I overheated my 04 Mini Cooper R50 the other day, warping?

[Sg113]

Hi all,

I'm new to cars but have been taking baby steps into learning more. The other day whilst buying a replacement door for my Mini, I topped up the coolant and must have left the cap open.

The car starts smoking white smoke on the drive home and my dumb arse just assumes I spilt some coolant on the engine when refilling and that it's fine. The engine is still not too hot, right in the middle of the meter on the dashboard.

As I get home the light comes on that the engine is overheating, I drive possibly an extra 3 minutes and pull into the drive. That's when I realise that there's no coolant in the engine and that I had f***ed up pretty badly. I refill the coolant, bleed the system and drive back home 80 odd miles or so with no overheating issues (I had been at my girlfriend's place).

My question is: should I take the car to the garage to check if I had warped or cracked the head? The Mini has 130k miles on it and I have had it for about 6 years. I think I could remove the cylinder head myself after watching a few youtube videos but I should stress I am new to this. I have a decent Milwaukee socket set, torque wrench, jacks and stands.

Can someone with more of a clue give me their advice?

Thanks!

[paintman]

What is the car doing that leads you to believe there's actually anything wrong with it that requires investigation?

[GreenV8S]

Sg113 said:

That's when I realise that there's no coolant in the engine

That seems a bit of a stretch under the circumstances. Did you top it back up to the right level? How much coolant did it take? Any reason to think there is anything wrong with it now?

[gazza285]

If you had warped or cracked the head, you would not have driven eighty miles without issue.

Do not remove the head.

[Sg113]

paintman said:

What is the car doing that leads you to believe there's actually anything wrong with it that requires investigation?

It isn't doing anything wrong, I just thought I might have caused a problem that hasn't shown itself yet

[Sg113]

GreenV8S said:

Sg113 said:

That's when I realise that there's no coolant in the engine

That seems a bit of a stretch under the circumstances. Did you top it back up to the right level? How much coolant did it take? Any reason to think there is anything wrong with it now?

Probably took about 3L, I did top it back up to the right level and then drove it back without any issue. Do you think given I drove it home no issue that it's fine and I don't need to bother looking at it?

[Sg113]

gazza285 said:

If you had warped or cracked the head, you would not have driven eighty miles without issue.

Do not remove the head.

Nice, that clears it up perfectly thanks

[Monkeylegend]

If it ain't broke as they say.

[Crafty_]

Sg113 said:

It isn't doing anything wrong, I just thought I might have caused a problem that hasn't shown itself yet

Don't fix what ain't broke.

Keep an eye on both oil and coolant, if there are signs of oil & water mixing (mayonaise like muck under the oil cap or on dipstick or similar in the header tank) then you may have a head gasket problem. Even then, do not remove the head, get a compression test and leakdown test done to confirm diagnosis.
If you took the head off you aren't going to prove anything is warped wthout taking it to a machine shop.

WHat you will need to try and figure out is where you lost coolant in the first place - radiator leak ? cracked/holed hose ? I once had a coolant loss problem on a car and found it was a seam int he header tank giving way under pressure. Have also seen header tank caps leak/not hold pressure.

Of course the original issue could be head gasket and coolant has been lost in to the cylinders, sometimes you can detect this by the exhausts gases smelling a bit sweet from the antifreeze.

Keep some water in the car and check levels every day

[rev-erend]

Putting a cap on the water system of a car serves 2 purposes:

1. Stops water escaping when it moves around..

2. When water gets hot it expands, pressurising the system which helps gain a few degrees of extra cooling
but in the winter its not really an issue.

So, just top it up with water and drive it.. should be OK.

Check the water level regularly when the engine is cold, if it looses water then that is the time to investigate further.

[GreenV8S]

Sg113 said:

must have left the cap open.

There's no reason to speculate about the cause. Obviously you've filled the coolant up since then so you know whether the cap was fitted and whether it was done up tight. Was it?

Leaving the cap off / loose would not boil off 3l of coolant in that short a journey unless the engine had also overheated and boiled the coolant. You need to know where the coolant went. Are there signs that a lot of coolant boiled out of the pressure cap opening?

[Sg113]

Crafty_ said:

Sg113 said:

It isn't doing anything wrong, I just thought I might have caused a problem that hasn't shown itself yet

Don't fix what ain't broke.

Keep an eye on both oil and coolant, if there are signs of oil & water mixing (mayonaise like muck under the oil cap or on dipstick or similar in the header tank) then you may have a head gasket problem. Even then, do not remove the head, get a compression test and leakdown test done to confirm diagnosis.
If you took the head off you aren't going to prove anything is warped wthout taking it to a machine shop.

WHat you will need to try and figure out is where you lost coolant in the first place - radiator leak ? cracked/holed hose ? I once had a coolant loss problem on a car and found it was a seam int he header tank giving way under pressure. Have also seen header tank caps leak/not hold pressure.

Of course the original issue could be head gasket and coolant has been lost in to the cylinders, sometimes you can detect this by the exhausts gases smelling a bit sweet from the antifreeze.

Keep some water in the car and check levels every day

Thanks for the advice, i'll keep an eye out for all those things - I saw a "test kit" online that sucks up some gasses from the engine and turns blue if there's coolant in it. It wasn't much so I think i'll pick one up

[Sg113]

GreenV8S said:

Sg113 said:

must have left the cap open.

There's no reason to speculate about the cause. Obviously you've filled the coolant up since then so you know whether the cap was fitted and whether it was done up tight. Was it?

Leaving the cap off / loose would not boil off 3l of coolant in that short a journey unless the engine had also overheated and boiled the coolant. You need to know where the coolant went. Are there signs that a lot of coolant boiled out of the pressure cap opening?

Hi there - when I was driving home there was lots and lots of white smoke coming from the back of the bonnet where the expansion tank is so that was why I assumed I hadn't put the lid on properly. There weren't any signs of it around the expansion cap opening but I'm not sure what i'd be looking for if it was vapour.

The engine must have also overheated and boiled the coolant like you said. I'll keep an eye on the coolant level.

Another question: If I have topped the expansion tank up to between the min/max before running the car when everything is cold, what should happen when I run the car? Should the level in the expansion tank drop whilst the engine is hot? Should the level go up? I find when I fill the expansion tank and then run the car the level drops and once it is cool it is back up to where I put it.

Thanks

[paintman]

Are you losing any coolant?
If you aren't & there's nothing else wrong then I suggest you stop worrying about it.
Unless you particularly want to buy & fit a new cylinder head.

[GreenV8S]

Sg113 said:

there was lots and lots of white smoke coming from the back of the bonnet where the expansion tank is so that was why I assumed I hadn't put the lid on properly. There weren't any signs of it around the expansion cap opening but I'm not sure what i'd be looking for if it was vapour.

If it lost so much coolant that it was no longer able to cool properly, that would explain the steam and overheating, but wouldn't explain why the coolant was lost. You'd topped it up before the problem happened so it would have had to lose the coolant pretty quickly.

An engine shouldn't lose several litres of coolant that quickly without a good reason. Running with the pressure cap off in hot weather might do it, but the weather is obviously not hot currently, and you didn't say you were running with the cap off.

You mentioned that you are new to cars and were topping up the coolant, so perhaps this car is new to you and it has a leak you aren't aware of. How long have you had it and how much coolant did it take when you topped it up prior to the problem?

[Sg113]

GreenV8S said:

Sg113 said:

there was lots and lots of white smoke coming from the back of the bonnet where the expansion tank is so that was why I assumed I hadn't put the lid on properly. There weren't any signs of it around the expansion cap opening but I'm not sure what i'd be looking for if it was vapour.

If it lost so much coolant that it was no longer able to cool properly, that would explain the steam and overheating, but wouldn't explain why the coolant was lost. You'd topped it up before the problem happened so it would have had to lose the coolant pretty quickly.

An engine shouldn't lose several litres of coolant that quickly without a good reason. Running with the pressure cap off in hot weather might do it, but the weather is obviously not hot currently, and you didn't say you were running with the cap off.

You mentioned that you are new to cars and were topping up the coolant, so perhaps this car is new to you and it has a leak you aren't aware of. How long have you had it and how much coolant did it take when you topped it up prior to the problem?

I've had the car about 6 years, when you say "pressure cap" i assume you're not talking about the lid on the expansion tank but the black cap further in the engine that says 1.1 psi on it or something to that effect.

Tbh that could have been open - I should have included it in the original post but essentially what happened was:

- I went to get this new door, the guy selling it to me needed access to my battery to power down the glass on the new door I had just bought (the mini he had taken it off of didn't have a battery or any engine for that matter).
- He used some jump leads in my car and some old cable out of the mini he was breaking to hook my battery to the door and power down the glass so it would fit in my boot.
- When I opened the boot he noticed the expansion tank was low and said I should top it up, he then took the black cap with 1.1 psi on it off (i think this might be the "pressure cap") and said "there's coolant in the system so just top it up and it'll be fine". That's when I topped up the expansion tank so either I left the cap loose on the expansion tank (it's on a hinge) or he left the pressure cap loose.

Hopefully that clears it up a little, i'm going to monitor the coolant level over the next few days to make sure I don't have any leaks that i'm unaware of.

Thanks for all the help

Edit: prior to the problem it didn't take much coolant, i just topped the expansion tank up maybe 500mL?

[Western Musketeer]

Make sure that you keep the anti-freeze to the required level if you are just topping up with plain water