Im scratching my head on this one and would really appreciate some help. 2 weeks ago, i brought my 2003 MCS, it was a spontaneous decision and one that im rapidly regretting. I intended to buy a Lupo GTi and kinda wishing i did now.
Ok, ill get into it now...Noticed the car loses water, as i was having to top up twice/three times in a day. A day or two later, it overheated on me, i didnt notice, until like a minute after, when a loud fan kicked in, looked at the temp gauge which was right at the top (red light on). So i immediately switched it off. Topped up the coolant after like 5 minutes and it didnt overheat. So i took it to a garage that my friend works at and started reading up on this forum and found loads of stuff on it.
I got him to replace the thermostat and the housing too. Which on inspection did not show signs of any leaks on the rubber with it or any part of the housing too.
We then suspected the radiator, he removed the bumper and got to the radiator and confirmed it was leaking from the bottom. So, i brought a replacement radiator and thought great, finally resolved! With the radiator replaced i was at the garage whilst he filled up the coolant to begin the dreaded bleeding.
After bleeding, we noticed that the water was pretty violent with the expansion tank and started to leak through that, from the cap and im pretty sure it leaked from the mid section of it too.
Now this is where im at now, ive ordered a replacement expansion tank and read up on the issues they have too.
However, my question is, should it be so violent in the expansion tank? If so, surely that'll mean that whilst it'll be temporarily contained by the new expansion tank, the life span of new radiator, expansion tank and all the rest of the cooling bits will be short, considering the pressure? Or could it be a more sinister issue (headgasket)?
Now, the other issue is, bizarrely the fan kicks in as and when it feels like it. Sometimes it wont kick in when the cars been on for awhile, but i must stress the temperature does not go up (remains at middle) and nor do i have a fluctuation in temperature internally (the hot air inside remains hot)..Yet sometimes it comes on after i switch the car off!!
Really sorry for the length of this, but felt the more info i give the clearer it is for me, whoever decides to help and for those that may have this problem too (God forbid!). I will really appreciate any tips, solutions, past experiences! Thanks in advance!
The first job would be to do a cooling system pressure test, that will soon show up any external leaks and if the pressure drops with no visual signs its probably internal, maybe a head gasket leak or even in the heater matrix behind the dash, are your carpets wet?
They can also do a sniff test on the coolant to check if any cylinder combustion gases are present in the water, that will give an indication if its the head gasket or not.
The fans can come on after you switch off the engine as the pump stops the heat momentarily builds up in the engine so triggering the cooling fans.
Also try this:
Fit a new pressure cap to the expansion tank this is often a cheap and easy fix on R53 MCS.......if the system does not pressurize correctly due to a faulty cap the boiling point of the coolant is lowered.
It is also essential to check the system is bleed of all air locks which can take time and patience and sometimes needs to be done more than once over a few days!
(Note: The R50 MINI One/Cooper have their pressure cap down on the engine thermostat housing with a plain cap/flap on the expansion tank)
Solving MINI Cooling Problems.......... Solving MINI Cooling Problems.......... - Forums Quote:
6) Coolant system pressure cap, which on an 'S' is on the expansion tank.....if this cap is opening too early because it's worn out, you'll get boil over, simply because the coolant is not being held at a high enough pressure and will therefore liberate gas at a lower temp....leading to gas pockets in the head and subsequent hot spots which liberate more gas, and so it goes. The pressure cap is often overlooked, but actually is a vitally important component.
R53 Cooper S - Supercharger / Water Pump
"A thing also worth checking if your MCS is having overheating problems is the supercharger water pump drive gears.
When they start to wear they don't drive the water pump properly this will cause overheating due to bad flow rates, and it's quite a hard fault to detect."
"In the case of the R53 MINI Cooper S, the water pump is driven off the end of the supercharger. This setup is a bit different than most cars (and R50 One/Cooper) where the water pump is driven off the engine belts. When a water pump begins to fail, youíll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a water pump, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running. You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, itís a fair bet that the water pump is failing." Pelican Technical Article: MINI Cooper - R53 Water Pump Replacement
PS. Stick with the MCS.......when fixed you will love it far more than a Lupo GTi
Thanks for the replies! I do appreciate them. Pressure test seems like my next step. I replaced the expansion tank, but more coolant actually started gushing out! I have the replacement expansion tank but not yet fitted as im worried the current pressure of the system is high, so im worried it'll force leaks from the new tank! The garage ive taken it to is a mate, who isnt too knowledgable but is doing it free of charge (parts on me obviously). He thinks that it might be down to not bleeding it right! He opens both bleed valves and pours water into the expansion tank, although water does come out both valves, it eventually starts to force its way out of the tank. Is that how you bleed it? Btw does anyone know of a good specialist in minis? (Midland area).
Thanks again ppl! Look forward to hearing from you
It is unlikely the pressure is too high but the coolant water will boil if pressure cap is not sealing/working correctly giving that impression, the pressure cap raises boiling point, it should be replaced first and only a head gasket leak to a cylinder will cause further excess pressurisation of the system.
Hi, update,what i meant was i replaced the cap on the original expansion tank, although i brought a new expansion tank but i never actually got it fitted in the end. The whole thing is acting strange. We fitted a new cap, it was leaking like i mentioned above, but this time i gave it a good squeeze. Wierdly, i drove it around today, no overheating and seems like theres no water loss ....one issue though...fan simply refused to turn on. I deliberately left it stationary but it just did not come on and it didnt come on when the car was off either. Question now is, how the hell does this fan system work? Im used to fans that come on whilst stationary for a length of time and that dont come on after the cars off. However, this fan has a mind of its own. Read up, that it could be a fan switch issue. Could it be a fan relay issue? Ive read countless posts that the fan has 2 speeds. (Low and High). With the low one being notorious for the resistor failing. People have put in a bypass so that when the car heats up, the high speed setting comes on, rather than the low speed. If so, ive been looking for a link for how to do this? Can anyone help? Is there no way of changing the resistor for the low speed setting without having to folk out for a new fan unit. Seems pretty silly that you'd have to change the whole fan unit just for a mild resistor.
Now youve sorted your water leak problem maybe the engine doesnt need the fan to come on, it will only come on if its getting too hot.
When it didnt come on was the temperature on the gauge higher then normal?
Hi its RuthlessMCS, i had to make a new account, because i couldnt sign in to my original account, even after using the "forgot password" option!
Water leak seems solved, again had a look at it today, no leaks same amount in there as before, chuffed about that. Now, i took it to my dads place (he has decent electrical knowledge), he had a look the fan connectors. Mine has two connections, to put it in simple terms (im pretty hopeless with this sorta stuff) 1 big connection and 1 small connection. He tested the connecting wire which i believe showed 12v. However, the connection did not show any resistance (sorry if this makes no sense, im not electrically minded, trying to repeat exactly what he said). He said the connection that comes from the fan itself (female) shows no power/resistance, he tested the earth with both bits (individually). He did not test the small female connection from the fan, he wasnt sure what the role of that was, it has two thin pins within it. So the reason, the fan is not coming on is because theres no power/resistance from the fan connection. However, the connecting wire and the relays were both tested and are fully working.
I seriously hope this makes sense to someone. Only thing i will add, is that previously i have heard the loud fan come on, it cant be ruled out that my friend who replaced the radiator may have knocked the wires for the fan. I will strip it down to the fan, but any ideas what the fault might be? Relay was in fuse box. From my understanding the test shows that both stage 1 of the fan and stage 2 are not working. Any ideas people?
All ideas/suggestions/thoughts as ever, much appreciated. My dad said he'll set it so that the fan kicks upon start up if i like. Worth doing?
PS. Your cooling problems have probably gone because you tightened the new pressure cap correctly if that is what you mean't by a 'good squeeze'......the cap must be tight and well sealed or higher pressure leaks out and the coolant boils in the expansion tank as a result.
"A liquid at high-pressure has a higher boiling point than when that liquid is at atmospheric pressure."
Google it if you don't believe me!
Hahaha i believe you ...I think ive read more on this website then i ever have in my life! Yeah the expansion tank cap needed to be tightened (thanks!)..
The issue with the fan, is not one that i can see in the links. The links that ive read refer to the low speed fan not working only. I seem to have an issue with both low speed and high speed. Neither come on. No response when air con is on either. I checked the fuse and relay and they seem fine. Im going to strip it down to the fan tonight and see whether anything has been knocked out of place, if not then ill get my dad on the case, to do some electrical tests! Hopefully the frame of that holds the radiator in place does not need removing! Is it me, or is the car built quiet flimsy? Esp under the bonnet?
If your checks indicate you have power going to the fan, plus good fuses and relays (eg. power when air con is switched on) then it seems to point to failure of the fan motor itself or its connections. The resistor if failed only causes the low speed fan to stop working.
The two connectors for the fan wiring are for the power to the fan (the big connector) and the low speed relay coil (the small connector). The big connector should have three wires, two red/blue, which are the power to the high speed and the power to the low speed, and a brown which is the earth connection. The small connector should have a green/red wire, which is power to the relay coil, and a brown, which is the relay coil return (earth).
The red/blue on pin 4 of the big connector is power for the high speed. This should be always at 12V as the power is switched through the relay, when it is turned on by power applied to the green/red wire of the small connector by the DME control module. The red/blue on pin 2 of the big connector is powered by the DME by turning on a relay in the fuse box. The power is fed to the motor through a resistor that is mounted on the fan assembly to give the low speed.
The Fuse box side of Pin 4 in the big connector will always measure 12V to ground, the fan side will read open circuit to ground as the relay contacts are open. With 12v applied to the small connector green/red wire the relay is turned on and the high speed fan should run.
The Fuse box side of Pin 2 in the big connector will only read 12V when the DME calls for the low speed fan to run. Measuring the resistance to ground on this pin on the fan side of the connector should read the resistance of the motor plus the low speed resistor.
Typical failures are the relay sticking, which will prevent the high speed fan from running, and the resistor going open circuit, which will prevent the low speed fan from running.
Thank you and mabs so much for your help, havent stripped it just yet, hopefully do it this week. Just a couple of bits i want help/clarification on, sorry..when you referred to the connectors are you referring to the male/female (male being the bit that goes in, female being the open bit that allows it to sit within it)? I should really know that. Im guessing your referring to the male, that correct. Other question is how do you determine pin 4 and pin 2...? Thanks again
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