Rear Heater Delete/Coolant Line Cleanup (1 Viewer)

[Will Van]

I just wanted to give a quick picture tutorial on how I cleaned up my heater and coolant lines under the hood.

On my '93, this method reduced the number of heater hose connections from over 50, to about 10. It also makes the whole system much more simple. This method requires deleting the rear heater (obviously), PAIR system (which Toyota did on later models anyway), and the throttle body coolant lines. On colder-climate trucks, you may want to avoid deleting TB coolant lines.


Replacement parts needed:

• OEM Heater Control Valve (Toyota PN: 87240-60140)
• Gates 5/8" Green Stripe Hose (Wits' End, Solutions for Problems You Didn't Know You Had)
• ‘95 to ‘97 model one-piece thermostat housing to firewall hard pipe (Toyota PN: 87208-60161)
• PHH hardline top "Elbow" to heater valve (Toyota PN: 87245-60480)
• Breeze Constant Torque Hose Clamps for 5/8" Hose (Wits' End, Solutions for Problems You Didn't Know You Had)
• One piece "U" Shape heater valve hose (Toyota PN: 87245-60420 or Gates PN: 19161, trim to fit)
• Two high quality 5/16" lined silicone caps (HPS PN: RSCC-032-BLK) and clamps

To start off with, now is a good time to replace your Pesky Heater Hose ("PHH") and heater valve, since you're going to drain the cooling system and replace lines anyway. There are plenty of great write-ups on this portion of the procedure, so I won't include too much on that topic.

Slee - PHH (Toyota 80 Series Land Cruiser)
ExpeditionLCMajorcoolingoverhaul


The 90* heater elbow (Toyota PN: 87245-60480) goes on top of the PHH hard line. You can bypass the hardline for even fewer connections, but I was afraid a rubber bypass line would rub somewhere and leak. Don't worry, I re-wrapped the engine harness after this photo was taken.

While you're in the DS front fender doing the PHH, pull the line for the "PHH Neighbor" that routes from the head to the intake manifold hardline.

Cap the "PHH Neighbor" port with one of your 5/16" rubber hose caps.

DO NOT use vacuum caps like I did in the photo below. Use a proper coolant cap like the HPS caps listed in the Replacement Parts list above (HPS PN: RSCC-032-BLK)

Now move to the water pump and pull the 5/16" line coming off the top of the thermostat housing.

Cap the thermostat port with the other 5/16" rubber cap.

EDIT: DO NOT use vacuum caps like I did in the photo below. Use a proper coolant cap like the HPS caps listed in the Replacement Parts list above (HPS PN: RSCC-032-BLK)

At this point you have isolated the TB and can remove all of the abandoned TB coolant lines/connections at the front of the motor and under the intake manifold.


Next, we'll move to the Firewall Heater Hoses ("FHH"), heater valve, and thermostat hardline.

I followed this excellent writeup and video tutorial for FHH (Project FJ4door: How I did my 80 series floor heater bypass fzj80 fj80 lc80 lx450). This is the meat and potatoes of the rear heater delete.

The majority of the rear heater deletes I have seen simply use a Gates 90* heater hose from a Dodge Cummins. This is what I did initially.

This setup still utilizes the factory "U" shaped hard pipe and simply deletes the rear heater hard pipe on the DS with the 90* Dodge heater hose.

Member @LandCruiserPhil came up with a very clever one-piece solution from Toyota/Gates (Rear Heater Bypass Hose - Land Cruiser Products - LCP). This converts the "U" shaped hardline to a one-piece hose, and reduces the number of connections at the firewall.

Finally, the '93 and '94 trucks had two-piece hard pipe and multiple connections from the thermostat to the firewall because of the PAIR system.

If you delete the PAIR system, you can run a one-piece hardline (Toyota PN: 87208-60161) and regular Gates 5/8" green stripe directly from the firewall to the hard pipe. This also deletes the PS portion of the rear heater at the firewall.

That's about it! Please let me know if you have any questions.

 

[Starlord]

Tag. Nice write up

 

[napir]

Love this, great writeup.

 

[TerraNerva]

I just deleted my PAIR system this weekend and have the 95-97 hard pipe ordered and I've already done the rear heater bypass and bypassed the EGR. My operating temp is down considerably from the minor mods I've done thus far, down to about 185 from nearly 200. Being relatively noobish to the 80 engine on my '94, this is first I've heard or read about simplifying the TB coolant lines. Can anyone comment about the benefit, other than the obvious, of deleting this portion? What's the purpose of the TB cooling lines? I live in the South, not 'that' cold in winter, but I'm all about eliminating unnecessary connections and potential leaks.

 

[Will Van]

I just deleted my PAIR system this weekend and have the 95-97 hard pipe ordered and I've already done the rear heater bypass and bypassed the EGR. My operating temp is down considerably from the minor mods I've done thus far, down to about 185 from nearly 200. Being relatively noobish to the 80 engine on my '94, this is first I've heard or read about simplifying the TB coolant lines. Can anyone comment about the benefit, other than the obvious, of deleting this portion? What's the purpose of the TB cooling lines? I live in the South, not 'that' cold in winter, but I'm all about eliminating unnecessary connections and potential leaks.

There is a risk that in very wet and very cold conditions that the throttle body butterfly could get frozen in the “open” position in a situation where you’re keeping the throttle steady for a long period of time (cruise control on + long flat road + freezing rain). The throttle body coolant lines are designed to eliminate that possibility by running coolant through the throttle body and keeping it warm.

Deleting the TB coolant lines probably yields no performance gain. Although you are removing heat from the intake, which would have some benefit. The main advantage is that it’s one less area for a potential coolant leak, especially since the lines are very hard to access under the upper intake manifold and through the DS fender-well. Not a repair you’re going to want to do on the side of the road.

The main reason I suggested it is to simplify the cooling system.

 

[TerraNerva]

I'll gamble it stays warm enough under my hood to prevent that situation ever happening. I'm in, thanks for write up.

 

[NLXTACY]

There is a risk that in very wet and very cold conditions that the throttle body butterfly could get frozen in the “open” position in a situation where you’re keeping the throttle steady for a long period of time (cruise control on + long flat road + freezing rain). The throttle body coolant lines are designed to eliminate that possibility by running coolant through the throttle body and keeping it warm.

Deleting the TB coolant lines probably yields no performance gain. Although you are removing heat from the intake, which would have some benefit. The main advantage is that it’s one less area for a potential coolant leak, especially since the lines are very hard to access under the upper intake manifold and through the DS fender-well. Not a repair you’re going to want to do on the side of the road.

The main reason I suggested it is to simplify the cooling system.

For that reason is why I use a simple shut off valve. In the winter I open it and summer I close it.

 

[RFB]

For that reason is why I use a simple shut off valve. In the winter I open it and summer I close it.

lololol winter in west hills must be brutal.

 

[NLXTACY]

lololol winter in west hills must be brutal.

I use to spend a lot of time in Mammoth. 20ft of snow on average and negative temps

 

[Jgunner]

Bad ass write up! I need to do this, like a year ago! Such a procrastinator.

 

[fz1boxer]

tag

 

[Alex Fogg]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

 

[Alex Fogg]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

 

[BILT4ME]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

This is due to the catalytic converters under the floor and the airflow down the transmission tunnel from the engine bay.

Most people install sound deadener and insulation inside under the carpet to offset the heat.

My center console keeps a cup of coffee warm all the time. Not so good for the cold drinks.

 

[TerraNerva]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

Yes, you can just bypass them and NOT remove them, its not difficult and probably wont need a mechanic. There are several threads on here describing the procedure. If you're having heat issues all the time, then either your heater valve is not closing properly or your issue is what bilt4me said above.

 

[amgraham]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

There's no real need to remove the lines unless they really bother you. I just bypassed it under the hood and left the hard lines and the rear heater in place. I've heard the lines are a real pain to remove with the engine and trans in place.

 

[amgraham]

@Will Van I would be careful of those 5/16" caps. In my experience they deteriorate pretty quick and leak (probably because they are generally designed for vacuum and not the heat/pressure from coolant). It's not as clean but I've always used a short section of hose with a bolt clamped in the end of it. I don't know if there is a cleaner option out there.

 

[Will Van]

@Will Van I would be careful of those 5/16" caps. In my experience they deteriorate pretty quick and leak (probably because they are generally designed for vacuum and not the heat/pressure from coolant). It's not as clean but I've always used a short section of hose with a bolt clamped in the end of it. I don't know if there is a cleaner option out there.

Thank you for letting me know. I’ll keep an eye on them. They are made of EPDM rubber, so I thought they would be fine. But you’re correct, they’re designed for vacuum.

 

[Will Van]

I'm currently having a problem with excessive heat on the front passenger side along the inner side, sort of next to the seat and the center console. I have been assuming it's the rear heater lines. Is all of the above necessary to only delete the rear heater lines? Or can I (or rather my mechanic) just bypass those lines and remove them?

Not all of the above is necessary to isolate the rear heater. The first section deals with the throttle body delete. That is not necessary to delete the rear heater.

You can cap/delete the rear heater without removing all of the hard lines or the heater itself (under the seat). But like was mentioned above, most likely it’s not the rear heater lines causing your PS to heat up, but actually the catalytic converter.

 

[Red Merle]

There is a risk that in very wet and very cold conditions that the throttle body butterfly could get frozen in the “open” position in a situation where you’re keeping the throttle steady for a long period of time (cruise control on + long flat road + freezing rain). The throttle body coolant lines are designed to eliminate that possibility by running coolant through the throttle body and keeping it warm.

Deleting the TB coolant lines probably yields no performance gain. Although you are removing heat from the intake, which would have some benefit. The main advantage is that it’s one less area for a potential coolant leak, especially since the lines are very hard to access under the upper intake manifold and through the DS fender-well. Not a repair you’re going to want to do on the side of the road.

The main reason I suggested it is to simplify the cooling system.

Too cold for that here, but good to know why I keep reconnecting that line. I just wire wheeled and painted all of the fittings and if I would have known about it, I would have dipped them in muratic acid first and then painted them. Much less labor intensive and easy to work with. Just don't shoot any in your eye...

I did take a closer look at PAIR and I am getting the itch to give that a dirt nap. Is there any cold weather reason why it's there, or is it all smog malarky?

New fender with brand new matching gasket material where the flare meets the fender here along with a bunch of other stuff, crank seal, oil pump seal, new AC system, rust and paint work. This was a big tear down and rebuild, but I am most of the way there. Still kinda waiting on paint to cure up a bit and then II will reassemble better than new when needed.