[JDNakaBomb]

Ok, So I am planning on removing my heater. Just wondering if I have to loop between the in and out (at the block) if that makes sense, or if I can safely block them off. Engine is a 1jzgte. . .

[IcE]

1. Why?

2. Loop them.

[Yiros]

You should be able to do either method (loop or block). On a 2J, the heater valve stops the coolant flow (essentially blocking the flow), so I coudln't see why the 1J is any different?

I recently repalce my heater core, pipe and valve assembly and when the valve is closed, it is closed i.e. no partial flow etc

[JDNakaBomb]

Thanks for the answers guys

IcE:
1: When I was doing my engine swap, the engine crane snapped a wheel and the engine and trans came crashing down when they were halfway in. One of the things that got damaged was the brass pipe where the heater hose goes through the firewall.

2: I have had a bypass hose running at the back/top of the engine for the last year. . . It's an unsightly/untrustworthy looking hose, the output from the block on a 1j literally has the bypass hose running across the top of the engine before diving down the back, looks like sht and rubs a fair bit. Now I could modify the piping, but I'd prefer to just block them if I could. . .

And yes I could fix the damaged pipe, but I decided long ago to remove the heater anyways. I have already done away with the air-con much to most peoples disgust (I never use a/c). Now all I have to do is find the time to pull the dash apart to get the heater out. . .

[harleyMKIII]

I know in my other supra the heaters were disconnected and the guy just looped the top hose back into the block (or however it goes), only because it blocks the coolant flow through the engine otherwise.
But thats for a 7M, I dunno about 1J's.
Hope thats help anyway haha.

[JDNakaBomb]

harleyMKIII, on 01 December 2009 - 10:11 AM, said:

I know in my other supra the heaters were disconnected and the guy just looped the top hose back into the block (or however it goes), only because it blocks the coolant flow through the engine otherwise.
But thats for a 7M, I dunno about 1J's.
Hope thats help anyway haha.

Cheers Harley, Thats what I was wondering and why I kept it looped. Its a decent sized hose. I might just look at modifying how it comes out of the block and running a satin chromed copper line down low and around the back to be safe, unless anyone else can say I'd be safe to block them. . . Guess the hose over the top stays for a while. . .

Edit; Although what if you get a blocked heater core? No coolant through engine? Doesn't seem right?

[IcE]

Same with mine. My heater is fubard and when i got the engine rebuilt (i dunno what it was doing before) Brenton just looped the in and out pipes together. But again, this is for a 7M, not a 1J.

I have a spare heater core sitting at home waiting to go in, but i just dont have the time to rip my dash out and try to replace it.

[harleyMKIII]

The hoses are supposed to go to a heater unit thing connected to the firewall. The top one goes in and then it goes out back to the block, without this the heater doesn't work.
Every single supra I've owned has had this done, thus why I've never had heaters hahaha.
I'd pressume the 1J is the same as this, PM me JDN if you want some photo's of what I mean, but if you're planning on ripping out your heaters then you only need to loop them back, as been said about 1,000 times now haha.

[JDNakaBomb]

harleyMKIII, on 01 December 2009 - 07:05 PM, said:

The hoses are supposed to go to a heater unit thing connected to the firewall. The top one goes in and then it goes out back to the block, without this the heater doesn't work.
Every single supra I've owned has had this done, thus why I've never had heaters hahaha.
I'd pressume the 1J is the same as this, PM me JDN if you want some photo's of what I mean, but if you're planning on ripping out your heaters then you only need to loop them back, as been said about 1,000 times now haha.

Cheers buddy, I know where they used to go (to the heater), and like I said earlier, already have them looped, I just want 2 get rid of the loop if its possible, looks like sht on a 1jz, the hose cant fit behind the block like on a 7m, it has to creep over the top, also, there is a massive metal u-shaped pipe next to/above the intake that looks like sht and throws the hose in a fkd direction. I plan on ripping out the heaters (already disconnected), just also want to remove/redesign the looping hose if I can and as such just wanted to know if it was safe to block them off. I posed the original question like I hadn't already looped them cause it was easier to explain what I meant . . . I think I might just fab up a copper hard line and have it chromed.

or I might try clamping the hose for a drive and seeing if my temps change. . . It's been awhile since I've stuffed an engine anyways. . . Lol. . .

[Yiros]

Looping is what everyone says without knowing why. We need to understand how the heater works.

Coolant runs through the core and air is heated up by passing the through the core (heat exchange process). If you don’t want any heat, the air still passes through the same core, the only difference is coolant is not flowing through the core thus minimising the heat exchange process. No coolant flow means there is no coolant leaving the outlet pipe of the heater core

So why is looped the only option?

[IcE]

Because its easy and cheap!

[JDNakaBomb]

Yiros, on 02 December 2009 - 11:49 AM, said:

Looping is what everyone says without knowing why. We need to understand how the heater works.

Coolant runs through the core and air is heated up by passing the through the core (heat exchange process). If you don’t want any heat, the air still passes through the same core, the only difference is coolant is not flowing through the core thus minimising the heat exchange process. No coolant flow means there is no coolant leaving the outlet pipe of the heater core

So why is looped the only option?

Cheers Yiros, what you are saying makes sense. It didn't make sense to me that, the hose has to flow, as people have blocked heater cores all the time. Im going to clamp the looped hose through the middle and take it for a drive just to be sure before I go to the trouble of blocking it off though. . .

[--Golli]

harleyMKIII, on 01 December 2009 - 10:11 AM, said:

I know in my other supra the heaters were disconnected and the guy just looped the top hose back into the block (or however it goes), only because it blocks the coolant flow through the engine otherwise.
But thats for a 7M, I dunno about 1J's.
Hope thats help anyway haha.

Sorry Harley... but this is wrong.
At the back of the head on the 7M is the union banjo bolt, this diverts flow from the head to either the heater or the water bypass line that runs to the water neck. If the heater is on, the water goes to both the bypass line or the heater core. If the heater is off, the water simply goes to the bypass line. No flow from the back of the head is blocked.

Yiros, on 02 December 2009 - 11:49 AM, said:

Coolant runs through the core and air is heated up by passing the through the core (heat exchange process). If you don’t want any heat, the air still passes through the same core, the only difference is coolant is not flowing through the core thus minimising the heat exchange process. No coolant flow means there is no coolant leaving the outlet pipe of the heater core.

This isn't entirely correct...
Most cars have a water flow valve, weather it is operated by a cable or a vaccum valve, so a lack of coolant flow is the main cause for no heat.
However, most "climate control" boxes (the thing behind the dash) actually have a gate the can divert the air passing through the box to either go through the heater core, or bypass it. This is how we can get a medium between full heater or no heater. Half the air goes through the heater, the other half doesnt.
I had to have my car run heater on full flow all the time as the VSV that controls the water valve was stuffed. The reason I was able to still get cold air was coz no air went through the heater core.
The only problem with having the heater on full flow with no air going through it, was that the motor was getting a portion of hot coolant. I'll explain this below.

Yiros, on 01 December 2009 - 05:06 AM, said:

You should be able to do either method (loop or block). On a 2J, the heater valve stops the coolant flow (essentially blocking the flow), so I coudln't see why the 1J is any different?

I recently repalce my heater core, pipe and valve assembly and when the valve is closed, it is closed i.e. no partial flow etc

The 7M is the same, blocking it will cause no harm
The cruicul part to take note of is how the water moves through the entire system. On the 7M, the bypass line I mentioned above goes straight to the water neck and the thermostat housing, which goes to the radiator to be cooled. The heater however goes to a differnt bypass line, the same one that sees flow from the ISCV and Throttle body (which are feed frome the side of the head). This bypass line goes into the water pump, which in turn goes back into the motor.
The reason for this is because the hot coolant is cooled down by the heat exchange process in the heater core, ISCV and the throttle body, essentially acting as mini radiators.

Essentially, by looping it (or the heater on flow without air passing through) the hot water from the back of the head is being fed straight into the motor again, dropping the effiency of your cooling system.

I hope this sheds more light on the situation. Playing with the cooling system is not something you want to do if you do not know how the system works. This actually goes for everything on all cars.

[JDNakaBomb]

No it doesn't :lol: I'm more confused now. . . :blink:

For starters, I have a 1jz, you refer to the 7m, a minute point, but enough to confuse me at 10am on a sunday :lol:

Secondly, I fail to see how loping the inlet and outlet of the heater would add extra heat, all that would be removed is the heater core as the outlet still flows to the same place - once again, this could be some difference 1j-7m or I just completely misinterpreted what you said. I also fail to see a separate coolant bypass hose on the 1jz. ? or for that matter where a separate bypass line came out through the firewall? Which is how I read the post below in red;

The 7M is the same, blocking it will cause no harm
The cruicul part to take note of is how the water moves through the entire system. On the 7M, the bypass line I mentioned above goes straight to the water neck and the thermostat housing, which goes to the radiator to be cooled. The heater however goes to a differnt bypass line, the same one that sees flow from the ISCV and Throttle body (which are feed frome the side of the head). This bypass line goes into the water pump, which in turn goes back into the motor.
The reason for this is because the hot coolant is cooled down by the heat exchange process in the heater core, ISCV and the throttle body, essentially acting as mini radiators.

How I read the post above in green is that the heater core acts as a radiator all the time. I fail to see how the heater core would cool the coolant flowing through it when the fans are switched off and thus no air flowing through it - It would be delivering hot coolant back into the motor anyways in my opinion.

Now I haven't said any of this to be argumentative or to say that you are wrong. I'm just trying to get my head around it and clarify how it works so in turn I can work out what to do. When I get home later tonight, I'll take a look at the tsrm so I can see the lines that you are talking of and the general layout of the 7m and then do a search for some pics of the 1jz setup, cause at the minute I am confused.

[--Golli]

JDNakaBomb, on 31 January 2010 - 09:34 AM, said:

Secondly, I fail to see how loping the inlet and outlet of the heater would add extra heat, all that would be removed is the heater core as the outlet still flows to the same place - once again, this could be some difference 1j-7m or I just completely misinterpreted what you said.

I've tried searching for a water flow diagram for the 1jz, but have had no luck.
What you need to figure out is if the water that would normally come out of the heater is feed back into the water pump.
http://img705.imageshack.us/img705/8804/p1251855.jpg
What is circled in orange is where your water bypass line to the water pump connects to.

JDNakaBomb, on 31 January 2010 - 09:34 AM, said:

I also fail to see a separate coolant bypass hose on the 1jz. ? or for that matter where a separate bypass line came out through the firewall? Which is how I read the post below in red;

There is no bypass line that comes out of the firewall on any mk3... the heater lines are the only things that go through the firewall.
From the above picture, it looks like you don't have a bypass line that connects to the water neck.
Here are what both mine look like, it's the only picture I got.
You can just see them half way down the block, the top one is to the water neck, the bottom one to the water pump.
http://i120.photobucket.com/albums/o194/golli_2007/PB291242.jpg

JDNakaBomb, on 31 January 2010 - 09:34 AM, said:

How I read the post above in green is that the heater core acts as a radiator all the time. I fail to see how the heater core would cool the coolant flowing through it when the fans are switched off and thus no air flowing through it - It would be delivering hot coolant back into the motor anyways in my opinion.

If you do what I did to get the heater working and hook the valve up so it's working all the time, then your above statement is dead right. However the climate control computer shuts the valve off (and thus coolant flow) when you don't want to heat the air up. This way, there is no hot water being fed back into the motor.

JDNakaBomb, on 31 January 2010 - 09:34 AM, said:

Now I haven't said any of this to be argumentative or to say that you are wrong. I'm just trying to get my head around it and clarify how it works so in turn I can work out what to do. When I get home later tonight, I'll take a look at the tsrm so I can see the lines that you are talking of and the general layout of the 7m and then do a search for some pics of the 1jz setup, cause at the minute I am confused.

I'll save you some time...
TSRM link - http://www.cygnusx1....l.aspx?S=CO&P=2

[JDNakaBomb]

Cheers Golli. . . Once again you are a bank of A70 info. I now understand what you are talking about in regards to the bypass.

I've all but decided (after finally bothering to look at the engine), that the easiest and safest way is to just fab up a copper bypass line to take over the place of the hose that currently loops back over itself on top of the engine. . . This will only remove the heater core from the equation, not any bypass lines etc. . . Plus I'll be able to start it out of view and keep it out of view (but will get it chromed anyway). . .