engine fan...is this right?
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Elder User
Joined: Mar 2007
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From: Canyon Country
engine fan...is this right?
I was going up a long twisty paved road (not very steep grade) today in the mountains, speed was between 30-45 mph, outside temp was in the high 20's low 30's. I was unloaded and just crusing and the engine fan kept coming on and off every few minutes...the eot was about 215 and the ect was about 210 when the fan was coming on. the fan also came on a few times going up the highway to the mountains. once the fan would come on the temps would drop to 190-195 then they would jump right back up. coming back down the mountain the temp dropped to about 190 (mostly idleing). I never saw anymore that a 10-12 deg difference between the eot and ect.
Normal? I don't ever remember the fan coming on before when it was so cold out...I had a oil cooler and head gaskets done about 6 months ago...no puking, coolant level is good. egr cooler??
temps were coming from a dashhawk...no tuner.
any thoughts??
thanks!
Normal? I don't ever remember the fan coming on before when it was so cold out...I had a oil cooler and head gaskets done about 6 months ago...no puking, coolant level is good. egr cooler??
temps were coming from a dashhawk...no tuner.
any thoughts??
thanks!
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
most fans come on 80-100 duty cycle between 208-212 degress ect. what bothers me here is the cycle time in cold weather and the condition it was happing under. The conditions sounds like it is happing under high load. did temp climb while boost was on the raise?
It looks as if the oil cooler is working but temps seem like they are a little bit high on a cold day. so that may still be an issue.
With out the truck diag is a little bit hard but it could be the signs of headgaskets if the temps have rapid movement while boosting or an oil cooler but once again the split is right.
It looks as if the oil cooler is working but temps seem like they are a little bit high on a cold day. so that may still be an issue.
With out the truck diag is a little bit hard but it could be the signs of headgaskets if the temps have rapid movement while boosting or an oil cooler but once again the split is right.
Fleet Owner
Joined: Nov 2003
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jlmotox -
The temps could be explained by a weak water pump.
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Elder User
Joined: Mar 2007
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From: Canyon Country
hope it's not the HG's...had the ARP's installed!
The temps begin to rise when steady throttle is applied,like 2000 rpms 6-10psi boost 35-45 mph light throttle...
also when on the highway today (grapevine I-5 in socal) speed 65-70mph, 2000 rpms, 15-20 psi boost, outside temp of 50 deg, unloaded. I started the bottom of the hill with 190 ect 200 eot then about 3miles up the grade i'm at 208-212 ect and 214-218 eot and the engine fan is howling...once the fan comes on the temps drop to 195 ect and 205 eot, then they climb right back up.
bismic- the water pump has been in the back of my mind...anyway to check without tearing it apart?
My warranty is up in Feb. really don't want to take it to the dealer again for them to tell me everything is fine and I am just crazy! after the oil cooler was done I had taken the truck back and told them the fan was coming on alot and they said all was fine...even hooked it up to the techs laptop and went for a drive...but that was back when it was 100+ degs here in Socal and I just said ok guess thats how it is...but now taking the truck up to the mountains empty when it's freezing outside and hearing the fan roar has got me worried again.
The temps begin to rise when steady throttle is applied,like 2000 rpms 6-10psi boost 35-45 mph light throttle...
also when on the highway today (grapevine I-5 in socal) speed 65-70mph, 2000 rpms, 15-20 psi boost, outside temp of 50 deg, unloaded. I started the bottom of the hill with 190 ect 200 eot then about 3miles up the grade i'm at 208-212 ect and 214-218 eot and the engine fan is howling...once the fan comes on the temps drop to 195 ect and 205 eot, then they climb right back up.
bismic- the water pump has been in the back of my mind...anyway to check without tearing it apart?
My warranty is up in Feb. really don't want to take it to the dealer again for them to tell me everything is fine and I am just crazy! after the oil cooler was done I had taken the truck back and told them the fan was coming on alot and they said all was fine...even hooked it up to the techs laptop and went for a drive...but that was back when it was 100+ degs here in Socal and I just said ok guess thats how it is...but now taking the truck up to the mountains empty when it's freezing outside and hearing the fan roar has got me worried again.
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
now im gonna bit on this one.. a week water pump. I have seen issues with broken impellers befor but they have all been early 03 style engines. waterpumps just dont seem to fail much here. I have never heard of a weak water pump just broken ones.
you try and see how much movement is in the impeller shaft best to check it warm as they seem to have that from time to time. most of the ones I have seen have cut the wires to the vdf.
Now after a little bit more thought on it. Your problem might be as simple as a radiator cap. this also fits the picture very well.
do you ever hear a high piched squeel noise when the fan comes on? if so you may need a water pump pully, a belt and a tensioner.
Just for kicks look at the water pump pully. is all the paint gone? if so this is a big sign of a slipping belt also a common failer.
do you by chance happen to have access to a pressure transducer?
you try and see how much movement is in the impeller shaft best to check it warm as they seem to have that from time to time. most of the ones I have seen have cut the wires to the vdf.
Now after a little bit more thought on it. Your problem might be as simple as a radiator cap. this also fits the picture very well.
do you ever hear a high piched squeel noise when the fan comes on? if so you may need a water pump pully, a belt and a tensioner.
Just for kicks look at the water pump pully. is all the paint gone? if so this is a big sign of a slipping belt also a common failer.
do you by chance happen to have access to a pressure transducer?
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Fleet Owner
Joined: Nov 2003
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now im gonna bit on this one.. a week water pump. I have seen issues with broken impellers befor but they have all been early 03 style engines. waterpumps just dont seem to fail much here. I have never heard of a weak water pump just broken ones.
you try and see how much movement is in the impeller shaft best to check it warm as they seem to have that from time to time. most of the ones I have seen have cut the wires to the vdf.
Now after a little bit more thought on it. Your problem might be as simple as a radiator cap. this also fits the picture very well.
do you ever hear a high piched squeel noise when the fan comes on? if so you may need a water pump pully, a belt and a tensioner.
Just for kicks look at the water pump pully. is all the paint gone? if so this is a big sign of a slipping belt also a common failer.
do you by chance happen to have access to a pressure transducer?
you try and see how much movement is in the impeller shaft best to check it warm as they seem to have that from time to time. most of the ones I have seen have cut the wires to the vdf.
Now after a little bit more thought on it. Your problem might be as simple as a radiator cap. this also fits the picture very well.
do you ever hear a high piched squeel noise when the fan comes on? if so you may need a water pump pully, a belt and a tensioner.
Just for kicks look at the water pump pully. is all the paint gone? if so this is a big sign of a slipping belt also a common failer.
do you by chance happen to have access to a pressure transducer?
Low flow is much more likely. The early water pumps had impellor issues for sure. they would come loose and barely pump. There are things that could cause a later model pump to not pump so much - mainly corrosion and erosion issues.
You certainly could be right that it might be more of a belt, pulley or tensioner issue. If the belt is binding then the water pump is not pumping as much - this falls into the category of a weak water pump also (allowing some room for generalizations).
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Senior User
Joined: Dec 2009
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From: Murray KY
Transmission?
Based on that info I expect it had nothing to do with water temps but tranny temps. The same fan serves both radiators at the same time on most vehicles.
Cargo Master
Joined: Mar 2007
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From: AB/BC
Good thinking Gale
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Elder User
Joined: Mar 2007
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From: Canyon Country
they put a new thermostat in when they did the HG's...I can see the thermostat open on my guage.
trans temps were between 165-175
little more background...after my last visit to the dealer 6 months ago and they said all is well, that was back when outside temps were 100+ and I heard the fan on alot, regular empty city driving would be 200 ect 210 eot...any hill or lots of stop and go they would be 210-215 ect and 215-220 eot...if I put my 26' bumper pull toyhauler behind it temps jump to 205-215 ect and 215-225 eot on the flat highway and when I climb hills the max I saw was 228 ect and 240 eot...the fan is pretty regular as far as when it comes on...about 212 I can hear it and 218 it is screaming! I haven't pulled my trailer recently but I did tow it when outside temps were in the mid 70's and it seamed to drop my engine temps about a few degrees. when I tow i'm usually doing 60-65 mph and not very aggressive...on the hills I am driving it by engine temp...
trans temps were between 165-175
little more background...after my last visit to the dealer 6 months ago and they said all is well, that was back when outside temps were 100+ and I heard the fan on alot, regular empty city driving would be 200 ect 210 eot...any hill or lots of stop and go they would be 210-215 ect and 215-220 eot...if I put my 26' bumper pull toyhauler behind it temps jump to 205-215 ect and 215-225 eot on the flat highway and when I climb hills the max I saw was 228 ect and 240 eot...the fan is pretty regular as far as when it comes on...about 212 I can hear it and 218 it is screaming! I haven't pulled my trailer recently but I did tow it when outside temps were in the mid 70's and it seamed to drop my engine temps about a few degrees. when I tow i'm usually doing 60-65 mph and not very aggressive...on the hills I am driving it by engine temp...
Fleet Mechanic
Joined: Jan 2007
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The water/coolant heat capacity does not change all that much with the pressure. Certainly the boiling points do, but not so much the temperature rise per pound of circulating coolant. A weak cap really does not explain high water temperatures in such cold (and no load) conditions - at least in my mind.
A weak cap COULD show these symptoms... The Freightliner ALWAYS starts showing temperature swings when the cap gets old/loose. What happens is that the coolant will spot-boil, from lack of pressure, and that will drive the overall temps up, even though it may not be enough to get vapor present in the system to start puking.
However, I do tend to agree that given the history of problems with loose belts that these trucks have, that could also be a problem
Also, check and see if there's any crap/grunge/dirt/buildup BETWEEN the charge cooler and the radiator and the AC condenser. The stack can accumulate lots of crap between the sections if it's been a while since they've been apart or been cleaned. Freightliner service folks recommend a cleaning every year and/or 100K miles, and CA is known to be extra dusty.
Also, I discovered the hard way that if your charge cooler is leaking, but still within leakdown spec, the extra fuel required to maintain boost will make temps swing pretty wide, too. So check to make sure your charge cooler is 100% leak free. My charge-cooler supplier said that 3 years was about as long as they last in severe service.
-blaine
Fleet Owner
Joined: Nov 2003
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I'm gonna beg to differ here.
A weak cap COULD show these symptoms... The Freightliner ALWAYS starts showing temperature swings when the cap gets old/loose. What happens is that the coolant will spot-boil, from lack of pressure, and that will drive the overall temps up, even though it may not be enough to get vapor present in the system to start puking.
-blaine
A weak cap COULD show these symptoms... The Freightliner ALWAYS starts showing temperature swings when the cap gets old/loose. What happens is that the coolant will spot-boil, from lack of pressure, and that will drive the overall temps up, even though it may not be enough to get vapor present in the system to start puking.
-blaine
It sure is a VERY cheap solution to try - just replace the cap! Also, as you and steelhead2 have stated - the op shoud check ALL the fins for dirt and bugs (etc) in all of the radiators (probably the first thing to do!). I might even try replacing the T-stat again (even though it is new) if none of these other things work (just on the chance it failed early in its life - these things can happen ...). Maybe even consider a coolant system flush w/ VC9. After that, as cheezit said - maybe something was not right in the head stud install ......................... certainly hope not!
BTW - Thanks for the info Blaine. There is no substitute for real life experience - I am just anxious to understand!