Overheating on 216i

Hi

My 7 year old P reg 216i (new shape) has recently started to overheat on short journeys (~5 miles) on the motorway. On a recent 1hr trip to Ikeaaaargh, the coolant overflowed bubbling out of the tank onto the road just as I was parking up, and I did smell burning while on the motorway but assumed it was a lorry's tyres or something.

I took it to the garage and they couldnt find anything amiss but they replaced the filler cap just in case (they've got to make their money...;o))

The symptoms are as follows...

The needle sits at less than 0 for about 2 miles then starts creeping up to halfway then shoots down as the fan kicks in then maybe 10 seconds later starts creeping up again then drops back to about 1/3 full scale then stays there and occasionally shoots up minutes later and then drops down again.

Currently its not getting above halfway before the fan cuts in but I'm worried its the start of something that could prove to be expensive.

Is this "normal" behaviour as it never used to do this? If not, anybody got any ideas?

Do the words "blown head gasket" loom large on the horizon...?

TIA

Mike

Reply to
Mike C
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It's not normal -s ounds like the thermostat is sticking and isn't opening soon enough - then sticking open/shut causing the erratic temperature. So the water in the engine is getting too hot, and when the thermostat eventually opens the near-boiling water immediately kicks off the radiator fan, and the cold coming back from the radiator causes the engine temperature to drop. A new thermostat would be a wise investment, making sure the whole system is flushed out at the same time

Very large if you don't get this sorted! These temperature fluctuations are putting additional stresses on the engine, and loss of coolant is the main reason for the gasket failing.

Reply to
Bob Davis

Get your Thermostat replaced - the cost is minimal.

Yep :)

If you'd stopped straight away when it first got hot, then it would prolly be fine. It's quite likely you've knackered it by driving around.

Reply to
Nom

A local garage suggests over the phone that the coolant system may not have enough water in it (though the level is showing near the max mark when the engine is cold) and needs to be topped up after running the engine hot at idle. I will try this but thanks for the thermostat suggestions - that will be my second line of attack.

I checked the surface of the liquid in the coolant reservoir and it may have a thin oily "rainbow" film on it which some other site suggested points to head gasket problems. The rainbowiness may not necessarily be oil though - how thick should it be for it to be head gasket problems?

Reply to
Mike C

I would be very suspicious - possibly a little oil seeped past the gasket when your engine overheated and the coolant boiled, so keep an eye on it. If the gasket has gone, the coolant will become more and more contaminated and it will be obvious. I wouldn't have thought that low coolant was your problem, if the coolant is low you get problems very quickly - the coolant will not circulate but just boil when the car warms up, so it would be obvious in a short time not just at the end of a long journey. If the header tank is up to the mark, and you have run the car a few times, any air bubbles will have worked their way out and low coolant is not your problem.

Reply to
Bob Davis

I've now checked the coolant level and after running the engine hot, it didnt need topping up.

What I dont understand is the unrepeatability of the symptoms (which is the needle creeping up to half way then dropping suddenly back to normal).

I do the same journey every day in the same traffic conditions - ~1 mile @ 30mph, then 7 miles @70mph. The weather has been about the same for the last few weeks (ie frosty (but >0degC) in the morning) Some days it doesnt happen, some days it happens after about 5 minutes. Today and yesterday it didnt happen at all. But today I stopped off at a shop at the end of my journey for three minutes (engine off) - I pulled away, a few seconds later the symptoms occurred.

Given roughly the same conditions of use (engine usage, traffic, weather, coolant level), shouldnt there be a repeatable pattern?

Would a sticky thermostat/broken thermostat give this unpredictability?

PS: The oil in engine is clear brown - no white sludge anywhere.

Reply to
Mike C

contaminated

Yes it could - the problem is that it isn't operating smoothly. When it sticks, the problem happens, but it's obviously not happening all the time. The thermostat uses expanding wax operating against a spring - if it sticks, the wax carries on expanding, but doesn't manage to force open the thermostat until beyond the normal temp. When it cools, the spring has to overcome the stickiness too.

That's a good sign!

Reply to
Bob Davis

contaminated

As I've already said :

Reply to
Nom

Thanks for your replies, esp Bob.

The plot thickens.... we've ruled out the head gasket we've ruled out a coolant leak there's a possible thermostat problem but...

I've been told that Rover 216's have their needle calibrated to be in the dead centre of the temp guage when the engine has warmed up. Mine reaches just above the min mark (and has for 5yrs+). When it rises suddenly it reaches halfway. This could mean the sensor's faulty, or even the guage? Do these sensors fail suddenly or just go intermittently.

Any Rover 216 users out there tell me where there needle normally sits after the engine has warmed up?

Reply to
Mike C

I don't think the guage/sender is always calibrated that accurately, so if it's not spot-on there's no cause for concern. It may well be that your gauge/sender combination is reading low, and fitting a new sender might give more centred readings, but in the meantime I would assume that any rise over

*your* normal warmed -up reading is a sign that things are getting hotter than they used to. The gauge part is normally extremely reliable, and if it does fail would usually just read zero at all times. The sender and wiring sometimes give problems, but you have other symptoms such as the overheating/boiling over which need addressing - a faulty gauge or sender could not cause this. Having said that, it's very cheap and easy to change the sender, but I would see what happens with a new thermostat first.
Reply to
Bob Davis

I see what you're saying "Nom" and if I was certain it was the thermostat, it would be in the garage like a shot but what I dont want is them to change the (possibly healthy) thermostat only to find it isnt the cause of the problem.

I've already been down this road with the garage and replaced a (presumably healthy) expansion cap as it didnt solve the problem. I dont want them spending any more hours (=££s) trying to trace the problem down when I can freely consult with people on this forum who may instantly recognise the symptoms and save me money.

thanks for your time in any case.

Reply to
Mike C

Why not ?

It's a 15 minute job, and the part costs less than a tenner. If it doesn't solve the problem, you're no worse off.

I am recognising the symptoms as a dodgy thermostat ! Why are you so reluctant to try the thermostat ?

Reply to
Nom

Stop this madness !

Both me and Bob have suggested the thermostat, so go and replace it !

Why ask here, if you don't act on the replies you get ?

Reply to
Nom

OK I'll get a new thermostat fitted and see what happens....

Reply to
Mike C

Let us know how you get on. Cheers Bob

Reply to
Bob Davis

Car now fixed - needle solid as a rock in the centre of the gauge - got both thermostat and temperature sensor changed just to be sure - mechanic thinks it was the sensor but could have been thermo as well.

thanks again

Mike

Reply to
Mike C

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