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The mkiv Supra Owners Club

Breather at the back of the head?


PhilMorrison

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That's what I originally thought it would be, but I've been told by someone that it's a breather. It did seem a strange place for a breather to be honest.

 

So okay, if it's a water feed to the heater matrix, is it used as part of the water flow through the engine? or can it be blocked? If it can't be blocked, where must it return to?

 

Sorry for all the questions, Obviously I don't have a car or complete engine to reference.

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I'm pretty certain the CJ manuals have a complete diagram showing water and oil flow paths........

 

I could try and pop a picture up later. I can't think off the top of my head where the return pipe from the heater matrix goes as you should have another 'loose end' somewhere so to speak!

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My heater matrix was bypassed so it is possible

 

Do you know how it was bypassed?

 

 

I'm pretty certain the CJ manuals have a complete diagram showing water and oil flow paths........

 

I could try and pop a picture up later. I can't think off the top of my head where the return pipe from the heater matrix goes as you should have another 'loose end' somewhere so to speak!

 

There's usually a water pipe with a load of inputs on it that I've got rid of. I imagine it would be one of those, but if you can get me a picture to confirm, that would be absolutely awesome. Thanks :cool:

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There was a discussion last year regarding the heater matrix. I'm sticking my head out here and saying don't bypass it with a joiner, but rather block the two pipes that would run the matrix. This will ensure that water flows through the head properly rather than taking the easier path with the thicker matrix pipes.

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Here's a diagram and a picture of the main pipework that goes around the block.

 

I think in the picture is how it is in place if viewing from the front of the car. The bottom joint attaching to the rear fo the water pump and going around the block to near the oil filter/cooler area.

 

The left most pipe is labelled as the 'from heater' pipe.........

 

if the pics are too small i can always email the full size ones direct to you, hope it helps :)

Water route.jpg

Pipework.jpg

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I'm sticking my head out here and saying don't bypass it with a joiner, but rather block the two pipes that would run the matrix. This will ensure that water flows through the head properly rather than taking the easier path with the thicker matrix pipes.

 

Very interesting. Has anyone actually tried blocking it? As you say, it could increase flow to the bit's that matter, but it could also increase the pressure enough to damage something I guess.

 

 

Here's a diagram and a picture of the main pipework that goes around the block.

 

I think in the picture is how it is in place if viewing from the front of the car. The bottom joint attaching to the rear fo the water pump and going around the block to near the oil filter/cooler area.

 

The left most pipe is labelled as the 'from heater' pipe.........

 

if the pics are too small i can always email the full size ones direct to you, hope it helps :)

 

Superb :cool: Thanks very much, it makes alot more sense now :cool:

 

As above, I'd still prefer to block it if it's an option, but if I have to fabricate something, I'd probably look at just having a pipe from that outlet at the top of the head, straight to the top rad pipe.

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The breathers are on either side of the engine, one normally goes back into the inlet after the air filter before the turbo and the other has a one way valve going into the inlet manifold.

 

As for by passing the heater matrix, mine has had a small joiner pipe in it since my matrix developed a leak a long long time ago.

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Flow of water inside the head is critical. The flow rate inside the head will have been designed, at considerable expense, to include all componants. If the heater is removed it should be replaced with a restriction equal to the restrictioin of the heater matrix in the system. Anything that could alter the designed flow could result in uneven cooling, hot spots and possible damage.

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Very interesting. Has anyone actually tried blocking it? As you say, it could increase flow to the bit's that matter, but it could also increase the pressure enough to damage something I guess.

 

Just so you know the background to Gav's post, we had 2 or 3 people report head gasket failures last year (almost unheard of on the 2JZ-GTE), the cars concerned all had heater matrix bypasses done.

 

I think when this was discussed last the consensus was to bypass the heater matirx but add a large restriction (to replicate the restriction the heater matrix causes) in the form of a much smaller diameter pipe to join to the matrix feed and return.

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Flow of water inside the head is critical. The flow rate inside the head will have been designed, at considerable expense, to include all componants. If the heater is removed it should be replaced with a restriction equal to the restrictioin of the heater matrix in the system. Anything that could alter the designed flow could result in uneven cooling, hot spots and possible damage.

 

 

Just so you know the background to Gav's post, we had 2 or 3 people report head gasket failures last year (almost unheard of on the 2JZ-GTE), the cars concerned all had heater matrix bypasses done.

 

I think when this was discussed last the consensus was to bypass the heater matirx but add a large restriction (to replicate the restriction the heater matrix causes) in the form of a much smaller diameter pipe to join to the matrix feed and return.

 

 

Very sound advice guys thank you :).

 

As I don't have any return pipework to work with, I'll be fabricating from scratch, so I guess the next question is, where should I send the water back to? Top rad pipe, or pre thermostat? and then the next question, what size restriction should I make? I guess as long as it stll flows, it can be pretty small..

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Just so you know the background to Gav's post, we had 2 or 3 people report head gasket failures last year (almost unheard of on the 2JZ-GTE), the cars concerned all had heater matrix bypasses done.

 

I think when this was discussed last the consensus was to bypass the heater matirx but add a large restriction (to replicate the restriction the heater matrix causes) in the form of a much smaller diameter pipe to join to the matrix feed and return.

 

Just to add my bypass is small copper household rad piping in a 180deg formation.

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As I don't have any return pipework to work with, I'll be fabricating from scratch, so I guess the next question is, where should I send the water back to? Top rad pipe, or pre thermostat? and then the next question, what size restriction should I make? I guess as long as it stll flows, it can be pretty small..

 

The feed is the one from the back of the block, the return should go directly back to the water pump (see attached pic).

 

no 1. is the part that connects to the heater return (normally has a vertical pipe attached that routes up and behind the block)

 

no 2. is the pipe that has the return from the oil filter cooler (goes all the way behind the block)

water bypass.jpg

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