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1991 560sl / 1987 300TDT / 1995 E300D / 1994 S350D / 1993 300SD /Cummins Diesel PU /2 airplanes
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Discussion Starter #1
New radiator, new water pump, new belt, new idler pulley, spring, damper/shock and my 1995 E300D is still running hot.

This has been interesting so far but now it's just frustrating. (ever felt that?)
I thought I had this overheating issue solved when I pulled out the dual fan assembly and undid the cover to find 17 years of bugs and debris clogging up the entire bottom of the radiator and
condenser. Literally over a quart of junk wedged in there.
I cleaned everything and installed the new "Behr" radiator made in South Africa. Dealer wanted $695 and I found this "OEM" for $127. It looked pretty good so, after installation I went for a test drive expecting a successful repair and the temp is still way higher than it should be it was aprox. 115-118 Deg. Centigrade. And it was rather cool today when I went for a drive about 76 Deg F.
This problem started after I did the delivery valves on the Inj. pump and put in new glow plugs. The wiring harness is sooo brittle that maybe I caused a short somewhere?
Any suggestions?
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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2,989 Posts
I'm sure you just forgot to type it, but did you do thermostat?
What temps are you seeing?
With or without A/C?
What are ambient temps where you are at?
Did you flush the system?
What did the old coolant/old radiator look like? Do you think there's gunk in the system?
 

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1992 300D 2.5T (124.128) 1999 S320 SWB (140.032) 1999 E320 4Matic (210.082) 1984 300CD (123.153)
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177 Posts
You should flush the cooling system if you have not done that. Who knows what has built up in those coolant passages over the years. Flush and refill with G-05 and distilled water, that is where I would start, and then on to more pars, as Zeitgeist said, fan clutch and thermostat.

Another thing to look at would be the temperature sensors and wiring to them. The sensor for the gauge could have failed, but you could have also disturbed some wiring while working on the injection pump.
 

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Banned
1991 560sl / 1987 300TDT / 1995 E300D / 1994 S350D / 1993 300SD /Cummins Diesel PU /2 airplanes
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861 Posts
Discussion Starter #5 (Edited)
I'm sure you just forgot to type it, but did you do thermostat?
What temps are you seeing?
With or without A/C?
What are ambient temps where you are at?
Did you flush the system?
What did the old coolant/old radiator look like? Do you think there's gunk in the system?
Tested with A/C off. Ambient temp was mid 70's in the evening when I tested it.
You are correct, I forgot to type in new thermostat, from the dealer, that's the first thing I tried, and I flushed the system,
used MBZ antifreeze 50/50. Fan clutch is good 1 year old, also from dealer.
I wanted to get a new coolant temp sensor (maybe there is more than one) but the parts guy from the dealership told me that I didn't need one, mine was fine. I have no idea how he knew this, they didn't work on my car, but I took his word for it. I think there is one temp sensor at the front of the engine right by the fuel filter housing.
Even when close to 120 Deg. C. I can open the cap on the expansion tank with no problem, no boiling over etc...
With my limited skills I am stumped! and losing my 'cool'.
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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I agree, ambient of mid 70's cooling should not perform like it does.
Your symptoms are exactly what I had this week. 110C was min operating, with spikes up to ~118
I did (in this order hoping each would be the answer)
Vent cap
Viscous fan clutch
Thermostat/cleaning front of condenser. (this procedure eventually fixed it, so I'm leaning towards T-Stat not opening all the way)


Do you have, or have access to infrared thermometer? (harbor freight $50 maybe?)
Check for actual temps of pump/radiator inlet/outlet hoses. If they agree with the cars sensor readings...then it gets complicated. Maybe time to flush again with the citric flush. Did you just flush with garden hose, or an actual flush (prestone etc.) Did you also open block drains? Sometimes it takes more than one flush to get the gunk out.
You should look for about 15 degree drop from inlet/outlet of radiator to show system is working properly.


If readings are way off from sensor to thermometer, then its probably sensor. Who knows, try cleaning sensor contacts first.

Also, its not impossible that the thermostat is not good right out of the box. What brand is it? My old one was made in germany, and was a dealer part (forget brand, but not wahler), and I replaced with Wahler. I believe Clark also noted the STANT thermo's are/were Wahlers (good, Whaler is what I just put in)
Also did you orient the brass vent/hole on the thermostat correctly (should point towards engine I believe). My old, and now installed yesterday one, the brass points at about 10:30/11 o'clock using the front of the car as the 6'oclock position, rear being 12 O'clock. I dont know the why's of this, but the t-stat does need to be oriented.

Try removing the thermostat *just for testing*, run car and see if temps stabilize. If car runs cool, that's the problem.

Good luck man, let us know how it works out.
 

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Banned
1991 560sl / 1987 300TDT / 1995 E300D / 1994 S350D / 1993 300SD /Cummins Diesel PU /2 airplanes
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861 Posts
Discussion Starter #7
I agree, ambient of mid 70's cooling should not perform like it does.
Your symptoms are exactly what I had this week. 110C was min operating, with spikes up to ~118
I did (in this order hoping each would be the answer)
Vent cap
Viscous fan clutch
Thermostat/cleaning front of condenser. (this procedure eventually fixed it, so I'm leaning towards T-Stat not opening all the way)


Do you have, or have access to infrared thermometer? (harbor freight $50 maybe?)
Check for actual temps of pump/radiator inlet/outlet hoses. If they agree with the cars sensor readings...then it gets complicated. Maybe time to flush again with the citric flush. Did you just flush with garden hose, or an actual flush (prestone etc.) Did you also open block drains? Sometimes it takes more than one flush to get the gunk out.
You should look for about 15 degree drop from inlet/outlet of radiator to show system is working properly.


If readings are way off from sensor to thermometer, then its probably sensor. Who knows, try cleaning sensor contacts first.

Also, its not impossible that the thermostat is not good right out of the box. What brand is it? My old one was made in germany, and was a dealer part (forget brand, but not wahler), and I replaced with Wahler. I believe Clark also noted the STANT thermo's are/were Wahlers (good, Whaler is what I just put in)
Also did you orient the brass vent/hole on the thermostat correctly (should point towards engine I believe). My old, and now installed yesterday one, the brass points at about 10:30/11 o'clock using the front of the car as the 6'oclock position, rear being 12 O'clock. I dont know the why's of this, but the t-stat does need to be oriented.

Try removing the thermostat *just for testing*, run car and see if temps stabilize. If car runs cool, that's the problem.

Good luck man, let us know how it works out.
Thanks, I think I'll take out the Thermostat as you suggest and see what happens, just two bolts anyway. I noticed the little detent in orienting the thermostat and wondered why it was there too. I don't have an infrared temp gun but it would be an appropriate purchase. I do have a very accurate probe temp sensor. I might take out the engine coolant temp sensor since it is very easy to access and put the probe in there. At least it's not 105 temp here today.
 

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E320/E250 Bluetec Ford F350 6.7l
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36,720 Posts
How about the thermostat and fan clutch?
What fan clutch >>>> diesels in California don't need them.
How is the injection timing? When I was playing with timing, I had the injection off by few degrees and even on my driveway the engine was getting hot. Now after I recheck and reset the ignition, the engine will not go above 85C on our mostly highway driving. When stuck in the traffic it might go up to 90C but that is top what I experienced. That is with old clutch and blades supporting the garage wall.
Infra red thermometer could answer lot of questions. The good ones with laser pointer were $29 at HF. I would expect that cheap radiator has less rows than OEM. That makes big difference.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
What fan clutch >>>> diesels in California don't need them.
How is the injection timing? When I was playing with timing, I had the injection off by few degrees and even on my driveway the engine was getting hot. Now after I recheck and reset the ignition, the engine will not go above 85C on our mostly highway driving. When stuck in the traffic it might go up to 90C but that is top what I experienced. That is with old clutch and blades supporting the garage wall.
Infra red thermometer could answer lot of questions. The good ones with laser pointer were $29 at HF. I would expect that cheap radiator has less rows than OEM. That makes big difference.
I'm not sure if your ambient air is different down there, but on both my 603 and 602, the fan clutch functions were the difference between overly high operating temps and normal operation up here in WA. I've seen your statements about driving without an operating fan, but that's not at all been my experience with these engines.
 

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E320/E250 Bluetec Ford F350 6.7l
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Didn't you say you are NOT using MB coolant? ;)
W124 was bought with green coolant and it is running warmer than our W210 where I put new radiator few years back.
Last sunday we drove W210 to Bay Area Hot Spot (Antioch) and I displayed engine temperature on dash LCD.
This is what I recorded at 98-102F outside.
driven at 70 mph the engine would stay at 78-80C.
in city driving the temperature would go up to 94C, but while parked with engine on the temperature would drop after 15 minutes to 89C. I check the electric fan when I stop the car and it was running on low.
That all with AC at full blast keeping the cabin comfortable.
Engine fan with new clutch for W210 are supporting the garage wall next to the fan from W124
I bought new clutch for W210 because occasionally we go to Vegas in the summer where 120-140F is quite common, but looks that I might not need the clutch even for such a trip.
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
I don't use the green stuff. I use the MB approved gold stuff.
 

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Banned
1991 560sl / 1987 300TDT / 1995 E300D / 1994 S350D / 1993 300SD /Cummins Diesel PU /2 airplanes
Joined
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861 Posts
Discussion Starter #14
What fan clutch >>>> diesels in California don't need them.
How is the injection timing? When I was playing with timing, I had the injection off by few degrees and even on my driveway the engine was getting hot. Now after I recheck and reset the ignition, the engine will not go above 85C on our mostly highway driving. When stuck in the traffic it might go up to 90C but that is top what I experienced. That is with old clutch and blades supporting the garage wall.
Infra red thermometer could answer lot of questions. The good ones with laser pointer were $29 at HF. I would expect that cheap radiator has less rows than OEM. That makes big difference.
Thanks for chiming in and giving your 'opinions'...but maybe you should read my post first.
You don't drive where there is snow, I do... There is lots of snow and cold weather in California. The MBZ engineers put a fan clutch there because THEY thought the engine needed one. Guess they didn't agree with your "opinion". and frankly using an honest request for information doesn't mean that you should always try to use the post as a platform to try and run your mouth about how clever you are.

Ever since you stated that you used the injector valve body locking plates as a wrench to tighten the valve bodies I stopped listening to you. That is just ridiculous. You got lucky, that's all.
The IR gun at Harbor Freight is $40 on sale and the radiator I got has the same number of vanes/ tubes and with the same diameter = same flow.
If you have something constructive to add please do, otherwise I'm not interested in your ego dance.
 

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1991 560sl / 1987 300TDT / 1995 E300D / 1994 S350D / 1993 300SD /Cummins Diesel PU /2 airplanes
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861 Posts
Discussion Starter #16
The truth is that if you are not interested in others experience and resolutions, that what exactly is your business on this forum?
The TRUTH is, I am not interested in YOUR posturing and "take off the fan" type of opinions.
Btw, how did you torque the inj. pump valve bodies using the locking plates as a wrench? Never mind, I really don't want to know.
 

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W124 E420 : W220 S500 : W222 S550
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402 Posts
please guys "no ignore".... we need both of you to offer opinions on the others offerings. Also we need comments by both of you in general...


It can be frustrating at times, but we all benefit........

please please please


The TRUTH is, I am not interested in YOUR posturing and "take off the fan" type of opinions.
Btw, how did you torque the inj. pump valve bodies using the locking plates as a wrench? Never mind, I really don't want to know.
FYI there is "ignore" option on this forum. If you don't want to read how I keep my cars in good running condition -use it.
I don't want to read your non-automotive comments so we both benefit from it.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
Have your aux. fans been cycling during your high temp situations?
 
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