Leaking Heater return pipe šŸ¤¬

Lowtechprime

Lowtechprime

Retro Grouch
The return pipe (or Outlet) from/to the heater is leaking at the threads. My original was rusted out, so I made a Stainless Steel one. It has a metric pipe thread on it. I initially installed it with pipe sealant about 2 years ago, after awhile it started weeping a little and I JB Welded the area which was fine until now. I removed the JB Weld and found the threaded in pipe felt a little loose, which is weird because it can't rotate with the hose on it. I removed it, cleaned all the threads, and applied a higher temp JB Weld to the threads and threaded it back in tight. Then JB Welded the seam/transition again, and finished with a silicone self fusing tape over that. I refilled the coolant and brought it up to temp, but it's still weeping. My latest idea was to get a 16mm aluminum tube and TIG weld it on instead of the threaded tube as there's no reason it needs to be removeable, but I want to do it in place since I recently had the head off and paid someone else to do it I'd rather try and fix this still in the car... Thoughts anyone?
128_HeaterPipe1.jpg

128_HeaterPipe2.jpg
 
The fitting is supposed to have a tapered thread, not a straight thread....

easiest fix would be to use the brass elbow fitting from a 1300 X19, and change your heater hose to one with a 90 bend on the end....

SteveC
 
Thanks! I thought I had the right threads on it but will give that fitting a try... It would be bad for an elbow to be there, but it seems long enough that I could cut the elbow off and still get a hose on it...
 
Lowtechprime said:
The return pipe (or Outlet) from/to the heater is leaking at the threads. My original was rusted out, so I made a Stainless Steel one. It has a metric pipe thread on it. I initially installed it with pipe sealant about 2 years ago, after awhile it started weeping a little and I JB Welded the area which was fine until now. I removed the JB Weld and found the threaded in pipe felt a little loose, which is weird because it can't rotate with the hose on it. I removed it, cleaned all the threads, and applied a higher temp JB Weld to the threads and threaded it back in tight. Then JB Welded the seam/transition again, and finished with a silicone self fusing tape over that. I refilled the coolant and brought it up to temp, but it's still weeping. My latest idea was to get a 16mm aluminum tube and TIG weld it on instead of the threaded tube as there's no reason it needs to be removeable, but I want to do it in place since I recently had the head off and paid someone else to do it I'd rather try and fix this still in the car... Thoughts anyone?View attachment 78287
View attachment 78288
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My goodness, you run a clean machine ;)
 
I don't know to much, but from what I understand welding cast aluminum is very tricky. If the weld were to fail you risk a very fast destruction of the engine. If a cut off brass elbow is too short you can always solder on a brass extension which should be safe.
 
JB Weld is a poor material to use for something like this where you have two different coefficients of expansion. Once hardened it is yet another rigid material with a different coefficient of expansion. It seems to be a go to for many but is really ill suited for many of the uses I see it applied to.

Impressive you got your old one out, many have had a heck of a time. Carl had to send his head out to have it milled out.
 
Lowtechprime said:
The return pipe (or Outlet) from/to the heater is leaking at the threads. My original was rusted out, so I made a Stainless Steel one. It has a metric pipe thread on it. I initially installed it with pipe sealant about 2 years ago, after awhile it started weeping a little.
Click to expand...
Problem leak is likely caused by Galvanic corrosion. Aluminum -vs- stainless steel being on the wrong ends of the galvanic scale will cause the SST to slowly dissolve the aluminum where it comes in contact with Aluminum. Corrosion inhibitors in coolant might reduce this, yet the root problem is dissimilar metals. Brass is not a better solution as brass is also galvanic in contact with aluminum. Most common example of this galvanic corrosion problem would be brass garden hose fittings in contact with aluminum garden hose fittings.. and the better hardware/home stores will note not to do this..
www.corrosionpedia.com

An Introduction to the Galvanic Series: Galvanic Compatibility and Corrosion

When metals are incorrectly combined and exposed to water and other types of electrolytes, the effects can be very harmful. Find out more about the galvanic se
www.corrosionpedia.com www.corrosionpedia.com

galvanic series_J.jpg


Note on this chart steel's galvanic relationship is closer aluminum or possible why Fiat discontinued the brass heater outlet then went to steel with an adjuster nut in later versions of the Lampredi SOHC.

The ideal solution to this problem would be to convert the internal threads on the heater outlet to straight treads instead of tapered pipe threads (which SUCK in too many ways, but a necessary evil in some cases), make an aluminum fitting with a Viton O-ring seal to the flat surface on that area of the cylinder head. Anti-seize at this joint would be wise as aluminum threads specially cut threads tend to gall.. badly..

JB "weld" is epoxy, not a band-aid or viable solution to this problem in any way.


Bernice
 
I had wanted to weld on an aluminum tube extension and delete the threads entirely, but I don't want to remove the head.. Most won't remember, but this is a 'test' motor. It's a temporary build to drive around until I build my 1.9 motor, so welding an extension on a 1300 US head doesn't bother me because I wouldn't be using it for anything else... It only needs to work for another year or so, so the galvanic effect probably won't hurt me much in that time but it's excellent info for the final build!
 
Dr.Jeff said:
You can also retap the threads in the head to use a different thread pattern if you wanted to install some other type of fitting.
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Not so simple to alter threads.

Not too bad if going from a tapered thread to straight thread of identical pitch. Apply the proper tap, cutting fluid (WD-40 works good for aluminum) thread away the tapered section.

Going to a different thread pitch is a completely different challenge. This demands drilling out the existing threads, then re-tap. Sounds easy, except this is very difficult to not possible without setting up the part in a machine tool. Yes, sure plenty have hand drilled then hand tapped.. except the hole and threads are not going to be parallel to the surface and there is a significant risk of tap breakage due to misalignment.

Bernice
 
Lowtechprime said:
I had wanted to weld on an aluminum tube extension and delete the threads entirely, but I don't want to remove the head.. Most won't remember, but this is a 'test' motor. It's a temporary build to drive around until I build my 1.9 motor, so welding an extension on a 1300 US head doesn't bother me because I wouldn't be using it for anything else... It only needs to work for another year or so, so the galvanic effect probably won't hurt me much in that time but it's excellent info for the final build!
Click to expand...
Temptation to weld is great.. Kinda like "glue it on" quick & easy... Except there are significant negatives to welding on the hose fitting. If the fitting becomes damaged or a different plumbing configuration is needed, then that welded on fitting become a messy affair.

Believe it or not, the easiest fix is to get a new plated FIAT oem steel fitting, then install it with teflon sealant paste (Loctite makes a good one) and keep coolant fresh and not corrosion inhibitor exhausted. Doing this will easily extend the life of all steel components in the cooling system including those coolant pipes and more.. The alternative is messy and involved if done properly with consideration to galvanic corrosion, future adaptability, serviceability and all that.. which is FAR more involved than most would wanna get involved with.



Bernice
 
I can't even find an online pic of that fitting, let alone find one to purchase... :confused: It's just a straight pipe with threads on one end, just couldn't find the exact specs for the thread...
 
Lowtechprime said:
just couldn't find the exact specs for the thread...
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It's 16 x 1.5. I have used a straight thread plug with a crush washer to bypass a heater many times. Here is a pic of the typical elbow. If it has any taper at all it is on the elbow only and almost imperceptible. The heater tube Steve posted above is a straight thread too. Tapered threads don't employ crush washers.

IMG_5608.jpg
 
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