Now in the last few days, my cars heating system, well, doesent heat. I'm assuming the engine temp gauge still works, it is reading barely off the peg. Temps here are in the mid 40's at 3:30 - 4:00 in the am. I have the '123' shop CD's but I cant make them work (for a few years now)

Will the thermostat staying open make that much difference?

Eventually, only a little bit of heat comes out of the ducts, but nowhere near enough. Defrost stays cold.

I dont imagine R&Ring thermostat is much hassle, , ,

-c-

('83 300CD turbo engine)

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"I applaud your elaborate system of denial"

not hard to do,they will stick open,when old.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Sounds like a bad thermostat. It is easy to change unless the bolts break in the housing. If the bolts are stuck be patient, put penetrating oil on them, tap them lightly with a hammer, drive the car then repeat the process. The warming/cooling cycles of driving will help break them loose if they are stuck.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I have a 'spare' motor (dropped a valve) I 'practice' on. I removed thermostat&housing no problem.

Somewhere I read to replace the seal, one parts place showed an 'o' ring which I got. However, there is no o-ring but a seal which 'wraps around' front & back of thermo. Appears to be something which would come with a new thermostat.

Am I missing something?

(motor w/bad thermo & junk motor are both 300 turbo's)

They want $40 + for a new thermo, have to order one, so I couldnt compare 'visually'

This is at 'O'Riellys auto parts", they have quite a # of mb parts. There's a Napa not too far away, they have lot$ of $tuff but are pricey.

Havent torn into the 300CD yet.

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"I applaud your elaborate system of denial"

$10 to $30 from our sponsor. I've paid $10-15 at local parts places for the beck/arnley tstats.

If it fails open, cold motor, bad mpg when it's cool/cold and little/no heat.

The bottom bolt on the 3 bolt flange will break easily because coolant/water pools in that spot and it corrodes in.

I've driven with the other 2 bolts secured and the pressure cap off, so it can be done, not preferred though. I just swapped a spare tstat housing in as soon as I had the chance.

No spare=handle with care.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

The 3 bolts came right out on the 'practice' motor. I'll check with sponser about parts.
Thanx for the tips.

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"I applaud your elaborate system of denial"

So a completely open thermostat (failed) would result in engine temp staying close to 40C indefinitely? Is this true (and it this what is happening)?

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1984 w123 300D anthracite (bought from fellow forum user rwthomas1, now approaching 300k and doing great)
1985 w123 300TD white (probably also from another forum member, ebay purchase, my problem child)

I'm wondering if you have more than one problem.

1. Failed temp sensor or something telling you your engine is always at 40 C
2. Monovalve or something not functioning resulting in no cabin heat

Maybe a combo of things really. Odd.

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1984 w123 300D anthracite (bought from fellow forum user rwthomas1, now approaching 300k and doing great)
1985 w123 300TD white (probably also from another forum member, ebay purchase, my problem child)

If the cooling system is healthy, this is exactly what will happen. When flushing the cooling system on my SDL this summer (in 90+ heat) I had the thermostat removed for full coolant flow and the engine never got above ~60˚ on the gauge.

Coupled with a bad aux pump or partially clogged monovalve, and that means little to no heat out of the vents in the cabin.

Stick the same car in winter conditions and I'd be willing to bet the temp gauge never gets off the peg. No heat in the engine, no heat in the heater core, no heat in the cabin either.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Replaced thermostat. Reason for post is, when I took out the 'bad' one, it was broken into two pieces. Never saw that before. Old one was labeled 'Germany', new one (from O'Riellys!) was 'Mahle' made in Germany. O'Rielly has outside suppliers for a lotta stuff, this thermo cost $29 inc the gasket(s).

How does one get all the coolant back in the radiator/system? '83 300CD, no radiator cap! That last quart +- wont go, , ,

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"I applaud your elaborate system of denial"

The rad cap is on the expansion tank. Start it up and get the engine warm enough to open the stat and then you should be able to get the coolant back in.

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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.

It is best to have the car "nose high", such as on ramps. This will help to prevent an airlock in the cooling system and may be why you can't get in that last quart.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Thanks!
The bracket that held the moving part broke in 2 places, at least nothing big enough to pass through the system, broken part was brass, new thermo all stainless, , ,

-corne-

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"I applaud your elaborate system of denial"