Bypass Heating Core - potential issues?! -

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post #1 of 8 Old 04-21-2010, 12:46 AM Thread Starter
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Bypass Heating Core - potential issues?!

Hi guys,

Been doing a little research on the procedure and effects of bypassing the heating core in my 1978 CJ7.

I live in a warm climate, and do not tend to use the doors or roof in my CJ, and as such have no need for the heater - I would like to remove the whole heating unit as it has little effect and would free up a bit more space under the dash.

From what I have found, this can be done by disconnecting the 2 heater coolant pipes from the back of the heater core, and connecting them together to allow for continued circulation of the coolant around the engine - this seems pretty straightforward and easy enough.

What I cannot find however, is what effects (if any) this will have in the general cooling of the engine (aside from not being able to turn the heater on if my engine started to overheat!).

Can anyone help and let me know any potential disadvantages from bypassing the heater core and whether this is going to cause any issues I haven't thought of (such as circulation problems / pressure, overheating etc.)?

Cheers in advance!

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post #2 of 8 Old 04-21-2010, 12:56 AM
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this is done in race cars all the time. couple things. your heater core does act like a mini radiator. you may see an averge temp increase of 2-5*. if you are going to bypass the heater core it is best to just cap the ports at the water pump. race guys with more years than me say do this as it eliminates the potential for a pressure loop which would affect the cooling as well. we went back on all of our race cars in the group and tossed the loops and put on caps with clamps.

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post #3 of 8 Old 04-21-2010, 05:59 AM
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I would just hook the hose at the back of the intake to the water pump on the V-8 motor

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post #4 of 8 Old 04-21-2010, 05:15 PM Thread Starter
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Cheers guys - am a little confused though, as there seem to be a lot of conflicting reports out there...

Most things I've read indicate that you should not just cap the ports, as need to keep circulation running around the engine - any thoughts?!

(Further details - i've got the 258 (v6) engine...)

Most people who bypass their heating cores seem to do so on a temporary basis, and not seen anyone who's made it a permanent feature - hence my queries on what knock on effects it might have to the rest of the engine...
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post #5 of 8 Old 04-22-2010, 08:18 AM
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Why would it have any effect other than what you mentioned, turning on the heater if the engine is in an overheating situation?

Create a loop without the heater core in it and call it good. No need to overthink a simple situation.
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post #6 of 8 Old 04-23-2010, 12:09 AM
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Originally Posted by SydneyBeast View Post

(Further details - i've got the 258 (v6) engine...)

79 CJ5
88 Grand Wagoneer
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post #7 of 8 Old 04-23-2010, 12:18 AM Thread Starter
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Originally Posted by SparkyB View Post
Apologies... my mistake (and clear lack of knowledge) showing clearly!

Am still learning and trying to teach myself as I go... just very slowly...
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post #8 of 8 Old 04-23-2010, 12:58 AM
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In 87-95 wrangler manual there is a coolant circulation chart for 258, 4liter, 151. it is best just stop by in an auto parts store and see for yourself.
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bypass , cj7 , heater core , problems

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