Bleeding K series radiators

[Nick Woods]

Could someone please give me a quick run-through on the best way to refill the cooling system on a K-series ? I may need to take the radiator off to get at all the loose powder coat and want to avoid the airlock problems that others seem to have.

 

I dont have a proper workshop / owners manual for my 1.6K supersport. The owner before the one I bought the car from photocopied it , lost half the pages and spilt antifreeze over the rest. Oh, and he copied it onto music paer, old emails and just about anything else he had to hand. eek.gif

 

I've found a few bits and pieces in here about the problems caused by not doing it properly but I figure it would help me to know what I'm supposed to be doing in the first place.

 

Thanks

 

 

 

 

 

Nick

P8MRA - The green one with red wings

[First Man]

Nick

 

If you don't get an answer to your question before this evening, give me a call and I will read you the relevant section from my owner's manual at home. I will email you the telephone number.

 

First Man.

[1400rs_0of30]

I could scan the relevant page and email tonight/tom if required

[John Howe]

To refill cooling system (JJ reflected once that it was a black art for K series engines, but not so) ensure that front of car is well jacked up and the heater (if you have one) fully opened.

 

Remove the cap head bleed plug on top of the radiator and fill the cooling system via the plastic header tank.

 

If you find that the water level has stopped dropping in the header tank but you still have no overflow from the bleed hole, on top of the radiator, then fill the radiator via this breather opening until full.

 

Replace caphead plug and your done.

 

The real secret for an easy fill is to jack the front of the car up as high as possible - effectively guaranteeing the top of the radiator as the highest point in the cooling system

 

 

JH

 

 

[Geoff Dixon]

Like John says fill the radiator with coolant, can I suggest you use something like Comma's Synthetic coolant or water with Redline Water Wetter (K series are very senstive to water temperature and anything you can do to assist cooling will help engine) from the fill point on top of the radiator - sunken key headed "nut". Start engine, have heater open and let engine run for a while without putting the cap back on, let engine warm up: as it warms the the water level will drop so top up with more coolant. When thermostat opens close radiator fill point. All the time you are doing this keep squeezing bottom hose to get out all the air. I have never actually had to jack the car up , maybe I have been lucky, but have always managed to get all the air out by this method.

[Johnty Lyons]

Ah the old questionsmile.gif yep and if you have a heater loosen the j clip on the top one of the two to allow any trapped air out.

on what you put in there I can heartily recommend Unipart 4yr not 2yr summer coolant NEAT as it comes from the container and possibly some water wetter keeps the corrosion and deposits at bay and drops the mean temp by around 7/10 deg.

 

jj

[Tony Martyr]

Johnty: whatever coolant mixture you use you are not going to get as much heat transfer from engine metal as you will with pure water. I suggest the reason you are getting a lower temperature with 100 commercial coolant additive is that you are measuring the coolant temperature which will be cooler while the metal, that has retained more of its heat, is hotter. This is not what you want to achieve.

The key variable govening cooling and heat transfer is the specific heat of the cooling liquid, which for water is 4.1868 kj/kgK. The specific heat of ethylene glycol which is a typical coolant additive is about 2.28kJ/kgK and if you take its density to be the quoted 1.128kg/l the specific heat of a 50%/50% mix calculates as 80% of pure water which means that the circulation needs to be increased by 25% to give the same transfer and liquid temperature rise. This is the flow rate that the pump etc is designed for. The chemistry of the the ethylene / water mix is quite complicated but modern engines design have been optimised such that is truely best to do what it says on the tin. The k series in particular has had a lot of micro cooling investigation and head cracking tests. I recommend that the Rover agent's 4 seasons stuff is used as described on the pack.

The water wetter data shows that the best results are got from it plus pure water while the worst are with the higher percentages of glycol, you just can't beat the basic physics.

[First Man]

Nick

 

For completeness (!) I have emailed you the instructions from the manual.

 

First Man.

[Peter Carmichael]

Ethylene glycol *is* a typical coolant additive.

 

Propylene glycol is the stuff in the Unipart 4 year coolant, which is premixed to the right proportions with deionised water. It has better anti-cavitation properties and its overall anti-corrosion package does not degrade over time. This is the same stuff as Comma Coldstream.

 

Is Rover data on micro-cooling relevant to a Caterham installation where the radiator capabilities seem to tie the thermostat to its opening temperature? I cannot explain Johnty's "it runs cooler with watter wetter" asertion. It makes no sense given the placement of the thermostat and the temperature sender. I don't think a true picture can be gained by looking at the temperature at only one point in the cooling system. Hasn't Bernard done some work on this?

[Nick Woods]

First Man,

 

You are a star !!

 

Thanks very much indeed, I appreciate the effort you've gone to.

 

Thanks also to everyone else for their help

 

 

 

Nick

P8MRA - The green one with red wings

[Tony Martyr]

Peter and Johnty. I got the wrong molecule and did not know that it was in an aqueous solution, however the point I was making about the cooling capacity of the liquid still stands as valid. I do not understand how and where the coolant temperature would be lower than some brew of similar brew unless the specific heat was lower The water etter as I understand it has the efffect of reducing surface tension and in some way reduces the insulating effect of micro boiling.

The whole k series cooling system in the Caterham is odd and at odds with the temperature control and monitoring when in the test cell that I saw at Biceri

[Peter Carmichael]

Agreed that both glycols have a lesser heat capacity than water alone. Surface tension reduction is a good thing from a cavitation erosion point of view, so water alone would be disastrous in an aluminium engine like the K.

 

In order for the same heat flow to come out of the engine, either the temperature rise of the coolant or the flow rate must increase (probably both, because of the feedback loop using the thermostat). I would expect bulk fluid temperatures to be higher.