Water rising in the expansion tank / idle problem
Discussion
Morning All
2 issues going on at present (1999 400 Chimaera) – not sure if they’re connected and any ideas happily received.
1) Water level rising in the expansion tank. Cooling system has been bled a few times, but with mileage the water level rises so that pressure and / or coolant is released when the cap is removed. Cap has been changed and this has helped to slow the rate that the water rises, however, guessing that air is getting in somewhere although there are no obvious signs of coolant leaks.
2) Intermittent idle problem. For example, drove to work last Friday morning (approx 18 miles) and all fine – idled perfectly at approx 900 rpm. Drove home in the evening, and idle didn’t seem quite right from the moment of starting the ignition – the drive involved quite a bit of slower 2nd and 3rd gear driving, and idle struggled when slowing down, so that with one foot on the clutch and the other on the brake, the engine stalled twice. Left the car until Sunday, and did approx 10 miles and all perfectly OK again.
Anyone experienced anything similar, or any ideas as to where to start looking?
Many thanks.
2 issues going on at present (1999 400 Chimaera) – not sure if they’re connected and any ideas happily received.
1) Water level rising in the expansion tank. Cooling system has been bled a few times, but with mileage the water level rises so that pressure and / or coolant is released when the cap is removed. Cap has been changed and this has helped to slow the rate that the water rises, however, guessing that air is getting in somewhere although there are no obvious signs of coolant leaks.
2) Intermittent idle problem. For example, drove to work last Friday morning (approx 18 miles) and all fine – idled perfectly at approx 900 rpm. Drove home in the evening, and idle didn’t seem quite right from the moment of starting the ignition – the drive involved quite a bit of slower 2nd and 3rd gear driving, and idle struggled when slowing down, so that with one foot on the clutch and the other on the brake, the engine stalled twice. Left the car until Sunday, and did approx 10 miles and all perfectly OK again.
Anyone experienced anything similar, or any ideas as to where to start looking?
Many thanks.
Its been thoroughly checked over and that the confusing thing - no sign of anything immediately wrong.
Cooling system appears fine - heats up normally, fans cut in at approx 90 degrees, cut out when temp drops. And as mentioned, car runs fine with no obvious poor running or loss of power.
The only slightly unusual thing is small patches of possible coolant on the radiator although no other sign of leaks. Wasnt sure how small any holes would need to be to draw air into the system?
Cooling system appears fine - heats up normally, fans cut in at approx 90 degrees, cut out when temp drops. And as mentioned, car runs fine with no obvious poor running or loss of power.
The only slightly unusual thing is small patches of possible coolant on the radiator although no other sign of leaks. Wasnt sure how small any holes would need to be to draw air into the system?
Cooling systems work by pressurising the system (usually about 8-10 psi)in order to increase the boiling point of the water, if you have any leaks you loose pressure and the boiling point lowers to normal.
See if you can get the cooling system pressurised to check for leaks and therefore loss of pressure.
Steve Heath does an adapter for the swirl pot IIRC, but a garage ought to have a cooling system pressure tester.
See if you can get the cooling system pressurised to check for leaks and therefore loss of pressure.
Steve Heath does an adapter for the swirl pot IIRC, but a garage ought to have a cooling system pressure tester.
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