Bypass Heater control valve?

[culturedredneck]

Hi all,

I've searched a bit but no conclusive answers....

The wife and I were all geared up to take a weekend backpacking trip and my 97 FZJ80 is leaking from the heater control valve. Its an easy fix to replace it, but I cant find one locally anywhere to fix it today. Does anyone know if its possible to bypass this for a temporary fix to get us out of town and back? Rental car prices are through the roof since its memorial day...

Thanks,
Kohl

 

[culturedredneck]

Even though we all know what they look like, heres a photo of mine. Leaking from the right side. If I didn't care about heater function for this trip, would i connect the two blue hoses, or plug them up?

 

[NLXTACY]

Sure. Just a length of 5/8". Remove both of the hoses on either side of the HCV and just run the longer piece of 5/8" from pipe to pipe.

 

[culturedredneck]

Thanks NLXTACY,

Provided its just the HCV thats bad, would you think this is a good enough fix for a 200 mile round trip?

 

[NLXTACY]

Thanks NLXTACY,

Provided its just the HCV thats bad, would you think this is a good enough fix for a 200 mile round trip?

If you don't mind a heated cab it's good forever

 

[Kaninja]

I just did this. I wasn't going to let a cracked heater valve get in the way of my offroading in hot weather.

 

[george_tlc]

OP, If that's silicone hose (sort of looks like it), you really need constant tension hose clamps versus the generic clamps you have on there.

Bypassing is not an issue as reported above. In fact everyone should keep a spare heater valve and/or a length of 5/8" hose to bypass the valve when it breaks. The design is essentially a bad implementation, the engine rocks on the mounts as it cranks and torques, the valve is fixed to the body the USDS valve nipple gets mechanical stress each time the engine rocks... The valve body is made of plastic...

cheers,
george.

 

[richardlillard1]

I don't understand how the heater isn't on when this is in place.

 

[Tools R Us]

I don't understand how the heater isn't on when this is in place.

It is, will heat the unit. When we did the trail repair bypass on mine, used a long hose, kinked it and held it kinked with a zip-tie.

Try asking the parts store for a FOUR SEASONS 74780. They are relatively common, fit a range of common vehicles. Some parts stores need to be spoon fed!

 

[culturedredneck]

EXCELLENT! Thanks everyone! I replaced it with a length of hose, and drove it around a bit and all is well. AC is broken, so we're going windows down anyways. Should be a mild weekend. When I took off the HCV, the two flanges fell apart in my hands, it was definitely the culprit.

@george_tlc Not sure if its silicone or not. Its the standard Autozone black hose for heating systems. Its actually 19/16th instead of 5/8th, which is about .5mm smaller so its pretty snug. It only needs to hold for about 4 days until I can order the HCV and replace it.

@Tools R Us Technically heat is on, but if the blower is off it shouldn't heat up the cab, right? We'll have the windows down but I definitely dont want heat.

 

[george_tlc]

Not the black hose, the BLUE/RED hose - that looks sorta silicone like.... The picture in post #5 shows the style of clamp that should be used with silicone hose.

Yes, the heater valves die with age. Most of us have posted warnings to REPLACE OLD valves...

I ran 500+ miles with the bypass hose in place after having a heater valve disintegrate on a trip - caught it immediately since we where on sand dunes and spotted the steam 'when she blew'.

It will be a little warmer in the cab, but the heater valve is only one aspect of the heating system. If you have your air controls in the dash NOT set to heat, then very little air will duct through the heater core. So, there's no worries about having hot air blowing on you during your trip.

cheers,
george.

 

[Tools R Us]

@Tools R Us Technically heat is on, but if the blower is off it shouldn't heat up the cab, right? We'll have the windows down but I definitely dont want heat.

Kinda, it will heat the units, under the dash and passenger seat. Short run isn't likely to be noticed, the longer it's run, the more heat will radiate out. Mostly on the passenger side, so depends on the weather and how you feel about your passenger?

Also, tie that harness up in place. along the firewall and looks like the clip by the EGR pipe is missing? Having it flopping around is asking for trouble.

 

[culturedredneck]

@Tools R Us I hear ya on the harness. I need to find a way to secure it that isn't the stock mounts. I was having trouble with the engine pushing back on the wires that run down between the firewall and engine block. Every time I accelerated the whole car would stutter. I had to pull it apart and wrap the wires that had been burned over time. Letting it sit freely pulls it out of the position where it was pinned against a hot pipe. But yeah, need to fix that...

 

[Tools R Us]

Take the clip remains off, zip-tie the harness in place through the hole in the mount tabs.

 

[Tools R Us]

Something like this.

 

[bloc]

I've had my valve wide open and running full-flow since the v8 swap. Turns out this engine needs warm water flowing through the heater lines constantly for the thermostat to work properly at low engine speeds.

How this is relevant: So far The blend doors in the distribution box are keeping any hot air from actually coming out of the dash in my case.

 

[culturedredneck]

@Tools R Us That makes sense. Thanks for the advice, I'll get on it.

 

[Tools R Us]

@Tools R Us That makes sense. Thanks for the advice, I'll get on it.

If you have one of these stores handy, a set like this would make short work, also handy for other jobs.
Fluid Line Clamp Set 4 Pc

 

[1911garand]

Sorry to dig up an old thread, but wanted to post my experience.

I used Gates hose # 28471 to replace BOTH of the 5/8" hoses that connect to the firewall (just one 28417 does both hoses for the FZJ80).

Totally removed the heater control valve.

It blows HOT and it blows COLD - I'll update on how it does this winter and next summer.

Good Luck!

 

[yellowgeko]

Sorry to dig up an old thread, but wanted to post my experience.

I used Gates hose # 28471 to replace BOTH of the 5/8" hoses that connect to the firewall (just one 28417 does both hoses for the FZJ80).

Totally removed the heater control valve.

It blows HOT and it blows COLD - I'll update on how it does this winter and next summer.

Good Luck!


View attachment 1821286

Can you please elaborate on how it blows hot and cold? I thought by passing only allows hot air to pipe in, if the air is on.