Running Hot

[Sully2908]

Hi all,

Thankfully my 64 just passed its MOT however... on tick over it sits firmly on the "N" but after running seems to go quite close but not quite touching the white segment of the "H" I can rememeber from my younger days that they run hot so I fitted a fletcher radiator to combat this so my first question is how close to the H is normal for the needle?

If its to high I need to start fault finding with the obvious point being the thermostat (take it out) but before that can one of the SMEs confirm that I have fitted the fan blade the correct way around (pictures below)if I have been a complete school boy is it worth changing it for a different one while I strip out the radiator?

The flipping carburettor is leaking fuel so I wont be going far in a hurry (bugger!)

Cheers

Sully

[Surgeryman]

Sully

Your fan blade is indeed fitted the wrong way round.

Peter

[360gts]

It shouldn't matter about the blade being installed this way (looks bad).......the blades will always be in the correct direction and will always blow outwards....on the other hand it will set the blade closer to the rad...again, shouldn't be the problem for the over heating....however, being that close to the rad may reduce the amount of air being pushed through the rad especially when you are in higher revs. The fan blade will act more like a disc.

I notice you have a wide gill rad installed...later cars have many more veins between the cooling strips. This allows much more cooling as the more veins you have...the more heat is dissipated.
Think of as a heat sync...more fins attached...the more heat is dissipated from the source.
Just a few ideas for you to ponder.

[Spider]

First thing to do is actually confirm 100% what the temps are, the sender you have for example may well be wrong (all the new ones I've bought over the past 3 or so years are). If it is right, then I'd suggest finding the root cause, not masking it with a bigger radiator. When everything is right, they don't run hot.

[Sully2908]

After a research I found out the that the concave of the fan blade should be facing towards the radiator, as Pete pointed put mine was facing the engine so sucking the heat away rather than blowing the heat away through the radiator and the vent. So it's

Engine --- fan blade (Concave C of blade towards rad ) --- rad

My thinking was in the past I remember my previous minis over heating, hence the flatcher rad, prior to fitting the rad the engine didn't overheat. Anywho I gave up my night of being bored to death by strictly come dancing and stripped down the rad and cowling and turned it around. I also noticed the fan blade had been clipping the new rad.

More details to follow after the rebuild

Sully

[Spider]

After a research I found out the that the concave of the fan blade should be facing towards the radiator, as Pete pointed put mine was facing the engine so sucking the heat away rather than blowing the heat away through the radiator and the vent.

Sully

Particularly with metal fans, as 360gts said ^ it won't make any difference, it will always blow the same way. It's the angle of the Blade (ie left or right) that changes the air flow direction. With the plastic fans, it does make a small difference to the amount of air flowing, but again, not the direction. With the engine running, put your hand up against the LH front wheel and you'll see which way it's flowing.

Sit a fan on the bench and mentally note which way the fan blades lean, then turn it over. If you can, compare it to say a Sprite one, then you'll see it for sure.

[smithyrc30]

First I would check the sender to make sure it is the right one for the gauge.

While the sender was out I would also pull out the thermostat and put it in some boiling water to see if it opens fully.

After that pull the radiator, seems coolant flow (or lack of it) is your issue to me.

Cheers

[minimans]

Get yourself one of those laser Temp gun's and find out what the actual temp is 1st!! the gauge is not an accurate indicator of temp. If you don't know what the temp is your just chasing your own tail!! Yes swap the fan the correct way so it sits in the correct position and wont chew through your nice new radiator. Don't just remove the thermostat it will make it run hotter where it counts, not cooler. If you must remove it get a bypass blanking sleeve to put in there. But 1st job is to accurately find out what Temp. it's actually running at. There really is a lot of crap talked about mini's overheating if it's a Std build engine there is absolutely no reason for it to run hot even on the hottest day if the engine is correctly tuned as opposed to "tuned up" If it is running hot you need to find the cause not mask it by fitting bigger rads or front mounted auxiliary rads. Oh and one thing that does make a difference is the inner wing shroud for the radiator if it's not there the gap causes a large amount of turbulence which impedes the flow of air trying to get out the inner wing

[Sully2908]

Good advice,

I'm a straight lines kind of guy so wI'll work my way through this in a logical manner, i have turned around the fan, I shall be replacing the rad this morning. I noticed last night that the sender seemes to be cross threaded in the housing, a though it seems to be working. there is a brand new thermostat fitted and I am getting a good flow of hot air from the heater, in fact it works better than the heater.

The engine has been rebuilt so there is not the normal crud in the rad issue.

Sully

[ianh1968]

Fan orientation, consider this...

Imagine you have a desktop fan, it's pointing straight at you.
It spins, for example, clockwise as you look at it, and blows
nice cool air in your face.

Now, turn the whole fan assembly found 180 degrees...
It will now blow the air away from you
BUT AS YOU LOOK AT IT,
THE FAN IS NOW SPINNING ANTI-CLOCKWISE.

If you could somehow change the fan so that it was spinning
clockwise again, it would again blow towards you....

Conclusion:
Changing the direction of rotation WILL change the direction
of air flow. Turning the fan over won't.

Whilst swapping the orientation of the fan WILL NOT affect the
DIRECTION of flow, it may work better or worse for other reasons.

Ian

[360gts]

As I pointed out in my earlier post...the fan just looks wrong when it is installed backwards....it doesn't change the orientation of the blades or direction of air flow.
However, the fan does need to be inside the cowling to function correctly as a 'blower' fan.
This is the whole reason why a mini fan has an offset..it is designed to function best when fitted just parallel to the edge rad. cowling.
When it is reversed...as this one was...it may be too close to the rad. itself and cause 'washing' of the air against the rad. and actually produce a backwash...sending air back into the engine bay.

What hasn't been established is this...is the engine actually overheating???
If not, it is quite possible that there is a an incorrect combination of sender and gauge....there are different senders and different gauges. A 64 should have the none voltage stabilizer type gauge and the corresponding sender.

[Sully2908]

Conclusion.

I turned the fan blade around it made no difference still over heated. Took out the thermostat, let it tick over drove it around for a while. Needle stayed at normal. I think I may have found the problem. Knackered new out of the box thermostat.

I put the radiator back in without fitting the bottom radiator cowling, i might leave it off doesn't seem to be an issue?

I then proceeded to tighten up the screws on the carb pot as it seemed like it was leaking through the gasket and managed to snap the head of the screw. Got to strip off the carb and try and get what's left of the screw out of the hole. Absolutely heartbreaking. Think Basil Fawlty when his car wouldn't start. Similar scene, to say I wanted to give it a dam good thrashing was an understatement.

Sully

[smithyrc30]

Conclusion.

I put the radiator back in without fitting the bottom radiator cowling, i might leave it off doesn't seem to be an issue?

Sully

I wouldn't do that. The lower cowl has the lower radiator to engine mount fitted to it. If you leave it off the radiator is unrestrained and might move into contact with the fan and get damaged

Conclusion.

I turned the fan blade around it made no difference still over heated. Took out the thermostat, let it tick over drove it around for a while. Needle stayed at normal. I think I may have found the problem. Knackered new out of the box thermostat.

Sully

So did you confirm the thermostat not working by putting it in boiling water? Without the thermostat fitted I would expect the gauge to move around as you drove about, getting cooler and warmer depending on road conditions. I would not expect it to remain constantly at N or anywhere else to be honest.

[tsumini]

As pointed out earlier it matters very little whether the fan is on "backwards". Difference in airflow probably is negligible. What is important is the relationship of the fan tip and the radiator shroud. Fan and shroud should be in the same plane and tip clearance should be small as possible. If the fan is too far forward the air will turn and go back around the fan tip rather than being forced thru the radiator.

[Sully2908]

Just when you think it's getting better. I fixed the carb screw problem, managed to get the screw out with a small mowl grips, had a couple of H4 carbs knocking about used the gasket/screw from one of them it will do for now.

Took the car to get fuel and drop my son off at cadets everything looked ok. As I was driving back to my lock up temp went up to just off the H again. I have taken on board the point about getting it checked with a infrared thermometer or whatever they are called I'm not ready to shell out for one of them just yet.

Just checked the thermostat in a pan of boiling water its working, opening and closing slowly as the water boils. Just to add there is no coolant currently in the car just water. Looking inside the top of the radiator there seemss to be movement flowing around. It's got a new water pump fitted during the rebuild.

So given the advice so far

it's possibly a problem with the sender.
Problem with the temperature gauge giving a false reading.
The fan is not good enough to cool the fletcher rad or the fletcher rad is pants.

Sully

[Sully2908]

First thing to do is actually confirm 100% what the temps are, the sender you have for example may well be wrong (all the new ones I've bought over the past 3 or so years are). If it is right, then I'd suggest finding the root cause, not masking it with a bigger radiator. When everything is right, they don't run hot.

Noted.. Where should I get a new sender from ?

[Sully2908]

First I would check the sender to make sure it is the right one for the gauge.

While the sender was out I would also pull out the thermostat and put it in some boiling water to see if it opens fully.

After that pull the radiator, seems coolant flow (or lack of it) is your issue to me.

Cheers

Noted.. Thermostat works, I shall buy a new sender

[Sully2908]

Fan orientation, consider this...

Imagine you have a desktop fan, it's pointing straight at you.
It spins, for example, clockwise as you look at it, and blows
nice cool air in your face.

Now, turn the whole fan assembly found 180 degrees...
It will now blow the air away from you
BUT AS YOU LOOK AT IT,
THE FAN IS NOW SPINNING ANTI-CLOCKWISE.

If you could somehow change the fan so that it was spinning
clockwise again, it would again blow towards you....

Conclusion:

Changing the direction of rotation WILL change the direction
of air flow. Turning the fan over won't.

Whilst swapping the orientation of the fan WILL NOT affect the
DIRECTION of flow, it may work better or worse for other reasons.

Ian

Noted and proven. I don't think it has made a difference.

[Spider]

First thing to do is actually confirm 100% what the temps are, the sender you have for example may well be wrong (all the new ones I've bought over the past 3 or so years are). If it is right, then I'd suggest finding the root cause, not masking it with a bigger radiator. When everything is right, they don't run hot.

Noted.. Where should I get a new sender from ?

OK, again, as many of us have said, best to measure the temp with a known means. Some of the guys have mentioned the IR type temp gun, they are pretty handy sure (I have one and love it) but these more than one way to skin a cat!

I had a reliable and known capillary type gauge that I used to use many moons ago for example. You could have your gauge and sender tested but I think these days an IR gun would be cheaper. You could try test it yourself in a pot of water that you can fairly finely adjust the temp on over the 75 to 95 C range and measure with one them old fashioned (but highly reliable!) Mercury Gauge. I'm sure a few of the other guys would have some suggestions here.

Also, have a look on ebay and other places for an IR gun, they were expensive years ago, but these days, you can pick up one that is quite suitable for around 50 bucks.

Once you've established the running temp of the engine, then that will show you if it really is overheating or if the gauge is telling you porky pies. You can then do what's needed to correct it or live with it.

As 360gts said above ^ the original gauge would have been a full voltage type and these have a matching sender. New ones from what I understand are NLA (and have been for a while), however is that the type of gauge you are running or has the car been changed over to a later set up that uses the voltage stabaliser?

[Sully2908]

First thing to do is actually confirm 100% what the temps are, the sender you have for example may well be wrong (all the new ones I've bought over the past 3 or so years are). If it is right, then I'd suggest finding the root cause, not masking it with a bigger radiator. When everything is right, they don't run hot.

Noted.. Where should I get a new sender from ?

OK, again, as many of us have said, best to measure the temp with a known means. Some of the guys have mentioned the IR type temp gun, they are pretty handy sure (I have one and love it) but these more than one way to skin a cat!

I had a reliable and known capillary type gauge that I used to use many moons ago for example. You could have your gauge and sender tested but I think these days an IR gun would be cheaper. You could try test it yourself in a pot of water that you can fairly finely adjust the temp on over the 75 to 95 C range and measure with one them old fashioned (but highly reliable!) Mercury Gauge. I'm sure a few of the other guys would have some suggestions here.

Also, have a look on ebay and other places for an IR gun, they were expensive years ago, but these days, you can pick up one that is quite suitable for around 50 bucks.

Once you've established the running temp of the engine, then that will show you if it really is overheating or if the gauge is telling you porky pies. You can then do what's needed to correct it or live with it.

As 360gts said above ^ the original gauge would have been a full voltage type and these have a matching sender. New ones from what I understand are NLA (and have been for a while), however is that the type of gauge you are running or has the car been changed over to a later set up that uses the voltage stabaliser?

When I bought the car it had only done about 5 miles in 10 years, everything on the car was original, The sender was corroded I cleaned it up prior to refitting.

I might invest in a IR gun, but would not be able to cope with the needle sitting at H on the gauge, besides if it's not a true and accurate reading how would I know if the engine was actually overheating ? Besides a lot of steam from a popped head gasket?

I have ordered a new sender from mini spares, I will fit that along with a new top hose. If that doesn't work I will buy a IR gun.

Sully