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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| [G320] Cooling system issue & questions
Hello all, I finally picked up my 1994 (registered; manufactured late 1994 so IMHO a 1995 model) G320 with the M104 and got it home to Houston, arriving mid-afternoon today. The truck has 92,000 miles on it and from everything I can tell, is an original Europa import. Russ is doing some research on it for me. Drove it from the San Francisco Bay Area to Houston in two installments -- one from Marin County to Mammoth, where my brother in law lives. Then a couple of weeks later (this past weekend) I took a long weekend and went back and drove the truck from Mammoth to Houston by way of Las Vegas, Flagstaff, Albuquerque, Clovis NM, Lubbock TX, Waxahachie & Ennis TX and on down I-45 through Huntsville to the Houston area. Great road trip, both legs of the journey. Definitely got to know the "G" because I drove pretty much over every kind of terrain and weather condition known with the exception of snow/sleet/ice. Had a major windstorm from Albuquerque onward, rain/thunderstorm pretty much all through Texas, limited visibility due to a dust storm. Drove over the Eastern Sierra through Yosemite over Tioga Pass, various passes up to and including more than 10,000 feet (quite a number over 7,000), desert, forest, and everything in between. "Getting to know the "G" surfaced one problem for me of major concern: the cooling system. Let me explain some of the characteristics I experienced with the cooling system - some of which give me strong concern. First of all, the engine, particularly when pushed hard but even moderately, runs VERY hot. Climbing up the Sierra out of Livermore, I first noticed things creeping up well over 100C ... then 110C....then 115....and on the higher passes even going slowly (or faster) things actually hit 120C. There were a few times I had to pull over because I simply couldn't get the engine to cool down. Coasting down a mountain with little to no load on the engine (no matter what speed) always returned the temp to the 85-95C range, which is normal. Just downshifting from 4th to 3rd gear on an uphill climb (even just short hills on the freeway) was enough to make the temp climb 10-15C in a minute or two. The biggest frustration was that I could hear the fans running, but perhaps not on the "high" speed that they need to, to move real air. My other M104 and my M119 also like to run hot in higher (80+F) ambient temperatures, often climbing up to 110C, but the fans kick into high gear at that point and RAPIDLY push the coolant temp back down to the 85-90C mark, and then the cycle repeats (if sitting in traffic or at a long traffic light, etc.).
I am also concerned about the fan clutch being faulty, and maybe contributing to the problem. I am going to order a new clutch out of hand and install it, just because I am sure the one on the truck is the original unit and it's 20 years old now. My truck has the original 6-blade fan, and I will look at replacing it with a 9-blade fan per some other threads.
I guess my question is .... do these engines run super hot? The manual says up to 110C is acceptable, and that may be so, but my truck is getting up to 110C-120C even in normal driving, and it DOES NOT like these temps. Output is dramatically down, transmission shifting gets balky and rough (not butter smooth with good behavior like at lower temps). Is the proper characteristic for: 1) whenever the A/C is on, the two fans in front are running at low speed based on refrigerant pressure (A/C on my G works very well, R134a) 2) whenever the coolant temp gets hot (I think around 105-110C), the two fans are supposed to kick into high speed and push more air across the condenser and radiator 3) the fan clutch is supposed to engage ("roar") at a certain RPM level with ambient temps at a certain level Can anyone help out with location of the switches for the fans in front so that I can test them for proper engagement? Has anyone tried the "CoolHarness" resistor setup to trick the fans into engaging their high speed at a lower temperature than stock? Has anyone had luck with RedLine Water Wetter or other similar products that are supposed to help cooling system efficiency? Can anyone talk about their fan clutch experiences and if that was successful at lowering operating temps? Has anyone had a custom radiator with more efficiency fabbed up for their "G"? If so around how much (knowing that list price of the raditor for my truck is over $800 today). Cheers,
Gerry
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DesertStar
Expert
Date registered: Apr 2006
Location: San Diego, CA USA
Vehicle(s): 85-280GE/95-G320/08-G500
Posts: 2156
| RE: [G320] Cooling system issue & questions
All I can add now is a comment on the cool harness...I installed one on my 1993 400E and it kicks the fans on earlier and runs much cooler in town and traffic scenarios, I thought it was worth it and am considering for my G320. I know there were some threads here relating to fan clutch and cooling issues. Mike |
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| RE: [G320] Cooling system issue & questions
gerryvz - 6/9/2014 12:39 AM I guess my question is .... do these engines run super hot? The manual says up to 110C is acceptable, and that may be so, but my truck is getting up to 110C-120C even in normal driving, and it DOES NOT like these temps. Output is dramatically down, transmission shifting gets balky and rough (not butter smooth with good behavior like at lower temps). |
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J.R.
Elite Veteran
Date registered: Apr 2006
Location: Southern Maryland
Vehicle(s): 00 G500, 09 911 4S, 11 Cayenne S, 86 280GE (sold)
Posts: 828
| RE: [G320] Cooling system issue & questions
A good number of discussions regarding cooling on the forum. Before trying any elixirs, I'd checkout the hardware first. Your temps are unnatural.
- I'd be inclined to check the radiator out for potential clogged airways. Dirt, bus, etc, shine a flashlight from the backside and see how much light makes it through
- Check coolant volume and content of antifreeze (antifreeze does not conduct heat as well as water. too much antifreeze can be a problem). Also check the coolant color for potential dark post combustion contaminants
- Test drive.
If not improved or nothing noteable found
- checkout fans and clutch as you have mentioned
- Thermostat. Take the current one out and test it in a pan of water at room temperature and raise the temperature, taking measurements at the 85/90C and monitor if it is opening, and then what happens after 85/90 to 100C
- Replace it, or a new one (be sure and test it too), back into the truck. Do not test the thermostats by mechanically pressing the mechanism. Just use heated water.
- test drive
If not improved, or nothing noteable found, things to consider
- water pump impeller worn
- engine coolant passages coated with "stuff" . A good deoiling first followed by a good demineralization. Forum search will yield details
- Radiator passages narrowed from contamination
Forum, what else am I missing?
Edited by J.R. 6/9/2014 7:17 AM
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Roly
Elite Veteran
Date registered: Apr 2006
Location: Australia
Vehicle(s): 1999 G500
Posts: 661
| RE: [G320] Cooling system issue & questions
An easy test for the rad is to feel the matrix after a run to check whether it's uniform across the area. If there are cold spots it indicates blocked cores.
Naturally, do it check with the engine off |
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nadd
Expert
Date registered: Apr 2006
Location: UAE, Dubai
Vehicle(s): G500 2016 LHD, numerous Chevys
Posts: 1285
| RE: [G320] Cooling system issue & questions
Roly - 6/9/2014 1:28 PM
An easy test for the rad is to feel the matrix after a run to check whether it's uniform across the area. If there are cold spots it indicates blocked cores.
Naturally, do it check with the engine off
x2, blocked radiator makes a big difference!
I would say check the head gasket but if you have clean coolant and no loss and no mayo in the oil then hopefully this does not apply, as I did not want to concern you unnecessarily. |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
Thanks for the input. I did some checking tonight. Ran the truck in around ~80F ambient temperatures, around the area, driving around 6-7 miles total tonight. Temperature crept up to 110C but not much above, this in ordinary driving with the A/C on, on flat ground.
When I got home, I parked the truck in the driveway and let it idle. Turned the A/C off and after 45 seconds or so the fans went off. A few minutes later I heard the fans come on, and checked the temperature indicated on the gauge - appeared as around 105C as indicated. The fans ran for a few minutes and pushed the needle down just below 100C, to perhaps 98C or so. After a few minutes, the temp built back up and the fans cycled back on again, and the process repeated. I did this also with the A/C on and the temps pretty much were the same, and the fans did run after starting the A/C system.
I looked down the back of the radiator and it looked very clean, though I know there can be a lot of hidden dirt and crud at the bottom on the INSIDE of the radiator. I think when I replace the fan clutch (I ordered a new one today) I will drain and remove the radiator, and double check for blockage of the fins. I don't think this is the problem, though.
I will order a new 87C Wahler or Behr thermostat and replace that too.
Please keep the suggestions coming and I will re-read the threads on the G320 cooling systems running hot.
Cheers,
Gerry |
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Roly
Elite Veteran
Date registered: Apr 2006
Location: Australia
Vehicle(s): 1999 G500
Posts: 661
| Re: [G320] Cooling system issue & questions
It's not the blockage of the rad fins, it's blockage of the circulating cores internally. You will be better off checking in situ. |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
Would you recommend getting the radiator re-cored locally or getting a new MB radiator, if that ends up being the problem?
One other question ... Does the G have a two-stage fan that runs when the A/C rubs, and a second "turbo" phase at high speed when the temps get to a certain point? |
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J.R.
Elite Veteran
Date registered: Apr 2006
Location: Southern Maryland
Vehicle(s): 00 G500, 09 911 4S, 11 Cayenne S, 86 280GE (sold)
Posts: 828
| Re: [G320] Cooling system issue & questions
Presuming you have an all metal radiator, if you can find a shop who can locate the right size, make sure they add corner reinforcements to the repair, otherwise, the solder joints in the corners eventually form cracks.
But before you do that, look at the data you collected yesterday. Test the fan clutch. sitting idle, raise the engine rpm above 3000-3500 rpm (darned if I can recall the number) and wait. If you hear a distinct change in the sound of the fan, then the fan clutch is working. There maybe a better way to check too that someone will share.
If don't already have one, invest in a non-contact thermometer like a Raytech http://www.amazon.com/Raytek-MT6-Non-contact-MiniTemp-Thermometer/d... With that you can check the radiator core, inlet and outlet hoses of the radiator, as recommended by an earlier poster. |
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: [G320] Cooling system issue & questions
It is almost certianly the fan clutch, BTDT.
I seriously doubt that what was probably a road driven G has ended up with a clogged (externally) radiator. On a truck that had seen a lot of dirt roads or lived in a very dirty place, maybe that would be the issue. The fan clutch though is quite a common failure and the symptoms sound exactly like a failed clutch.
You could confirm by locking the engine fan on. Bend a few of the metal fingers into the clutch locking the fan on. If it cures the overheat, you found your problem. |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
I have a new MB fan clutch and thermostat en route. I agree Brent, I think that the radiator is fine as the truck was mainly road-driven by the previous owner as far as I can tell. I examined it closely last night with a flashlight and didn't see any dirt and debris buildup externally. I'm going to blast it with compressed air and see if I can work anything loose from behind.
I'll continue to give reports here, though I'm heading out to Europe for my annual holiday on Thursday and won't be around to do any work on the truck for the next few weeks.
I drove the truck to work this morning in lower ambient temperatures (72-75F) and even in commute traffic and waiting at traffic lights, the temp didn't get above an indicated 100-102C (a hair above the middle line). When I was moving again it went back down to the 90-95C indicated mark. This was with A/C on. The fans did appear to be working.
I will do the test for the fan clutch later today.
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: [G320] Cooling system issue & questions
When the fan clutch on my 320 gave up I was on vacation where I ended up living. The truck would drive on the road fine. It would overheat quickly if I started up the mountain road towards the trail system here in the San Juans. At first I suspected the transmission or torque convertor. Turns out it was the fan clutch. I successfully made it home 1300 miles on MB's bendable finger set up to lock the fan on. I wouldn't reccomend much over 65 mph, I lost quite a few of those fingers trying to run 75 mph in the G320, which if I recall correctly is a good 3500+ rpm.  |
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nadd
Expert
Date registered: Apr 2006
Location: UAE, Dubai
Vehicle(s): G500 2016 LHD, numerous Chevys
Posts: 1285
| Re: [G320] Cooling system issue & questions
Roly - 6/10/2014 7:45 AM
It's not the blockage of the rad fins, it's blockage of the circulating cores internally. You will be better off checking in situ. Yes I meant that too, internal blockage due to corrosion and build-up was common in these radiators. Various causes were mentioned (horizontal channels vs. vertical, mix of aluminium and ferrous metals, etc.) but it's easy enough to check by hand with the engine off after warming it up for a few minutes.
On the other hand if it is the fan clutch hopefully it won't involve draining the whole system and refilling it. If the radiator hoses have not been replaced since new it might also be a good opportunity to do that.
Edited by nadd 6/11/2014 2:52 PM
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: [G320] Cooling system issue & questions
I do like the bendable finger as a fallback scheme. Switching from the 9 bladed diesel fan to the 11 bladed fan meant giving up that feature. The new fan uses a different hub. I suppose I should figure out some sort of hack to jamb the hub (before a actually need it).
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nadd
Expert
Date registered: Apr 2006
Location: UAE, Dubai
Vehicle(s): G500 2016 LHD, numerous Chevys
Posts: 1285
| Re: [G320] Cooling system issue & questions
Did one resourceful owner not use a length of cord or leather belt? Memory is very vague but I'm sure I read it somewhere. |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
Fan clutch is an easy job -- requires two special tools ...one is a long bar with a hooked end, that holds the back of the fan pulley so it doesn't rotate. The other special tool is a small, "stubby" socket that is used to loosen and then tighten the fan clutch center bolt.
It's about a one-hour job to replace a fan clutch -- I take my time so it's probably two hours for me. I have documented a 104 fan clutch replacement on my web site at 500Eboard.com.
You basically have to remove the plastic radiator shroud, put a piece of cardboard or thin plywood in front of the radiator fins to protect them, then hook the tool into the holes/notch in the back of the pulley/timing cover, then loosen the fan clutch center bolt. IIRC it's a 45 Nm torque to tighten it back up.
MB recently superseded the fan clutch center bolt from "hex" to "female Torx", which renders the stubby factory socket a moot point. I always make it a point to snag exposed center hex bolts where I can at wrecking yards to have spares on hand, as they can very easily get stripped.
Cheers,
Gerry |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
nadd - 6/11/2014 3:33 PM Did one resourceful owner not use a length of cord or leather belt? Memory is very vague but I'm sure I read it somewhere. Yes, there was a thread on this recently. I think a length of nylon rope, with two knots about 2.5-3 inches apart at one end. Then you let the engine wind the rope around while turning over the motor. But for emergency only.I have a spare M104 9-blade fan from an E320 and I'm going to measure it when I get the stock fan out of my G and see if it is large enough to fit...
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| Re: [G320] Cooling system issue & questions
Don't know about other engines but on mine there is at most 2cm of clearance after the bolt has been backed out. There is no room to fit any kind of socket in there, much less the driver to turn it. Instead I use a hex "L" key hose-clamped to a long stiff rod. |
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gerryvz
Extreme Veteran
Date registered: Apr 2014
Location: Annapolis, MD
Vehicle(s): 1994 G320, 1989 560SEC, 1994 E500 (W124)
Posts: 336
| Re: [G320] Cooling system issue & questions
It appears on the G320 M104 that there is enough room. A hex key with a length of skinny pipe attached would be a good alternative.
The stubby socket is quite stubby though. Here's what it looks like.
 (114841.jpg)
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