I noticed today that there was steam coming out from under my car on the driver's side. I figured it was the rain water evaporating off the coolant pipe. I checked the other side and there was no steam. I reached underneath and discovered that the passenger side pipe was cool, and the driver's side pipe was hot (ouch). My temp guage has read near 220 in the city and down to normal on the interstate after I've been driving awhile. It's done this with a 180* and 195* thermostat, ever since I put in my 3.4. I just noticed the coolant pipes today. My question is:

Is the coolant pipe situation normal? If not, would it contribute to engine pinging? (it pings with timing at 10* and 93 octane fuel, always has)

It sounds like you are having restriced flow through the cooling system. One pipe takes the hot engine coolent to the radiator, the other brings to cooled coolant back from the radiator. Your car should be running ~ 195. Time for a flush.

Whether it is restricted or not the coolant pipes will have different temperatures due to the heat removed by the radiator. The flow will be the same through both pipes since it is a closed system.

However a clogged return pipe would allow the coolant to sit in the pipe longer due to low flow and cool down further just due to heat lost through the pipe wall itself.

I agree with Old Lar. It might not hurt to disconnect the hoses at either end of the pipe and flush it out. If you find a lot of buildup you might run a plumbing snake with a brush through it to loosen the buildup. Don't get too aggressive though, the pipe is pretty thin walled.

Good luck,

Carroll

Sounds like you may have air in the system. You may want to burp it and top off with coolant.

Both pipes should be warm.

Also, 220 is not overheating with the V6 (and your 3.4 should be the same). The Fiero radiator fan doesn't even come on until 235F, so even with a 160F thermostat, it's still going to get up to about 220+ in traffic. If you want the car to run cooler, you have to change the fan switch as well as the termostat.

I also agree with batboy. You may have air in the cooling system. One pipe may be hotter than the other, but both should be warm.

Well, I'm gonna disagree with everyone this time coop.

If the coolant pipes didn't have substantially differnt temps then there would be something wrong.

The hottest water from the engine should be traveling through one pipe to the radiator and that pipe should be very hot. When it reaches the radiator, the radiator cools it off and the return pipe should have the coolest coolant in it that is anywhere in the entire cooling system. Besides just having been cooled by the radiator, it also gets cooled by the ambient air passing by it as it returns back to the engine.

So, as you can see, the cooling system is acting exactly as it was designed. If the return pipe was close to as warm as the inlet pipe then it would indicate a restricted radiator. The system is working exactly as designed.

Phil

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GTDude
OVER 25 years GM experience