PTT manual release valve

[emmo1210]

Hi Guys,

Bit of a problem, I think I have damaged the internal threads where the manual release valve screws into the power tilt and trim unit on my 1990 evinrude 90hp.

I think i need to use a tap to clean the threads out.

Would anyone have any idea as to what the pitch would be?

I am only used to metric here in the UK.

Thanks for any help

Regards
Emmett

 

[emmo1210]

Re: PTT manual release valve

Although it doesnt look exact looks like it could possible be 7/16,

is it known for pitch to ever be UNS in evinrude or more likely to be UNF?,

There are only 3 thread to measure so is difficult to figure tpi

Thanks
Emmett

 

[ezeke]

Re: PTT manual release valve

1/4 npt

 

[emmo1210]

Re: PTT manual release valve

Hi Ezeke,

Thanks for your reply.

But the valve is not 1/4".

On the calipers the major diameter of the thread is reading between 10 and 11 mm ie around 7/16 "?

Do you think the thread is pipe thread?

thanks
emmett

 

[ezeke]

Re: PTT manual release valve

What's the part number of your valve? Most of the valves are NPT US standard, but I was going by part # 0435340. The outside thread on that is about 13.8 mm.

There's a chart here that might help with the conversion. 10 mm is about .4" which would make it around 1/8 NPT. http://en.wikipedia.org/wiki/National_pipe_thread

 

[emmo1210]

Re: PTT manual release valve

Hi ezeke,

The part number of my valve is 0387990,

so it is 1/8th npt tap that i need?

thanks
emmett

 

[ezeke]

Re: PTT manual release valve

Hi ezeke,

The part number of my valve is 0387990,

so it is 1/8th npt tap that i need?

thanks
emmett

Probably, but I don't have the fitting to check it.

Maybe someone else has one.

My 1/8 NPT tap is 27 threads per inch. It requires a Q drill bit which is .332".

 

[emmo1210]

Re: PTT manual release valve

Thanks for looking ezeke.

Just to confirm you say i9t requires a Q size drill bit. I am just cleaning the threads out so thought the tap would do on its own?

Thanks
Emmett

 

[ezeke]

Re: PTT manual release valve

Thanks for looking ezeke.

Just to confirm you say i9t requires a Q size drill bit. I am just cleaning the threads out so thought the tap would do on its own?

Thanks
Emmett

Yes, the tap should do it on its own.

 

[emmo1210]

Re: PTT manual release valve

Thanks for your help ezeke, really appreciated.

I will let you know how i get on.

Emmett

 

[emmo1210]

Re: PTT manual release valve

Hi ezeke,

got the 1/8th tap but its definately not correct, the outside diametre is about right but the teeth per inch are not. the tap has 27 tpi, which is much finer than the valve, which muct be about 18-22 at a guess. Also the teeth dont look as deep on the tap.

An other ideas what the thread migth be, doesnt seem to be npt, unless it is unc?

thanks
emmett

 

[emmo1210]

Re: PTT manual release valve

got the correct tap, 7/16 unf.

thanks anyway
emmett