Low Temperature Gauge /coolant

[porsche4786]

I recently did my timing belt/water pump/ thermostat. And ever since that the engine temp gauge seems to be lower than normal, just above the low line, barely. Sometimes will go maybe a 1/8th of an inch above the line, and other times like after climbing a hill it will go up to almost half/half way. But not every time I climb a hill (the same hill). Still loosing coolant every couple days. And yesterday I filled it up when it was cold. Drove to work (about 12 miles one way) and home and the level was down to low already. This morning I filled it up and drove to work and since it's warm now the overflow level is a quarter inch above the high line, which will go down after it cools, I'm guessing to the high line or slightly below. So far the only leaks I've found, was the radiator, which I replaced. And then a leak on the thermostat hose that goes to the radiator. Which I also replaced. No drips on the garage floor. Did the engine block test, with no change in liquid color, I pressure tested the system yesterday (again) and it's holding pressure better than it was before I did the water pump replacement. I'm not sure where the coolant is going, but I'm thinking that the thermostat may possibly be bad/not working properly. But that wouldn't cause me to loose coolant that I know of.

[pulxar]

I recently did my timing belt/water pump/ thermostat. And ever since that the engine temp gauge seems to be lower than normal, just above the low line, barely. Sometimes will go maybe a 1/8th of an inch above the line, and other times like after climbing a hill it will go up to almost half/half way. But not every time I climb a hill (the same hill). Still loosing coolant every couple days. And yesterday I filled it up when it was cold. Drove to work (about 12 miles one way) and home and the level was down to low already. This morning I filled it up and drove to work and since it's warm now the overflow level is a quarter inch above the high line, which will go down after it cools, I'm guessing to the high line or slightly below. So far the only leaks I've found, was the radiator, which I replaced. And then a leak on the thermostat hose that goes to the radiator. Which I also replaced. No drips on the garage floor. Did the engine block test, with no change in liquid color, I pressure tested the system yesterday (again) and it's holding pressure better than it was before I did the water pump replacement. I'm not sure where the coolant is going, but I'm thinking that the thermostat may possibly be bad/not working properly. But that wouldn't cause me to loose coolant that I know of.

It is possible that the thermostat is bad, from what it sounds like it could be stuck open or mostly open, or possibly was set to a different temperature than the one you had in there before. I really don't know a lot about this, but I do know that they have a "right-side-up" that needs to be aligned to function properly. There is a small, loose fitting metal valve on it that can allow some bypass that needed to be at the top, IIRC.

 

As for the coolant loss, I had a similar issue a while back and it turned out it was a bad radiator cap, so the pressure test was fine, but the cap let the coolant blow by it. I'd take a look at the cap and see if perhaps it is not holding pressure like it should. They aren't expensive, you could try just replacing the thing and see if it makes any difference.

[Alkorahil]

Check your coolant level.

Sometimes air pockets can develop when you drain/refill the radiator. So the level is fine when you fill it up after putting it back together, then after running the vehicle awhile the air pocket moves out of the system.