How hot is to hot?

CRDMiller · **Posted:** Thu Apr 22, 2010 2:38 pm

I have a coolant temp gauge, and installed the probe on the 3/8 id line from the thermostat to the coolant bottle

I had the probe installed in the egr cooler line however i decided to move it.

Anyway, how hot is to hot for engine coolant output?

I have replaced my fan clutch, thermostat, and flushed my system repeatedly, however i still get what i consider to be elevated coolant temps.

Unloaded in fair weather 60-80f i can regularly hit 230f. This is at 70 mph on a very steep grade that is about 11 miles long (around 12% grade)

Is this normal?

On normal flat land unloaded i cruise at 165 to 180.

warp2diesel · **Posted:** Sun Apr 25, 2010 5:57 pm

A 50/50 mix boils at 223F at sea level. For every PSI the cooling system runs at, you can elevate the boiling point by 3F. When the coolant boils the liquid no longer contacts the metal surface of the cylinder walls or cylinder head causing hot spots and resultant failure. As long as your radiator cap is good, 230F should not hurt your engine.
I would never do this to my CRD, but some people with older Mercedes and VW diesels have run straight Propylene Glycol with a no pressure cooling system and a 275F thermostat. To get the coolant to become close to straight Propylene Glycol, they would drive short trips and keep adding PG antifreeze until all of the water evaporated out. Unlike the parent bore of the old Mercedes and VW Diesels, we have wet sleeves and trying this experiment is a risky way to get a couple more miles per gallon.

CRDMiller · **Posted:** Sun Apr 25, 2010 9:43 pm

I hit 240+f today

I dont like this

I am trying to buy a house in this area and it will soon become my commute.
No other vehicle i have ever driven has ever had a problem in this area.

I need help.

Thinking of buying another fan clutch. I replaced my last one 6 months or so ago.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

The engine should be at a full safe power cut at 242 F and the AC is automatically disabled. Can you notice either of these happening? Is your coolant gauge on the fully pegged hot at the same time? When it is this hot the fan clutch should be locked on and causing a noticeable 'roar' as you rev the engine in neutral. If not, the clutch is most likely failed.

Are you pulling a large trailer up a grade for this to happen? Maybe the gauge location is getting heat soak and reading higher than the coolant gauge in the engine, otherwise it could also be a failed impeller on the water pump. Is your coolant bottle clean or are there dark deposits inside the bottle?

Thanks, GDE

CRDMiller · **Posted:** Mon Apr 26, 2010 9:22 pm

GDE the 230-240+F temps are occurring around peak torque and probably 1/3 throttle.

I have replaced my fan clutch and t-stat.

I am at 72k and i did the fan clutch at 52k (about 6-7 months ago) and the tstat at 68k

I flushed the coolant system with 8 gallons of distilled water, added g-05 concentrate and measured with refractometer to 50/50 at 58k

at 68k i flushed it with 18 gallons of distilled water and added shell rotella elc, at 50/50 with a refractometer

at 71k while on vacation, i lost a coolant hose (viscous heater to tstat housing), added bottled water, when i got home i flushed it again with about 14 gallons of distilled water and again achieved a 50/50 mix of elc, with a refractometer.

I have never heard the fan engage.

The reason i changed the fan clutch initially was because the factory gauge was pegging the H, 15/16 of the gauge and i never heard the fan clutch (this only happened once) The chime never went off, the engine never de-rated (as far as i know)

The next winter (and i am using the term loosely, i live in san diego), it would not warm up for anything, replaced tstat, problem solved.
Then i figured hell i've had so many thermal issues, i better add a gauge to find out what's really going on, before i hurt something.

Witch leads me to now.

When i had the aftermarket gauge installed in the line from the egr cooler to the tstat housing, it hit 230-235f about 3 times (different trips) factory gauge indicated just past 12 o'clock, i did not hear fan clutch.

The weather had warmed up a bit this time (the most recent event) it was about 70f and i had moved the gauge to the 3/8 id line between the t stat housing and the coolant bottle.
It pegged my aftermarket gauge from between 240 and 250. I did not hear the fan clutch. The factory gauge was right at 12, and eventually made it's way to 3/4.

My gauge pretty closely matches the factory gauge right up to the 12 oclock position, normally the factory gauge rides just under 12, and the aftermarket gauge rides just at 165-170.

MY coolant is in excellent condition, there are no deposits of any kind in the bottle.
The radiators/cac/condensor are clean, and not packed with mud (they were at one time, but i now clean them after off roading, since my shroud is removable)

I have trimmed the bumper for clearance, and i added a set of hood louvers, nothing that other people have not done.
This is UNLOADED, without a trailer!! in top gear, without much effort! egt's were elevated, 1-1.2k F. But nothing unexpected for the conditions. 12-17 psi of boost, sometimes spiking to 26 for short periods.

My fan clutch passes the hand test and my fan is not mounted backwards, it actually moves a decent amount of air at idle.

I cant get the thing to 220 f in park with a thermometer between the radiator and mechanical fan. It's been to cool. i got it to about 190 last time i tried (3 weeks ago) but it took 2.5k rpm for about 22 minutes. the fan noise SEEMED to be louder.

The first time i tested my faulty fan clutch is did not make more noise or move more air at 225f following the fsm procedure, minus the timing light.

I'm ready to get a bigger radiator and/or using a perm flex fan. I would have gone to a rad shop today but i've been busy. It's the next thing on my list.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Since the coolant gauge only hit the 3/4 mark the coolant in the cylinder head was only 230 F. If the engine get much warmer the mechanical fan will engage. Are you running the AC on full? Electric fan running? This tends to cause the engine temps to vary between 218-230 F if doing city traffic driving in very hot weather.

The placement of the sensor you are using does not sound like it is reading the same temps as the coolant gauge. The thermostat by-pass line might give a more accurate reading. We sometimes measure the coolant temp at water pump inlet as the temp rise across the cylinder head in wide open throttle trailer tow situations is about 10-12 F. It does not sound like anything is wrong with your system based on what you stated. Thanks, GDE

Auberon · **Posted:** Tue Apr 27, 2010 11:08 am

G'day,
sorry to hear about your troubles. It sounds as though you have been meticulous. It certainly sounds as though you did everything you could to exclude air-locks and I am not questioning the advice so far offered or your mothods. What a bugger about losing that hose.

As a serious thought, have you "burped" your system?
If you continue unhappy, it might be worth it. Reserve tank cap cracked but not off, heater on. It may be a small airlock somewhere, as the thermostat opens to allow some flow, a little burp of fluid may be noted into the reserve header tank. It migh need repeating. Trouble is even with the best of care, there are so many nooks and crannies in these new systems....
Clearly this is not the whole technique, it is out there on the net....some call it burping automotive cooling systems but you are clearly clever enough to work out other names for the technique to search for.
Best of luck.
Auberon

CRDMiller · **Posted:** Tue Apr 27, 2010 10:54 pm

Baked my fan clutch today
(removed fan to replace serp belt anyway, figured, why not)

Baked it at 220 verified with 2 thermometers and the oven temp setting, clutch rotates pretty freely.

Did it again at 250 and same result, i can easily spin the clutch with a wrench and my hand. Should it be VERRY hard to turn? it takes about 5 ft-lb.

CRDMiller · **Posted:** Tue Apr 27, 2010 11:24 pm

Had it at 350 and it was easy to turn, threw it int he sink and hit it with water, cooled it down, it was harder to turn cool than it was hot.

I'm guessing it was faulty when i bought it.

MrMopar64 · **Posted:** Wed Apr 28, 2010 7:47 am

Just because you heat the clutch in an oven doesn't mean that it would be hard to turn. In order for the viscous fluid to pump into the chamber and engage the clutch, the shaft should be turning.

For your coolant temps, on the driver side of the engine above the EGR valve, you'll see a plug in the side of the head - this is the coolant jacket. This is where your coolant gauge probe should be placed for accurate readings. The de-gas line going from the T-stat housing to the expansion bottle is very low flow and isn't representative of the temps in the engine.

Have you tested the coolant with a dye to see if there are any exhaust gases in the coolant system? I would also think it might be a good idea to wash the radiator from the backside towards the front, to try and remove any debris/sand/dust/pollen that might have collected in the fins. Above and beyond this, there are only a few explanations - water pump is bad (impeller spinning on shaft) and you're not moving much coolant, exhaust gas is somehow entering the coolant system, etc.

kapalczynski · **Posted:** Wed Apr 28, 2010 5:44 pm

My solution to keeping my temp where I want it to be - a flex fan directly connected w/o the fan clutch:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=51618

Works like a champ. I run much cooler when under load. Keeps tranny temps down also.

So far no adverse fuel economy drops. Waiting on this tank's results. I got 24mpg to work & back with the stock fan clutch which is 15 miles of mostly hwy driving (first 5 miles are not up to operating temp). My wife averaged 23 with the new fixed fan design with a lot of in town driving so its looking good. I am betting my work/back mileage will still be around 24mpg this tank as the evic is looking about the same as w/ factory fan clutch. Also of note I am running my 192* F thermostat design with this setup.

How hot is to hot?

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