17 replies to this topic

[dgear1984]

Rebuild my 1275 s and it seems to be running around 95-100 deg water temp with normal driving with the heater open with the fan running.

I have checked this by warming the sensor to known temperatures and measuring the resistance and then putting the same resistance throught the gauge to get a set of photos of the needle position for 80-100 deg.

I have got a new 11 fin per inch recored rad, 13psi cap, new hoses. Has a cooper s water pump pulley and a metal 11 blade fan, 75deg thermostat, 940 head with bypass, new minispares water pump, austin mk1 grill.

Carbs and mixtures have been set, have also checked dizzy setting. Engine performance seems ok to me, although have not yet rollered it.

Engine is only lightly tuned, ported head, 270 cam, 10:1, twin hs2. Head and block have both been skimmed. The engine at present only has plain water, no coolant so maybe that may make a few deg difference.

Is this fairly normal, I was expecting nearer 90 deg.

Thanks Dave

[smartie93]

Why not get a proper temperature gauge? Mine at normal road speeds doesn't exceed 80 degrees. Anti freeze will help with heat transfer. Have you done a head flush?

[smartie93]

By head flush, I mean coolant flush haha

[dgear1984]

I want to keep the original gauge in my mk1.

I changed the water after about 100miles of running in.

Think I'll look into the temp issue a little more.

Maybe I'll pop the hoses off and check nothing has got dislodged and blocking them slightly

[Carlos W]

Anti-freeze contains a coolant and rust inhibitor

[smartie93]

Why not hook up a temporary one just to check? :)

Changed the water? But have never used anti freeze?

[gazza82]

I want to keep the original gauge in my mk1.

Doesn't have to be permanent .... lead to sender on a double spade terminal and wire with power from live (from memory though so check as I use a capiliary temp gauge as reacts more to temp changes).

Are top and bottom hoses as hot to touch as one another?

[Earwax]

Hi sounds like a good build , with a good spec on the cooling side of things. If 95-100 is the correct temp ( and again you seem to have verified this) it is a bit hotter than ideal, but not problematic. If however it is actually running hotter than this and the heater is the only thing managing to keep this from higher temps then it is a concern .  Do you know the oil pressure/ temps?

 

From easiest to less easy.. thoughts.    

Fan/radiator and shroud.. is the fan parallel and close (under the shroud).. otherwise not all air directed to rad.

Pulley size... i don't know if the S had a larger pulley,,, so better at high revs but at low revs slightly less volume

Radiator, ..you can get 16 fin per inch,,,, but yours should be better than most anyway

Water pump, tolerances can be a bit variable, which could affect volume

 

I have a similar car, running in the tropics with 16 fin Morris 1100 radiator( slightly wider) but everything else is similar including thermo 75 degree... mine runs closer to 85.  I sometimes add an auxiliary cooler ( basically a heater core mounted at the front behind grille, just a take off from heater outlet on head and reroute back to radiator)  and it operates too well in just normal driving , but is ideal for track days.

[dgear1984]

Why not hook up a temporary one just to check? :)

Changed the water? But have never used anti freeze?

I can't really see why I need to hook up another seeing as I know what the actually temp is with the gauge I have? I could put a thermocouple of the head for a digital reading.

The car has only done 300 miles of running in so with using just plain water, while still playing around you don't have to worry about splashing the paint with anti freeze when you drain it.

[klivins]

The original gauge might be inacurate. Check with other gauge, or other means.
My 1275 with 266 cam and tropical fan and 82 deg thermometer runs at 85 degrees max.

[Alex_B]

Run it with the proper mix of coolant and see what the temp readings are then, it is designed to raise the boiling point of water so its more effective at cooling the engine. 

[smartie93]

 

Why not hook up a temporary one just to check? :)

Changed the water? But have never used anti freeze?

I can't really see why I need to hook up another seeing as I know what the actually temp is with the gauge I have? I could put a thermocouple of the head for a digital reading.

The car has only done 300 miles of running in so with using just plain water, while still playing around you don't have to worry about splashing the paint with anti freeze when you drain it.

 

All I was suggesting is that you try another method to confirm that your method yields reliable result.  That would be the first thing I would do if you brought it into the workshop. I once ran a car with no fan and it ran below 90 as long as you were moving, and that was the complete opposite of a fresh rebuild. Hence why I would want to make sure there was actually a problem before looking for a solution :)

[dgear1984]

All I was suggesting is that you try another method to confirm that your method yields reliable result.  

 

 

 

Agree, yes, maybe my response tone read wrong, was not intended that way. Think also after the "playing" at the weekend my confidence in the gauge tests i did where a little inaccurate, somehow.

[dgear1984]

Hi,

 

Thanks for the replies. I realise I need to get to the root cause rather than "patching over it".

 

I put a temp sticker on the top of the head as soon as I got home from brighton, before the engine had time to heat soak too much and that only just blew the 93, the gauge was just onto the H, which according to my bench testing was around 105. It was running cooler on the gauge when actually travelling and yesterday was very hot in the afternoon.

 

Played around on the way down to brighton, didn't seem to make much difference if the heater was on or off, or with the fan on.

 

I think I need to run another test on the gauge as somewhere along the line, i think that has gone wrong. Ill see if I can find some temp sensors to borrow, either a capillary or an infra one. I think ill stick some more temp stickers on and see what I get. I think initially I was too confident in my gauge after the tests, which put me on the back foot i think.

 

All the basics are there, head was clean, block was clean, new pipes, rad, thermo, so its not like it is full of 40years of crud. Water level remains constant and not "blowing". Cowling is good and the fan is round the right way, i believe, although the fan becomes useful below something like 30mph i thought.

 

Hopefully it is just a badly calibrated gauge and I was having a little panic over nothing.

 

 

 

[dgear1984]

Got a thermocouple on loan now so ill put that in the water pipe and see what I get next time I get a day off. After my temp sticker test, I'm sure its the voltage regulator now..........

 

Ill get to the bottom of this and list my findings