Leaking Heater return pipe 🤬

Lowtechprime said:
O-ring, or a copper crush washer
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In this case - I would prefer a crush washer. Good solid surface to crush against. An O ring typically requires more precision and will definitly require replacement purely as rubber ages. I would use the straight fitting - aside from whatever routing you prefer, the straight can be tighened up fully without worrying where it is pointing as would be the case with an elbow.
 
Yeah, I'm using a straight fitting, if I used the 'elbow' I was gonna cut it off before the bend..
Straight threads, with a flat mating surface on the head.
 
Lowtechprime said:
Yeah, I'm using a straight fitting, if I used the 'elbow' I was gonna cut it off before the bend..
Straight threads, with a flat mating surface on the head.
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If both surfaces are flat (check/verify this) use an aluminum crush washer if possible, if not copper is less preferred due to galvanic scale differences. There are Steel washers with O-rings, these can work as another choice. Do know all O-rings degrade over time, temp cycles and all that.. Coolant is usually ok with most O-ring compounds.. but not all.. Typical O ring material choices for coolant would be EPDM or Viton with Nitrile (common) being less preferred.

Loctite (# 567) makes a good teflon joint paste specific for fluid joints that needs this.

LOCTITE® 567

LOCTITE 567 is an off-white, UL approved, low disassembly strength methacrylate thread sealant, ideal for sealing coarse threads
www.henkel-adhesives.com www.henkel-adhesives.com


Bernice
 
Hey All! I just realized I never posted my 'Fix' for this issue!😴 I ended up using a 16mm x 1.50 to AN -10 adapter with an aluminum crush washer and thread sealant, then a -10 AN soft 45° Hose barb fitting.. There was some debate over whether it was a Tapered or a straight thread port. After this install, it seemed to be Straight thread to me . At least in this head, maybe they vary by model/year? Who knows? No more leaking now, + easy disassembly!😃
IMG_20231028_173304466.jpg
 
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Lowtechprime said:
I ended up using a 16mm x 1.50 to AN -10 adapter with an aluminum crush washer and thread sealant, then a -10 AN soft 45° Hose barb fitting.. There was some debate over whether it was a Tapered or a straight thread port. After this install, it seemed to be Straight thread to me . At least in this head, maybe they vary by model/year?
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Internal threads will always be a straight thread... it's always the plug that screws into it will be a tapered thread.

Think about a regular sump plug... the hole in the sump is a straight thread, the plug is tapered... (just like all plumbing / pipe fittings) so there is no variation by year, it is as I said to begin with, from the factory the screw in fitting is a tapered thread, that is what locks it in and prevents it leaking.

The reason that an X19 DOES NOT use a taper thread sump plug is because it's screwing into relatively thin alloy, I've seen loads of X19 sumps that for whatever reason the owner/mechanic has swapped ina taper thread plug and cracked the sump around the plug as a result, far too common. Thats why there's a copper sealing washer on all Fiat / Alfas with alloy sumps which all use a straight thread plug.

There are straight threaded holes all over the engine that are filled with tapered threaded plugs, the water temp sender in the head... the alloy screw in plugs that block the casting risers in the cylinder head.

The alternative is something like an ORB (O ring boss) fitting, which uses a straight thread but with an O ring to seal...

SteveC
 
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I've used those before.. I used the crush washer this time because I didn't want to have some rubber seal that would eventually fail... The head had a nice flat surface for sealing against the washer... Fit and forget😁
 
fiatfactory said:
Internal threads will always be a straight thread... it's always the plug that screws into it will be a tapered thread.


SteveC
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That would be a no.

Industry standards for tapered threads state both internal and external threads are tapered and there are very specific tolerances involved. One of common tapered threads are National Pipe Thread or NPT.. which has a specified taper of .750" per 12" or 1° 47" 24"" (1.7899°) for both internal and external threads.
www.cjwinter.com

American Standard External Taper Pipe Threads

ANSI’s American National Standard Pipe Thread Standards regulate the formation and size of the screw threads on parts with straight or tapered threads.
www.cjwinter.com www.cjwinter.com

Illustration of how tapered threads fit and attempt to create a seal:
www.hoseassemblytips.com

What is NPT?

Learn about the characteristics, commonly used sizes, and leakage issues of NPT
www.hoseassemblytips.com www.hoseassemblytips.com

To make tapered threads properly for internal threads demands drilling the proper hole size for taper tap reamer:

Followed by a tapered pipe thread tap:

High Speed Steel-Taper Pipe-NPT

www.titancuttingtools.com www.titancuttingtools.com

And the threaded length must be correct within the specified length.

Notes on making internal tapered threads..

Inverse/opposite applied when making external NPT tapered threads..
Sure, one can apply straight threads on a tapered thread.. if kinda-sorta works until the joint is subjected to high operating pressures like steel cylinders (nee 3,000 psi) or hydro system where the pressures involved are in the thousands of psi/Kpa.. This is when the incorrect straight to tapered thread joint can fail resulting in high drama explosive failures.. Operating pressures table:
https://catalog.myssp.com/Asset/Working Pressure.html

Stuff machinist folks deal with often that non-machinist folks are often no aware of,
Bernice
 
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Rupunzell said:
That would be a no.

Bernice
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I know all this, I deal with things like this daily in my engineering role in the resources sector where I deal with very high pressure water / hydraulics and steam fittings on machinery / fixed plant

I guess I should have qualified my statement to be more specific...

The internal threads on a Fiat where a tapered thread plug / fitting / screw in sender of any sort is used will be straight internal threads, not tapered internal threads... . you won't find a tapered internal thread anywhere on a Fiat X19/128/850 or 124... but you definitely will find a tapered plug/ fitting etc used on even simple items like the temp sender on the cylinder head, the heater offtake fitting in the head, sump / differential drain plugs

SteveC
 
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