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  #46  
Old 09-09-2011, 06:10 PM
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Location: Sierra Nevada Foothills, CA
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Depends on what you mean by "easy" - that's sorta relative. You have to pull the radiator if you're just using standard tools. Make sure you torque everything properly. I think it took me three or four hours all told to change mine.

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  #47  
Old 09-09-2011, 08:41 PM
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smoke gets in your eyes
 
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Location: Eastern TN
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For some reason the water pump pulley is always a bear to remove.

Sixto
87 300D
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  #48  
Old 09-14-2011, 11:38 PM
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Location: Los Angeles, CA
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Overheating - oxidation catalytic converter must go

Quote:
Originally Posted by Jason SVO View Post
Well, after a citric acid flush and new expansion tank, I am still getting high temps. The gauge does sit right above 80 C on downhills, where it hasn't before. But the car still cannot maintain it's temp under load.

What's next? New radiator?
I had exactly the same problem with my '87 300SDL. Fixed all the things you have fixed and the vehicle kept overheating. Going up a long steep hill with constant boost, it would get to ~ 90 C and hang there and just when I thought things were good, the temperature would shoot straight to 100 C & beyond (if I let it, which I tried to not to allow).

I was reading about what exhaust backpressure is normal (2 Bar or less) when I saw a reference to an "oxidation catalytic converter" in my service manual. At first I thought that this was the dreaded "trap oxidizer" which I knew my vehicle did not have. Then I saw the attached figure. The first of the 3 cans is the oxidation catalytic converter and I did have one of those.

Now I have a nice empty metal shell in that location, having removed it's innards. My car no longer overheats and hangs near 85 C, when under a light to moderate load, instead of hard against 90 C most of the time. I don't know why this is not very frequently mentioned as a source of overheating issues. It should be gutted before even doing a citric acid flush. 2 Bar exhaust backpressure is not a good thing for any engine.

The ceramic honeycomb in the OCC had about 75% blockage. It takes a fair amount of hammering to get it out, but it is satisfying work, with great benefits. The turbo sounds much happier.
Attached Thumbnails
300sdl Overheat #17 head-oxygen-catalytic-converter.jpg  
__________________
1986 300SDL
1987 300SDL
1997 F-350 Powerstroke Turbo Diesel
1969 32' Luhrs Perkins HT3.54M Turbo Diesel
WVO & biodiesel when I can get it
(there is a de-facto ban on biodiesel in CA
- ask the Water Quality Resources Board why
underground storage isn't allowed for biodiesel -
heck, you can drink the stuff )
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  #49  
Old 09-17-2011, 11:01 AM
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How can I test exhaust backpressure? Is it as simple as hooking up a pressure gauge to one of the ports in the manifold?

Jason
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  #50  
Old 09-17-2011, 12:52 PM
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Also, are you saying I should be hearing the turbo? Haven't heard that high pitch wine in this particular vehicle yet.
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  #51  
Old 09-17-2011, 04:45 PM
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smoke gets in your eyes
 
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I don't hear the turbo in my 87 300D and I know it's working.

Sixto
87 300D
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  #52  
Old 06-17-2012, 03:33 PM
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OK. So I'm getting scary temps(over 100) again when going uphill on hot days(90+). I've heard of these cars running cooler for people and want to know if I'm missing anything.

So far I've replaced:
Thermostat
Expansion tank
Radiator
Fan Blade-switched to plastic
Water Pump

Done a citrus flush
Drove around the neighborhood with exhaust pipe off(still creeped over 85)
Pressure tested system(good)

The aux fan comes when it's supposed to(up to 45mph) so that actaully works well and cools the temp down. But at 50+ uphill the temp just keeps rising gradually

The car just seems to have a tough time regulating itself under load

At idle, in traffic at 100*F ambient temperatures, the coolant temps don't get quite as bad(only around 90) as under load.

The problem doesn't seem to have gotten worse after 7000 miles.

Any other ideas? Blockage in the cooling system somewhere?

Thanks.

Jason
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  #53  
Old 06-17-2012, 03:59 PM
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smoke gets in your eyes
 
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Residual pressure in the cooling system overnight (upper hose pinch test)? 1.4 bar radiator cap? IP timing?

Sixto
87 300D^2
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  #54  
Old 06-17-2012, 07:16 PM
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Location: los angeles
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Check condensor , could have blockage, rinse with slight pressure, also hows fan clutch , should sound like turbine airflow when working, you said rad looked like new, is it , easy to check, drive at speed above 35 mph , quicky pull over and use infrared tenp gun measure radiator top to bottom, or feel by hand if you can get your hand in there should be no cool spots,is coolant mixture 50-50?, how old is headgasket, could be blocked passages
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  #55  
Old 06-18-2012, 10:26 AM
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Quote:
Originally Posted by Jason SVO View Post
OK. So I'm getting scary temps(over 100) again when going uphill on hot days(90+). I've heard of these cars running cooler for people and want to know if I'm missing anything.
The problem is the driver. He gets scared. The engine couldn't care less if it runs at 90C. or 110C., provided that the vehicle has proper coolant and a 140 cap.

The cooling system on these vehicles is insufficient to remove the heat generated under high loads and high ambients without a typical rise in coolant temperatures.

Many folks complain about 110C. coolant temperatures under these conditions, however, none of them (with properly maintained and repaired systems) have ever suffered an overheat.

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