beejay
Part of things
Posts: 203
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Nov 23, 2011 22:01:42 GMT
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Right, I have the head off my Mini engine and one of the things it needs is the heater bypass blanking off. The stub the bypass hose connects to is screwed into the head, so the plan was to unscrew and replace with a blanking screw. However as it's all a bit rusty the stub is seized in there properly. My efforts at removal have just broken the stub off so its near enough flush with the head. I'm now pondering my options to blank it off. Dremel the remains out from the inside? Ignore the threads and just drill it all out and knock in a blanking plug? Fill it up with some chemical metal type substance? Any other suggestions from the learned types on here  |
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Last Edit: Nov 23, 2011 23:02:21 GMT by beejay
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Nov 23, 2011 22:25:52 GMT
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Not sure what you mean by heater bypass hose? Assuming you have a 998, do you mean the bypass hose that sits under the RH side of the head as you're looking at it, goes to the water pump, or the outlet on the top of the head, LH?
If you mean the top LH one that is the inlet to the heater, then you can just block it, I have made a plate before out of thick plate steel, and bolted it down using the heater tap bolts and making a gasket out of gasket paper.
If you mean the bypass hose under the RH, it's nothing to do with the heater, it's to allow coolant to flow through the engine before the thermostat opens. You could get this welded up, but you'd need to drill about 6 3/16th holes around the periphery of the thermostat to keep a bit of coolant flow prior to thermo opening. Alternatively you can fit a metro thermostat housing sandwich plate with a hose takeoff, and plumb it through the heater like metros, but you'd still need to block the hole in the head. If you're blanking the hole in the head, you will also need to fit a water pump without the bypass hole. Any 1275 type will fit, which is good as they have a larger impeller to you get better water PUMPAGE.
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1989 Mini MG 1275 ~ 1987 VW Polo ~ 1989 Citroen 2CV ~ 1998 VW T4 ~ 2006 Volvo XC70
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beejay
Part of things
Posts: 203
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Nov 23, 2011 22:41:21 GMT
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I meant the one that goes to the water pump. Which has nothing to do with the heater I suppose, not quite sure what I was thinking when I wrote that |
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Nov 23, 2011 22:44:42 GMT
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Edited my initial reply ^
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1989 Mini MG 1275 ~ 1987 VW Polo ~ 1989 Citroen 2CV ~ 1998 VW T4 ~ 2006 Volvo XC70
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beejay
Part of things
Posts: 203
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Nov 23, 2011 23:03:55 GMT
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Thanks I have a non bypass type pump on the engine and am down with the need to drill the stat. It's just the best method of blanking the hole in the head that I'm sure about at the moment. |
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I drilled the remains out, cut a larger thread and put in a large scrub screw with some sealant. Worked for a while, but always leaked tiny bit. Another head I just welded the spout - doesn't leak. But to be fair; with some better/different sealant the grub screw might have held tight I just didn't have a welder at the time... The spout is in almost any case rotten so solid, it's like 'cold welded'.... It's easyer to just weld it up. |
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I agree with Diesel Weasel - weld it up or tap it larger and use proper hardcore sealant - trying to get those tubes out is a right pain in the backside...
but yes, to maintain the design intent you should really drill the thermostat to allow flow around the head before it opens but don't drill too many holes to begin with or else the engine will ake forever to warm up - same as with a stuck open thermostat! having said that the thermostat end will warm up pretty fast without the bypass and lead to it opening earlier, releiving any problems due to lack of flow without needing to modify the thermostat - I always thought those bypasses were dubious at best...
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i always used rubber blanking cups with a jubilee clip, some austin/leyland car had them as standard, i used to buy them at the local non halfords shop
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but yes, to maintain the design intent you should really drill the thermostat to allow flow around the head before it opens but don't drill too many holes to begin with or else the engine will ake forever to warm up - same as with a stuck open thermostat! Or at the same time install a good cooling system that always allows flow through the whole cylinder head; like used on the Rover Cooper / RSP Cooper:  This is basically a bypass from 4th cylinder back down to the bottom rad hose. I run this flow sheme on all my engines - they never ever got too hot, no matter what I tried to do ;D But well, drilling a hole is easyer - this is the 'highly sophisticated' solution realy ;D |
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Nov 24, 2011 21:17:26 GMT
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yes, that is a good system but a little bit involved...
thanks for the picture, I don't think I'll try putting that system onto my classic Mini though, now I fitted a sensible minispares two-core rad it doesn't overheat anymore!!
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jonw
Part of things
Can open a Mouse with a File
Posts: 768
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Nov 25, 2011 13:34:33 GMT
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My mini ran for years with a stout piece of hose and a brass blank jubilee clipped on.
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