2000 S70: Code P0116, engine fan runs unnecessarily, sometimes difficult to turn over, disappearing coolant

[itsmekirby]

Hey folks, I started getting code P0116 and before I do the obvious solutions (thermostat and ECT) I wanted to mention this combination of symptoms and see if anyone has any other ideas:

2000 Volvo S70 GLT SE, 100k miles

Engine runs fine, normal power output and fuel efficiency. Temperature gauge behaves normally, starts at 0 and heats up to 3oclock and stays there.

Check engine light comes and goes on different days. The engine fan also sometimes runs in conditions when it didn't used to need to. I think the "sometimes" here correlates with the check engine intermittency.

About 20% of the time I have to turn the engine over for about 5 seconds before it starts. The other 80% of the time it starts perfectly. If it's been run within the last 30 minutes or so it always starts perfectly.

Coolant has been disappearing and I haven't noticed a leak or smelled it in exhaust.

Does this seem like a case where I should replace both the thermostat and ECT, or might there be something else at play? The part that really throws me is the temp gauge behaving normally, shouldn't a problem with either the thermostat or the ECT show there? Can a bad thermostat/ECT be causing my coolant issue too or is that probably something else?

[abscate]

That P0016 is a cam adaptation code. A bad ECT will cause those symptoms so it’s a decent first check

[scot850]

Check the water pump area and below it for residue leaks. They can leak when warming up and cooling down when the bearing or seal is failing.

Check the sides of the radiator for dampness and if you car has the small pipe to the header bottle check is not loose or splitting.

Check the pipe from the bottom of the header tank to where it connects to the metal pipe at the rear of the engine. It can leak with age at the clamp. You will see corrosion on the pipe.

Check the header bottle cap for leaks or staining around the cap.

As it is a GLT check the turbo coolant hoses at the back of the engine for swelling.

Finally check the driver's side floor for dampness and weird sweet smell for the heater core or it's seals leaking. You need to lift the carpet to check as it has a rubber in the carpet which can prevent the damp reaching the top layer.

Neil.

[itsmekirby]

Neil, thanks for the advice. I just looked around those areas for residue and for active leaks with the car running and couldn't find anything.

[misha]

If coolant disappears somewhere and it isn't exhaust,hoses or radiator....check heater core leaks.

Also check oil for coolant contamination and coolant for oil contamination.