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Caligarinet

New Member, coolant loss

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Hi,

6 years after selling my S1 and regretting it ever since, I’ve managed to pick up an early S2, with 96k on the clock. 

So with that kind of mileage, kind of expect a few issues. 

First issue is it seems to be losing coolant, and getting a froth in the expansion tank (as though it’s got fairy liquid in there, no emulsion). Was initially a hissing from cap, so replaced this. No sign of coolant loss anywhere  

Exhaust gas to coolant compromise?

no issue with overheating as yet. 

Any recommendations of who could look over the car? Anyone who could pressure test the coolant system, or test for exhaust gases? Seen mention of Gav in Burton, tried emailing, is he still in business? 

If going down the line of HGF...repair or just swap the engine out. Swapped the engine on the S1 without too much difficulty, certainly easier than doing the head gasket. 

Based in Stafford. 

Thanks in advance

Paul W

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Hi Paul,

First of all welcome to MLOC :tup:

I'm pretty sure you have HGF, Mine only should on my S1 when on track with continuous high rev's, similar symptoms to what you describe but nothing evident when driving on the road, No oil/water mix or emulsification in the header tank.

As you say, to be sure get it to someone who can pressure test, Gav is still in business, probably best to call him, there's also PJS in Burton and Top Gear automotive in Wolves, All Lotus specialist and well known & respected in the Midlands area.

If you decide to do the head gasket at least you know it will be done, The risk with the engine swap is you could end up with the same or /& other problems......

Andy.

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Thanks for welcome, mate. 

Flushed coolant, replaced with OAT, replaced cap. 

Seems to holding its level for now, but not taken it for a decent run yet. 

Think next step is sniffer test, if problem persists. 

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Fingers crossed it was a combination of the cap and air in the system 🤞

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Yup, hope so. 

Taken her out for a half hour spirited run, no coolant loss and still nice and pink. 

Just have to keep an eye on it for next week or so. 

 

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Hi Paul, I'm based at Kingstone near Uttoxeter, I have pressure test equipment, if you want to call round one day I'll happily check it for you

Graham

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Welcome to MLOC. Easy way to check for a blow across the fire ring on a K series. Take it out for a spirited drive  lol. Leave it to cool for a couple of hours or so. Slowly remove the coolant cap. If you have pressure still in the system, it will either hiss loudly and or water will rush back into the coolant bottle. If you only get a small hiss breath a sigh of relief. Another symptom when it gets worse is the temp will dodge about as the coolant cap releases the pressure in the system and reseals when its gone. Dont panic as i drove home from Le Mans once slowly when i had this.

Changing a head gasket is far easier than an engine swop. Pop the rear boot lid off and crack on if needed   :) Best to phone Gav if you need him.  Have fun.

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Could have been something as simple as a leaky coolant bottle cap which you reseated when changing coolant. 

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Just an update on this, should anyone ever have similar issues. 

Coolant level, no issue at all now, several long trips and no loss.

Car was running rich, as shown by soot deposits on back of car and getting 18mpg even on the motorway. 

Changed coils, plugs, and ECU coolant temperature sensor. 

Now getting an average of 32 mpg, but Stack is indicating that it’s struggling to get up to temp, sitting around 70 degrees unless in traffic or stationary. 

Ordered new Stack temperature Sensor and new thermostat....so will have to see if it’s the temp reading or the temp that’s the issue. 

Changing the thermostat looks kind of tricky....

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4 hours ago, Caligarinet said:

Changing the thermostat looks kind of tricky....

Not too bad with the inlet manifold and TB removed.  You will of course need to empty the cooling system, re fill and bleed ☹️

 A digital thermometer with the probe taped to the cylinder head water outlet will give you an accurate enough reading to diagnose if it is the sender or not.

 

 

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You can suspect a stuck thermostat from extended warmup (typically only a couple of miles to get the coolant up to temperature), poor heater output, and most reliably from the radiator getting warm very quickly after the engine is started.  Or dive in and feel the hoses for more precise results.

A faulty sender can obviously be diagnosed by comparing it with a more reliable thermometer, although there could be electrical issues also causing the Stack to read wrongly.  You can also compare it with the brown sensor, which ought to be working well now.  The ECU will switch on the cooling fan when the brown sensor indicates around 102C.  The blue sensor ought to read within a couple of degrees of 102C when that happens.  Test the fan first by unplugging the brown sensor plug so you don't accidentally overheat your engine trying to force the fan to run.  The Stack reading is affected by poor earth connections between the engine and battery, so it may read low and may increase when you switch on high-power electrical items at the front of the car.  An extra 1C from turning on the interior fan is common, but more than 2C and you definitely want to look at your electrics.

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I’m guessing the reading from the OBDII socket will be brown sensor (ECU)...this matches the Stack Dash read out. 

Very little heat coming from heater. 

All good info, thanks. 

Definitely need to check my grounds anyway. Once I’ve worked out how to stop the alarm going off, every time I disconnect the terminal...

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