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MG Midget and Sprite Technical - Why is my bypass hose too short?

Finishing off the engine. I put the waterpump on and intalled one of those little flexible bypass hoses but it's too short. Previously had just used standard hose. Engine hasn't been together for a long while so I can't recall how it looked before. New waterpump too. I can just put a bit of hose in but wondered why it's too short and whether something isn't quite right. The pipes don't quite line up, not that that really matters. Any ideas?


Greg H

First impression is that the water pump is at an angle. The two pieces of pipe should line up and IIRC there should be about 1/2" between the two. Also, the main inlet should be horizontal, not sloping downward. If you look at the paint on the engine block, it looks like the pump was originally at a different angle. Check if the impeller turns freely inside the block and if it does, I'd just use apiece of heater hose that fits nicely. That's what I normally use instead of those flimsy hoses. With it being so difficult to replace them, heater hose lasts a lot longer.
Martin Washington

As Martin put

don't use that flimsy concertina type hose as it’s not always long lasting, instead use a good quality (thicker walled) hose as to replace the flimsier concertina type hose when the engine is in situ a real PITA

I used to give away off-cuts of ½” silicone hose and two round-edged clips as the wall is thicker and the silicone hose is more pliable if you have to fit with engine in situ, plus silicone lasts longer – sorry I’ve none left

I'm not sure how you've got that wrong but it is
N Atkins

I meant how you've got the pump wrong

oh, and remember not to line up and tighten any jubilee clips anywhere until everything is fitted back into the engine bay as it would be with a running car

otherwise you might find you can't get to them to tighten for leaks or undo when you need to replace something

you may well find that clip in that position difficult or awkward to get at when everything is back in the engine bay
N Atkins

Yep the the pump does look to be on an angle. Perhaps it was drilled late on a Friday and the guy at BMC didn't line the jig up before drilling it. lol

I only just painted the block and left that bit unpainted until after I'd fitted the pump. Block was dipped so no paint left on it to give any hints. I bought the 134 pump which is the late 1275 I think. I believe it has the larger impeller. It does just clear the cylinder and spins nicely. The alternator holes are in line so that's ok.

Are the pump outlets for the 132 and 134 at different angles or is the only difference the impellor?

The top hose clamp had to go around that way as the other way the nut hits the block. I did think the hose was very thin and a bit wimpy looking. I'll go with a bit of silicon hose instead.


Greg H

The top of the pump is mormally at an angle, but the outlet pipe shouldn't be.

It looks to me like the pump is wrong.

Do you still have the original?


Dave O'Neill 2

I agree. Wrong pump. -- Wrong casing.

Should work though, as long as you sort the bypass hose, and the impeller is clear inside (as you say it is).

I have no problem with the concertina hoses. Mine last for years.

However, in your case, since you have extra length and can flex the straight bore hose more easily, I would just use a longer bit and have done with it. :)

Where did you get the pump?
Lawrence Slater

I thought the 132 was the original cast iron body, and the 134 is the ally one. Personally I hate bypass hoses so would block the head and use a 154, with a 5mm hole in the thermostat (or no stat and a blanking plate).
David Smith

How do you get the engine up to temp in the winter if you take out the stat?
Lawrence Slater

it will always 'come up to temp' as you put it; the question is just one of 'how long will it take'? The blanking plate helps. Most pre-WW2 cars have neither thermostat nor water pump, think about it.
David Smith

134 has a deeper impeller than 132. Yes, it does look like an odd pump. I can't see how it could be the right pump mounted at the wrong angle, after all the bolt holes in the block are fixed not moveable.

I agree with comments about the bypass hose. Just use a solid bit of hose for the job - good 1/2" heater hose would be fine. The concertina type is good for repairing a split bypass hose without taking the head off, but that's all. The very properties which make it flexible enough for that (thin walls) are also it's weak point and the reason it doesn't last anywhere near as long.

In the unlikely event of a solid hose failing, it's easy to remove it with the head and water pump in place if you have to - just cut it in two.
Paul Walbran

I'm with Dave on the pump numbers

I fitted a GWP 134 to my '73 1275 two years ago, unfortunately I wouldn't be able to get a good photo or even see well how it is fitted as it's in the car

you want the clips with the heads pointing to the right (as you look at the engine from the front) for easier access to tighten or loosen once the engine and rad are in the car
N Atkins

I think I'd cut my losses and get the correct pump, because that one just looks so wrong. As for the bypass hose the solid one which can be fitted if you remove the pump is IMO the best.

Bernie.
b higginson

Just a tip
throw away that hose order a silicone hose kit from Daniel
when you trimm the hoses to fit you are left with the prefect durable piece for that place
Onno Könemann

As the rubber hoses are (were?) of such poor quality that a top hose surface cracked after only 9 months I got a set of silicone hoses

from here - http://www.classicsiliconehoses.com/
N Atkins

Daniel will deliver the same quality at a lower price (cost) as long as we can get a group together
Onno Könemann

£100.80 I thought was a very reasonable price

plus if you buy at a show you get a good discount

I tried to get in touch with Daniel about silicone hoses (before joining here) but his christian racing brethren were more secretive than the scientologists so by the time I got through it was too late
N Atkins

I've had as few as a single set made before now. My price is a lot cheaper because it was set at a break even price based on the original 50 sets made. VAT, hose price and postage prices have all crept up since then.

Recently I sent out a price list to someone but didn't receive a reply.

I think a crossflow set works out at aabout £65 including post and packing.

My e-mail address is pretty much available to the whole world!

Anyone for a set of Orange hoses for a downflow radiator car!
Daniel Thirteen-Twelve

too late for me (as usual) but good for others to know

I wasn't on here at the time and got the information from an article and possibly your book!

not sure why but my line of contact went through the christian racers web site/forum

IIRC you didn't have a set at the time anyway when we finally made(?) contact but this was a couple of years ago

if you wanted I'd certainly recommend going to you instead of Classic
N Atkins

How about a set for MGBs?

I'm sure there would be plenty of demand.
Dave O'Neill 2

I've had a rubber concertina on mine for yonks and it hasn't burst yet. I carry a spare just in case, always have, but never needed it.

Actually mine is not just the regular type, it has a reinforced canvas covering if you get my drift. No idea where I got it, too long ago to remember.

If the thermo' can be dispensed with in favour of a sleeve, then why on earth are they fitted in the first place?
Lawrence Slater


Now back on topic guys! Remember were trying to work out what's wrong with Greg's pump not sourcing Silcon hose sets for the complete range of MG's. lol.

Lawrence I got the pump from one of the big suppliers in the UK so it should be right. Checked box and it says GWP134/M272 1275 X flow.

My radiator isn't a crossflow but that shouldn't matter. I checked in Horler (p103) in it stated that from engine no. 12CEDAH874 forward they had the larger pump and it proceeded the change to the crossflow radiator. My engine is 1029. The Moss catalogue also states the two pumps are interchangeable with the only difference being the outlet pipe is a different size and so you need to make sure you get the matching hose for it.

Dave I dont have the original, havent seen it for many years and I cant even remember if it was cast iron or alloy.

I'm curious as to what's wrong but it doesn't really matter because apart from the slight twist everything else is ok. Perhaps the design has been tweaked to make it easier to change the bypass hose should it fail?

I thought this would be an easy one for all the midget experts but if you guys don't know then I don't feel too bad.
Greg H

Greg,

I would repeat the advice above to just block it off. If you walk around and look at spridgets at a car show (as I did a few months ago when we had 80 odd at a British car show) then you will find most have done this. I had my engine rebuilt early this year, and never managed to get the bypass hose to seal 100%, it always leaked a bit until the thermostat opened and released some of the pressure on the hose. I had a straight piece of hose first, which leaked so I replaced it with a convoluted hose like yours, which split within a few days (admittedly my fault - I used standard worm hose clamps which chewed out the rubber) and then replaced it with another convoluted hose that I could never get to seal properly on startup. Sick of fiddling with it, I tapped the holes and blocked them off with bolts this weekend past. Finally, no leaks!

It shouldn't be this big an ordeal I'm sure, but that's my 2c. Cheers,

Andrew.
Andrew Fraser

Hi Greg,

Either they mixed up the boxes then, or the pattern has changed. Everywhere I check the 134 is the right number.
If I happen to visit my local supplier I'll take a look.

Andrew,
I would still like to know the function of the bypass. If it was always superfluous, why was it ever fitted in the first place?

Lawrence Slater

My understanding of the bypass is it stops airlocks in the block when the thermostat is closed. This is why some thermostats have a small hole in them.

If you fill the radiator up from empty without a bypass the air in the block can't get out so you think it's full but the top half of the block is just air. You go down the road, car starts running hot, thermostat opens and air bleds out and when you check the radiator it's half empty. A trap for new players.
Greg H

Definitely the wrong pump IMHO.
Picture shows pump on '71 1275 (before heater hose added between pump and head - pity it's not that clean now!)
Just replaced yet another rubber hose so may go silicone next time.

Jeremy


Jeremy 3

mmmm.....

On mine the outlet hose is parallel with the top of the pump but it looks like with the two shown on here the pipe angles up a bit.

I don't know, I bought it from England because it's only the best for my little car and I like to keep it as pure as possible. Oh well one dodgey part on it shouldn't hurt.
Greg H

to me your pump 'looks' correct and all pumps seem to be with large outlet horizontally level, mine on my ’73 car seems that way

I'm sure you're joking about the design being changed to make bypass hose fitting easier

so IF the pump is correct then could it be that the engine block is from a different BL car – others may know I don’t

I had a part sent to me that at first the manufacturer insisted to me was correct and that they were very careful and wouldn’t pack and dispatch the wrong part but it was the wrong and I had to completely redo the work having broke one of my own rules of carefully checking a part before fitting it I’d checked all but one thing and of course that’s the one that mattered

I’m not saying the following applies in this case but never assume the part you are sent is the correct one or that your car has the correct or original type of parts already fitted
N Atkins

No Nigel I wasn't joking about the design change but with you thinking I must have been joking then perhaps it's a bit unlikley and so of course I was joking.

I find it a little hard to believe it's the wrong pump. It came from MGOC and I'm sure they've sold quite a few. Seems a bit unlikely that the pump is wrong when it fits on ok and even the alternator holes line up.

The engine is the orginal for the car and there's definitely no BL on my car. What an offensive remark! :) I rebuilt it many years ago and can't recall the orignal pump but don't think it was like this. Perhaps in Aus they drilled the blocks differently and originally had a special Aussie pump. :)

I could buy another pump from somewhere else to see but will probably just leave it as one of lifes little mysteries....
Greg H

Hi Greg,
Well your original pump can't have been the same, as you would have noticed before now. So something has changed.

Also, if the block holes were drilled differently for Oz pumps, I suspect others would have reported this "mismatch" long ago.

However, I have worked with a number of you blokes in my time, and perhaps you really do drill your blocks a little "down under" lol. :)

Seriously though, I can't see the harm in leaving it as is, but just for the sake of interest it would be interesting to solve the mystery.

So perhaps someone with a contact in MGOC, could compare an original and recent pump of the same part number, and see if something has been altered.

Lawrence Slater

sorry Greg by BL I of course meant Austin/Morris/Wolsely/Riley/Vaden Plas, if you get all those in your neck of the woods

bit of a mystery but as long as all hoses are long enough can't see that it makes any odds

and it might be unique, a quirk on your car only so you know it's your car :)
N Atkins

I doubt that it's unique...more likely a 'feature' of the latest batch of Chinese pumps!
Dave O'Neill 2

arh, now, if it's the same as the pump I got two years ago from MGOC it's good quality and made in Turkey(?) I think

if I've got the right country it's the one that is (was?) doing a lot of good and high quality work cheap as the skilled (ship builders?) had no work, when I told a friend this he told me that an Aston Martin restorer of good repute was sending work over there because of quality and price
N Atkins

Poland, Nigel.
David Smith

I could well be wrong but I don't remember it being Poland

I can usually remember Poland but usually mix up Turkey, Greece, and the other countries that I can't think of at the moment but mix up

and even the gap for the by-pass hose on Jeremy's engine seem much bigger than on my car especially when in situ
N Atkins

Is this to do with the use of a larger diameter impeller?

If you look at Greg's pump the upper line of the pump outlet tube intersects the top bolt slightly more than on the one in Jeremy's photo. And more specifically it would appear that the "root" of that outlet tube where it leaves the circular part of the casting containing the impeller is slightly higher. Using a larger diameter impeller would necessitate the outlet tube starting from slightly further from the centre of the pump spindle. But the whole outlet tube cannot be raised up because of that top bolt. The result is the downhill slope. What is odd perhaps is that the stub pipe for the bypass hose wasn't canted over to compensate, since they were altering the casting moulds anyway.
Guy

<< the gap for the by-pass hose on Jeremy's engine seem much bigger than on my car >>

That may well be to do with the length of the tube fitted to the cylinder head. They weren't all the same length, particularly later ones.

My neighbour once spent several hours trying to fit a bypass hose to his daughter's 1979 Mini. He eventually admitted defeat and asked for my advice. When I looked at it, it was apparent that there wasn't enough gap between the two pipes to fit the hose or the clips.

Guy, I wasn't aware that there was a difference in the diameter of the impellers, only the depth.
Dave O'Neill 2

Getting back to Greg's pump, with the outlet at that angle, the heater take-off from the bottom hose may be too far from the metal pipe to fit properly.
Dave O'Neill 2

All pumps I've ever seen look like the others pictured; a distinct angle between the top of the pump going to the alt fixing and the outlet. And the bypass always lines up straight. I say your casting is plain wrong.

FRM
FR Millmore

this time Dave's agreeing with me - about hoses being long enough to fit

and confirming different gaps for by-pass hose

Greg,
have you tried offering up the fan, might just be different photos but the pulley flange looks(?) a bit bigger(?) on your pump (possibly, to me, in that photo, maybe?)
N Atkins

Guy I like your idea that it's made that way to accommodate the larger impellor. It was an intentional design change that provides a performance improvement by increasing the flow rate while also reducing its energy consumption. The reduction in energy is achieved with the downward facing outlet pipe which provides "gravity assist". A must have for the serious 'A' driver. :)

Dave - Heater take off not lining up? What on earth are you talking about? It's a convertible, why would it have a heater, and why would you drive it on a cold day when you need a heater? lol

Mine has no heater. I don't think heaters were standard in Aus, perhaps an option. You could buy the blower option for extra cooling i.e empty heater box with fan and ducts.

Radiator hoses might be my next challenge. I've noticed everyone in the UK only sells the bottom hose with the heater take off. Moss do have it listed in the book without or I might be able to get that one locally.

Nigel I offered the pulley and fan up to the pump and it was happy to have it. Nice and snug and to my surprise the belt even lined up, so we'll be fine.
Greg H

Heater take off in hose is no problem. Just insert a bolt and clamp it. :)
Lawrence Slater

Done that before, I could even a spark plug or whittle a broom handle down to size, but I won't.

If you blocked the heater hose then how did you keep warm when you went cruising on a mid summers day? Perhaps in sunny Kent with an extra pair of socks and a scarf you just get by. :)
Greg H

Actually I blocked the heater take off at the tap and return with a bolt, when the heater sprung a leak many years ago.

Took me about a year to get around to fixing it. I lived in sunny London at the time, which is always a couple or 3 degrees above kent. :) In fact I froze not only my own tits off in winter, but almost those of my girlfriends too. lol.

But hey, what's a bit of cold? We were dirt poor when we were kids we were. I used to sit in bed reading when I were a nipper, wearing my gloves, hat, socks, overcoat, AND, there was ice on the INSIDE of my bedroom windows. No heating. It was either eat or heat, so my mum chose eat. Enter violins.

What? That's nuthin. When I were a lad, we used to live ont' hard shoulder of motorway, and eat the roadkill to stay alive.

What? That's nuthin at all lad. When ---------- :)

Lawrence Slater

When I was..... in sunny london, well it wasn't always sunny! I remember standing on the platform at Clapham Jcn on several occasions getting snowed on and also freezing my tits off.

I never saw road kill over there so I think staying alive on roadkill may be a bit of a fib. They often say we're the lucky country and we certainly are! Plenty of good sized road kill over here and it's considerably larger and I suspect tastier than grey squirrels. Possums, wombats, wallabies, roos and even fluffy white rabbits, but if you're using your own car only try the rabbits and possums because I can tell you from experience the others will leave their mark and it will not polish out! In a Midget a roo would defintely be a bit ambitious and you could end up with a lively front seat passenger who's not a happy camper and intent on kicking the sh*t out of you because he thinks your little english sports cars is a wee bit pretentious and unAustralian.
Greg H

you need the heater to stop the car overheating :)

but not now with your gravity assisted pump
N Atkins

oh what a great idea, that sounds just lovely! A stinking hot day up in the 30's, stuck in traffic with the car starting to overheat so I turn the heater on to help it out. My legs will just love it!! The joys of driving a classic! Although not really and issue for me as Tassie's only a few degrees warmer than the south of England.

For what my restoration will probably cost me I could have bought a more modern convertible with both a heater and aircon. I may have even got a radio too :) but where's the challenge in that.

Greg H

no, no, you keep the footwell flaps, or at least drivers side, shut that way the heat gooes to the windscreen possibly making your head hotter

your legs and feet get the heat from the engine, g/box and exhaust

you should never be anywhere in traffic in the summer as all around will say "I bet you're nice and cool in that" when you're not

on the plus side you don't need a radio when you have the music of the car and the excitement of new and unexpected sounds to try and identify :)
N Atkins

Greg,
If I could change the font for this post, I would use 28 + to type LOL. Truly you had tears rolling down my cheeks at the thought of skippy sitting in a sprite kicking the crap out of it's driver. Brilliant.

OK, the road kill was a BIT of a lie, but motorway service station food was/is a bit like road kill, in that some people do die eating it. :).

And yes, I too have fond memories of Clapham Junction in the rain and snow. Esp if there was the usual train drivers strike or the like.

Nigel, my footwell flaps are useless, seals are useless, so the hot air still gets in. And sitting in Madrid mid june is not pleasant with hot feet.

My solution was to move my heater tap inside with the judicious use of 15mm copper pipe, fittings, and a gas tap. So now when it gets hot in the summer, I simply reach down between my legs (no need to even stop the car), and turn off the heater. If the engine starts to cook in stationary or slow traffic, I switch on the electric fan.

As regards music. I'm convinced that a partial explanation for my diminished hearing, is too many years driving open top, with the music loud enough to be heard at 80+ mph.

Lawrence Slater

I was only joking about a heater in Greg's car - he wont need it as he's sorting out his car's cooling systems

I can just see the brass ½” thumb-tap in your car

I don’t think 2½ w mono or even 5w per channel stereo in an open car would cause much loss of hearing :)
N Atkins

Nah Nigel, it's a chrome modern tap. I'll take a pic just for you.

Lot's more watts than that Nigel, plus a graphics eq. Even at 90mph it's still very audible. It could even wake the grateful dead. :)
Lawrence Slater

Found the old bypass. Short and straight so the engine is ok it's the new waterpump.


Greg H

This thread was discussed between 22/10/2011 and 29/10/2011

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