Morris Minor Owners Club

Hi,

My engine has developed a fairly serious coolant leak. It is at the front right, as looking from the front of the engine. It drips every few seconds onto the floor, and seems to come from somewhere behind the water pump. It only drips when the engine is running, AFAIK.

I have removed the radiator and the fan, but not the water pump as yet. I can't see any obvious signs of leaking.

The water pump does not look or sound worn out. I do have a new water pump and will replace it if necessary, but I am trying to avoid a scenario where I replace the water pump, put everything back, and it's still dripping.

Could it be the water pump seal gone? Is there any other thing I should be looking at?

Thanks,

Daniel

Have you checked the by-pass hose and the by-pass stub in the head? The by-pass stub is known to corrode and subsequently leak.

Things to check are the little bypass hose between water pump and cylinder head, and the bottom hose coming off the water pump. You might get away with tightening the clips, which should be either double wire or genuine worm drive (Jubilee) clips. A leaking water pump is a poor liar and is given away by water sprayed in lines across the bonnet and inner wings as it flies off the fan.

thats a lovely job replacing that. i had fun getting the old one out a while back. Fitted a stainless one now.

Hi all,

Thanks for replying.

The upper and lower hose look fine and weren't wet.

The bypass hose doesn't look great, but also isn't wet.

The only place I can find that does seem wet is directly underneath the water pump, underneath the timing cover.
I did read elsewhere on the forum about internal seals going if the engine is not used for a long time. Since my engine was (apparently) rebuilt and then not used for a long time, would this produce a slow drip or would it spray all over the engine as described above?

I think I will have to remove the water pump, and either replace it or try to reseal it, and replace the bypass hose - all I have at hand is generic heater hose - and see if this works.

Thanks again,

Daniel

If your by-pass hose and by-pass stub are serviceable it could well be that the water pump seal has failed.
There is a small hole in the bottom of the water pump spindle boss, if the seal has gone coolant will be apparent at the hole.
A short piece of heater hose will suffice for the by-pass hose.
If possible use stainless 'Jubilee' style hose clips of the appropriate size.

When I brought Basil it was about 18 years since he had been rebuilt and his engine fitted.
I don't know how many miles he did in that time, but for various reasons I doubt it was more than 20,000, but I can't tell exactly since his Milometer hadn't been working for the last 5 years.
Point is the seal on the water pump went soon after I got him. The pump seemed fine with regards the actual shaft, vanes etc all looked fine, But it trickled coolant like a good'un, as you say, only when running.
Like Phil says, out of the hole on the bottom, and back across the engine, none of the "sprayed in lines across the bonnet and inner wings" as commented by JOWETTJAVELIN .

Like Phil says, out of the hole on the bottom, and back across the engine, none of the "sprayed in lines across the bonnet and inner wings" as commented by JOWETTJAVELIN .

The only time I’ve seen that is when the weep hole has been completely blocked and coolant has come out through the water pump bearing.

Water needs to hit the fan to spray it around. Seen enough with pin-holes in the radiator core doing that.

geoberni wrote: ↑Fri Jun 25, 2021 4:27 pm When I brought Basil it was about 18 years since he had been rebuilt and his engine fitted.
I don't know how many miles he did in that time, but for various reasons I doubt it was more than 20,000, but I can't tell exactly since his Milometer hadn't been working for the last 5 years.
Point is the seal on the water pump went soon after I got him. The pump seemed fine with regards the actual shaft, vanes etc all looked fine, But it trickled coolant like a good'un, as you say, only when running.
Like Phil says, out of the hole on the bottom, and back across the engine, none of the "sprayed in lines across the bonnet and inner wings" as commented by JOWETTJAVELIN .

Hi,

That sounds rather familiar...

New water pump will go in tomorrow and we'll see what happens.

Thanks to all for all the help,

Daniel

Hi all,

The new water pump is in, and the leak has stopped.

While taking it apart, it seems that the immediate cause of the leak may really have been the bypass hose, which was knackered, but the pump itself turned out to be more worn than I thought it was; the bearings feel and sound like they are on their last legs, so I put the new one in.

The result is that the leak is gone, so once again thanks to all for your help.

I don't actually think I have any more excuses for not driving the car...

D.

Well done , removing ( or changing ) the water pump makes replacing the by-pass hose much easier . When I changed my water pump / by- pas hose the stub pipe from the head was badly worn .
Currently surviving but for how long

Ah good, so it was the pesky by-pass hose. Don’t forget to check the hose clips again after they’ve settled. And get some use out of your moggy!

the by-pass stub in the head

I note from your picture that you seem to have replaced this stub. I have been lucky with mine, so far, in that, whilst worn and corroded, they have been still serviceable once cleaned up a bit. (Touching wood! )
However, how difficult are they to change out? Is this an engineering shop job or could it be done at home?
I have found this:
https://www.googleadservices.com/pagead ... RBP&adurl=
From the image it appears they screw in but getting an old and corroded one out will presumably require allot of heat?
Would a blow torch be sufficient?
Best wishes,
Mike.

Replacing the by-pass stud is a reasonably easy job.
It does mean taking the head off.
The thread is 5/8" x 16 TPI Unified National Special (UNS). It is not as some make out 5/8" UNF.
The best way of removing the stub is to drill out the stub just leaving the thread in place. The thread can then be unwound out of the head.
BullMotif used to supply a stub with a hexagon so making it much easier to screw in. The stub in the earlier photo was supplied by Mini Sport.
https://www.minisport.com/12a2075-cylin ... e-kit.html

philthehill wrote: ↑Tue Jun 29, 2021 12:12 pm
BullMotif used to supply a stub with a hexagon so making it much easier to screw in.

I noticed a while back that ESM sell one with a flat blade screwdriver slot in the top....

The slot is good for fitting but not good for removing as the slot has usually corroded away when the time comes to remove the stub.

philthehill wrote: ↑Tue Jun 29, 2021 12:26 pm The slot is good for fitting but not good for removing as the slot has usually corroded away when the time comes to remove the stub.

Very good point. Classic case of not thinking something through completely; OK for fitting, but not removing.

BullMotif used to supply a stub with a hexagon so making it much easier to screw in.

A much better design, shame ESM didn't think it worth reproducing when they took over Bull Motif's stock.
Best wishes,
Mike.

Edit: Bull Motif appear to still supply this in with their 'Classic Mini Spares'
https://www.bullmotifminispares.co.uk/p ... 75/12A2075
However I also found this one (link below), what do you think? Which would be better?
https://www.google.com/url?sa=i&url=htt ... egUIARDdAg

The longer length of the by-pass stub in the link above would be better.

As an aside you can get a similar stub to replace the water pump by-pass stub. Originally for the Cooper S but can be made to fit.

https://www.ebay.co.uk/itm/174322272913 ... XQSnVRZPiS

Replacing the bypass hose stub is a job I have to do on my (non-running) '62. There's only about 1/4" inch of metal left protruding, too little for a clip to grab. With the engine still in the car, I've tried to unscrew the stub, but the angle is impossible and I just break more off of what's left. So off with its head, and I'll try to drill it out. Question is, should the new one be installed with thread sealant?