Why would the by-pass hose ever be blocked off? Is there a benefit for doing this? Should it be done? I don't run a heater at all.

What is the actual purpose of the by-pass hose??

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http://www.youtube.com/user/Hanras

The by-pass is to keep the water circulating until the thermostat opens up i believe.

Benefits for blocking it off include not having to change a blown by-pass hose.

I believe there is another reason, to do with stopping hot water from the head going back into the block.

As Matt said it's for circulation within the block & head before the thermostat opens.
If you get rid of it, drill a 3mm hole or two in the thermostat to allow limited system circulation.

BTW if you have a heater and the tap is on (or it's the fresh air type) you have plenty of circulation anyway. The heater circuit bypasses the thermostat.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

What are the methods used to block it off? Is it any benefit at all to cooling?

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http://www.youtube.com/user/Hanras

You screw a 5/8 UNF brass plug into the head with some sealant on it.
For the water pump, you can either buy a Rover one with no bypass tee, or block it off. The neatest way to do this is tap a thread inside and screw a grubscrew in with sealant.

AFAIK there is no cooling benefit, just added reliability.

You can improve reliability of the bypass hose by using 1/2" Pirtek MPH-08 hydraulic return hose instead. It is thicker, and rated at 500psi... Works for me...
I use a brass fitting in the head, they don't rust like the originals. PM me if you want one made.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ah righteo, I dont think Ill bother. If I remember rightly when I built the engine I used some type of heavy-duty hardcore by-pass hose that was fitted as the head went on. I would not be able to remove the hose currently without removing the head....

For me, if it dosnt improve cooling then there is no point in doing it!

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http://www.youtube.com/user/Hanras

It would probably be easier to remove the water pump than the Head

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If you do need to change the bypass hose, pop the water pump off, not the head.
Far less work...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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did I tell you that I won a trophy?

Those dang graffiti kids got into your engine bay again I see .

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Respect mine and I'll respect yours.

yeah, but they missed a spot, the grey bit is primer

that one was a while ago, I gave the kids a can of paint each and hung the motor up in the back yard

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did I tell you that I won a trophy?

I bet the clothes line didn't like that .

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Respect mine and I'll respect yours.

nice

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did I tell you that I won a trophy?

Yeah I think Ill leave things as they are! Cant see that by-pass hose that I have currently failing anytime soon!

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http://www.youtube.com/user/Hanras

My metro 1300 head doesn't have a bypass at all. I drilled 3 holes in my thermostat and have never had any issues in 8 years.

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Lillee - 1969 Morris Mini K