Radiator temperature

[jammacdo]

Guys

Sorry for the noddy question but I seem to be having cooling issues.

Basically the rad was removed with the clam and I thought it had been bled properly but it seems the following is happening.

The bottom hose (nearside) doesnt get that hot. In fact its positively cold when the offsite edge of the rad (feeling inbetween the slots in the front clam cover) is roasting hot. The other side of the rad (nearside) is also barely warmer than cold.

I bled the bottom hose from inside the wheel arch and did get some air out. But its not exactly what you would call an even temperature. Is this normal?

I installed one of the Elise Parts adjustable radiator thermostats and put it in the hose below the bleed nipple. Even when its set to lowest temp it takes until its 90c at the dash display (temp sensed from the block sensor) before it kicks in. So Im wondering if its worth it as this is when the standard setup would start the fan.

Note: What I mean is I got some air out and then the hose/nearside edge of the rad did get hot but then after cooling it doesnt exactly warm up like the other side does.

Advice welcome

[robin]

The point of the radiator is to shed heat, so you expect the egress pipe to be cooler than the ingress pipe. Normally if you have an air lock, revving the engine will overcome the air lock temporarily, so you can see whether anything changes in terms of temp gradient across the rad whilst you are doing this.

Did you bleed the engine bay nipple also?

It can take time to get all the air out - keep bleeding it periodically.

I am sorry to say that I didn't understand the bit about the elise parts stat install - are you saying you've installed a stat into the return path from the radiator to the engine? I don't immediately see how that helps ... but maybe I am being dumb!

Cheers,
Robin

[jammacdo]

Robin - Correct

I installed the adjustable temp sensor on the return pipe so I could potentially lower the temp that the fan came on. Trouble was I should really have put it on the other side of the rad. I switched the wiring back to use the sensor at the block (the standard setup) since it seems to work about the same temp anyway.

Looking at the car again tonight and bleeding both front and rear nipples again, I didn't see any air coming out.

The car was running just under 90c but I used to see it run at 85 (before the rad was removed). Maybe I am being paranoid. Is a temp of 89 - 93 when running normally (and its pretty cold outside) normal?

I had though I might have a sticking thermostat but perhaps it was just not hot enough since I understand the thermostat opens at 90c and it wouldn't go higher than 87c sitting in the garage tonight.

Maybe I should just drive it

[jammacdo]

Suppose I should add the resolution....

I managed to drive for 45 mins home on Saturday. Checked the nearside radiator endcap and it was still cold. Offside was roasting hot. So presumably the thermostat was still closed since there was clearly no flow through the system. With no flow the rad fan certainly isnt going to trip. Temp didnt read higher than 86c according to the Stack display. So for nearly an hour there was no circulating water, isnt than air cooling only?

Once in the garage at home, sitting still I held the revs at 3k. After a couple of minutes the thermostat opened and then the rad fan kicked in. So it does all work but it seems to be happy with being cooled by airflow plus heater into the cabin. I should note that it was about 5c outside and I was driving on rural roads sedately.

So it seems its fine but I was just re-familiarising myself with how the car really works.

[robin]

That all sounds about right.

According to your previous post, your stat opens at 87 indicated (that's why the temp levelled out at 87 - it's being regulated at that by the stat).

Note that the indicated temp will increase when you add electrical load due to the rubbishosity of the wiring. Thus with cabin blower and headlights on 86 will become 90

I now understand you've installed a remote temperature SENSOR not a STAT into the return hose. I see no benefit in this approach vs relying on the block egress temperature (which is where the standard sensors are installed). The block egress is the hottest point of the coolant, so it makes sense to use this to trigger the fan operation. Note that the stack display and fan operation are controlled by different sensors (from memory the brown sensor controls the fan and provides the ECU with engine temperature and the blue sensor is only used for the stack).

Finally please note that the fan is a last resort measure on the S1 (at least in normal UK weather) - the cooling is such that it should only be required when the car is sitting in traffic or climbing hills where engine load is high and airflow is low. In all other cases (cruising on motorway, A/B road driving, etc.) the air flow exceeds what is required to maintain engine temp, hence the return pipe is cold after a run.

Cheers,
Robin

[campbell]

With the car left at idle for 5-10 mins (when fully warmed) the fan should kick in.

Craig of Murray fame recommends this as a regular procedure, as the fan is otherwise little used and prone to seizing up. Then the fireworks really start...!

[Dominic]

With the car left at idle for 5-10 mins (when fully warmed) the fan should kick in.

Craig of Murray fame recommends this as a regular procedure, as the fan is otherwise little used and prone to seizing up. Then the fireworks really start...!

With the Elise Parts radiator in mine, it never gets above mid 80's at idle - even after a thrashing, and come to standstill, the most it reaches is 89 - only once on a very hot summers day did it go high enough for the fan to kick in, and that was after a good blast, followed by a long tie stationary with the engine on.

Must check my fan at some point!....

[campbell]

Interesting. And impressive! I have all-Alu rad but it's not the EP one, just std but without the silly placcy end caps.

[robin]

Campbell, your water pump is 100,000 miles old (about 250 million revolutions of the water pump) ... it may well not pump that well at idle

Holding 2,500RPM in neutral for 5 minutes should certainly bring the temperature up close to fan operating point, and it is worth making sure it kicks in now and then.

Cheers,
Robin

[Dominic]

Campbell, your water pump is 100,000 miles old (about 250 million revolutions of the water pump) ... it may well not pump that well at idle

Holding 2,500RPM in neutral for 5 minutes should certainly bring the temperature up close to fan operating point, and it is worth making sure it kicks in now and then.

Cheers,
Robin

Might try that for mine to check the fan.

[jammacdo]

Thanks for the feedback guys. Was worried there for a few minutes on Saturday and nice to get confirmation that mine is working as expected

At least I now understand the cooling a bit more than before. Oh to think I used to drive the thing without a clue about what was going on underneath

[campbell]

Campbell, your water pump is 100,000 miles old (about 250 million revolutions of the water pump) ... it may well not pump that well at idle

Should I be worried?!

[robin]

I assume it will be replaced as part of the engine overhaul? I wouldn't worry about it ...

[woody]

Campbell, your water pump is 100,000 miles old (about 250 million revolutions of the water pump) ... it may well not pump that well at idle

Holding 2,500RPM in neutral for 5 minutes should certainly bring the temperature up close to fan operating point, and it is worth making sure it kicks in now and then.

Cheers,
Robin

Might try that for mine to check the fan.

The manual tells you to do that after bleeding the system...thought you had a copy?

[campbell]

I assume it will be replaced as part of the engine overhaul? I wouldn't worry about it ...

Oh yes.

Which reminds me. I need to give that project some thought. Wonder if my 2014 bonus will cover it...might need to be post-Frolic...