Very frustrated. Recently rebuilt head on my '06 r53-S, New CAM, head gasket, etc. Car was running a bit hot AND the coolant was leaking and we thought the thermostat had an issue. Replaced thermostat and coolant tank. All looked good until coolant started overflowing out of the overflow tank.???????
Could it be the water pump?
Help!!!!

 

What type of coolant tank? Some have some cheap caps.

Did you burb the coolant system? How many miles on the water pump?

 

New tank and cap from Mini (like the original), wonder if that's the problem again. Water pump may be original - mini has 110k miles. Mechanic pressure tested the system before I picked it up.
Thanks!

 

There is a screw on the radiator hose at the top. It is vitally important to get all of the air out of the system, or it will cause things like you are describing.
Also the cap need to be sealed well, as the tank is a pressure type. Many of us switch to aluminum cans.
Is the temp gauge reading high, when it looks like it is boiling over?

If you need to get it worked on by others, make sure to use a good indie dealer, that knows Minis well. Many little quirks that need to be done right!

 

With the engine cold, remove the black plastic screw that is in the radiator hose about 4" from the left end of the radiator. Start the car and when the water starts to rise and come out the hose, put the screw back in.

 

Guys, thanks much for the pic and the advice! I will try that and let you know how I make out. ������

 

I think Wayne is spot on. Air in the system. Not a good thing if you let the engine run too long. Picture when you douse the hot rock with water in a wet sauna. The other possible cause is defective expansion pressure regulating cap, but your is new and MINI so very unlikely.

 

^^ +1.

 

OK, got any air out of the system as was recommended. Don't think that was the issue. I've made sure the tank cap is firmly tightened and I can't see any coolant leaking from anywhere but yet it seems like the car is running hotter than it should be. I know that in the chrono package the temp gauge should normally read straight up. When I'm driving all seems ok, the needle is just to the right "12 o'clock", BUT when I slow down in traffic the temp starts climbing a little and I start smelling coolant. I've attached a pic if the temp gauge when this happens. Very odd?? Don't know where the coolant smell is coming from.

 

Did you overfilled the overflow tank? There is a max level indicator marking on the side, or a feature inside the tank. It should be called expansion tank to accurately convey its function.

The sweet smell may be the coolant drain from the drain hose at the tank and drip down onto the header.

Are your high and low speed fan functioning?

Also you said you got any air out, are you sure? It would be a question I ask myself if in your situation.

 

With no AC on, the low speed fan comes on at 221 (105C) and the high at 234 (112C). Can you hear the fans come on?

 

Check the heat shield under the expansion tank to see if there is coolant, or coolant stains, if so, that would indicate a bad cap or tank. Just as pnwR53S, make sure you didn't over-fill the tank. I know you replaced those items, there were many who purchased them new and they were no good..

 

The expansion tank has two hoses that need to be tight, or they will leak onto the header usually. The one on the bottom is most likely the culprit.
If the system can not maintain pressure, the temp gauge will go up at lower speeds and idle.
Smelling coolant is a definite sign of a leak and needs to be found right away, where it is coming from. Also check waterpump and thermostat housing.

 

+1 on checking cooling fan operation if temps are climbing while at a stop.

Also, to triple check bleeding, here's my superduper-trillion-time-tested R53 coolant bleeding procedure, for science:

1. Park car on a slight incline, so that the coolant bleeder screw is at the top of the cooling system. (optional)
2. Open radiator cap, start car, allow to idle until warm.
3. Close radiator cap, rev up to 2.5k, rest at idle for a few seconds, repeat 5-6 times.
4. Open coolant bleeder screw, and unscrew until you get the spray to arc. (Relevant)
5. Turn off car, and stand by the stream, listening (but not too close!) until it doesn't make any more "PSHHH" noises of the air bubbles interrupting/mixing with the spray of coolant.
6. If all the coolant pressure is relieved through the bleeder with the car off, but you still have some air, repeat steps 2-5 until you have a slick, uninterrupted stream of coolant arcing through the air and all over your favorite shirt/engine bay/garage floor/neighbor's dog/etc.
7. Troubleshoot all other steps with certainty that coolant is bled.
7a. Once the car is warmed up at idle, turn on the A/C to full blast. The high speed radiator fan should kick on around 10 seconds after the engine starts to shudder at idle from the drag of the A/C compressor.

If the radiator, thermostat, or expansion tank aren't leaking, the next logical place is the heater hose area behind the airbox. There are 3 plastic joints that connect the hoses and they get brittle with age. The best way to diagnose this is by jacking the front of the car up as high as possible and looking around underneath the thing with a high power flashlight. Look for crusty white crap. The good thing about these joints is that they're like $5 apiece at your friendly local dealership parts department. The bad news is that replacing them is a total PITA. In addition to the tools required to remove the airbox/ECU/etc, you'll need long needlenose, curved long needlenose, at least a growler of beer, and a few hours of patience--you'll be swearing at the thing the whole time. I've heard that a set of remote hose clamp pliers can make this job a piece of cake, but alas, I'm not a very bright cookie. If all other troubleshooting is unsuccessful and you have reason to believe these guys are leaking, you might save a substantial amount of time by picking up one of those. Although I only remember seeing coolant temp spike in traffic because of these things leaking when my coolant would get low.

Good luck and let us know how things work out!

 

So my quest to solve this problem continues. Thank you all for your advice and help. Don't seem to see any leakage from the new oem plastic expansion tank. Possibly from the lower hose but really can't positively say yes. will ke p checking it. Haven't tried what Sarom058 suggested with keeping the bleeder screw open to produce a stream of coolant to get out any air. Yesterday I noticed that the coolant level dropped a bit. Didn't see any coolant under the car. So I added some today and aired out the system. Also, after i added coolant I was going to air out the system and when I unscrewed the bleeder screw I noticed that there was coolant right to the top of it and some came out as I moved the hose. Is it normal that coolant would be there with a cold engine?

Tried the other trick of squeezing the top hose to see if pressure would build up and then release after I let the hose go. I was told that's a good test to see if the water pump is going but I don't think the water pump has a problem.

I'm gonna check the head gasket to see if theres a leak there but other than that I can't figure out why its running so hot and now all of a sudden dropping coolant level.
I should mention that after the car warms up and I shine a light into the expansion tank, I can see the coolant bubbling. And the temp gauge hasn't even peaked yet.

Oh, and had to jump the fan before all this started because the relay went. It comes on when I put the A/C on and after I park as is supposed to. So don't think the fan is the issue, but I could be wrong.

Keep sending me some advice and things to look for- it's much appreciated!

 

Well...I think I found the cause of my issues. Take a look at the pics.
There is a significant Crack in the valve cover below the ignition coil.
Looks like my shop over tightened the coil and cracked the valve cover.
I forgot to mention earlier that I was detecting some oil residue as well.
What do you guys think?

 

If the shop was the one who overtighten it and cause the crack, it is a definite sign of incompetence. I would wonder how well they perform the job of "rebuiding" the head, installing it onto the block, and carried out all the needed work to get the engine to proper running condition for a turnkey service.

I reread all you posts, and you never mentioned this job was not done by you. I also see no where you describe you witness coolant leak. The photos are oil leak, not coolant.

If you are sure about the car is running hotter, you need to investigate further. I don't have chrono package so I have no idea where the needle should be. Also since you have to have the head rebuilt, may be you are just used to seeing a worn engine that put out very little power, and hence also very little heat, and you simply are use to seeing the low gauge reading. There are a lot to think about, and there are insufficient information you provided.

There may be other issues with your car.

 

Yep, you're going to need a new valve cover. New ones come with new hardware and sticker, plus the cap. I would see if they will fix it for you.

https://www.ecstuning.com/News/MINI_R50_R53_Valve_Cover_Kits_25285/

 

I didn't see this long post from you until just now. If you are seeing bubbles rising from the coolant in the expansion tank, there are a few possibilities:

1. There is air in the cooling system because it has not been properly bled.
2. There may be a problem with your water pump, or your thermostat not opening when it should.
3. The shop F'ed up the head installation and combustion gas is leaking from a cylinder into the coolant passage. This most likely happen at the head gasket.
4. Because of the cooling system was not properly bled the engine overheated and cause a breach at the head gasket, or worst, a cracked head.

The plastic bleeder should always have coolant. Its purpose is to allow the air to escape as it is the highest point of the radiator. So when you unscrew it with the engine not hot but running there should be some coolant coming out.

 

If you are seeing bubbles, I would get a Block Tester to see if exhaust gases are in your coolant which would indicate the shop you had the work done, doesn't know what they are doing.

A bad head gasket would exhibit the symptoms of loss of coolant and overheating.

http://www.blocktester.com/instructions.htm

 

On my "real" Mini's center speedo the temp gauge noodle always point at dead center like this one once the engine is warmed up:




Your's definitely looks very hot:


There is no need to panic right now, just try to get to the truth. With luck the bubble you are seeing might just be air in the system that was not properly purged. When I pulled the engine/gearbox it was so easy for me to bleed the system that I can't remember exactly how. The most important part was at the beginning, I open the bleeder and let the engine run (from cold) and kept adding coolant as the expansion tank level dropped. I didn't drive the car until I saw the tank level stabilized, and that eventually the temp gauge pointed at the middle.

Like I said, with air in the system it is like dosing the red hot rocks with cold water in a wet sauna. You don't want to do that on an engine.

 

Based on the rather curious 27.5-degree increment on the temp gauge, you're at appx. 209°F when this phenomenon occurs -- not a ridiculously high temp, and if your coolant system as well as the coolant itself is "working." i.e., "fresh," that temp is not cause for alarm.

A few things:

A) As gumbedamit suggested, go to your local Autozone or similar and loan out a Block Tester, so you can check your coolant for exhaust gasses, and either confirm or rule out a head gasket failure. You're losing coolant 'somewhere' if you've correctly purged air from the system.

No leaks from the driver's side front of the block below where the water pump connects?

Check your carpet to the right of the pedals for wetness/coolant, as that's where a heater core would leak.

B) If your fan's low-speed resistor is blown (low-speed should come on at 221°F), the fan will not come on until your temp reaches 234°F, so if you're stuck in traffic, the temp will spike to that point until the 2nd-stage fan comes on. My guess is if your fan is coming on after you shut off the engine, your low-speed resistor is gone, and you either need to replace it, or the entire fan.

C) Find yourself a new mechanic, but before you do - make sure it is HE that pays for his ham-fisted destruction of your valve cover. It's beyond repair, and it needs to be replaced, not gooped up with JB Weld or similar...

 

Also willing to bet your low speed fan is gone and it is only the high speed working. If your fan is turning on after the car is off, and you weren't tracking it or doing some intense spirited driving, then your low speed fan probably isn't working and only the high speed is. With the low speed fan working you should rarely exceed 222F.

I have the chrono package as well and the needle is only straight up when you're at the 195-200F level (verified with a scangauge). It usually shoots to the 11:30 position when im stuck in traffic till the low speed kicks in at 222F and bumps it back down to 195. With AC on, the temperature rarely goes about 200 since the low speed fan is constantly running. If you're hearing a loud speed cycle on and off with AC on, thats the high speed fan only since the low speed is shot.

 

When it became clear that my coolant overflow tank was due for replacement in my '02 R53, I replaced it with one of the M7 aluminum ones earlier this year. I didn't get the M7 cap and have had issues ever since with losing coolant when I leave the car sitting for any length of time...

What cap should go on these tanks and how much pressure should it hold? Appreciate anyone who has had similar issues - everything else seems to be secure.

 

I hope you didn't pay too much for your tank, if it does not come with a pressure relief cap. The cap is to ensure the coolant does not boil too early or too late, including those live in the mile-high altitude.

My take on these tanks.

Your best bet is to use the stock cap.