Blew rear freeze plug on 408

[mbaird]

I took my Swinger for a quick drive yesterday and got on it for the first time since building the car .
It hit 7k pretty quick then I could smell coolant . Luckily I was 1/4 mile from home . I popped a heater hose off on an earlier test drive but attributed that to the idiot that assembled the car not tightening the hose clamp ... LOL
Either the freeze plug wasnt seated tightly or I have a head gasket problem .

 

[Treblig]

If the block was low on water maybe the air in the block expanded with heat creating enough pressure to blow out the plug???

 

[mbaird]

Possible .... I will pull the engine and go thru it again just to be safe .

 

[jos51700]

Pulling the engine is extreme, the air expansion theory is less than plausible.

#1 where did you get your freeze plugs? Chinese crap is known to be sized wrong.

#2 what's your cooking system pressure?

#3 have you installed your new radiator cap?

#4 were there any signs of overheating?

 

[toolmanmike]

Possible .... I will pull the engine and go thru it again just to be safe .

Blew a side plug out of my 383 in my Super Bee years ago. I drove a mile to the shop. It was hot. I put a rubber expandible in and filled it up. As far as I know it still has it in and the engine is still running without a overhaul. Those Mopars are tough.

 

[TT5.9mag]

Yea going through the engine at this point is a very large step that is possibly unnecessary. There are a lot of diagnostic “things” you can do to determine if you have a bad head gasket.

 

[mbaird]

Pulling the engine is extreme, the air expansion theory is less than plausible.

#1 where did you get your freeze plugs? Chinese crap is known to be sized wrong.

#2 what's your cooking system pressure?

#3 have you installed your new radiator cap?

#4 were there any signs of overheating?

Its the plug under the bell housing so I dont have much choice than to pull engine.

I used brass freeze plugs . Not sure of country of origin .

Havent had any cooling issues . But everthing is new and I havent had it very far from home .

It does have a new cap ... but???

No idea of pressure but the cap is 16lbs
2 rows @ 1" aluminum radiator.

 

[TT5.9mag]

Well that makes sense why you decided to pull it so quickly. Personally I’d pull the trans.

 

[mbaird]

4 speed car so its just as easy to pull the entire enchalada. And if it is a head gasket I will need to pull it because of the headers and studs.

 

[brian6pac]

What did you put on the freeze plugs when you installed them ?

 

[TT5.9mag]

View attachment 1715755369

4 speed car so its just as easy to pull the entire enchalada. And if it is a head gasket I will need to pull it because of the headers and studs.

Stop making such good points.

 

[mbaird]

What did you put on the freeze plugs when you installed them ?

Black RTV

 

[yellow rose]

Black RTV

Yeah, silicon is pretty slick to be used on core plugs. I’d knock them all out, clean the bores and put them back in with weather strip adhesive or something similar.

 

[mbaird]

Never thought about using adhesive . Good tip .

 

[rustycowll69]

Yeah, silicon is pretty slick to be used on core plugs. I’d knock them all out, clean the bores and put them back in with weather strip adhesive or something similar.

I always used that tarry-looking dark brown permatex form a gasket(#2 (?)) in the short, white bottle with the brush built into the cap. It is excellent for water pump bolts and other bolts that thread into water jackets. When you loosen them to adjust a belt or something, you can tighten them right back up with no leaks.

 

[fishmens67]

Indian head

 

[Ricks70Duster340]

Indian head

Yeah, that stuff is really sticky too. Fun trying to get it off of your hands.

 

[mbaird]

Now I know ....

 

[yellow rose]

Pematex #2 and Indian Head are good too. I always forget about those.

 

[rustycowll69]

Pematex #2 and Indian Head are good too. I always forget about those.

if I remember correctly you use rubbing alcohol to clean up #2, don't know about indianhead.

 

[Treblig]

if I remember correctly you use rubbing alcohol to clean up #2, don't know about indianhead.

I use toilet paper to clean up #2????
Alcohol would really sting!!!

 

[brian6pac]

Yep, I use spray hightack, seems to work good. I take a piece of cardboard cut a hole the size of the plug to cover the block and spray the hole and the plug and pound it in.
I have never had one pop out using it. I blew one out on a 383 in the back of the head on the right bank at about 7500RPM. Had to pull the head to put it in, the gasket looked good so I pulled the left side and that gasket looked good also. Been using hightack ever sense.

 

[67autocross]

In Canada we would just grab a block heater out of the tool box and install it…

 

[missing linc]

I never use any sealer, just knock them in dry.

 

[Max1196]