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Bypass Hose Removal?


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#1 Indy495


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Posted 10 September 2019 - 08:42 PM

Hi all

Just started to work on our 1275 1992 engine which has been neglected in the past

Water pump question please.

It has the bypass hose in place, but I have bought a replacement water pump from MiniSpares, which doesn’t have the bypass outlet as I have been told it is better to do away with this bypass hose altogether.

I see MiniSpares do a screw in bung to block the head side of the hose.

Is this easy to fit for a amateur mechanic.?
The head is coming off in due course.

Am I making the right choice in getting rid of this bypass hose?

Many thanks
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#2 richmondclassicsnorthwales


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Posted 10 September 2019 - 09:26 PM



Just buy the GWP134 with the by-pass hose facility


You can sell the GWP187 on or keep it for future developments You bought the wrong pump and to return the item will cost 4.95 and another 4.95 for delivery of another pump. Just buy the correct pump and keep the other, someone will buy it from you.


Don,t cut corners for something to fit that will cost you the same to buy anyway - if you get my drift. We sell the full kit 



#3 cal844


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Posted 10 September 2019 - 09:43 PM

Just buy the correct bypass pump. You want one with a cast impeller, not a press fit impeller, I've had the press fit ones come off in the past, the worst result is rapid overheating. Either purchase that complete kit from Richmond classics for a very good price! These guys are reputable, like Minispares or see below if you prefer Minispares.

Minispares.com part numbers

Pump is GWP134

Youll also need a new kevlar non convoluted bypass hose which is alot better lasting than other hoses.

Part number GZA2083

I'd advise a thin smear of RTV sealant on both sides of the gasket to aid sealing.

Hope this helps


Edited by cal844, 10 September 2019 - 09:54 PM.

#4 nicklouse


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Posted 10 September 2019 - 10:22 PM

remove the fitting on the head and close it off. the bypass causes more issues than it ever cured. just make sure you use a genuine mini thermostat with the bleed hole in the side..

#5 DeadSquare


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Posted 11 September 2019 - 06:48 AM


To answer your question about an amateur mechanic fitting a bung in the head.  This is quite simple, but may I suggest that you wind some plumbers PTFE tape round the threads to make a good seal, making sure that you wind it so that the tape is trailing anti clockwise as you look at it as you screw it in.  If you do it clockwise, the tape catches, tries to come unwound and bunches.


HOWEVER,  getting the nipple out of the head can be very difficult.


You say that the head is coming off "in due course".


In the mean time, to keep the car running, leave the hose untouched on the head and plug the other end.  The head and unthreaded shank of a suitable sized bolt is ideal, having slightly shortened the hose.

#6 gazza82


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Posted 11 September 2019 - 08:25 AM

It's a very odd thread ... personally I'd use Hylomar or similar to seal that plug.


The existing pitting is often harder to remove as it tends to break up as you try to remove it .. but it will collapse in if you can tap it in the right place.

#7 Indy495


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Posted 11 September 2019 - 01:13 PM

Thanks for your help everyone.

I think I’ll go with the proper part as advised and replace it as it was originally.

You lot are brill

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