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Engine temperatures
mike89011 Offline
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#1
Engine temperatures
Ok, so this thread is to discuss engine temperatures for the OM606, and see if some clarification can be obtained!

From what I understand, the OM606 NA is supposed to run at 85ºC, as it comes with an 85ºC thermostat, and the OM606 turbo should run at 80ºC, having an 80ºC thermostat.

In a real world setting however, most people see a coolant temperature between 80 and 100ºC, and my question is hence if anyone has ever determined what exactly is optimal?

Apparently, there is some small improvement in MPG with increased temperature, but at what temperature would increased engine wear start to occur?

The question is relevant, because if the typical usage by one person causes their engine to run typically, say, 90ºC, then things can be done to decrease this temperature. i.e. through a different thermostat, or changes to the oil cooler system.

Or if a person's engine runs typically 80ºC with typical usage, reverse changes could be made if 90ºC is felt more optimal, i.e. with a higher temperature thermostat, etc.

As an add-on question though, can someone also explain the difference between coolant temperature and oil temperature? 

From my understanding, the stock oil cooler for the OM606 starts to open at 110ºC and is full open at 125ºC. But isn't coolant temperature supposed to approximate oil temperature to within a few degrees?

By this logic, the engine hence shouldn't be getting so warm that the oil temperature is ever up in the 110ºC range!

Thanks!
12-05-2016, 04:49 PM
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AlanMcR Offline
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#2
RE: Engine temperatures
I've got two OM606s, one in the E-class and one in the G-class.  Both run at just under 80C in normal traffic.  The E's temperature gauge hardly ever varies.  The G weighs twice as much when loaded for travel and has the aerodynamics of a postal truck.  Climbing long steep hills in the heat gets the temp up to 87C.  The only time I've seen 100C is when the fan failed.
(This post was last modified: 12-05-2016, 09:41 PM by AlanMcR.)
12-05-2016, 09:41 PM
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barrote Offline
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#3
RE: Engine temperatures
hy mike,
i´re reading too much , and in strange places...
indeed there´s 80º and 85º thermostats, and 90ºC, and in after market parts producers 78C. in the end all has to do with the place of the world your vehicle was sold and what thermo MB recommend, as far as i know , 601/02/03/04/05/06 all use the same thermostat part number, of course in 1988 the part number was A602.020XXXXX and now most probably is something like A605.030 00 03. they change part numbers and made improvements , u got to see what engine is and if there is a breakpoint tech.
Like the heads in 603 , from a 87 on the parts were modified , but a pre 87 head fit a 93 engine, most probably will warp and crack.....
About oil temp , of course it can´t run at temp higher than the coolant, most mb engines i know have a oil/coolant exchanger which purpose is more like to bring the oil to operating temp as fast as possible , than cooling the oil.
taking this in account i can tell u for sure that if u can run your engine at 80 to 90º u´re in the safe side , 80º internal temp temperatures is engineering agreed by many as the best mechanical behavior complex machines have, before exhibit heat build.
FD,
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12-06-2016, 01:27 AM
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Hario' Offline
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#4
RE: Engine temperatures
The stock 606 runs at just under 80 Celsius all the time, unless the viscos fan clutch is bad like mine..



Installed:

OM606/722.6, big IC, W220 brakes.
Planned:
DIY manifold, compound, 722.6 controller, built IP.
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12-06-2016, 12:19 PM
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charlysays Offline
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#5
RE: Engine temperatures
(12-06-2016, 12:19 PM)Hario Wrote: The stock 606 runs at just under 80 Celsius all the time, unless the viscos fan clutch is bad like mine..

|For a long time I thought they didn't even need a viscous fan Big Grin
Then I went to London in a heatwave.... and it went up to 120 in a traffic jam. One second it was just under 100, then jumped to 120! Electric fans knackered, had to put the heater on.
I now run a new viscous fan but without the shroud and its fine all the time now. I hate the way you can't really get the shroud out with the fan on, and can't really get the fan out with the shroud on.
12-09-2016, 07:16 AM
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deviance Offline
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#6
RE: Engine temperatures
Too much! Always too much heat!
12-10-2016, 07:45 AM
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Mallinman Offline
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#7
RE: Engine temperatures
So what’s the max safe temperature for these engines then. Mine generally sits at 80’C -90’C normal abuse driving. Stays at 75’C just pootling around. Only reason I ask is I had 4 tonne behind it today. Did a 150 mile trip. Outside temp was 25’C. Truck pulled like a tank. I was very impressed with it compared to the last crappy jap engine it had in. It sat between 80-90 most of the way. But on one big long pull (about 3/4 of a mile) up a steep hill it got to 100’C. EGT’s got to 600’C. Was a long pull and I had foot flat down and she was pulling at 65mph. Soon as I hit the flat on top again it dropped back to 90’C. Does anyone reckon this would Be a problem for short periods. I don’t tow too often, just when no one else will take the big loads. But I was thinking of a larger ally rad. I’m paranoid about cooling after blowing two heads on the last jap engine and I’ve put soo much time and effort Into this build that I don’t want to ruin it. Any thoughts
L200 manual om605  7.5mm 
05-31-2018, 03:12 PM
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AlanMcR Offline
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#8
RE: Engine temperatures
What kind of oil cooler do you have on it. The internal spray oil cooling transfers a lot of heat to the oil. A large fan cooled oil cooler can efficiently remove that heat from the engine.
06-02-2018, 12:35 PM
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Mallinman Offline
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#9
RE: Engine temperatures
It’s just the standard water cooled oil cooler. Do you reckons she’s getting too hot?? Ive got plenty of space to put in an external cooler if needs be.
L200 manual om605  7.5mm 
06-02-2018, 05:25 PM
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AlanMcR Offline
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#10
RE: Engine temperatures
An oil->air cooler would certainly help. Right now you are just adding the oil heat to the water.
You have an intercooler, correct? If not, that would be a good start, since that helps keep added heat out of the engine to begin with.
06-03-2018, 12:00 PM
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Mallinman Offline
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#11
RE: Engine temperatures
Yea I've got an intercooler on. Il put an oil cooler on to help on big pulls.
L200 manual om605  7.5mm 
06-04-2018, 03:33 PM
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tjts1 Offline
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#12
RE: Engine temperatures
On my 97 om606 na, I ditched the viscous fan and replace the belt driven aux fan with a second electric fan, like the baby Yezus intended. The first fan runs as normal triggered by the AC, the second fan is belt driven until its own switch and relay which turns it on at max speed at 90c. That also feeds full power to the first fan as well so both are going full blast. Last summer we sat in traffic in 115f with the AC blowing 45f out the vents. The coolant temp never exceeded 90c.
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(This post was last modified: 06-06-2018, 08:10 PM by tjts1.)
06-06-2018, 07:57 PM
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AlanMcR Offline
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#13
RE: Engine temperatures
I should hope it stays cool at idle.  AC or not.  The discussion relates to an OM606 turbo in a heavy truck towing a trailer uphill.  This generates massive heat.  The factory fan system is excellent as long as the fan clutch hasn't lost its fluid.  There is a larger pump and smaller pulley that help too.  Discussed here:
https://clubgwagen.com/forum/viewtopic.p...28#p107653
06-06-2018, 10:59 PM
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tjts1 Offline
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#14
RE: Engine temperatures
No, the OP has an NA engine.
[Image: 208104.png]
06-06-2018, 11:56 PM
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AlanMcR Offline
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#15
RE: Engine temperatures
Hmm. Rather strange that he's got an intercooler on it, eh?
06-07-2018, 01:48 PM
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tjts1 Offline
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#16
RE: Engine temperatures
(06-07-2018, 01:48 PM)AlanMcR Wrote: Hmm.  Rather strange that he's got an intercooler on it, eh?

Get your eyes checked.
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06-11-2018, 07:11 AM
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Mallinman Offline
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#17
RE: Engine temperatures
Il have a look into the larger pump and smaller pulley. Thanx for the link alanmcr. I really like to keep the thing cool under load. No point doing half a build. Want it to work properly. I’ve got two 16” electric fans blowing the radiator. It’s the rad out of the l200 so it’s got a nice big surface area and the fans cover well over 80%. Only real upgrade there is a custom ally rad. Might build one at a later date. Il be interested to see how the temps are when I’ve put the s200 turbo on. It should have lower EGT’s then. Definitely the oil cooler rad. Got one ordered.
L200 manual om605  7.5mm 
06-11-2018, 04:41 PM
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barrote Offline
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#18
RE: Engine temperatures
Not to highjack... but just a small detail about the fans....
Usially they work better when pulling intead of pushing...
The fans work the same the cooling effect is better...
FD,
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06-13-2018, 01:21 PM
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Mallinman Offline
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#19
RE: Engine temperatures
I couldn’t fit the fans on mine to pull. There just wasn’t the space unfortunately. Had to front mount them bud. For such a big truck there is bugger all space in the engine bay. Same reason I had to tilt the engine clockwise on the install to fit in a bigger turbo. Very small bay. Width and length.
L200 manual om605  7.5mm 
06-15-2018, 10:55 AM
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