Remote oil filter housing with oil pressure sensor leaking

[Quinten]

Hi all, been lurking for a while now, but think I need to ask for some advice now.

I've got a Westfield SEiGHT with a 3.9L EFI Rover V8 fitted which uses a remote filter housing to avoid the steering column in a very tight engine bay. On Friday I came back from a trip and there was a lot of oil on my drive. After everything cooled down and cleaning everything again, it turned out that the oil pressure sensor has started to leak where it screws into a T-piece that screws into the remote filter housing



At first I thought it was the T-piece itself as there seemed a big gap between housing and T-piece, but it was definitely the sensor end.

I removed them both from the car and it appears that I can not tighten the sensor enough for it to form a good seal, so I was thinking of adding a dowty washer to it. Or should I use a tiny bit of PTFE on the end of the (tapered) thread of the sensor?



I was planning to add a 3mm wide o-ring to sit between the T-piece and housing to get rid of that gap, can anyone see an issue with this?

[GDCobra]

Think I’d be trying the PTFE on 5he thread first. I always use that on these threads, it fills in between the peak & trough of the male/female threads

[stevieturbo]

Taper threads are never ideal, but yea some PTFE tape around it should sort it.

[Ian Anderson]

Not sure about the ptfe

It can cause a very good insulator so the sensor does not get a proper grounding.

It may work but not always ….. depends how much tape you use

Ian

[Quinten]

As I've got both parts on the bench I wrapped the last bit of threads on the sensor with PTFE tape and then did them back up together (only hand tight) and then undid them again. The PTFE was now cut into the grooves into a tiny PTFE strip with nothing on the 'hill' of the male thread. I seriously doubt it would create a good seal.

Did lots more googling and found Permatex 59214 (along with Loctite 577 but thats a lot more expensive) which seems more suitable to this type of installation.

[GDCobra]

As I've got both parts on the bench I wrapped the last bit of threads on the sensor with PTFE tape and then did them back up together (only hand tight) and then undid them again. The PTFE was now cut into the grooves into a tiny PTFE strip with nothing on the 'hill' of the male thread. I seriously doubt it would create a good seal.

Did lots more googling and found Permatex 59214 (along with Loctite 577 but thats a lot more expensive) which seems more suitable to this type of installation.

Where there is metal to metal contact the PTFE will not be needed (and a circuit will be made if necessary), the PTFE is needed where the metal surfaces don't meet which is typically between the peak and root of the mating threads, if you think about it there is a helical void in these areas, as long as the PTFE fills these voids it will seal.
PTFE has been used for this purpose for many years and has got to be worth a try before bodging or modifying.
Perhaps you are overthinking?

[Quinten]

Like you say, I'm most likely overthinking things, mainly because I hate fixing things twice. I went with the Permatex for the sensor and PTFE and an o-ring for the T-piece



Have put it all back together and run the engine and so far no leaks. If the weather wassn't so temperamental I'd take it for a longer spin, although with the petrol shortage and the car liking a drink, I may not be able to go far

[GDCobra]

Like you say, I'm most likely overthinking things, mainly because I hate fixing things twice. I went with the Permatex for the sensor and PTFE and an o-ring for the T-piece



Have put it all back together and run the engine and so far no leaks. If the weather wassn't so temperamental I'd take it for a longer spin, although with the petrol shortage and the car liking a drink, I may not be able to go far

Not too famimliar wtih Permatex but name sounds like it's intended to fill in any gaps in the threads (similar to what PTFE does) so should be good, personally I'd have put the PTFE tape on the whole of that thread, you only seem to have gone part way up.
Personally I don't think the O'ring will do anything apart from psychological support as it is not very well supported so any pressure behind it will most likely push through (could be wrong, difficult to tell without seeing it installed) but hopefully with that PTFE in place that should not arise.

[Quinten]

The o-ring is just there to bridge a gap that I spotted when I investigated the original leak. It felt like there should have been an o-ring due to the way there was an empty section behind the thread. As for doing the whole thread in PTFE, I read everywhere that you should skip the 1st thread.

[GDCobra]

The o-ring is just there to bridge a gap that I spotted when I investigated the original leak. It felt like there should have been an o-ring due to the way there was an empty section behind the thread. As for doing the whole thread in PTFE, I read everywhere that you should skip the 1st thread.

That's fair enough and as long as you've used enough tape I'm sure there'll be no problem however that gap was not a problem, in fact it would be more of a problem if no gap existed as that would mean the flanks of the thread may not be contacting each other (the o'ring will compress so that won't cause an issue).

Must admit I'm a bit unconvinced about the possibility of the PTFE preventing an earth (I've been wrong before though!), when the thread is tightend the pressure between the thread flanks should displace the tape. Think I'd rather add a separate earth wire than skimp on the PTFE along the thread