Bypassing heater core

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Jun 18, 2006 | 11:37 AM

bunklash

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Joined: May 2004

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From: Northwest Florida

Bypassing heater core

Had my heater core replaced a few months ago with no problems 'till last 500 miles. Intermittently you can smell antifreeze in the cabin, and it seems to be getting worse. I cannot find any external leaks, and the coolant level has not dropped a bit. Since I'm over a thousand miles from home, I want to bypass the heater core until I return to get it fixed properly. I'm looking for advice on the best (easiest) way to do this considering I'm on the road with limited tools. I'm driving a '98 150, 5.4L.

Jun 18, 2006 | 05:00 PM

87 XLT

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Joined: Oct 2003

Posts: 4,516

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From: SoCal

Cut the hoses at a convieniet spot-or remove them from the core- & splice them together with a connector from an auto parts store.

Last edited by 87 XLT; Jun 18, 2006 at 05:03 PM.

Jun 18, 2006 | 07:32 PM

bunklash

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Elder User

Joined: May 2004

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From: Northwest Florida

Thanks, that's about what I figured. Does anybody know if both hoses are the same size? Will I be able to get at them at the core?

Jun 20, 2006 | 09:28 AM

CABROCK

Freshman User

Joined: Feb 2006

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bunklash,
Both hoses should be the same dia., about 5/8". Both hoses pass into the firewall, connected to the heater core inlet and outlet. Purchase a male to male brass union, the same dia as your heater core, remove the hoses from the core, and couple the inlet and outlet hoses together with clamps.
by-pass complete!

Jun 20, 2006 | 06:23 PM

bunklash

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Elder User

Joined: May 2004

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From: Northwest Florida

Mission accomplished, but with minor deviations. The hose coming from an elbow on top of the engine block is wider in diameter at the connection end than it is the rest of it's length, and the clamps at the firewall end of the hoses are some kind of factory quick-install that can't be easily undone. So I ended up having to cut both hoses near the firewall so I could connect them together using a hose-end flush adaptor. Wasn't the way I hoped it would go, but worked just fine, no more smell in the cabin. Thanks again for all you who replied.

Jun 21, 2006 | 10:40 AM

Bdox

Fleet Owner

Joined: Sep 2005

Posts: 28,609

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From: Lake Tahoe, Nevada

Take a look at the post in this forum on "heater core leak and grounding."

Jun 21, 2006 | 01:49 PM

bunklash

Thread Starter

Elder User

Joined: May 2004

Posts: 812

Likes: 1

From: Northwest Florida

Wow, whodathunkit? I appreciate the heads-up on this. It wouldn't do any good to take the voltage reading now that my heater core is bypassed, would it?

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Jun 21, 2006 | 11:04 PM

Bdox

Fleet Owner

Joined: Sep 2005

Posts: 28,609

Likes: 18

From: Lake Tahoe, Nevada

Wouldn't hurt. If your problem stems from a stray current, due to a poor ground it might show up. But if it is a poorly grounded dash or firewall, maybe not. Can't hurt to check your grounds anyway.

I'm just thinking this through, but perhaps you could set up a voltmeter, (lowest scale,) between the battery neg and the heater core itself using a clip wire and see if you read anything. It should be zero. If you can keep an eye on the voltmeter and run all the electrical functions, if you have a poor ground causing the trouble with the heater core, you would likely get a reading. Remember, it only takes as little as .015 volts to cause galvanic corrosion. It's a slow process, but that's what makes it hard to diagnose.

Last edited by Bdox; Jun 21, 2006 at 11:11 PM.