Bypass hose nipple removal from aluminum intake manifold

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Mike69cuda

Mike69cuda

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I am swapping my water pump from a 69 cast to a 71 aluminum pump. I need to remove the steel adapter from the intake. The 69 uses a 3/4 nipple and the 70 up uses a 1 inch.

I am worried about the aluminum LD340 manifold stripping out. Mine actually has a 3/4 to 1/2 reducer and a 1/2 pipe nipple (3/4 external diameter) to fit the 3/4 in 69 hose. The steel to aluminum interface may be corroded some.

Do I need to be worried about it stripping? Anyone got any magic techniques? Thanks, Mike
 
If you have a torch, I heat the nipple until it’s cherry red and keep it there for about 30 seconds. Turn off the torch and spray the nipple with WD-40 or similar. Give it a good shot of it, and if you are of the type that likes it, you may get a contact high off the smoke (that’s a joke for all you prude types...don’t breath the smoker off that crap).

The rapid cooling of the nipple will shrink it enough to get it out, usually fairly easily.

You can also use paraffin. I know some guys use candles and stuff the candle up against the nipple and manifold where the two come together.

What ever you use, it should make the nipple come out easy and without damaging anything.
 
Mike69cuda said:
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I am swapping my water pump from a 69 cast to a 71 aluminum pump. I need to remove the steel adapter from the intake. The 69 uses a 3/4 nipple and the 70 up uses a 1 inch.

I am worried about the aluminum LD340 manifold stripping out. Mine actually has a 3/4 to 1/2 reducer and a 1/2 pipe nipple (3/4 external diameter) to fit the 3/4 in 69 hose. The steel to aluminum interface may be corroded some.

Do I need to be worried about it stripping? Anyone got any magic techniques? Thanks, Mike
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Have you already started disassembly and drained coolant?
 
Yep, coolant out. Was planning on heating it. Didn’t know about the WD-40 trick.
 
I had too do this not long ago on a ld340, i tried the heat and srink method also but only had a propane torch and i think it didn't get hot enough, anyway when i try turning it out it began to crush, i was shitting myself at that point that i may destroy an otherwise good manifold, i then used a air hack saw and made a few cuts parallel with the nipple being careful not to go to deep and hit aluminium, then i was able to crush thhe nipple in on itself and turned it out.

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20200419_235302.jpg
 
dodgy said:
I had too do this not long ago on a ld340, i tried the heat and srink method also but only had a propane torch and i think it didn't get hot enough, anyway when i try turning it out it began to crush, i was shitting myself at that point that i may destroy an otherwise good manifold, i then used a air hack saw and made a few cuts parallel with the nipple being careful not to go to deep and hit aluminium, then i was able to crush thhe nipple in on itself and turned it out.

View attachment 1715511559

View attachment 1715511562
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Mine actually has a pipe thread reducer with a hex flange, so I don’t think mine will crush. I have a torch so I think I can get it hot enough. I have minimal experience with aluminum, mostly bad.

just noticed your bypass hose removed. Any issues doing that?
 
Mike69cuda said:
Yep, coolant out. Was planning on heating it. Didn’t know about the WD-40 trick.
Click to expand...
That's how I've done it and then soaked the crap out of it. There are some really good penetrants other than wd4o, but once you start removing the nipple "just go easy" and back and forth to allow the penetrant to get down in there, if you're not using the torch treatment. Every situation is different.
 
Mine has a ton of paint on it, so I will probably need to torch it first anyway, just to get the paint out of the way for penetrant.
 
Mike69cuda said:
Mine actually has a pipe thread reducer with a hex flange, so I don’t think mine will crush. I have a torch so I think I can get it hot enough. I have minimal experience with aluminum, mostly bad.

just noticed your bypass hose removed. Any issues doing that?
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Can't say yet as it's not in the car yet, i plan to run a 10an hose from the manifold (not the one pictured) to radiator so i can run a thermostat and still bypass through the radiator, let you know how it go's.
 
dodgy said:
I had too do this not long ago on a ld340, i tried the heat and srink method also but only had a propane torch and i think it didn't get hot enough, anyway when i try turning it out it began to crush, i was shitting myself at that point that i may destroy an otherwise good manifold, i then used a air hack saw and made a few cuts parallel with the nipple being careful not to go to deep and hit aluminium, then i was able to crush thhe nipple in on itself and turned it out.

View attachment 1715511559

View attachment 1715511562
Click to expand...


Yep...propane won’t do it. You need to get it cherry red and hold it there for a bit, then quench it with something.
 
Depending on condition, find a bolt or if you have a lathe, rough turn an arbor to fit inside the pipe, that way you can put pipe wrench/ vise grips on and not worry about crush
 
It’s a pipe fitting, so I can get a good grip on it, just worried about stripping.

281A4FAE-4886-4755-81C9-1B049E8FC3F7.jpeg
 
I use a acetylene torch and heat the fitting cherry red. Let it cool some then spray penetrating fluid around the threads. You want to do this while its hot but not so hot it burns the fluid as your spraying it on. Its going to smoke so open the doors. After you spray it immediately put a pipe wrench on it.
If its really thin you can heat it cherry red then take a punch and collapse the fitting away from the threads. These methods work 99.9 % of the time on the worst fittings.
If you try turning without heat you risk galling the aluminum threads. At that point you would be stuck using a heli-coil or going with a reducer bushing. Both not great options in this application.
 
Heated it up good with a torch, let it cool a little bit then sprayed it with liquid wrench. Came right out.

I would have thought there would have been a more substantial boss for this, but there wasn’t. It might have had about 3/16 to 1/4. Pretty thin, but the threads were good enough to tighten back up.

Thanks for all the help!
 
By my understanding - Yes there is a problem with doing away with the bypass hose unless you have no thermostat. When the thermostat is closed the bypass is all the water circulating in the block, but that water bypasses the radiator, letting the engine warm evenly. Without any water circulating the block can develop hot spots and expand differentially in a way that might ruin the block.
 

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