32 replies to this topic

[Ethel]

The bypass hose may be 1/2" but the holes in the pipes it fits on are much smaller.

I never found the proper hose that unreliable and there are better alternatives available now.

[Dan]

I've never had any problems with them either. As with everything if they are put together properly using good parts they are fine.

If your 'stat has only one hole in it then it is likely to be the standard bleed hole, the float has gone missing if it's just an open hole though.

[the boy howard]

Yowzer, im even more undecided now! Thanks for the replys, its a 1380 with fast road cam blah blah blah if that makes any difference to peoples opinion. I see Mini Spares sell the blue silicon type bypass hose, surely thats upto the job?
cheers
lee

[m1tch]

Yowzer, im even more undecided now! Thanks for the replys, its a 1380 with fast road cam blah blah blah if that makes any difference to peoples opinion. I see Mini Spares sell the blue silicon type bypass hose, surely thats upto the job?
cheers
lee

That item was out of stock when I looked at it, so I just got some uprated Goodyear rubber hose instead lol really nice thick walled stuff

[Sprocket]

I cannot see how a propper piece of 1/2" hose used for the bypass ( as was used by the factory) can be any more un reliable than any other hose in the cooling system.

Deathrow is absolutely right. While drilling holes in the thermostat is A solution, it is not THE solution.

The SPi engines use a sandwich plate which feeds the inlet manifold as well as the heater. The inlet manifold acts as a bypass. The MPi on the other hand does not have this heated inlet manifold, but still has a pypass from the sandwich plate. I can confirm that the MPi bottom hose has a 1/4" restrictor on the bypass.

Its there for a reason! Remove it as others have suggested if you want to, but at least consider why any A series engine has a bypass in which ever form, its there to ensure efficient operation of the cooling system.

Oh and the reason it is called a 'bypass' is that it bypasses the radiator. Standard physics means that the coolant will take the easiest path. That path with the thermostat closed is through the bypass. As the thermostat starts to open, the easiest path is through the thermostat and the radiator.

A note on running without thermostats, while it might be a get you home fix, it is not a permenant solution. The engine temperature will not be regulated at a high enough temperature, the heater will not work, and there is a possability that the cylinder head will overheat, due to localised areas of boiling.

[TimmyG]

Totally agree with Deathrow and Sprocket on this, the bypass is there to maintain a coolant flow around the engine (not the rad) until it warms up and the thermostat opens, otherwise you'll get stagnated coolant and locallised boiling, like in a kettle around the element.

Also, about thermostats, unless your existing thermostat is failing to open properly in the first place, changing it for a new lower opening temp one will not cure any overheating, because by the time you're starting to overheat, your existing one will be fully open anyway.
It will only lower your running temp if your cooling system is working correctly in the first place.

Edited by TimmyG, 12 September 2009 - 02:24 AM.

[jonlad]

Hello

Sorry to resurrect an old thread but i'm trying to keep info on one topic in one place.

 

I was reading this topic as i'm struggling to figure out how to plumb my water pump with bypass. Ultimately i think i have the wrong one for the car, but would like to make it work. What i have in mind is as follows, is this correct?

 

1) heater valve on LHS of head. Pipe to heated inlet manifold, pipe to heater, pipe to bottom hose.

2) water pump with bypass. Pipe from pump bypass to sandwich plate below thermostat.

 

Is this correct or indeed will it work?

 

My head doesn't have a bypass fitting included (1275 A+ for info)

 

Any advice appreciated

Thanks

Jon

[panky]

I think you need to blank the by-pass connection on the pump and connect the heater return to the sandwich plate,

[jonlad]

Hi Panky

Thanks for the reply! I see you probably aren't far away. Is that the red mini I've seen in Holmes Chapel occasionally?

 

Maybe I'm being a bit slow (it has been known) but the earlier posts in the thread talk about bypassing the stat. Both the heater valve and the sandwich plate will be on the same side of the stat so I'm not sure there would be a bypass. Does that make sense?

 

Thanks again!

Edited by jonlad, 10 June 2017 - 06:13 AM.

[Ethel]

I don't think you'll have room to attach a hose to a water pump bypass connection other than the intended straight one to the underside of the head.

 

Sandwich plates were used in a couple of ways, either as a take off to single circuit via a heater with no water valve. On Minis, where a water valve is the only way to regulate the heater temperature, there are two branches off the bottom hose. One for the heater and the other as a permanently open return via a restriction, as Sprocket mentions. Not that sandwich plate equipped cars use 5/8" hose while the earlier ones with valves on the head use 1/2"

[panky]

Beat me to it and very well explained. The by-pass is built into the way the hoses run on my '91 Cooper, with the two branches on the bottom hose and floating heater valve .

It wasn't me you saw, I've only just got it back on the road this week after five years

[nicklouse]

change the pump for one without the bypass take off or have the current one drilled out and tapped and a grub screw fitted to close and seal it off,

 

as to your plumbing it depends on what you have now.

[jonlad]

Thanks everyone for taking the time to help! I'll tap and plug the water pump bypass

 

Cheers

[Compdoc]

I'd be interested to know why a by-pass hose on a Mini is a "must have", but the same engine in a Metro doesn't need one. If its all down to "progress" can we not just plumb the Mini the same as the metro?

[jonlad]

Good question, i wish i knew the answer. I'm still not sure that with what i have there will be any bypass, but i guess that's why people drill the stat

 

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