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#46
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I just don't buy the excuse that the temperature gauges are not accurate. It's easy to say, but I've never seen one that really was. All the gassers I've ever had sat right on the thermostat setpoint regardless of operating conditions. The Mercedes diesel seems to be a completely different beast that varies it temperature depending on load -- mine sits around 80C +/- 5C until I get up to freeway speeds, then it rises, and if I'm cruising up a hill, especially at high altitude, I can get close to 100C.
I also hear the thermal load for a diesel is higher, but I cannot understand how. A diesel is a more efficient engine, and in theory should shed less heat to the radiator as more heat is used doing work -- it has a cooler exhuast and better mileage than a gasser.
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'83 240D with 617.952 and 2.88 '01 VW Beetle TDI '05 Jeep Liberty CRD '89 Toyota 4x4, needs 2L-T '78 280Z with L28ET - 12.86@110 Oil Burner Kartel #35 http://i16.photobucket.com/albums/b1...oD/bioclip.jpg |
#47
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So, what is the purpose of the arrow on the thermostat anyway? I used to think those were on the models which had the little bleeder valves in them but I noticed there is an arrow on the MB one I just removed even though it has no bleeder...why does the arrow need to point up? It seems like the thermostat is symmetrical and there is nothing special about it when it points up.
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Marty D. 2013 C300 4Matic 1984 BMW 733i 2013 Lincoln MKz |
#48
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Quote:
It runs at 82-85C. when it's below 2000 rpm with a light load. It runs at 90C. when at 2800 rpm at highway speeds. It runs at 95-98C. when at highway speeds at maximum power (held for more than 30 seconds). It very slowly returns toward 90C. after 10-15 minutes. I've checked the cylinder head and confirm that the head runs about 7C. cooler than the gauge. Therefore, don't draw any firm conclusions on the capability of a 617 to maintain a perfect temperature under all conditions. The 606 may be different. |
#49
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Brian,
I may be missing the point, but your SD does not sound as if it is controlling temp appropriately. While I can understand some increase in temp under heavy load, with appropriate air flow at speed the transfer should offset the increased heat load. Something isn't right ... or, am I missing the point?
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George Stephenson 1991 350 SDL (200K and she ain't bent, yet) former 2002 E320 4Matic Wagon - good car former 1985 300 CD - great car former 1981 300 TD - good car former 1972 280 SEL - not so good car a couple of those diesel Rabbits ...40-45 mpg |
#50
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Quote:
You can't condemn the radiator if the performance is identical at 0F. It's the only item in the system that is "aged". |
#51
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Hmmm - was the temp maintained in the same manner prior to all the replacements? Prior to the new tstat?
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George Stephenson 1991 350 SDL (200K and she ain't bent, yet) former 2002 E320 4Matic Wagon - good car former 1985 300 CD - great car former 1981 300 TD - good car former 1972 280 SEL - not so good car a couple of those diesel Rabbits ...40-45 mpg |
#52
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However, it has changed behavior over the course of the last eight months or so. Previously, it would very rarely climb above 90C. The ambient would have to be very high. Now, it climbs to 95C. just about every day.......... |
#53
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Of course, when the thermostat went bad a few days after we got the car in 2004, the temp would soar to 100 on highways. Replaced it with what I think is a Wahler brand, and it sits just above 80, maybe 85 to 90. This is consistent regardless of outside temp too, and even the fan replaced with a good used one.
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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg |
#54
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Quote:
tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#55
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they dont make them overly big cause of weight, i believe. tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#56
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While we are on the subject of cooling,,, try blowing out your radiator fins with compressed air . Apply the air from the back , fan side. I was amazed at the amount of crap that came out of my 79SD..
I have to do this all the time with my tractors when I am bush hogging.. My tractors have screens to catch the big stuff , but a radiator will get clogged with dust over time.
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Second owner 1979 300SD 250K miles. 1995 Ford Lightning 66 Mustang 87 5.0 Mustang 08 Ford Edge 46 Willys Jeep 89 Transalp 97 Dodge Ram 2500 Cummins.. |
#57
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If the rad was marginal, it wouldn't hold 95C. at 98F. ambients.
The fact that the performance is identical, independent of the ambient temp. would effectively rule out the rad.........don't you think?? |
#58
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Actually, I think there is a production vehicle with an electric water pump already... the Colorado maybe? Don't know if it has any funky control algorithm though.
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John Robbins '05 E320 CDI - 240k '87 300TD - 318k |
#59
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I have had thermostat problems too. My thermostat that the car had when I bought it started to fail and kept temps from exceeding 60 degrees C. I replaced it with a new one and it would seem to hold temps at 85 degrees C. The previous one used to keep temps at just above 80. The new one started to fail recently and its not even a year old. If I keep my heater on full blast I can still maintain about 83 degrees C temps in the winter. If I turn it off however the temps slowly climb to 100C. Temps rise to the 80 degree range quickly then creep up slowly from there.
I have bought a new one from napa. Last night I drilled 3 3/32 holes around the edge in the new one. This will provide some flow but it won't interfere with warm up much. I do have something to say that I haven't seen stated here yet. If you have an engine that has run at 80 degrees C all its life and you change thermostats to one that causes it to run at 90, it will cause excess wear due to thermal expansion. You want a thermostat to hold a temp closely no matter what to limit this.
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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons ) white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank) desert storm primer 63 T-bird "The Undead" (long term hibernation) http://ecomodder.com/forum/fe-graphs/sig692a.png |
#60
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Brian,
Perhaps the fan clutch? Have heard of a lot of radiators being replaced with no real change ...
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George Stephenson 1991 350 SDL (200K and she ain't bent, yet) former 2002 E320 4Matic Wagon - good car former 1985 300 CD - great car former 1981 300 TD - good car former 1972 280 SEL - not so good car a couple of those diesel Rabbits ...40-45 mpg |
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