Hot k-series, what's the cure?

[gundersen]

Yes I know, it has been done several times on the forums...but still after reading almost all k related cooling threads I am still none the wiser ☹️

 

Symptoms:

During the last two track days the temperature have been in the 115 degree region for both coolant and oil. We run in 20 minute heats so this is after 20 minutes of "spirited" driving. On normal use, the coolant stays at about 90 and the oil between 80 and 90 degrees.

 

The car is a 1.8l 140bhp X-Power SV with wet sump + apollo, the cooling system in the car is standard. As I understand it, the standard cooling system should be capable of cooling this setup even on track, so I am a bit stomped as to why it is getting so hot. I am new to trackdays, but I try to behave I don't rev the engine past 7000, but I do downshift while breaking as instructed by the trackday instructors.

I know 115 degrees is not catastrophic, but I would like to have the temperature under control before throwing performance upgrades at the engine

 

I am aware of three possible solutions:

1) Fitting a Laminova oil/water cooler

2) Fitting a bigger radiator

3) Fitting a PRRT

 

Seeing as both the oil and water temps where high, I am guessing that option 1 is not of much use. So should I go with a bigger radiator? any adverse affects by that?

I would like an option that works both on track and road as I do most of my driving on road

 

Any oppinions/ideas?

[shn7]

Have you checked the fan is cutting correctly before anything else?

[Paul Richards]

Make sure you have not overfilled the sump. Crank thrashing in the oil tends to raise temperature of the oil/entire engine.

[Roger Ford]

Do you have a thermostat? If so, bin it. You might need a bit of tape on the rad for cold days on the road.

 

Our race cars are a little down on your power (125 - 130) but they never overheat with standard radiators and cooling - the only difference being no 'stat.

 

(Actually we don't have heaters either, not sure if that's significant).

[makingff]

I had this problem on my 1.8 VVC although on the road rather than the track. Tried everything suggested in the forums but it would always run at around 95 and occasionally higher. In the end I bought a Radtec Extreme radiator and the problem went away. I can only assume that my standard radiator was not allowing the coolent to flow sufficiently to cool the water (or flowing too fast to allow it to cool - I'm no mechanic or scientist).

 

It now stays at 80 the majority of the time.

 

Simon

[gundersen]

Quoting Steve Newman: 

Have you checked the fan is cutting correctly before anything else?

Fan usually kicks in at about 100, so I think that is ok. Someone suggested that I check the direktionen. So I will be doing that when I get home.

[gundersen]

Quoting Paul Richards: 

Make sure you have not overfilled the sump. Crank thrashing in the oil tends to raise temperature of the oil/entire engine.

On the first day there where a bit too much oil in the engine, so I thought that was the reason for the high temps. On the second day I had the oil level in the lower half of the crossed section of the dip stick. Is that still too much?

[gundersen]

Quoting Roger Ford: 

Do you have a thermostat? If so, bin it. You might need a bit of tape on the rad for cold days on the road.

You think the termostat could be the cause when both water and oil is hot? I have checked the bottom radiator hose, and it warms up nicely.

[gundersen]

Quoting makingff: 

In the end I bought a Radtec Extreme radiator and the problem went away.

That was my initial thought, I just need a bigger radiator. But two things kept me back: 1) will it work ok with the rest of the standard system and 2) the standard system is usually sufficient at this level of power, so why is it not in my case

[CharlesElliott]

I don't see any reason why you should need a bigger radiator. Your temperatures seem off - the fan kicking in at 100 for a start. Can you see what the thermostatic switch on your radiator is rated at? That should be the temperature that the fan kicks in. Have you independently validated the temperatures shown on the gauge? Above 90 for water and above 100 for oil would seem hot to me. On track - so 20 minutes of extremely hard driving - I would not get above 90 deg for oil.

[charlie_pank]

Airlock?

Sticky thermostat?

Misreading temp gauge?

 

The fan cutting in at 100 sounds far too high. Don't know your car but in mine I'd check the water level in the read was right up to the bleed screw at the top of the rad...

[CharlesElliott]

I just checked and the standard K series fan switch is on at 95 off at 86. I (and most racers) have the low range switch which comes on at 82 IIRC.

[gundersen]

The temperature is bang on 90 during normal driving, so I think that excludes air locks and stuck stat. I am not sure how I can verify the temp reading, I am not too keen on opening a 100 degree pressurised system 😬 I have taken a reading from the ecu through the obd interface and it agreed with the gauge.

 

I did not know that the fan also plays a part in the cooling during driving, so I will give it a good check when I get home.

 

Thanks for all the support.

 

Edited by - gundersen on 22 Jun 2012 08:35:05

[mav]

I have noticed on occasion mine runs a it warmer - but not this hot.

 

You could try seeing if you can duct the air through the rad by blocking the gaps between the rad and nose cone.

 

Also a laminova will do you no good if both oil and water are at 100+

 

Check coolant level and type is correct.

 

Drain oil and dependant upon system (wet / dry sump / Apollo) re fill, measuring how much you put in.

 

You don't mention if you're drafting either - how close do you follow someone else, your temps can go up significantly if you're less than 10 - 15 metres away...

 

Check the fan switch, although it sounds like it is working....

[CharlesElliott]

Is your engine a standard Caterham supplied unit? Sounds like you have an 88 degree stat whereas I thought most people ran with 82 deg.

[charlie_pank]

Check gauge and sensor by removing sensor from water rail and dropping in to a pan of hot water with a thermometer. Switch on ignition and compare gauge reading with thermometer.

[Roger Ford]

You think the termostat could be the cause when both water and oil is hot? I have checked the bottom radiator hose, and it warms up nicely.

The 'stat restricts flow, even when open. If the water isn't properly cooled (due to not flowing well enough) then it can't do it's job of cooling the oil/engine. Not saying this is necessarily the problem, but removing it might help.

[Paul Richards]

Quoting gundersen: 

On the second day I had the oil level in the lower half of the crossed section of the dip stick. Is that still too much?

 

Sounds OK

[charlie_pank]

The stat is in the out, not the return so even if it's stuck you could find the bottom hose getting hot through conduction from the engine. Check it by taking it out of its housing and dropping it in a pan of hot water with a thermometer. Put the pan on the stove and heat it until the stat opens. If it doesn't, there's your problem!

 

You can check the fan thermoswitch the same way: put a multimeter on the terminals then drop it in a pan of water and see the resistance drop to 0 at the correct temperature as you heat the pan.

 

You can check the fan just by shorting the terminals on the thermoswitch

 

Then you can test the fan and thermoswitch together by running the engine whilst standing until the fan cuts in. Do the radiator and the top AND bottom hoses get hot? The fan should then cut in and out to hold temperature fairly stable, does this happen?

 

So far you have instructions for testing:

1) The temp gauges

2) The thermostat

3) The fan thermoswitch

4) The fan

 

If it's none of these things, we assume that the cooling system is specified well enough to do the job, so you must have a blockage/airlock?

 

 

 

[makingff]

Knowing that what I'm about to suggest may be completely stupid, here goes anyway.

 

When trying to get to the bottom of my problem, I did wonder whether the water pump could affect the overall temperature. My non mechanical / non scientific brain assumes that the pump must have to flow the fluid round the system at a certain rate for it to be effective and, if the pump was not functioning effeciently, it may cause the symptoms seen.

 

Am I being stupid?

 

Simon

[Nev]

I would be inclined to firstly check that the gauge reading is valid ( as other have said). I would also have thought that at the high temp you were showing that the expansion tank pressure relief valve may have started to open at least a bit ( may be wrong). If they are correct then next I would recheck for air in cooling ( preventing proper flow) and then check/change the thermostat.

Water pump efficiency could cause poor flow and reduce cooling so I dont think that is a stupid idead at all, however I think it unlikely to be causing your problem, and certainly not the first place to start .

ps. If you do remove the stat, use this as an opportunity to flush the radiator.

Hope this helps in some way.

good luck.

Nev

[gundersen]

Thank you sirs, very comprehensive suggestions. It is much appreciated!

I will get to work as soon as I can get off work 😬

[Myles]

Maybe not directly relevant to your current situation, but as something to possibly avoid for the future...

 

I changed to a Caterham triple-pass rad a few years back (with the biggest, high-performance fan I could fit) and the damned thing still does not like traffic one bit. It's absolutely fine on the move - temp drops rapidly leaving traffic for instance - but it couldn't control the temp effectively *in* traffic.

 

Swapped back to a standard rad a few weeks back - and the traffic situation seems much better contained - the fan kicks in, temp starts to drop (didn't used to effectively with the triple-pass) and then fan stops. I.e. works as designed.

 

My theory on this is twofold - firstly, the triple-pass contains more coolant (I understand) than a standard-rad (and therefore takes longer to cool) and/or the convoluted pipework impedes flow compared to the simpler rad.

 

Neither of these things seems to matter when you chuck 40mph+ wind at it - but even a decent fan seemed to struggle below that.

[Johnty Lyons]

On track the rapid fwd movement should render the fan irrelevant

Are you sure your Rad core is completely clean /clear and able to pass all the air through it that it is presented with.If Oil /water temps are similar Laminova is a waste of time

I suggest you also try a different gauge as if its a Caterham electric one its as much use as an ashtray on a motorbike.

[John Vine]

Quoting Johnty Lyons: 

I suggest you also try a different gauge

Yes, I'd agree with that. 90C in ordinary road driving strikes me as a bit on the hot side (I'd have thought 80C was more usual). Presumably you're measuring the oil temp using the sender in the Apollo? Are you reading oil and water temps on the same gauge (using a two-way switch)? If so, the fact that you're seeing the same track temps (115C) for both confirms that the two senders are equivalent (a good thing), and suggests that the gauge is over-reading.

 

JV