Coolant temp.

[Itzhaky]

Caddy ’97, 230,000 M, 4.6L. What is the acceptable range of coolant temperatures while driving in suburbia, averaging 30 MPH at 80 deg. F outdoor temp?

[Cadillac Jim]

If you've kept the coolant changed, the temperature gauge should stay more or less straight up once the car has warmed up, unless you are stopped a very long time in traffic or have other circumstances that would cause overheating. If the needle gets more than halfway to the 3/4 mark the fans will turn on high and you should be able to hear them. Most common causes are under 50% anti-freeze, blocked bypass passage, blocked heater hose or core, blocked surge tank hose, and radiator problems, in that order.

Turning the A/C on actually helps in slow traffic because the radiator fans automatically are kept on low speed, so you always have some circulation through the radiator. Turning off the A/C helps best if the car is moving 20 mph or faster.

[Ranger]

205-215

[Itzhaky]

The thermostat opens at 197, stays there for a while and then the temp varies between 200 & 230. At 230 the radiator fans turn on. Turning the heat up and Hi, lower the coolant temp somewhat. I consider 230 F too high and variations of 200-230 too much.

Any suggestions?

[Ranger]

Check the purge line to be sure it is clear and flows coolant. Have the coolant tested for the presence of exhaust gases.

[BodybyFisher]

The thermostat opens at 197, stays there for a while and then the temp varies between 200 & 230. At 230 the radiator fans turn on. Turning the heat up and Hi, lower the coolant temp somewhat. I consider 230 F too high and variations of 200-230 too much.

Any suggestions?

Is your AC on or off, when you see these ranges?

[KHE]

The thermostat opens at 197, stays there for a while and then the temp varies between 200 & 230. At 230 the radiator fans turn on. Turning the heat up and Hi, lower the coolant temp somewhat. I consider 230 F too high and variations of 200-230 too much.

Any suggestions?

Perfectly normal. Drive it and forget about it.

[BodybyFisher]

The thermostat opens at 197, stays there for a while and then the temp varies between 200 & 230. At 230 the radiator fans turn on. Turning the heat up and Hi, lower the coolant temp somewhat. I consider 230 F too high and variations of 200-230 too much.

Any suggestions?

You have not noted the outside temp by you.

200 to 230 is FINE, I do not see a reason to panic. When are you seeing 230?, traffic, stop and go? What do you see at 60 miles an hour?

[Itzhaky]

Outside temp 80 f and A/C off.

[JimD]

The thermostat opens at 197, stays there for a while and then the temp varies between 200 & 230. At 230 the radiator fans turn on. Turning the heat up and Hi, lower the coolant temp somewhat. I consider 230 F too high and variations of 200-230 too much.

Any suggestions?

You could be second guessing the powerplant design engineers. And that might be the very reason the numerals were removed from the coolant temperature display on later models.

Powerplant engineers want the engine (coolant) temperature to exceed 212 degrees F to promote vaporization of condensation (and other nasty elements) from the crankcase oil. Condensation is a by-product of combustion.

Temperatures above 212 are to be expected. Temperatures approaching the limits of dino oil will set off bells and other warnings.

If the variation of 200 to 230 tests your tolerance, I suggest you place your HVAC in one of the A/C ON modes and happily motor on down the road.

[BodybyFisher]

As JimD noted, running with your AC off will produce wider range temp swings. Put your AC on, your will see your PEAK temp be lower as your FANS run FULL TIME when the AC is on. That is why I asked if your AC was ON or OFF..

[rmac-etc]

Used to run my '95 etc up winding mountain roads in southwest va from the valley floor up to Skyline drive, maybe 1000-1500 feet elevation change, cool autumn early winter temps and I drove it as hard as I could and watched the engine temp just to see how high I could get it. I did see the mid 230's in those circumstances. Wasn't running moonshine, wish I were.

oh, that was 9 years and >70k miles ago.

And about a year later (~2000) in san francisco after I had inadvertently moved the fuse for the cooling fans trying to diagnose an hvac fan failure unknowingly rendering them inoperable and in rush hour city traffic it topped 252, and went into 4 cylinder get home safe mode. Recovered to normal 8cyl hot rod as soon as it got moving again on the highway.

And it is still my daily driver (>160k) and I still drive it like i stole it and it still does not burn oil, leak coolant or anything else of that nature. Daily WOT's is my primary maintenance strategy.

Go figure.

My attitude is if it ain't leaking, the fluid levels are ok, its not warning you about anything .... it's probably ok.

[Itzhaky]

Here is a stupid question: What is and where is the purge line? Two separate garages here failed to find it and a traveling mechanic said that my car may not have one.

Caddy '97, 4.6 L, 230,000 M, DeVille.

[Ranger]

The purge line purges air from the system and routes it back to the surge tank. It is the 3/8" line that runs from the pump housing, along the front cam cover (under the beauty cover) to the top side of the surge tank.

[BodybyFisher]

Here is a photo of the area, in it moving clockwise, you can see the transmission filler (lower right with red letters), the water pump, the thermostat housing, the water pump CAM pulley and the air purge line "bolt with a metering hole in it" that can clog and cause overheating.. hope this helps. The follow this line ACROSS the engine and it goes into the coolant TANK, while the engine is idling, pull the hose off the tank and see if you have a steady flow of coolant flowing.. If not, disassemble the hose and bolt with a hole in it (circled in the photo) and look for a blockage there...

[Itzhaky]

Thanks, the picture helped, but unfortunately there was a steady stream of coolant. I am at a lose. There are times I can drive with no problems and other times the engine overheat after 10 miles, or less, in similar driving conditions.

Two stupid questions:

1) Is it possible for the water pump to work on and off? The belt is tight.

2) Is it possible the thermostat sometimes working, other times not?

A few times I drove 15-20 miles in town with no problems, parked, return after 15-30 minutes and the engine overheated after 3-5 miles.

[KHE]

Thanks, the picture helped, but unfortunately there was a steady stream of coolant. I am at a lose. There are times I can drive with no problems and other times the engine overheat after 10 miles, or less, in similar driving conditions.

Two stupid questions:

1) Is it possible for the water pump to work on and off? The belt is tight.

2) Is it possible the thermostat sometimes working, other times not?

A few times I drove 15-20 miles in town with no problems, parked, return after 15-30 minutes and the engine overheated after 3-5 miles.

This is new information. The engine truely overheats and displays the STOP ENGINE - COOLANT HOT" message? Or is the coolant temp just 230 degrees?

If the engine is truely overheating, then I'd either have a radiator shop test the coolant for combuston gasses or pressure test each cylinder with shop air.