10 replies to this topic

[flamejob]

Hi/Help!

Another case of engine too hot. After reading about five other threads about it I would like to know the actual temps that are normal.

The car is a completely standard Carb sprite. The system has been flushed with flushing agent (left in for four days), thermostat tested and replaced (after grinding the housing off) and fresh new coolant added. The plugs look normal and the timing is as close to dammit as you could get without RRing it.

I have an optical thermometer (a bit like this so can very accurately measure the external components.

When the temp gauge reads half (too hot historically), the top hose is 90deg and the heater inlet is about 88deg. I havn't measured it yet, but at motorway speeds the temp goes up to 3/4 on the gauge. It never tops out because the electric fan kicks in and stops the temp going into the red when at idle. In past experience the belt driven fan should stop the car getting that hot at idle.

I think what I would like to know is what should the top and bottom of the radiator be so I can rule out getting a new one.

Could it be the pump? The Haynes seems to thing you only replace the pump when it is leaking or seized.

My gut feeling is that the gauge is correct because of the smells and noises the car makes when run.

[alexcrosse]

that lovely water and oil smell? id replace the rad, put a 2 core in it. Mine used to be a sprite and did it all the time. Water pumps £20 or so and well worth doing, radiators however much you want to spend and could be the problem. Whats your oil pressure doing? What does your rad look like inside? orange? mind did!

2 degree's cooling isnt enough, also, put the fan on a switch next to a water temp guage measured in degree's. £17 for a guage and nothing for a switch. Run it off the relay in the top right corner as you look into your bonnet, gr/w cable i think, just needs to go through a switch to an earth

Edited by alexcrosse, 03 September 2007 - 08:07 AM.

[biggav]

under normal conditions, (car moving over 20mph) the engine temp should not really be going across to the hot side of normal. air flow around and through the engine bay should be adequate to keep the temp at ideal.

When my car was overheating it turned out to be running lean, not due to carb setting but due to a gasket on the carb spacer alowing air in, changed all the gaskets and also i changed a 4 core rad for a 2 core which made it loads better. also an oil cooler helped. (bear in mind i have a stage 4 1380, so oil cooling is a necessity.) you can check for a lean burn with colour tune or a rolling road.

basically, if any coolant is overcoming the the seal on the rad cap, its too hot... once this happens, your coolant boils off and your engine overheats. as long as i'm not loosing coolant under normal driving (exluding very hot days and traffic jams) then all is fine (though i switch the engine off in traffic jams)

[alexcrosse]

yer nice on biggav that reminds me, take your plugs out, mine were grey (lean) and there was nothing i could do about it, no adjustment on the HIF44, have you put a different filter on your car? cone or internal job? stage one kit? because the needle will need changing in your carb for a richer one all over.

[Ethel]

It would be impossible to give a temperature, it will vary according to the load on the engine and from engine to engine depending on the compression ratio amongst other factors. It will also range from nigh on a thousand degrees in the exhaust manifold to under a hundred (hopefully) in the water jacket.

If your cooling system is adequate it should be able keep the coolant fairly close to the rated temperature of the thermostat regardless of the operating conditions.

[Ethel]

By heater inlet do you mean the hose on the opposite end of the head to the thermostat? Water flows from there to the hose that branches off the bottom hose: it should be as hot as the top hose.

88c is also likely to be exactly the temperature rating of the thermostat.

[flamejob]

Ta alex/gav

It seems weird that the rad could be that affected by scale etc. Water flows through it as normal (when flushing the system) so I assumed it would be ok. I had avoided replacing it because it's MOT time and there are other things (front ball joints & emmisions) that are worrying me.

I think I might just bite the bullet and buy them. Saves worrying eh?

[alexcrosse]

yer, there not too expensive. water will still flow through it fine. Get a 2 core. But i reccommend changing the needle first, have you put a stage one, or just a cone filter or K&N like element in there?

[flamejob]

No stage 1 yet, I am trying to unravel the MOT red tape around early '92 cat/carb sprites. To keep cat capability or not etc.

Edited by flamejob, 03 September 2007 - 03:31 PM.

[redhotmini]

you should be ok with removing the cat on the early carb/cat minis. quite a lot of mot testers dont really know every rule in the book

[biggav]

just because water flows through a rad doesn't mean it will work A1.... air flow through the veins of the rad is where it looses its heat from. yes you need good water flow but i remember reading somewhere (either on here or from the vizard book) that the water pump is at its most efficient fairly low in the rev range and an increase in flow rate makes little difference to the cooling efficiency theoretically a 4 core rad has a bigger surface area to exchange heat over but i have been told that the 2 core has better air flow through it which makes it a more efficient choice....

There are some very good Mini Docs here somewhere who will be able to sift my statements for myths and facts as i have been told in the past, a little knowledge is a dangerous thing!!!!!! (and i have not had much sleep!!!)