4 age Cooling Problem

[warrenc]

Hi guys, I'm having issues with the cooling of my 4age which I've installed in my mini. The cooling system is pretty standard except the rad is from a Nissan Micra. Now before you all shout 'fit a bigger rad' hear me out:

When driving on a flat dual carriage way at up to 3500ish rpm, its fine. Up hills it will start getting warm. If I sit at 3500-5500ish rpm, it gets almost to the red. Over 5500rpm, it cools down a bit but is still near the red. If I sit at 5500rpm with it near the red and floor it (which is quite interesting in a 4age powered mini :icon_lol: ) the needle actually drops as if its had a shot of cool water through the engine.

I'm wondering if the cool water in the rad isn't getting circulated very well? Can anyone help with this? I need to get it sorted as I've got a DTA ecu and ITB's waiting to be fitted, but there's no point if I can't keep it cool :icon_sad:

[Jiff Lemon]

Hows the cooling system laid out? got a fag packet drawing of it?
What are you reading the water temp from? Aftermarket temp gauge? MR2 cluster?

[snowtigger]

i know this sounds simple but have you bled the rad of air, the standard mr2 has a bleed valve in the front rad and one in the bulkhead for the heater matrix, is it front engined or rear in the mini?

[Whore of Babylon]

Front, its setup like a normal car i believe. Maybe the lines are too small and its cavatating insted of pushing water. what size/length are your hoses?

[warrenc]

Thanks for the reponses, I'll try and get some detailed pics of the installation up tonight. The engine is front mounted:

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/126.jpg

Here it is with the rad removed:

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/127.jpg

The plumbing is pretty much as it is in the MR2, except for the hoses to the rad which are much shorter. If you look closely at the second pic above, you can see that the bottom hose to the rad has a hump in it before it joins the thermostat housing which could cause an air lock. The rad top hose is slightly higher than the rad filler cap, but I jack the passengers side up when filling it so the filler becomes the highest point. I've just had a look at my rolling road power graph and the engine produces 58bhp at the wheels at 3500rpm, which equates roughly to the peak bhp of the Micra at the wheels, but they must build in some over capacity so the rad should be up to the job. I have the cooling fan and heater on full blast all the time when its running and I've cut away as much of the fibreglass front end and grill away as possible so most of the rad is exposed to fresh air from the front. The gauges are in the standard MR2 cluster and the sensor is the MR2 one as well.

[cdwood2010]

I agree with Jiff! A quick sketch of the cooling system may very well answer your question.

Assuming that the stat is sound and you've flushed the rad?

C.

[snowtigger]

And the 4age should be producing in the region of 120/130+ bhp double the 57bhp agze supercharger 190bhp or turbo.

So double the rad size and hey presto, I know the hotted up A series turbos need a bigger rad and there in the 150+ bhp, plus the k series needed bigger rads even with the 1.8 into the mini plus don't get me started on Honda vtec 250+bhp.

Would love a pimlico with 500bhp rear mounted hyabusa engine.

[warrenc]

Yup, it peaked at 112 bhp atw, so maybe the rad is a tad on the small side. It was the drop in temp when you floor it that made me think there was a problem with circulation. Not going to be able to detail the system tonight, so it'll be in the next day or two.

[snowtigger]

Obviously the footies on my bet is the rads too small and thin look at a mk1 rad a v6 copes equally as well as on the mk1 rad were as a mk3 v6 will overheat on spirited driving and is to thin plastic alloy modern crap rad.

[warrenc]

Well, I've found the time to have a fiddle with the cooling system with some success. The hose with the hump has been replaced with a hump free hose. I also found a small leak from the hose from the thermostat to the pump. This leak seemed to draim water from the back of the engine, but not from the radiator. This meant that although the water level in the rad was fine when checked, the system was actually low on coolant. I've now cured the leak, topped up the system and bled it thoroughly and been out for a 'spirited' drive. The cooling is now massively improved, but I may still look at fitting a bigger rad.

[cdwood2010]

Good news, all part of the journey.

Bugger rad sounds like a good idea. You're kinda in uncharted territory so some fishing around to get things spot on is always expected!

C.