95 e320 w124 Luke Warm Heat at slow speed or idle - PeachParts Mercedes-Benz Forum

berryrice · #1 11-30-2011, 11:20 AM

So after my huge b3 friction disc and seal tranny over haul (tranny now works awsome!), my yellow coolant light came on. Since it had been about 3 years since my last coolant change I when ahead an flushed the system with water and refilled using 50/50 (eye balled) MB coolant and distilled water. The last 5 days my car has been blowing out luke warm air at idle or low speeds and hot at highway speeds. The engine temp now stay at or under 80c after running 20min....which is 5-10c less than before (ranged 80c to 90c). I've been searching for this issue with little success..I've read t-stat, monovalve, to heater core issues? I tried burping the sytem by squeezing the upper hose and running it with the coolant over flow cap off. I've also ready the w124 self purges the air out of the coolant system. Great toasty heat at highway speed with the engine temp at 78-80c..but a stops it's luke warms and engine temps at 80-85c) I think it's gotten a little better slowly but ...what gives? Could have my eyeballed 50/50 been wrong...too much water or too much coolant? Any ideas? Thanks!

mbdoc · #2 11-30-2011, 12:30 PM

Possibly the aux water pump isn't working.

TAG · #3 11-30-2011, 01:09 PM

Mine is exactly the opposite. Hot air when cruising around town but on the highway it turns lukewarm. I just changed my t-stat today and it did bring the operating temp. up a bit.
With the old t-stat the temp gauge sat under 80 on the highway, now it's a tic over.
Did you change your t-stat too?

berryrice · #4 11-30-2011, 02:15 PM

I didnt change the t-stat yet but I do have a behr one ready to install. From what I gather it's not the T stat but I'll change it.

Mbdoc. .. Anyway to to test the aux pump. Is it tough to replace?

ps2cho · #5 11-30-2011, 02:35 PM

Thermostat is fine.

Aux pump or monovalve. Aux pump is more logical. With the key on engine off you should be able to feel it moving coolant.

berryrice · #6 11-30-2011, 04:12 PM

Nice...I'll give the "key on/enfine off" test. I'll report back after it's fixed. Those aux water pumps a dang spendy. Oh well

Thanks for all the feedback!

compress ignite · #7 11-30-2011, 06:15 PM

No, that's an Insane Price!
[$271.00 to 323.00 , depending on online vendor]
One Stealership wants $350.00 USD !

Zomezing iz Up !

1st picture

Auxiliary water Pump '95 E320 Part # (May Be) 001 835 37 64
[That's the $270 to $323 dollar pump]
You'll notice it has no Pump Chamber,just what looks to be a Naked Impeller
mounted on top of the Electric Drive Mechanism.

2nd picture

Auxiliary Water Pump '90 to '93 300D (AND LOTS of other Mercedes)
part # 039 202 00 26
[$58.00 from an online vendor,WILL BE A BOSCH PART NUMBER / OEM type]
It has the pump chamber secured with the three screws to the top of the
Electric Drive Mechanism.

I'd propose the $58.00 dollar Bosch Pump might fit the $323.00 application.
(You'd have to remove the pump chamber)

Somewhere in a Forum Far, Far Away an Intelligencia Mechanica discovered
that the OM606 Viscous Fan Clutch and 11 Blade Fan
would fit other Mercedes models at about 1/2 the cost of the Factory Specified Setup!!!!!

COULD THIS BE ANOTHER HIDDEN GEM ??????????

Heck, If I had the E320 I'd be willing to get the Inexpensive Pump and use it
to Power the Uber Expensive Naked Impeller type pump gear.
[Take the Motor off the Cheap Pump and put it on the Ridiculously Priced gear.]

YMMV

berryrice · #8 11-30-2011, 08:54 PM

OK...I feel lame. I spent the last hr looking for this dang aux water pump. I removed the air filter box thinking it was underneath it but it was not. I saw some old pics of Ph2cho of his aux water pump along the passenger side front/below the coolant expansion tank. I saw the monovalve assembly behind the fire wall in front of the battery...is the bigger cylinder on the monovalve the Aux pump for the m104 95 e320?? They look the same but I'm a little stumped. thoughts?

compress ignite · #9 11-30-2011, 11:25 PM

Some of the Pictograms I've seen seem to intimate that the "Auxiliary Water
Pump" we've seen (With the Naked Impeller) Fits into the Bottom of a Device
that is also the Mono-Valve(S).(On the Topside of the Device)

Which MIGHT explain how the Clowns think they can charge RIDICULOUS
prices for the "Drive" section of the "Pump".

berryrice · #10 12-01-2011, 12:14 AM

Compress Ignite, your right...the Aux pump and the mono valve are on the same plastic assembly behind the firewall next to battery. That's why it's "naked" cause it doesn't sit by itself like in other years and models.

I just checked the voltage output and it's still showing 12.7 volts but the aux pump does not buzz or vibrate. Looks like it's the issue. Thanks for all the help...more to come

compress ignite · #11 12-01-2011, 01:20 AM

Some (Or Maybe All of the Mono-Valves) regulate the Hot Water Flow to
the Heater Core by Fluctuating the Valve Portion On/Off Multiple times
Per Second (?).
The Vibration Could/Might be symptomatic of a Failed/Failing Mono-Valve (?)

Although the MVs usually Fail Open to allow for the DEFAULT defrost function.

[You do realize I'm "Winging It" here Based on Incomplete Knowledge of this
particular Model ?]

Where are the Experts?

compress ignite · #12 12-01-2011, 06:33 PM

1.Tobybul's pictorial and tutorial on the Older Style:
Fixed Auxiliary Water Pump!!
Is excellent.
Note: no metal "Crimps" to hold the motor housing onto the Pump.
('Uses Long bolts Through the Motor to the Pump...Like a Bosch Diesel Starter)
He does not separate the upper and lower halves of the pump housing,so that's
a mystery.

2.Bosch (OEM type) 0 392 020 026 purchased from the AA(Verboten) online
retailer in 2002.[Manufacture date of 2000]
NOTE: This is an Induction type Electric Motor,no direct connection between
the Motor and the Impeller of the Pump.
AND the Motor Housing uses Crimps to secure the Motor to the Pump Drive Housing.
AND the Pump Housing Halves are secured by 4 and not Three screws.
PICTURES BELOW

3.The type on the post facelift '95 e320 which is also an Induction type drive
BUT the Upper Pump housing is part of the Mono-valve assembly.
[I can't tell from all the Online pictures if this unit uses 3 or 4 screws to
secure the Induction Motor/Impeller assembly to the Upper Pump/Mono-Valve
assembly.]
If it does use Three instead of 4 screws,it will be necessary to Un-Crimp the
Induction Motor assembly from the Impeller Housing of the Bosch OEM unit
and Re-Crimp it to the O.E. type

berryrice · #13 12-02-2011, 12:15 AM

Success!!! I pulled the Aux water pump (mine right next to the monovalve on the same plastic assembly). There was three torx? screws holding it in place and took just a few minutes to remove (magnetic bit helps with the third screw against the firewall). Based on the pics Compress supplied and a little guess work I was able to take it apart and clean it out. Before I took it apart, the pump maybe started up once every 15 taps. After cleaning all the crud out (black dust from the magnet and brushes) it work every time I gave it current...also it ran ALOT stronger too! I suspect the two spring loaded brushes were not sliding very well or stuck in the little track from all the black dust. I took some pics...sorry it was 15 deg outside so I was in a rush...I'm whimpy. Hardest part was to get the two spring loaded brushes pulled back so to could get the motor between them....I used sewing thread to pull both springs back while I positioned motor? between the brushes.

I took it for a test spin ..the heat from the vents came in toasty in just 5-7 min of freeway driving (engine temp at 79-80c) and at idle....just as toasty! Success! Dare I say the cabin vents heat up faster than I can remember.

Thanks MBDOC and Ph2Cho for pointing out the aux pump and Compress for the ideas.

compress ignite · #14 12-02-2011, 01:34 AM

Congratulations!

Thanks for being the Pathfinder on this!

[So, the Brushes and Holders and Springs are in the Bottom (White) cap.]

If the ID and OD measurements of the Rotor and the Permanent Magnet
holders inside the Metal Motor Casing are the same...

You could, conceivably, when your Brushes and Commutator wear out
replace them with the Innards of the $58.00 unit.

Mayhaps the Rotor is the same also.

berryrice · #15 12-02-2011, 10:34 AM

Compress, Yes the brushes are on the white cap part but I'm not 100% sure if you can swap the black casing area. It looked like the spinning magentic cylinder inside the black part of the casing was permantly press fitted on the shaft of the motor. It's pretty cool that the actual impeller part is "floating" within the spinning magnetic cylinder...quite genious as coolant can never get inside the actual motor area. BUT the real wear part are those brushes that contact the motor on the white cap...mine look pretty worn and looks like it caused alot of the black dust. I'm thinking folks could clean out the pump with just the white cap off, buy the $58 pump, and use only the new white cap assembly with the new brushes...it really would only take maybe 30 min to to the whole job too.