Whats a normal idle temperature

[ibenz]

At idle my car is seeing 100 celsius. Is this a normal range. while driving im always at 80. I need to flush my coolant anyway but does that redline additive work good for these cars to keep the heat down

[vstech]

sounds warm to me. what car?

[barry123400]

No description of model but a poor fan thermal coupling might do this on an otherwise good cooling system if it has one. Easily tested. Bring car to operating temperature. Freewheel turning of the fan upon shut down more than a time or so the fluid fan coupling may not be as strong as it should be.

Or if the fan can be kept immobile with a rolled up newspaper on a hot restart. The coupling may again be too weak. Others may suggest better tests. Plus the problem of course may be otherwise. Watch how you preform the last test as it could be dangerous in the wrong hands. Or avoid that test if uncertain.

Waste heat generation at idle is usually less than when under load. Wind created through the rad when underway removes heat. You may be getting away with this again if the cooling system is good. At idle that breeze is missing or of less force unless the fan is functioning as it should.

[charmalu]

81 300SD.

Charlie

[ibenz]

Originally Posted by charmalu

81 300SD.

Charlie

yep your good.. it is a 81 300sd. I probably post too much on here but my car is in alot better shape then when i bought it. All thanks to people i bug on the forum.

I also tested the fan clutch it was fine. I just put in a new one around 5k miles ago. Could it maybe be too much straight coolant and not enough water... i had a leak in my hose one day and kept filling it with coolant instead of the mix.

[macdoe]

I wonder how much can be put down to variables such as sending units and the guage itself. Our 85 wagon now runs normally right between the 80 and 100 marks. Sometimes if leaning into it, the guage will climb to a couple needle widths below the 100 mark.

If I put on the heater it drops the guage down quickly to a needles width above the 80 mark. It stays there with the heater on for a couple minutes and then goes back to normal right in the middle. I consider that 90C obviously....but have shot the head with an infrared laser temp gun and the most I have seen with the engine running at idle is 74.5C and that is at the base of each injector. At that temp. gun reading.... the dash guage is saying it is 90. Which guage is correct ...the temp. gun or the dash guage?.... Don't know.... I always thought that these VDO guages had a good reputation for being accurate and maybe it is??. I guess I could try to find something to compare it to as a known accurate temp. This 85 wagon has two sending units in the head....I think the front one is for the guage and the back one is for?? My other diesel 617's only have one sending unit in the head.

We wired a toggle switch into the auxiliary fan and have removed the A/C condenser. That auxiliary fan switch was a waste of time according to my dash guage as it does nothing to lower temperatures when the aux fan is running.

I wonder if you have one of these temp. guns to check your temperature out for a comparison? They come in handy and are always going on sale for like $30...Princess auto. I think you guys to the south have a place called Harbour freight which sounds like an equivilent type store.Could be a cheap general diagnostic tool.

[qwerty]

Originally Posted by ibenz

Could it maybe be too much straight coolant and not enough water... i had a leak in my hose one day and kept filling it with coolant instead of the mix.

Excess coolant is bad news in several ways. Unless you really need additional freeze protection, 50% coolant is as much as you want.

[Jim H]

Originally Posted by ibenz

At idle my car is seeing 100 celsius. Is this a normal range. while driving im always at 80. I need to flush my coolant anyway but does that redline additive work good for these cars to keep the heat down

Your cooling system should not need any additives to keep the temperature within range, and the mix ratio has more to do with anti-freeze and anti-corrosive properties than with operating temperatures.

80C driving and 100C idling sounds like a lack of airflow at idle... Are you sure that the fan clutch is OK???

[Stretch]

Chapter 20 in the FSM has a whole load of information on how the cooling system on the OM617 works. It is worth a read because these cooling systems operate slightly differently than most cars - there's a by pass system - and removing the thermostat doesn't have the result that you might think!

[cho]

Originally Posted by ibenz

... i had a leak in my hose one day and kept filling it with coolant instead of the mix.

did temp show started after your intervention?
how much of pure coolant did you add?
what is your level in jar now?
I assume that you can add easily distilled water to correct mixture..

btw,I have fixed vent so in my case 85runnin'/95idleC is expected

cheers
ChO

.

[layback40]

Originally Posted by Army

Chapter 20 in the FSM has a whole load of information on how the cooling system on the OM617 works. It is worth a read because these cooling systems operate slightly differently than most cars - there's a by pass system - and removing the thermostat doesn't have the result that you might think!

X2
Removal of thermostat will cause high idle temps.
Unless you are seeing below freezing a lot you can run lower concentrations than 50%. Over here you can buy the additive package with very little glycol.
If you have been adding straight glycol & not mixing it with dematerialized water you are asking for trouble.
How did you test your fan clutch?
Is the radiator clean in the fins? If oil has been spilled & dust accumulated it can block.
Are your temps with aircon running?
Is this a heat soak situation?
The 100 you speak of is ambit until the conditions are given.

[t walgamuth]

I didn't see where anyone mentioned removing the t stat but most definately put in a stat if there is not one and be sure to get all the air out of the system. It won't cool correctly without a thermostat.

[qwerty]

Originally Posted by layback40

Unless you are seeing below freezing a lot you can run lower concentrations than 50%.

According to at least one manufacturer, 44% is the lower limit for HOAT coolant. Anything less fails to deliver adequate corrosion protection. In the final analysis, unless you are using a refractometer, you are stabbing in the dark anyway, when it comes to determining the coolant/water mix.

[Junkman]

I haven't seen anyone note in this thread that the dash temp gauge should be checked for accuracy by comparing its reading to some other measuring tool ie IR thermometer. I do this after confirming that the temp isn't obviously so hot my engine is in immediate danger.

[mach4]

Originally Posted by Army

?..these cooling systems operate slightly differently than most cars - there's a by pass system - and removing the thermostat doesn't have the result that you might think!

Indeed. When I swapped in a new engine, my temps were really weird. Took awhile to figure it out, but the PO had cut out the guts of the thermostat. Putting in the proper thermostat solved the problems.

Engine Temperatures