By-Pass Hose Fitting Issue (Leaking)
08-30-2015, 05:54 PM
#1
Instructor
Thread Starter
By-Pass Hose Fitting Issue (Leaking)
I have installed a 326 water pump onto my L-79 (recently rebuilt by Bill Mock) and I have a question regarding the by-pass fitting on top of the pump.
I have installed this fitting (a couple of times now) but I still continue to have a small leak around the threads. I have tighten the fitting down as far as I can muscle it while using the Type 3 Aviation sealant on the threads (the brown stuff). This last time I got it tightened down 5 full revolutions before I got it pointing in the right direction. Actually, I went too far and had to back it off because it would not rotate another full revolution. I let the sealant cure for three full days before finishing it up by putting the by-pass hose on and getting water back into the system. Started the engine (radiator cap off) and I had no visible leaks. Once the car warmed up, I topped off the water and put the radiator cap on. Once I got pressure in the system, it began to seep out at the threads, again.
Question(s): How far should I be tightening that fitting? Is five revolutions too much (it was getting hard to turn it by that time)?
Since this is a tapered thread, did I mess up the threads on the fitting by going too far and then backing it off? Will I need a new one?
I know that I will need to remove it again and clean the old sealant off with alcohol but this little leak has pestered me for the last week or so and I am seeking your collective advice on the proper installation of this fitting so I can stop the leak and get back on the road for the fall car show season.
Thanks for your advice!
John
I have installed this fitting (a couple of times now) but I still continue to have a small leak around the threads. I have tighten the fitting down as far as I can muscle it while using the Type 3 Aviation sealant on the threads (the brown stuff). This last time I got it tightened down 5 full revolutions before I got it pointing in the right direction. Actually, I went too far and had to back it off because it would not rotate another full revolution. I let the sealant cure for three full days before finishing it up by putting the by-pass hose on and getting water back into the system. Started the engine (radiator cap off) and I had no visible leaks. Once the car warmed up, I topped off the water and put the radiator cap on. Once I got pressure in the system, it began to seep out at the threads, again.
Question(s): How far should I be tightening that fitting? Is five revolutions too much (it was getting hard to turn it by that time)?
Since this is a tapered thread, did I mess up the threads on the fitting by going too far and then backing it off? Will I need a new one?
I know that I will need to remove it again and clean the old sealant off with alcohol but this little leak has pestered me for the last week or so and I am seeking your collective advice on the proper installation of this fitting so I can stop the leak and get back on the road for the fall car show season.
Thanks for your advice!
John
08-30-2015, 06:37 PM
#2
Hi John,
Is it possible that your pump has the thread insert installed? Those pumps came with either a 1/2 inch or 3/4 inch thread in the bypass hole. If your pump originally had a 3/4 inch thread and an insert was installed it may be leaking around the outside of the insert and not around the threads of the fitting. From your description of how you installed the fitting I don't see why it should leak. Take a closer look at the bypass hole, you might see signs of this insert.
Dan
Is it possible that your pump has the thread insert installed? Those pumps came with either a 1/2 inch or 3/4 inch thread in the bypass hole. If your pump originally had a 3/4 inch thread and an insert was installed it may be leaking around the outside of the insert and not around the threads of the fitting. From your description of how you installed the fitting I don't see why it should leak. Take a closer look at the bypass hole, you might see signs of this insert.
Dan
08-30-2015, 07:27 PM
#3
Race Director
Hi John,
Is it possible that your pump has the thread insert installed? Those pumps came with either a 1/2 inch or 3/4 inch thread in the bypass hole. If your pump originally had a 3/4 inch thread and an insert was installed it may be leaking around the outside of the insert and not around the threads of the fitting. From your description of how you installed the fitting I don't see why it should leak. Take a closer look at the bypass hole, you might see signs of this insert.
Dan
Is it possible that your pump has the thread insert installed? Those pumps came with either a 1/2 inch or 3/4 inch thread in the bypass hole. If your pump originally had a 3/4 inch thread and an insert was installed it may be leaking around the outside of the insert and not around the threads of the fitting. From your description of how you installed the fitting I don't see why it should leak. Take a closer look at the bypass hole, you might see signs of this insert.
Dan
An excellent thread sealant is Loctite 565 with TFE. Put it on and thread in the fitting. Wait 24 hrs.
Teflon tape is the best, but a lot of guys (self included) don't use it because of originality. But if that is not a concern, use 5 wraps and be done.
Another fitting may also be a fix.
If all else fails, clean the parts and assemble with regular JB Weld. Let sit overnight. Leak is gone.
Larry
Last edited by Powershift; 08-30-2015 at 07:34 PM.
08-30-2015, 10:06 PM
#4
Instructor
Thread Starter
Thanks guys. No, there is no insert, this 326 is the real McCoy. Based on previous threads, this afternoon I ordered a small tube of Locktite 565 and a new fitting just to be on the safe side. Should have those by the end of the week or early next week depending on when UPS shows up.
I had read of folks using Teflon tape but I didn't get a feel of whether that was the right approach or not. I was also concerned whether I was tightening the fitting too much but apparently I was okay at five full turns?
When I get the new parts, I'll update. In the meantime, I'll have plenty of time to take the old fitting off and clean off all of the old brown goop on the top of the pump.
I had read of folks using Teflon tape but I didn't get a feel of whether that was the right approach or not. I was also concerned whether I was tightening the fitting too much but apparently I was okay at five full turns?
When I get the new parts, I'll update. In the meantime, I'll have plenty of time to take the old fitting off and clean off all of the old brown goop on the top of the pump.