Bypassing the heater core?

[willem445]

Hi guys,

At some point in time either my dad or grandpa decided to bypass the heater core. Im sure the heater core leaked or didnt work or something like that. I just want to bypass it for now until I get time to fix the heater core (not in any rush at all). The current bypass job is pathetic and leaks. I tried taking a small piece of hose and directly connecting the inlet and outlet but its a very awkward angle and the hose kinks slightly. Any idea what the best way to do this would be?

I attached some pictures to give a decent idea of what im talking about.



Also what are the sizes of the two different hoses so I can get replacement hose?

[rich weyand]

5/8" and 3/4" heater hose. Those are inside diameter numbers (ID).

You will also need a 3/4" Barb x 5/8" Barb Reducing Coupling (on this page, for example: https://www.plumbingsupply.com/barb.html) and some band clamps.

[willem445]

Originally Posted by rich weyand

5/8" and 3/4" heater hose. Those are inside diameter numbers (ID).

You will also need a 3/4" Barb x 5/8" Barb Reducing Coupling (on this page, for example: https://www.plumbingsupply.com/barb.html) and some band clamps.

Thanks for reply.

Are the threads on the barbs also 3/4" and 5/8"? Thinking about getting some angled ones to make the angle easier to deal with.

[rich weyand]

There are no threads on a reducing hose adapter. It is one hose size on one end, the other hose size on the other.

[willem445]

Originally Posted by rich weyand

There are no threads on a reducing hose adapter. It is one hose size on one end, the other hose size on the other.

Im talking about replacing the actual inlet and outlet barbs on the block to a 45degree so I can just use a short piece of hose that doesnt kink. Im not sure what size the threads are that actually screw into the block. I will pick up one of the reducing couplers to avoid leaks.

[mrolds88]

If you are going to replace the end fittings for a temporary thing, why not put in plugs and not worry about the hose?

[nonstop]

Plugs sound like the cleanest and best bet!

[tucsonjwt]

x 2 on plugs. I got 2 brass plugs in the PEX aisle at Home Depot when I bypassed a heater core. You can leave the heater core nipples open or cover them with some aluminized tape or any kind of tape. Or, you can use a hose designed for bypass with two nipples or lengths of tubing.

Amazon.com: Gates 18701 Molded Heater Hose:...

[LuckyLightning]

Funny, we were just talking about this in another thread. The PEX valve works great, no leaks. About $10 from Home Depot. Buy two hose clamps too. I like this better because you can turn it on or off when you want, but if you never really want to run the heater core then the bypass hose is great because then you're still getting fluid circulated to your intake (although it does not seem to damage anything when using the valve to shut off the fluid altogether).

[willem445]

Originally Posted by mrolds88

If you are going to replace the end fittings for a temporary thing, why not put in plugs and not worry about the hose?

I was actually curious about this. You can simply just plug the holes and the coolant will still flow properly? Still raises the question of what size the holes are to by the correct fitting threads for plugs. Thanks.

[willem445]

Originally Posted by tucsonjwt

x 2 on plugs. I got 2 brass plugs in the PEX aisle at Home Depot when I bypassed a heater core. You can leave the heater core nipples open or cover them with some aluminized tape or any kind of tape. Or, you can use a hose designed for bypass with two nipples or lengths of tubing.

Amazon.com: Gates 18701 Molded Heater Hose: Automotive

http://www.homedepot.com/b/Plumbing-...s/N-5yc1vZbuvt

Something like this i would assume? What size did you buy?

[tucsonjwt]

I used PEX shark bite brass test plugs when I bypassed the heater core on my CAV. I see 1/2" and 3/4", so I would try 3/4" on both the 5/8" and 3/4" line. I would bring calipers with me to HD and measure the OD on the plugs to be sure. I think the 5/8" line will stretch enough to accommodate a 3/4" plug, but check first to be sure.

http://www.homedepot.com/p/SharkBite...8LFA/202270641

[willem445]

Originally Posted by tucsonjwt

I used PEX shark bite brass test plugs when I bypassed the heater core on my CAV. I see 1/2" and 3/4", so I would try 3/4" on both the 5/8" and 3/4" line. I would bring calipers with me to HD and measure the OD on the plugs to be sure. I think the 5/8" line will stretch enough to accommodate a 3/4" plug, but check first to be sure.

http://www.homedepot.com/p/SharkBite...8LFA/202270641

Oh you just pluged the hose, not the actual block? This still seems like a good solution. Ill be stopping at Home Depot tonight to find some plugs.

[tucsonjwt]

Actually, I used the plugs on two short hoses coming from the heater core on the Caviler. Those short hoses connected to metal connections on top of the engine, so I installed the bypass hose on the metal connections. The plugs are not necessary if you are totally disconnecting the heater core. If you are just going to unhook the two heater hoses at the heater core and plug them at that point you can use two plugs, but I would use a bypass hose and loop the two hoses together with two nipples.

You would tape off or cap the heater core nipples if you did not want insects or other critters to get inside your heater core.

As a practical matter, if your heater core is bad you should just install an new heater core - maybe $25 at a parts store -preferably copper/brass. Installation requires removing the dash pad and box + cables and hoses under the dash but probably doable in 2-3 hours even without experience.

[willem445]

Originally Posted by tucsonjwt

Actually, I used the plugs on two short hoses coming from the heater core on the Caviler. Those short hoses connected to metal connections on top of the engine, so I installed the bypass hose on the metal connections. The plugs are not necessary if you are totally disconnecting the heater core. If you are just going to unhook the two heater hoses at the heater core and plug them at that point you can use two plugs, but I would use a bypass hose and loop the two hoses together with two nipples.

You would tape off or cap the heater core nipples if you did not want insects or other critters to get inside your heater core.

As a practical matter, if your heater core is bad you should just install an new heater core - maybe $25 at a parts store -preferably copper/brass. Installation requires removing the dash pad and box + cables and hoses under the dash but probably doable in 2-3 hours even without experience.

Yeah that makes sense. The heater core has been completely disconnected for about 10 years now but the connections to the heater core were duct taped off thankfully. Eventually I will get around to replacing the heater core but right now it is not a priority, I just want to get it street legal for the time being. Just looking for a cheap solution now that doesn't look horrible. Ive gotten pretty good at tearing apart my truck so replacing the core shouldnt be all that hard.

Thanks for the help guys! Ill try and post some pics of my solution when I get time to go home and work on the truck.