-
Water Temp reading
What is normal water temp readings? In 90+ degree Ga. weather, mine has been showing (guessing 190) since the next mark is the 210 degree on the guage, and it’s a little below that, it never gets close to the 210 mark. The reason I question it is that the Prevost in dash computer shows 208-221 degree, and it normally stays around 210 or so cruising at 65-70. I never hear or can tell that the fan is coming on. I have stopped, and immediately go to the back and raise the engine bay to look, and the fan is turning, but not fast enough IMO. Idling, it cools down to 180-190.
My oil Temp is in the 190’s.
Should I be concerned? Which reading is more accurate?
thanks
-
9 Replies
-
The oil temp will go up if you are working it hard if it’s raining you will see oil temp go down because water on the engine or oil pan
-
Jerry,
Mine never gets beyond about 190 on the gauge and the oil temp runs pretty close to that. I’ve never seen anything beyond that until getting out west and the retarder got it up to about 208, never reached the 210 tic mark.
-
Jerry,
Some engines come with 2 or 3 water temp sensors. One for the DDEC, one for an analog dash gauge and one for the engine compartment guage. What you are reading on the Prevost digital display is what the DDEC is reading and using to turn on the fan.
When the readings differ how do you tell which is correct? Unless you have a transmission retarder you see the water temp to be almost identical to thr transmission temp reading when driving on level roads at moderate speeds. Your dash needs to be off.
Your thermostats don’t begin to open until 190 degrees and aren’t fully open until 200 degrees. The low speed fan trigger is 198 degrees and high speed is 204 degrees. If you have your dash air on the high speed fan will be on after the air has been on for about 5 minutes. With dash air on the engine temp will likely run close to 190 degrees. Start the coach, turn on dash air, and wait 5 minutes and the fan should go to high speed. If so, 2 of 4 relays are likely good. There are 4 relays. Get a new relay. Remove the low speed relay and break the positive terminal off that energizes the relay. Replace the relay turn the igntion key on with dash air off. You should feel more resistance to turn the fan than it does with the engine off. This proves the low speed side of the fan clutch works. Install the new relay and keep the relay with the broken pin. It can be used to lock the fan on high or low speed.
-
Jerry,
The engine ECM controls the cooling fan. It is a two stage fan and will not come on until about 204 degrees. If the coolant temperature continues to rise the second speed engages at 208 degrees. The engine thermostat with the fan clutch locked will cycle between 190 and 195.
The engine is designed to perform best at the higher temps so the only time you need to be concerned is if the coach is pulling a long hill and you do not see the temperature cycle up and down, but instead it keeps climbing past the 208 degree temp.
-
OK, the 221 degree I saw on the digital readout seemed high to me. It did come back down, but I was cruising, not going up hills or anything.
I have OTR air, so no way to check by turning dash air on I guess.
Gill, is there a way to check the fan with OTR air?
I have had no lights to come on or anything saying to hot. I do have a retarder.
Also, the engine guage you mention, I do not seem to have one in my engine bay, unless It’s hidden somewhere.
-
Jerry,
First the trigger temps are as Jon stated, 204/208.
The procedure for low speed will work for high speed as well. The relays power the fan clutch when the relay is deenergized. That’s the reason for breaking the relay terminal that supplies power to the relay’s coil.
If you were using the transmission retarder I understand 220+ can be normal if you’re reading trans temp and not engine temp.
-
Since GA is not one of the mountainous states and since it takes a whole lot of retarder use to drive up the coolant temperature I am suspecting the engine dash gauge for coolant temperature is showing the accurate reading.
But being one to err on the side of caution I would likely seek out a charter company with Prevost coaches or a Freightliner dealer with Detroit technicians or a Detroit dealer, any of whom would have a reader that can be hooked up and the temps monitored on a short run. Those temps can be compared to the dash and message center to see which is more in agreement with the reader.
I would rather spend $100 or $200 by mistake worrying about a non existent problem, than scheduling the replacement of an engine. I think that would be DDEC III or DDEC IV. I would offer the use of mine but I only have DDEC V software.
-
A Detroit shop can trigger the fan relays, both high and low, from their computer.
-
You guys are exactly right….as usual, after reading the post, it hit me….I went out to the coach and looked at the driver info display. What I was seeing as coolant temp, I think is the Trans temp. It is a thermometer beside a circle with tick marks around the circle with level waves in the circle.
That makes sense that I’m seeing 205-221 for trans temp!
Back to coolant temp, I have never seen it even close to 210, so the fan shouldn’t be on.
Guess I should wear my glasses more…..
thanks
Log in to reply.