View Full Version : Causes for higher operating temps?

08-20-2013, 03:38 AM
My 2008 with 165000 KM on it has been showing some higher then "normal" operating temps. Mind you its been warm in calgary, but nothing crazy hot. Usually my van runs between 185-195. For the longest time it would run at 185 almost spot on, and run up to 190-195 under load or hills.

Last couple days I have been seeing it running around 195 and load has been 200-205.

The only thing I have noticed is it being sluggish when accelerating. I dont drive the van hard but I have noticed anything under 1800 ish rpm showing 99% load. I dont get into the pedal hard enough for it to want to down shift and because it is usually second gear its only under 99% load for 2-3 seconds, but it doesnt feel like the turbo picks up at ALL until 1800-2k. I know that normal but I always felt I had better low end power.

Van has always (since 90,000km that I have owned it) had correct oil changes under correct intervals. My last oil change (7000km) was done at MB and they used the correct oil as I checked the receipt.

Recent work done has been front brakes :idunno:

EGR was changed at 120000km.

(something I just thought of, maybe do my fuel filter? would that explain the higher temps if its running lean or something?)

08-20-2013, 03:57 AM
A common cause of higher temps is bugs, greasy dirt, leaves caught between the rad and intercooler and air conditioner fins. A second cause is the serpentine belt on wrong, turning the water pump backwards. I'd check that you can see light between all 3 layers of rad fins 1st.
3rd cause is lower coolant level.

Aqua Puttana
08-20-2013, 11:32 AM
I'd first try the light through the stack test. It's pretty simple given a flat light source.

Radiator Blockage Quick Check


Waynerodd did report that he saw unusally high engine temperatures a bit prior to a cylinder failure which he believed to be related to injector over-fueling. If the radiator stack and other things mentioned for checking don't yield anything then maybe an injector leak off test would be worthwhile just for peace of mind. vic

08-20-2013, 12:47 PM
Those temps your quoting seem very normal to me. 185 actually seems lower value than I ever see in warm weather. Mine will runs 190 to 205 most of the time higher value seen depending on load and hills. Also seems normal since your experiencing warm weather.

That being said cleaning the radiator and condenser, and checking the fan operation would be a good idea just for piece of mind.

Old Crows
08-20-2013, 01:42 PM
Help a Crow understand! Absent a real, honest to Gawd "gauge," .... How do we tell if the engine is over heating? There's a warning light.. Right? So, what's the trigger point of the high temperature sensor? ??? That would be the point just below meltdown or thermonuclear reaction... Anything below that is normal operating temperature, albeit higher or lower than you normally expect to see on a daily basis.

I'd stick my neck out and say that Mother Benz's engineers have established a conservative trigger point for the warning light to give one warning before you toast the engine. We've been living with "idjit" lights for generations and in all kinds of situations and all kinds of applications. I want a bright light in my field of vision and a klaxon horn that keeps honking till I shut it off. Properly designed, they should be adequate (just) to protect the system and enough time for operator response ..BEFORE.. bad stuff happens. They are color coded warning lights to give you a sense of the warning's importance.

So what is the trigger point for the height temp sensor?

(Crow opinion: the problem isn't the sensor but the design of the annunciator panel or warning light. Important info has to be concisely conveyed to the operator. Case in point: TPMS. I think loss of tire pressure or impending blow out due to over pressure is pretty dam important. TPMS warnings are usually amber (should be red); too small & hidden in an obscure part of the panel & easily obliterated by bright sunlight. Most have an single elevator chime that can't be heard over the radio, road and wind noise. Nor are the easily heard by Old Crows whose misspent youth is robbing me of my hearing. Sometimes you want a warning that grabs you by the tucker so you can focus on the problem. That being said, there's legion of folk who have obliviously driven on with a temp gauge pinned in the sinful zone.....

Graphite Dave
08-20-2013, 02:14 PM
Scangage required to monitor water temperature. My 08 8000 lb conversion normally operates at 193 degrees. In cold weather(California?) it sometimes can not get up to the 193 degrees. I have used the Espar to bring engine up to temperature while driving.
Some 08's came with two electric radiator fans and others were delivered with only one fan. Mine has two. The operating temperature climbs above 193 degrees in warm weather under heavy load. The first fan comes on around 205 degrees and the second around 215 degrees. In my opinion the radiator is undersized. Not much of a safety factor. Any load causes the temperature to climb. I had both fans operating in 100 degree weather. You can hear them start.
Be sure your fan (s) is operating.

Old Crows
08-20-2013, 02:19 PM
Thanks Dave... So...A/C off, we have fan on set points as 205F & 215F. Anyone know the trigger point on the high temperature sensor?

Aqua Puttana
08-20-2013, 05:07 PM
I believe that T.J.T. is basing his question on observations of what is "normal" for his vehicle more than what the safe operating range is. He's been running around a certain temperature and now under similar conditions he's noticed a change. I give full credit for observing that. Often the gauge info can give a clue as to impending problems so you can avoid a major repair.

Until it is established why it changed, it is worth exploring. When I'm towing in hot weather it is not unusual for my engine to run up near 215F. When I'm unloaded, not towing it is a tick above 180F. If I'm running unloaded and I saw it approach 215F I would begin to suspect a problem, even though that is well within the OK range.

Waynerodd commented that he noticed a slightly higher operating temperature before his engine bit the dust. He said it wasn't extremely high and not enough to cause alarm, but it was higher than his normal. Whether that was indicative of impending doom, who knows?

Until it is established that the operating conditions are just the new normal, I feel that it is worth exploring.

In addition to the other suggestions maybe his fan clutch is going bad?

By "trigger point" are we talking audible alarm? I don't know if there is one.

The T1N's have a 195F thermostat. The T1N aux electric fan is designed to come on at 221F engine temperature and per Doktor A.

The aux. coolant fan is activated by refrigerant pressures above 290 psi
by coolant temps above 221 degrees F.

Doktor A

I haven't seen any "official" numbers yet for the NCV3. I expect that if the refrigerant type hasn't changed then the high pressure setting would be the same.


Aqua Puttana
08-20-2013, 05:35 PM
I looked up the 2010 info which JDCaples posted in database.

We miss you Jon.

2010 MB Operator Manual Pg. 88

The temperature displayed may climb to
250 F (120 C) when the vehicle is being
driven in normal conditions and if the coolant
contains the correct concentration of
corrosion inhibitor and antifreeze. It is acceptable
for the coolant temperature to
rise to the end of the scale at high outside
temperatures and when driving in mountainous

What to do if....? Pg. 229

"Coolant symbol with Thermometer" dash icon goes here.

Stop, turn
engine off

The coolant temperature is too high.
* Stop your vehicle as soon as it is safe to do so.
* Do not drive any further.
If the vehicle is switched off after being subjected to extreme
loads (for example driving in mountainous terrain,
trailer towing, etc.), this message may be displayed when
the ignition is switched on or the engine is restarted.
* Run the engine for approximately 1 minute at idling
* Consult an authorized Sprinter Dealer if the message
remains displayed.


It didn't mention any audible alarm that I saw. It wouldn't surprise me if there was one.


Old Crows
08-20-2013, 05:40 PM
Right Oh, Vic! Credit for situational awareness and the need to check the obvious things ... like a jammed radiator (could be a piece of plastic bag blocking the air flow). Credit for knowing the operating typical operating parameters of a particular van. Need to check that which needs checking for obvious problems. Finding none, we should accept it as being normal for that particular day.

On the other hand, the 'normal operating range' can vary quite a bit and still be OK. Especially true on a hot day. No gauge in the Sprinter! However, the temperature gauge in my Sienna runs a little higher on 90+ to 100+ days than it does in normal temperatures. It also runs a little lower on days below 40...and it's slow-er to get up to its normal position when its cold out. But that's just the car. I think Sprinters are the same... there's going to be variation depending on the ambient, load, speed, terrain.... that's just what they do.

I don't think there is an audible alarm.... maybe there should be? The manual says as high as 250F is OK. That sounds about right for most engines. Looking for the switch point temperature for the sensor that tells the light to turn on. There has to be a high coolant temperature sensor somewhere in the system. Knowing that temperature should give us a normal operating 'range' .... something like 195F (thermostat opening) to ??? (overheating light turns on). Since it can operate at 250F on occasion.... the switch point for the light must be somewhat higher.

08-23-2013, 06:49 AM
Old Crows - Yes as others pointed out I have noticed my temps go up slightly on my scan gauge, I am merely now looking for reasons why in hopes to save me some money and time if something needs work.

vic - Thank you again for your ideas, I will run through them this weekend if I can get some time.

Dave - I two have an 08 with 2 electric fans, it keeps it a Nice temp in the summer. I have to run my ESPAR almost all winter when the temps drop to -40 to -50. I fight to get them up to 180-185. Usualy have to block the rad and even then its a pita to keep the cabin warm without insulation... I keep thinking I will find time in the summer to do that but it always get pushed back until its too cold.

08-23-2013, 11:31 AM

I have a little of your same issue. In fact pulling a one mile hill at 35mph in 3rd gear the whole time and the temp will go from 185 up to 205 when it's 80 or higher outside and that's with my heat on full blast. I am going to pop my dpf off as an experiment. My van has been slightly anemic, mpg is 21 average with a mix of driving and I have been gettin oil pushing out my oil fill cap. I will report back temps when I'm done.

08-23-2013, 12:26 PM
205 deg. F is not even to the boiling point of plain water (without the increase in boiling temp that anti-freeze adds) so your cooling system seems to be doing precisely what it's supposed to.
"In fact pulling a one mile hill at 35mph in 3rd gear"....so which rear end do you have....that should be 2701 RPM with the 4.182:1 Rear ratio....2211 RPM with the 3.916:1 Rear ratio.....2104 RPMs with the 3.727:1 Rear ratio.
I sure hope you have the 4.182 rear end ratio as 2700 RPMs is right near the bottom of where your Sprinter starts to make power. 2211 and 2104 RPMS pulling up a hill is nonsense......the engine is not even up to it's peak torque RPM yet and makes almost no power down that low.
This whole discussion is about not knowing what's going on with your Sprinter's engine.
Add a Scan Gauge II (or similar) and you will know "to the digital degree" what your coolant temperature is, and if you have the PID for % engine Load (LOD) displayed, you will also know why the temperature has risen.
Sprinter radiators are not particularly oversized, but with the fan systems and the temp sensors they do a remarkably good job of keeping our engines cool enough not to hurt themselves.
I was under the impression that (as JD's quote seems to indicate) when the temp gauge (T1N's here) or the Scan Gauge II gets to the red range @~250 deg. F (121 deg. C) it's time to get off the road and cool it down.
Actually, I would be stopping if my Scan Gauge II told me I was @ 240 deg. (115.5 deg. C) to find out what is wrong BEFORE I cooked the motor.
BTDT in my Mitsubishi-Fuso box truck/trailer going up Deadman Pass on I-84E into Idaho.
Alternator was not charging, gauges were low on voltage and not reading correctly.
I should have noticed when the engine started "cycling" when I turned the flashers on to pull the grade that something was wrong.
I was listening to a book on tape and just cruising on my way back to the east coast. I finally heard the "overheating" beeper going off... but by then it was too late. Running over temperature pulling heavy up the grade had scored all 4 cylinders. Motor still ran good, got me home to the east coast, but needed a gallon of water every 200 miles.
Hope this helps,

08-23-2013, 12:44 PM
I sure hope you have the 4.182 rear end ratio as 2700 RPMs is right near the bottom of where your Sprinter starts to make power. 2211 and 2104 RPMS pulling up a hill is nonsense......the engine is not even up to it's peak torque RPM yet and makes almost no power down that low.

Sailquik, max torque is around 1200 rpm actually, max horsepower higher obviously. Yes they pull good 2700 and up from my experience

08-23-2013, 01:46 PM
Watching the water temp just as another data point for this thread....this week 400 mile trip pulling a trailer in rolling hills:

Outside temp 90-92
A/C set on 68 fan on 3 position

Engine temp ran from 195 to 213
Pulling the rolling hills in 4th gear with no drop in speed.
Road speeds 65-72 mph
Mpg 13.9. This a real common avg for my rig

08-23-2013, 04:30 PM

I have an ultragauge and I monitor it like a hawk. In fact thats why I noticed the temps, I don't much care about the 205 temp. It's when it gets hot out like 90 or more and I have to put the heat on high to keep the temp below 220. If the coolant is at 220 what is the temp at the turbo, I dont want to shut it off that hot. I am not a fan of shutting off my van unless its under 200 degrees. My engine % is the first thing on my display and it constantly hits 99% and thats with me downshifting. I want to try the DPF removal as a test, no harm in trying and knowing. It's always had the correct oil and it has 150K on it. Dpf's from what I have read don't last forever and I may be in that prefailure area.

09-26-2013, 02:55 AM
Just a quick update, this may not be related but my Glow plug light has stayed on for 30 seconds in cold starts the last 2 mornings, also have a check engine light, but my Ultragauge still wont pick up a code from it. The glow plug goes off after about 30 seconds if I start it. Warm starts its fine.

I have a service booked tuesday morning, I read about the glow plugs but have zero extra time and they are doing a boat load of work on my sprinters.

B service
check engine light/glow plugs
Rattle sound (u bolts maybe?)
both my tie rods are getting done.
Ac recharge

At 170000km now so I guess I was due for a big bill :(

I told the service rep to be gentle and he put it on the work order. lol