What should I use to block off heater core hoses?

[mikeb23ft]

My core is blown and I'm going to block it off at the firewall. What should I use to do this? I don't think there's a specific product so I might have to make something up. Dose anyone know the inside diameter of the hoses I'm going to be blocking? Thanks.

[jlevie]

I don't know of any "off the shelf" solutions. On a race car I make up a plate for the outlet in the back of the head and turn an aluminum plug for the other hose. On a street car it would be easier to just replace the heater core,

[Joe G]

Le butt plug

[mikeb23ft]

Le butt plug

I thought about this, but I was thinking the heat of the coolant might melt the rubber.

[MR 325]

How about just a little piece of pipe and loop the hoses?

The real question though, why not fix it?

[5Toes]

Just take the lines going in tot he core near the firewall and buy a brass "hose splice" at Lowes for like $2. Few hose clamps and you are good to go

[jlevie]

How about just a little piece of pipe and loop the hoses?

That is a bad idea. The heater supply is from the back of the head and the return is to the inlet of water pump. If you loop the hoses the coolant flowing through the hoses will not go through the radiator and the engine may run hot. When the heater is in use the heater core becomes a mini radiator and when the heater isn't being used the valve blocks flow through that loop.

[mikeb23ft]

I used a Sharpie marker and a socket adapter. They don't leak but the car is still running hot. I'm thinking it's the thermostat?

[Joe G]

Could also have air in the system. Have you bled it?

[gr8skyr]

Wonder if you could find a bolt large enough to cram down each hose, with a tight fit then hose clamp them tight so they don't blow out?

Seems like I tried some sort of hack mechanic thing like that on my '75 subby 4x4. Owned 1980-2001.

Yes I'm the guy who once used a coat hanger to run his manual windshield wiper when wiper motor died, and used a 7-up 2 liter bottle for a coolant overflow tank, rigged a manual choke to my carb using the hood release spot. Second thought, maybe I shouldn't be offering mechanic'n tips.

[5Toes]

Im telling the hose splice will work fine



This is how I bypassed my throttlebody heater (mine actually had a leak)

[Joe G]

Im telling the hose splice will work fine



This is how I bypassed my throttlebody heater (mine actually had a leak)

I used a ball point pen housing and apoxy haha. My m20 days are behind me. Only ze best for my 24valves

[mikeb23ft]

I bled it. Still overheating. Thinking maybe thermostat, but it's obviously opening if there's coolant coming out when I bleed it. Maybe it's just not opening all the way or at the right temperature?

[jlevie]

Im telling the hose splice will work fine



This is how I bypassed my throttlebody heater (mine actually had a leak)

Looping the hoses for the throttle body is okay. The system was designed for there to be flow in those hoses all the time. The same is not true for the heater core.

[TobyB]

If your cooling system is stout, it'll work.

If it's marginal, it will hurt.

What it WILL do is let the back of the head bleed off any trapped air.
My version is to couple the 2 with a union with just a small hole in it.
Then it'll purge itself, but lots of hot water doesn't get to bypass the rad.

fwiw
t