A question for the mechanics out there...

[Omag 2.0]

I recently had some car-trouble... the engine would overheat when driving slow and cool down when going faster... Seems the radiator had to be replaced... But now the engine doesn't come up to temperature. Even after 20 minutes of driving, it only goes to about 80

[C]

Sounds like you need a Haynes manual Kris.

[expat]

Sounds like you need a Haynes manual Kris.

If you can get you hands on an original Haynes then they are of use. They would show you how to strip you car to the last nut and bolt, clean it, reshape/repair it and then put it all back together before embarking on that drive around the world. Today they seem to be written for schoolgirls who do not want to get their fingers dirty  :P

Matt

PS Omag, remove your thermostat and put it in a glass, poor boiling water over it. Please be very careful, as boiling water is very hot and you could burn yourself. Suggest you put on heatproof gloves, and some sort of insulated protective outer covering at the front of your body. A non-slip floor matt just in case to happen to spill said hot water and don't forget safety goggles (not beer goggles). I would hate to fall fowl of the PC wrap you up in cotton wool types, and for you to sue me because I told you to do it. If it pops open then I would say it is ok, if not, replace it.  

[Mushroom_Farmer]

Even if the new radiator is more efficient, it's the thermostat that regulates the engine temperature. I would be asking Mr. Mechanic why he didn't install the correct radiator specified by the manufacturer. A cooler engine temperature often results in poor mileage and sludge buildup.
The engine temperature sensor is usually located in the cylinder head and the thermostat is normally located in a housing where the upper radiator hose attaches to the engine. A parts outlet employee should be able to help you locate it and recommend the proper temperature rating.

[ozzy72]

Kris the engine temp. sensor will most likely be on the block as it needs to check the coolant temperature as it goes through the block. Look for something that looks like a nut sticking out of the block with two wires attatched.
What kind of car do you have?
Another thought is that with winter impending the mechanic may have put pure glycol in the cooling system and this will cause a lower reading until it gets properly cold

[Woodlouse2002]

Another thought is that with winter impending the mechanic may have put pure glycol in the cooling system and this will cause a lower reading until it gets properly cold

I thought engine coolant was always a water/antifreeze mix. And that the antifreeze didn't affect the temperature it just affected the way it reacted at both extremes.

[Mushroom_Farmer]

I thought engine coolant was always a water/antifreeze mix. And that the antifreeze didn't affect the temperature it just affected the way it reacted at both extremes.

It is, be it 50/50, 60/40, or 70/30 depending on climate. A proper mix is required for heat transfer. A pure glycol mix will not carry away the heat efficiently and may actually damage engine components.
It's also important to be sure that the proper coolant type goes into the system. There's ethylene base, propylene base, long life, extended life, normal life........  ::)

[RichieB16]

It could be the thermostat.  If you have one of those "safe" theromstats in your car, they are designed to fail open rather than fail closed.  So, if it has failed in the open position the engine won't be able to get warm because cold coolent will be flowing from the get go.  Thermostats work by opening at a certain temp, when the engine is cold they are closed they to not allow the coolent to circulate which causes the engine to warm up, once warm they open and allow the coolent to flow so it doesn't get too warm...so that is possible.

I would think it is an odd coincidence that it happened right after the radiator is changed though.  However, thermostats are typically cheap (usually $5-$10 at the most) and really easy to change so it wouldn't be bad to do just in case.

Personally, I have never had a car "too cool" unless a thermostat has failed open.

[beaky]

Thermostat OR temp. probe OR temp. gauge... definitle ybuy a service manual for your car; it's fun to learn just enough to get into real trouble...