speed of water flow across top of rad

[cormorant]

My car does have a bit of a tendency to run hot and so far I have:
replaced thermostat (82 degrees now)
new rad cap
back flushed rad and block also used descaler
hosed out any debris from front of rad
set timing to 3 degrees static, vacuum unit working and springs in dizzy seem to work fine
mixture good plugs coffee colour
brakes not binding
Car generally drives and pulls well.
The water pump was not renewed by me, it is an alloy unit and does look fairly recent so my suspicions have not fallen on it, however when I warm the engine up and rev it I am noticing only a pretty minimal flow across the top of the rad. Should it be a considerable flow? I am now wondering if the impellors sometimes fail or corrode on the later alloy pumps

[bmcecosse]

They can corrode - but only after a long long time ! Your 82 stat is quite high - so it will likely only be partly open with engine idling - hence you don't see a great flow. I would fit a 72 stat for summer - although 82 or even 88 will be great in winter for best heater action.

[Dru]

I had a blocked radiator which continued to cause overheating after serious cleaning, purging and backflushing. I finally replaced it and - problem solved... a bit of a give-away for this prob is if the temperature stays really high even when you're bowling along, in conditions when you'd expect the radiator to be working best...

[M25VAN]

I have a similar problem and have fitted a 72c stat. I can watch the temp guage and see the stat open/close a few times as temp builds up. On a prolonged run though the temp will creep up to anywhere between 80 and over 90 depending on situation. With the cap off at 90 I can see flow in the rad but not much. Rad is dual core, pump is new. Does anyone have a measurement for how far the pump blades protrude as I have seen short and long reach pumps mentioned. Maybe it is a short reach pump you have fitted?

[bmcecosse]

Later pumps are all certainly 'long blade' - and if fitted to early small bore blocks they can sometimes foul the casting internally. Then of course they don't turn at all ! But it's certainly true that early engines will have short blade pumps unless they have been changed - but presumably they were adequate at the time !
My own car has no overheating problem despite being regularly thrashed - I have no temperature gauge (well I do, but it's been waiting to be fitted for 8 years now!) - so it doesn't worry me! The engine loses no water and it's never been known to 'boil'. And that's with about half the little fins missing between the water tubes - but then it is only used in the cool fresh air of Ecosseland!

[Dru]

..by the way, where can I find a 72 thermostat? -I've checked the usual suspects (BM, JLH, ebay) and can't seem to spot one. I changed out the thermo the other day (the engine had been running progressively cooler) and put an 82 in, and it is running at an indicated 78C and smelling hot hot hot... *remembers last summer's head gasket and shudders...*

[Kevin]

..by the way, where can I find a 72 thermostat?

Have you tried minispares

[Dru]

Hadn't even heard of minispares. Order now placed, thank you

[bmcecosse]

With winter fast approaching - keep that 82 stat in there for some decent heater action!

[cormorant]

Well I have found a 74 thermostat (minispares) - thanks dru - so will try one anyway as it's pretty warm in Kent still - maybe I will need a new rad but hope not.
What's the thinking behind a thermostat that is so much lower than the standard one bmc, especially as you are in a much cooler climate than most of us?

[bmcecosse]

As far as I know - 72 (or 74 -not much diff!) is/was the standard stat. Modern engines run much hotter nowadays - to get very best efficiency - and so higher rated stats are around - right up to 92 C I believe. Handy for winter use - with no daft by-pass hose - would make for a very good heater!

[cormorant]

That's interesting so none of the suppliers of bits for the Minor sell a stat that is original. I assumed 88 was original as everyone sells this.Surely not such a good idea when our cars are all over 40 yrs old and have blocks and rads that are likely to be a bit clogged up at the least? So if we have a 72/74 all year round we will have cold toes in winter...and if an 88 we will have a hot engine in summer.
Think I'll be doing a 74 from May till Sept then and an 82 or 88 the rest of the time

[bmcecosse]

That's probably best. Origionally I'm sure it was ~ 164 F - which equates to ~ 72 C !! But it should run ok at 82 or 88 or 92 - it will be hotter oif course - with a bit less margin for short burst of high energy running, but then the radiator will also be more efficient at losing the heat with a higher Delta T !

[Dru]

there was some bumph on the Mini Spares thing about unleaded fuel being more comfy in a hotter engine (or something)...

I am cautious (perhaps excessively so) about engines running hot; it reached the point with me that I was driving with the heater on full blast and the windows wide open and me expiring of the heat, and the temp gauge indicating the wrong side of 90... then the cylinder head cracked...

But good point, Ecosse; the chill winds of autumn are almost upon us. I'll save the new thermo for next year.

[linearaudio]

... I changed out the thermo the other day (the engine had been running progressively cooler) and put an 82 in, and it is running at an indicated 78C and smelling hot hot hot... *remembers last summer's head gasket and shudders...*

????

My Traveller runs an indicated 80 degrees, and doesn't smell at all hot. Putting the 940 head etc on made no difference either, and she runs the same winter and summer, and I only re-fitted the fan recently as I was getting caught in traffic a bit which made her go up to 90 degrees (but still not niffy),so I am a bit baffled about the discrepancies here! Can only be:

a/ Radiator blocked internally somewhere, or
b/ Inefficient impellor or........
C/ CRACKED HEAD!!!

[Dru]

Gosh, I hope you're wrong!

The hot smell is less evident now; I think it was just the engine clearing its throat of the assorted gunk that had accumulated after its sustained bout of low temperature operation...

I don't think the radiator is blocked, because it was brand new less than a year ago and the cooling system is pretty well clean after all the moil, toil and hurlyburly of last summer. No loss of coolant, no oil evident in it

Impellor on water pump was in good order too.

I'm not sure just how accurate these temperature gauges are, but I look for relative values and consistency rather than pinpoint accuracy. The gauge seems to be indicating good functioning.

Remaining eternally vigilant...

[bmcecosse]

I like my idea - no temp gauge -no worries.

[linearaudio]

.....I'm not sure just how accurate these temperature gauges are, but I look for relative values and consistency rather than pinpoint accuracy. The gauge seems to be indicating good functioning.

If in doubt, check it like I did, surreptitiously, before the household woke up and wanted a morning cuppa <br><br>
There will be an adjuster screw on the back of the gauge in case it doesn't read 100c when the kettle boils!

[Dru]

que inventos!

I wonder if I put some Assam and condensed milk in the radiator, it would make it smell nicer?

[linearaudio]

que inventos!

I wonder if I put some Assam and condensed milk in the radiator, it would make it smell nicer?

Why not? An egg will seal the cracked head and give you full English breakfast with a bit of toast on the exhaust manifold