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Heater bypass bypass


graearea

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It seems to me that the bypass for my heater matrix is not stopping the coolant from getting through and I end up with a roasting heater when I want some cold air coming in to cool the footwell. The valve seems all the way closed with the cable all the way in. Is there a better way of doing this? Not looking forward to getting incinerated again. 

Do I drop out the coolant and put a hose from the top to the bottom and live without a heater for a couple of months?

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The cable not closing the valve fully is a common fault. 

A faulty valve not closing doesn't seem to be. 

I'd take it out and have a good look and play by hand. And if it can't be persuaded to close then replace it.

Connecting the top and bottom hoses directly until it's sorted should work fine.

Jonathan

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I have had a similar issue. First of all check the hoses to the valve are the correct way round. The bottom hose to the valve should come from the back of the head, the top hose returns the coolant. The top of the valve is a straight through connection on the valve ie the valve only operates on the bottom of the valve only (supply). There will always be some heat "bleed" through the top connection.

The valves do have a habit of over time letting a small amount of hot water through but it is enough to put significant heat into the heater matrix. I have had 2 faulty valves over the last 5 years.

Changing the valve is simple and cheap.

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It is 16mm bore heater hose. Just remove both from valve and join them together, preferably with a barbed straight hose connector. If on tour, a short bit of 15mm copper tube will do .... Both options with hose clamps of course.

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In a few weeks time with cooler weather you will probably be reversing this and reconnecting the heater but still with the same problem. Surely far better to replace the valve, speak to Chris @Redline Components, he has them in stock and nearly always next day delivery.

If you raise the car as high as possible at the rear and syphon all the water out of the expansion tank you will have little water in the heater matrix to clear up after disconnection. After any changes lower and refill expansion tank.

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For the track day, would you get away with just blocking off the heater air intake on the bonnet? I doubt the heater will transfer much heat into the footwells if there's no air flow through it. I'm thinking something as simpke as a rectangle of cardboard over the heater intake before putting the bonnet on. PS: I'm also thinking K Series and I'm aware the heater design changed on more recent cars so if that's just not relevant please ignore.

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