a glue. It still needs the fitting to be mechanically secure, and it sounds anything but.Loctite 577 is pretty awesome stuff in my books, I go for it every time over PTFE tape.
What isn't compatble is when people don't leave a couple of threads clear at the beginning - so when they wind it in, the tape gets chopped up, and enters the system - bits then block something up and . . .Interesting, I was told by a time served mechanic who taught me engine rebuilds, it's not compatible with diesel and engine oil.
All PTFE tape is resistant to temperatures well above that of engine oil.
Everything You Need to Know About PTFE Tape | RS
This guide looks at what PTFE tape is and explains how to use it properly, as well as exploring the different applications across a range of industries.uk.rs-online.com
This post is correct about the sealing arrangement of this pressure switch. There shouldn’t be any ptfe or sealant of any description on this because there should be a dowty washer of the correct size between the bottom of the switch and the block. Clean the block with fine emery paper to give clean metal and ensure a new seal is fitted.Has that switch got a flat washer underneath it - if so it actually seals on that washer, and not on the taped threads, though putting tape on the threads always makes it easier to get the switch out in future.