Thread Sealer and Locker?

[ChasingSand]

Cant seem to find what I am looking for and hoping someone has experience with this. I had to drill out the freeze plugs that are in my cylinder head and replace them with pipe plugs. Problem is the hole does not have a bottom so the plug can just keep going. These plugs separate the coolant from the oil. I was thinking of using red loctite as they will never need to be removed but not sure of its sealing capabilities? I found some Permatex "Blue" sealer and locker but I am not sure the blue is strong enough. Anyone have a chemical back ground or experience with this?

 

[megadesertdiesel]

they all have different max temperature ratings and fluid sealing recommendations. Pick for your operating temp and fluid it will be sealing against. Lots of choices.

 

[Grease Monkey]

Pipe threads are tapered. If you tapped the threads too deep, the taper may be too big and the plugs will not fit the taper and continue thru the hole. The plug threads are designed to bind up and tighten up on the threads. If this is the case and the plugs are to be fixed permanently, I might consider using an epoxy on the threads. JB weld for example. This may need something to take up the missing space in the threads and seal completely. Without thread and taper bind, pipe thread wont hold or seal.

 

[ChasingSand]

Pipe threads are tapered. If you tapped the threads too deep, the taper may be too big and the plugs will not fit the taper and continue thru the hole. The plug threads are designed to bind up and tighten up on the threads. If this is the case and the plugs are to be fixed permanently, I might consider using an epoxy on the threads. JB weld for example. This may need something to take up the missing space in the threads and seal completely. Without thread and taper bind, pipe thread wont hold or seal.

So they are not NPT threads actually. I tapped the aluminum head to 22MM and the plug is a 22X1.5 stainless plug. I didnt think to use JB weld. I need to read on the spec sheets but it should work as long as the temp is rating is high enough.

 

[Grease Monkey]

So they are not NPT threads actually. I tapped the aluminum head to 22MM and the plug is a 22X1.5 stainless plug. I didnt think to use JB weld. I need to read on the spec sheets but it should work as long as the temp is rating is high enough.

If its a straight thread, the plug should be shouldered to use a crush washer on the head surface. The crush washer usually soft aluminum or copper will be the seal in this application. Use of some thread sealant can be used if need be for insurance.

 

[ChasingSand]

If its a straight thread, the plug should be shouldered to use a crush washer on the head surface. The crush washer usually soft aluminum or copper will be the seal in this application. Use of some thread sealant can be used if need be for insurance.View attachment 137354

I tried to use one of those, the low profile one as well and the cam unfortunately hits it. There is almost no clearance between the two so I have to use a plug.

 

[Grease Monkey]

Can this be drilled and tapped to the next pipe thread size???? Then using a true pipe plug could solve this for ya.

 

[ChasingSand]

Can this be drilled and tapped to the next pipe thread size???? Then using a true pipe plug could solve this for ya.

Unfortunately I don't think so. My worry is that when the threads start to deform it will not go in all the way and it will not go deep enough to clear the cam. there is only about 1/8 of clearance between where the plug will be and the bottom of the cam. Do you think JB weld will hold for this?

 

[Rockwood]

Sounds like JB Weld is your only choice.

With the pipe thread, you can always guess and check with the tap depth or the plug depth (grinding the plug's length outside of the hole to fit), whichever is easier.

 

[Rorschach]

Depending on the location and structure of the head a tapered plug may cause unwanted stress applying outward pressure 360° at the location that could result in a crack in the aluminum. Have you considered welding the holes.

 

[Rorschach]

As far as JB Weld goes, I've seen that stuff do some amazing things. I fixed a silver dollar sized hole in a cast iron Volvo head on a loader 4 or 5 years ago. The follower for the retarder came apart and rolled under the cam on a shallow part of the head casting that faced down. The cam lobe pushed it through the casting to the outside of the engine. Fortunately this was an overhang area where there was nothing underneath. Think I might have just put some gorilla tape on the underside to support the JBW until it set up. After the first set up I did one or two more layers. I was trying to raise the area higher bcuz this was an area where the oil would pool but not alot of room directly below the cam lobe either. It did seep a little bit but was still better than replacing the entire head.
I knew an old mechanic growing up that JB Welded a broken camshaft back together on a Mazda B2000. He said his dad drove that truck for several years after the repair untill he passed.

 

[rivermobster]

Unfortunately I don't think so. My worry is that when the threads start to deform it will not go in all the way and it will not go deep enough to clear the cam. there is only about 1/8 of clearance between where the plug will be and the bottom of the cam. Do you think JB weld will hold for this?

Then just tap it a tiny bit deep, till you get the fit you want.

The dissimilar metals would be my biggest concern...

 

[Rorschach]

So they are not NPT threads actually. I tapped the aluminum head to 22MM and the plug is a 22X1.5 stainless plug. I didnt think to use JB weld. I need to read on the spec sheets but it should work as long as the temp is rating is high enough.

Another problem is the risk of galling between the stainless and aluminum. Stainless tends to gall in aluminum very easily. If you don't get the fit you want on the first try and attempt to remove the stainless plug for a re-fit you run the risk of galling the threads. Especially in a hand cut thread made without a lot of precision.

 

[wesinls]

Maybe one of the Gasoila products...they sell the soft set at tractor supply (the blue one)

 

[ChasingSand]

I ended up using JB weld on them. I am going to let it cure for 36 hours then pressure test the cooling system to make sure there are no leaks.