Hi Dolac, I've been able to remeasure the T piece today. Apologies for the delay.
The main tube is 1.75 inches (44.45mm) external diameter, with walls about 2.2mm thick.
On mine the thin copper(?) tube coming into it from the Y piece is about 6.1mm external diameter. The fittings on the end of it have two hexagonal nuts on the outside of the T piece tube, and one nut inside the tube. It therefore appears to me that the fitting was originally made by the main tube simply having a hole drilled into it, and a fitting bolted through it.
Maybe you could repair your T piece simply by drilling out the hole to the next larger fitting size, and putting a reducer to your thin tube size? Alternatively, an appropriate sized fitting in a suitable material could perhaps be welded into the existing hole?
I notice that my T piece shows signs of leakage (white salts on the outside) both between the main tube and the first fitting nut outside, and between the first and second nut. So it would seem perhaps they all fail this way eventually. (But it has lasted 40 years so far!)
I didn't know (not even expected) that there are any nut, as all I could see, there were two hose clamps but I didn't touch it as I didn;t have spare part.. Did you maybe take any picture?
I didn't even think about repairing the T tube but I would definitely do that to this one and to have as a spare one on the boat
Good luck to you too with replacing T part, mine is 35 years old, so I would be more than happy is the new one last even half less
PS. my flight is cancelled, I am getting really angry about this covid situation
I finally managed to solve my problem, it was done 2 weeks ago but I had to go to work and didn't have time to write it before :/
So, first of all, Sula big big thanks! Your measures were right, so once I came back home, the T part was waiting for me and I went immediately on boat. I did change T part, exhaust hose, new impeller (as did't throw any water on exhaust), I changed the inlet pipes, new engine oil with oil filter and after all it runs great!!
I don't know why I can't post more than 3 photos in one post so I have to post three times :/
and the final product.. on last photo you can't realize much but the hose from Y part to T part is straight down, ofc Y part is maybe 20cm above the T part.. picture was taken from bottom..
in 10 days I am going to take the boat on a dry dock and apply new antifouling
I appreciate all your help guys! Wish I can treat you with some beers
Having thought about it further, I now think that my T piece was originally the same as yours, failed in the same way as yours, and that the nuts and fitting are a later bodge to repair it. Yours is the neater solution.
I have never found the broken piece so I don't know did I have nuts or not :/
as you can see, I put small clamp on for small hose and two big clamps for exhaust hose and after 1,5h running still everything dry.. I did my first DIY gasket for the inlet part that goes after impeller housing into the engine and so far still dry I have spare part so every year do change them and then at home clean the old one with acid..