I have a 1996 899 cinq with a temp gauge, trouble is the gauge stays at the bottom or just above the bottom (about 50 degrees if the gauge is correct), the fan cuts in around 90-95 degrees (again if the gauge is correct).
I'm sure there's a problem, as I thought the whole point of having a pressurised cooling system is to raise the waters boiling point over 100 degrees.
So, surely my car's operating temperature must be more than about 50 degress and the fan should cut in at a higher temp than 90-95?

So there's my problem, as for a solution could it just be a temp switch on it's way out? Or perhaps the wrong temp switch fitted?

Or could it be a problem other then the temp switch?

Many thanks in advance for any help/suggestions.

Your thermostat has stuck open. It should be closed until the engine reaches operating temperature - approx. 70 to 80 degrees. Then it opens allowing the hot coolant to flow into the radiator where it is cooled before going back into the engine. The thermostat will close again if the temperature drops. This keeps the engine at a constant (and at the the optimum) temperature.

If your thermostat sticks open then the coolant is constantly being cooled. It never has a chance to work up to operating temperature, especially so at this time of year when the weather is cold. It's a common fault if the thermostat is over five years old.

The easy solution is to change your thermostat.

Thanks for your quick reply. One question though, how does this explain the fan cutting in at 90-95 degrees? Unless of course the girlfriend cannot read the temp gauge properly when asked :doh: I will check this myself (I should of done this first!), I guess if it cuts in at over 100 degrees then the thermostat is the way to go.

Thanks again,

Mark

The engine fan should cut in at 90 - 95 degrees - this is normal. At 100 degrees the water is at boiling point, though if it's under pressure (such as a car cooling system) the boiling point is raised. Either way, you want to keep below 90 to be on the safe side.

I thought you meant that your car was running at the bottom end of the scale? If it is then that means it isn't warming up properly, the most probable cause is a stuck thermostat. If you sit in traffic the temperature will eventually creep up to 90 degrees and the fan will kick in.

My Cinq currently has the same problem. In normal driving the temperature gauge is lucky to get above 60 - 70 degrees. In slow moving traffic it will rise to 90 degrees and the fan will then kick in. I will be changing the thermostat hopefully in the next week or so.

Hope this helps!

Yes, it sits at or just above 50 when moving but in traffic or stationary it will raise to 90-95 (according to my girlfriend)!

looks like a Thermostat hen, there's a good place on Ebay for Cinq bits called centotime - £12 for a thermostat so I'll order one along with my leads, plugs, aux belt and air filter.

Cheers for your help buddy, I'll post back once it's sorted.

No problem, and glad to be of help!

You could always press the 'thanks' button on one of my posts (the thumbs up icon) if you feel I've really helped you

£12 is about right for a Cinq 899 thermostat. Should be a fairly simple job as well, as I should hopefully find out when I do mine shortly. Done plenty on the FIRE engines, but never on the 899.

I've no idea what you mean by this thumbs up business, if you explain to me I'll be more than happy to do it.

Mark

Four little buttons at the bottom right of each post. The far right is a 'thumbs up'.
Press it and see what happens.

Cheers

D

I'm sure there's a problem, as I thought the whole point of having a pressurised cooling system is to raise the waters boiling point over 100 degrees.

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Yes. So, for all practical reasons it should never reach 100 degrees. It'll be a stuck stat, as above. Less than 15 quid.

90 to 95C is the coolant temp at a certain point of the cooling system, which iirc is somewhere between the rad and the hot spots in the engine. Inside the engine its self the coolant will get to higher temps. You might find that in those hot spots it's getting well above 100C and not boiling, so you need to start the fan at a level that keeps those hot spots cool enough not to boil even if the system is pressurised

I think I have this problem too. The engine never seems to get up to 90 even when driven hard and then sitting in traffic. I was wondering if this is an MOT fail or if they overlook it? I have an MOT on Friday so would need to know beforehand. Also, to change the thermostat do you need to drain the coolant completely or can you preserve most of it and just top up what comes out of the thermostat housing?

Thanks.

A stuck thermostat isn't an MOT fail in itself, but will probably mean the engine fails emissions. Drain the coolant. Just undo the bottom radiator hose, or you'll make a mess. Don't forget to bleed it afterwards.

Thanks fingers,

I've been looking at the guide to modding the thermostat for cooler running and was wondering can i use what's left of my seized thermostat or do I have to use a fully working one to donate parts?

The original thread is up there someplace (J333EVO). I think you use the body of the old one and the innards out of something else. But a lot of us were able to buy lower temp thermostats through the kindness of Asteris, who lives in Greece and was able to get them over the counter there.

In England, there isn't one listed for the Cinq.

Aliweasel said:

I think I have this problem too. The engine never seems to get up to 90 even when driven hard and then sitting in traffic. I was wondering if this is an MOT fail or if they overlook it? I have an MOT on Friday so would need to know beforehand. Also, to change the thermostat do you need to drain the coolant completely or can you preserve most of it and just top up what comes out of the thermostat housing?

Thanks.

Click to expand...

I just changed my 899 Cinq thermostat last weekend. If the car is on level ground you don't need to drain the coolant. You disconnect the hoses to the thermostat (some coolant will be lost) and then remove the thermostat (a bit more coolant will be lost). I then poked the coolant inlet on the cylinder head to dispel some more coolant so that the coolant in the engine was a few mm below the mounting surface.

Then I made sure the surface was clean, gave it a wipe with Methylated Spirits and then fitted the new thermostat. Reconnect all pipes, top up the coolant expansion tank if noticeably low, run the engine up to operating temperature then stop the engine and check the coolant level again. Top up if needed, though wait for it to cool down first! You should then also bleed the system.

For the Sportings I would think you do the same as for the 899 ohv engine, except that the thermostat is on the side of the cylinder. I haven't done a thermostat on a Sporting but I have on a FIRE engined 999cc Uno, which by all intents and purposes uses exactly the same priciple.

Both FIRE and ohv engines can therefore have their thermostats changed without needing to drain the coolant. However, if your coolant hasn't been changed in the past couple of years then you might as well take the opportunity to drain, change and refill it and do the thermostat at the same time.

As for failing the MOT, no a faulty thermostat won't do this on its own. However, if the engine doesn't get up to operating temperature then the ECU may be running the engine in 'rich' warm up mode and you may find your emissions will be too high as a result. Then again, just leave it ticking over for about 15 minutes and it should get up to temp even with a faulty thermostat.

Aliweasel said:

Thanks fingers,

I've been looking at the guide to modding the thermostat for cooler running and was wondering can i use what's left of my seized thermostat or do I have to use a fully working one to donate parts?

Click to expand...

You only need the housing as it's the thermostat part inside that is the bit that fails. You will be replacing this part when doing the mod. The housing is literally an empty aluminium body so as long as it's not cracked it will be fine.