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  #1  
Old 06-09-2018, 07:23 PM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 372
w116 servo

1979 300sd (w116)

Would a bad servo prevent the bleeding of all air from the cooling system.
I recently reported that my servo magically turned on after being dormant for a few years. Well its inoperable again.

My diesels temp gauge seems to be reading higher (hotter) than usual (195-205 deg F) when driving uphill or flooring the accelerator pedal on a flat stretch of highway, and this happened right after I replaced the coolant and thermostat. Not sure if I got all of the air out.

The temp gauge NEEDLE eventually does settle down to around 180-185 deg F when descending a hill or driving on a flat stretch of highway (the needle will sit right between the actual number 175).

I'm using the number 175 on my temp gauge as a reference to where the needle settles but keep in mind that the ACTUAL MARKING for 175 deg F is before you get to the number.

Not comfortable with this because I know from experience that my temp gauge is really sensitive and can register even the smallest coolant leak. I've looked around and haven't seen a drop of coolant. Will have to double check that.

I'm bleeding the air bubbles out by parking my car on an inclined driveway, removing the reservoir cap and running the engine for approximately 10 minutes. Since warm air is no longer coming out of the vents I feel that the coolant is not flowing thru the servo, thus preventing all of the air to be properly bled out.

Thinking about removing the servo and giving it a backwash to see what happens.

Replaced the fan clutch maybe 6 or 7 months ago
Using Zerex 05 concentrate and mixing it with distilled water (50/50).

Any advice on how to properly bleed the air out of the cooling system is greatly appreciated.
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  #2  
Old 06-10-2018, 10:55 AM
tdoublenastywitit's Avatar
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Rip it out and bypass it
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  #3  
Old 06-10-2018, 11:18 AM
vwnate1's Avatar
Diesel Dandy
 
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Location: Sunny So. Cal. !
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Post Cooling System Bleeding

You might want to test the small auxiliary water pump as they tend to seize up over time .

I made up a jumper and run it directly when bleeding out the Klima I HVAC system .
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1982 240D creampuff 370,000 miles
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  #4  
Old 06-10-2018, 01:07 PM
Control Freak
 
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Location: Columbia, SC
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+1 on the aux pump trick, just be sure to observe the polarity or it will run backwards.

Remember brown = negative on just about everything Mercedes
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  #5  
Old 06-10-2018, 02:43 PM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 372
Question

Would a seized servo or Aux water pump cause the engine to run warmer or maybe even over heat? What is the proper way to bleed all of the air out of the cooling system and do all of the cooling system components (Servo, aux water pump, etc..) need to be in good repair to bleed the air out?

Last edited by xaliscomex; 06-10-2018 at 02:55 PM.
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  #6  
Old 06-10-2018, 03:59 PM
Diseasel300's Avatar
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I don't see how a failed servo or failed aux pump would have any bearing on the main cooling system. If they trap air, who cares as long as the main cooling system is circulating water. If they "burp", you'll find air in the radiator which you can then bleed out. It's a non-issue.

If your cooling system is operating correctly, the temp gauge should be pretty well dead-center. 190-205˚ isn't out of line for pulling up a hill or hard acceleration. If the temp comes right back down, it isn't an item to worry about. Check your boost pressure. If the turbo is making low boost, you'll be running high EGT's.
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  #7  
Old 06-10-2018, 11:16 PM
vwnate1's Avatar
Diesel Dandy
 
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I disagree, having owned several Klima I equipped cars, all were hot runners until I learned to properly burp them .

To each their own, just the thought of air in the water jacket makes me cringe, maybe because I live in the Desert.....

If the Evil Servo is dead, by pass it, I use a late 1970's vintage Dodge manual hot water valve as it's cheap and has the correct mis matching size hose barbs on it .

One simple way to avoid any air in the cooling system is to drill a tiny hole in the flat flange of the thermostat .

I don't think this is good policy but many newer engines come this way from the factory .
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-Nate
1982 240D creampuff 370,000 miles
1978 300CD back from the dead&1980 300CD ~ SOLD
1984 300CD KEEPER ! 430,XXX miles
1984 Euro 300TD Fully optioned SWMBO's
1974 350SLC 4 speed stickshift SOLD & missed
Krazy Kommie Ural Motos (3)
BMW Moto R60/6 Barn Find, 8,000miles
1959 VW #113 Deuxe Beetle, 36hp engine, stock
Junk, Rust, Arthritis, Crushed Spine,Broken Neck&Back
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  #8  
Old 06-11-2018, 01:02 AM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 372
Quote:
Originally Posted by Diseasel300 View Post
I don't see how a failed servo or failed aux pump would have any bearing on the main cooling system. If they trap air, who cares as long as the main cooling system is circulating water. If they "burp", you'll find air in the radiator which you can then bleed out. It's a non-issue.

If your cooling system is operating correctly, the temp gauge should be pretty well dead-center. 190-205˚ isn't out of line for pulling up a hill or hard acceleration. If the temp comes right back down, it isn't an item to worry about. Check your boost pressure. If the turbo is making low boost, you'll be running high EGT's.
Thanks,

I will keep an eye on the needle and watch out for leaks.
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  #9  
Old 06-11-2018, 01:08 AM
xaliscomex
 
Join Date: Feb 2006
Location: Ventura County, CA
Posts: 372
Quote:
Originally Posted by vwnate1 View Post
I disagree, having owned several Klima I equipped cars, all were hot runners until I learned to properly burp them .

To each their own, just the thought of air in the water jacket makes me cringe, maybe because I live in the Desert.....

If the Evil Servo is dead, by pass it, I use a late 1970's vintage Dodge manual hot water valve as it's cheap and has the correct mis matching size hose barbs on it .

One simple way to avoid any air in the cooling system is to drill a tiny hole in the flat flange of the thermostat .

I don't think this is good policy but many newer engines come this way from the factory .
Thanks, going to consider by-passing the Servo.
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  #10  
Old 06-11-2018, 11:12 AM
vwnate1's Avatar
Diesel Dandy
 
Join Date: Nov 2005
Location: Sunny So. Cal. !
Posts: 3,519
Post Klima I Service

The main thing to remember is : this is the Chrysler Air Temp II system used under license .

There are several manufacturers still making the evil servo, I bought the alloy bodied one and it was fine, some of them leak even though new .

Pretty much any crud in the cooling system will cause the servo to jamb up sooner than later, red / brown coolant is a BIG red flag, if you see it, get busy cleaning and flushing NOW, doesn't matter if it's Summer, suffer the heat of proper flushing as the servo traps sediment, binds up or drags, causing the amplifier to burn out or the Bakelite servo housing to crack and leak out all the coolant whilst you're driving along.....

I hate this system greatly but once working it's wonderful, until the next time it fails .
__________________
-Nate
1982 240D creampuff 370,000 miles
1978 300CD back from the dead&1980 300CD ~ SOLD
1984 300CD KEEPER ! 430,XXX miles
1984 Euro 300TD Fully optioned SWMBO's
1974 350SLC 4 speed stickshift SOLD & missed
Krazy Kommie Ural Motos (3)
BMW Moto R60/6 Barn Find, 8,000miles
1959 VW #113 Deuxe Beetle, 36hp engine, stock
Junk, Rust, Arthritis, Crushed Spine,Broken Neck&Back
Memories &Peace Of Mind
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