Safe to bypass heater core?

[yonyon]

Bypass it for now, but don't wait for cold weather to put a new heater core in.

Buy the new core and wait until you have a day off with nice weather. Start early and take your time. Put some decent music on. Don't be afraid to stop for a snack or a beer or whatever along the way. Keep track of where each and every fastener goes. Don't try to speed through this as that will make it take longer.

This task might eat a good portion of a day, but that doesn't mean it has to be unpleasant. Of course if you wait until the car is covered in snow that's dripping on your ankles and your hands are all slimed up with a mix of glue from electrical tape and antifreeze and then the driver of a sanitation truck accidentally drops a load of garbage on you, well, I guess it might be very unpleasant. It's only work if you make it work.

 

[Chris142]

Originally Posted By: TFB1
Originally Posted By: AuthorEditor
Quote:
what engine?


My '95 Grand Marquis has the standard 4.6 V8. I don't think there was any other engine available.


Correct, only engine available in ANY '92-'11 Grand Marquis, or Crown Vic...

I asked because I can't keep every car and engine in my head any more.

I asked because if it was a Windsor engine you can safely plug the heater hoses. I'm not too familiar with the cooling system in the 4.6L.

I'd loop that hose back to the engine on that one. I don't think it has a bypass hose or internal bypass.

Many newer engines use the heater as the coolant bypass. If you plug the heater hoses you can create cavitation problems in the timing cover and water pump areas.

 

[KB2008X]

You can buy adaptors that are 1/2" on one end and 5/8" on the other, and 5/8" & 3/4", too. But you may need to go to a real auto parts store to get one. Get them in brass if they have them, although the plastic ones will work.

Be sure to secure the now looped heater hose to something so it doesn't fall onto something hot, like the exhaust manifold.

There are several good write-ups on heater core replacement at www.crownvic.net

It is possible to replace the heater core without pulling the entire dash all the way out, but for your first time that's an unrealistic goal.

Keith

 

[KB2008X]

Here is a direct link to good step-by-step instructions for changing the heater core.

http://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=1588408#Post1588408

There are others, too. Try searching the Body of Knowledge sections first.

http://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=cfrm

Keith

 

[AuthorEditor]

Thanks for all of the advice! Took a quick look last night and at a glance the hoses look to be the same size on either side. Am I wrong on that? Anyone know what ID I need on each side for the hoses going to the heater core?

 

[AuthorEditor]

Update: Looked up the heater core part on Rock Auto and they say the inlet and outlet are both 3/4" ID.

 

[Jarlaxle]

Originally Posted By: mechtech2
Bypassing is good and safe.
But you have one of the worse vehicles to replace the HC in!
They should be horsewhipped for doing that to us!


A 1997-2001 Cherokee isnt any easier!

 

[yonyon]

Originally Posted By: Jarlaxle
Originally Posted By: mechtech2
Bypassing is good and safe.
But you have one of the worse vehicles to replace the HC in!
They should be horsewhipped for doing that to us!


A 1997-2001 Cherokee isnt any easier!

Oh, come on! There's only one invisible bolt that you can't see, can't feel, have no idea where is, and can't even be entirely sure actually exists!

Okay, so maybe that one's a pain.

 

[AuthorEditor]

You know, seeing how difficult it is to take these things apart, it would be interesting to see exactly how they put them together in the first place.

 

[TFB1]

Originally Posted By: AuthorEditor
You know, seeing how difficult it is to take these things apart, it would be interesting to see exactly how they put them together in the first place.


I haven't actually seen the CV/MGM being built but I have seen F-Series assembled at the now closed Norfolk Assembly plant..

The heater/AC plenum is mounted on firewall prior to the dash being mounted(came in on a long arm through driver door opening, doors not yet installed)... This is prior to the body being installed on chassis, that would already have engine and drivetrain in place...

.

 

[TC]

I drove an aging 1995 Audi for two years with the heater core bypassed, no problemo. Only problem was driving up in the mountains when it snowed on ski trips -- having to wipe down the inside of the windshield every 30 seconds with a rag (literally!) was NO fun.

 

[yonyon]

Originally Posted By: TC
I drove an aging 1995 Audi for two years with the heater core bypassed, no problemo. Only problem was driving up in the mountains when it snowed on ski trips -- having to wipe down the inside of the windshield every 30 seconds with a rag (literally!) was NO fun.


Not that I wish you to ever be in that position ever again, but should it happen just buy the cheapest heater core you can find, some heater hose, and a 12V fan. There's got to be enough [fish] laying around in the junk drawer in the kitchen to rig up a mounting. An ugly heater is better than no heater when it's snowing.

 

[TC]

Good point. The car becomes almost undriveable in humid conditions like rain or snow without a defroster!

 

[AuthorEditor]

Quote:
Not that I wish you to ever be in that position ever again, but should it happen just buy the cheapest heater core you can find, some heater hose, and a 12V fan. There's got to be enough [fish] laying around in the junk drawer in the kitchen to rig up a mounting. An ugly heater is better than no heater when it's snowing.


Probably won't do it, but I was thinking of that if I could figure out a way to route the hoses into the cabin through the firewall. By the way, many moons ago on my first car when I was broke I drove all winter with no heater core in. I can vividly remember driving from Rhode Island to New York wearing a snowmobile suit, ski hat, and gloves in the car.

 

[AuthorEditor]

Minor update. Apparently it was a leaky heater core draining back through the plenum drain and onto the exhaust and the ground. Bypassed the heater core and all seems to be well in a short test run. FYI both hoses are 3/4" ID.

 

[Whimsey]

I had a 1972 bought new VW Bug. It being air cooled was like having no or little heat in the winter. But in the summer the heater worked great

.

Whimsey

 

[Jarlaxle]

Originally Posted By: AuthorEditor
You know, seeing how difficult it is to take these things apart, it would be interesting to see exactly how they put them together in the first place.


Simple: the first thing on the line is a heater core and box. They build the vehicle around it!

!

 

[AuthorEditor]

Well, it is now October and I decided to do the heater core today. Needless to say, it is a very difficult job. I found Heater Core Removal this tutorial, which is generally excellent. But, I have found there is a third lag type bolt that is holding the bottom of the heater box, in addition to the two studs with nuts. The lag bolt is screwed in from the firewall side and the pointy end comes through the bottom of the heater box and into the cabin just about where there is a small indentation in photo #25 in the tutorial to the right of the drain port. I tried to locate the other end of this bolt by jacking up the car and going underneath, but I can't see anything but the heads of the two studs that hold the bottom of the heater box. Apparently this lag bolt was installed before the AC/Evap housing on the engine side of the firewall. I'm contemplating cutting the business end of this thing off with a Dremel tool in the cabin to see if that will allow me to remove the heater housing, which has budged backwards, but seems to be pretty secure still. Has anyone heard or seen this before?

 

[yonyon]

It sounds to me like there may have been some sort of broken hardware on the other side of the firewall and this was someone's idea of fixing it. If that's what it is you might do well to crack the housing or heat the bolt enough for the housing to melt a little around it so you can pry the housing off that screw rather than lose the screw. If you go with heat, don't use fire under the dash. A sander, a grinder, or your dremel should be able to get a scew hot enough to soften the plastic pretty easily.

For a hose or wiring harness to burn or rub through would not be a pleasant way to find out you need that screw.

 

[AuthorEditor]

Got a quick response from the author of the tutorial I linked to, and that lag type bolt does not hold the box to the firewall. He suggests it is something else holding it in place, like the so-called "problem bolt" which has to be driven back out of the bulkhead. I've driven it through a lot, but maybe not far enough. I'm guessing I have to drive it completely out. I'll need to get some sort of long punch or steel rod to drive it out. This job is enough to make me want to skip Panther platforms from now on, though every car seems to have its problem repairs.