Changed coolant now engine overheats - Page 2 - PeachParts Mercedes-Benz Forum

vstech · #16 12-29-2014, 10:46 AM

Quote:

Originally Posted by fahrvergnugen

Prove it to yourself then; remove the cap on the reservoir, put water in until overflowing. Get the engine up to temp, And it begins to overflow. Then immediately Rev the motor to 3k or so. No longer overflowing. Is it compressing it because it is cooling it? On reflection, probably. Either way, it pushes out bubbles.

Water does not compress. What you are noticing is the water being pushed into crevasses in the block, and rubber hoses expanding to handle more volume.

fahrvergnugen · #17 12-29-2014, 11:09 AM

True, esp with hose expansion.

winmutt · #18 12-29-2014, 11:58 AM

Come on people, just put the defroster on and drive around the block and top off. Never had any problems...

Lucas · #19 12-30-2014, 04:05 AM

Haha.

Still curious. Why can't you use a radiator cap with a hole and funnel on a turbo motor to burp the air out? I swear we did this on my passat 1.8T.

Mxfrank · #20 12-30-2014, 07:38 AM

Quote:

Originally Posted by winmutt

Come on people, just put the defroster on and drive around the block and top off. Never had any problems...

Exactly. ALL Mercedes diesel cooling systems are self bleeding. There's no need for all of these shennaigans.

Mxfrank · #21 12-30-2014, 08:23 AM

Quote:

Originally Posted by vstech

Water does not compress. What you are noticing is the water being pushed into crevasses in the block, and rubber hoses expanding to handle more volume.

Static pressure in the radiator is higher when the thermostat is closed...

Lucas · #22 12-30-2014, 12:23 PM

Ok I'm back to my original thought. Take an old radiator cap, drill a hole for a funnel, drop the funnel in the hole and fill with water.

Run car with heater on. Squeeze hoses and watch bubbles come out. Takes about 20 min.

And pinch off the overflow tube.

vstech · #23 12-30-2014, 12:30 PM

Quote:

Originally Posted by Mxfrank

Static pressure in the radiator is higher when the thermostat is closed...

yup... water does expand as it is heated... and minute amounts of steam are created, and pressure is exerted from the increased volume of that...

pimpernell · #24 12-30-2014, 12:42 PM

Quote:

Originally Posted by Mxfrank

Exactly. ALL Mercedes diesel cooling systems are self bleeding. There's no need for all of these shennaigans.

If that were the case, then why on the E300d does the block have a bleed bolt installed right next to the radiator hose??

vstech · #25 12-30-2014, 12:51 PM

Quote:

Originally Posted by pimpernell

If that were the case, then why on the E300d does the block have a bleed bolt installed right next to the radiator hose??

to facilitate filling with coolant during service.

sure...
if the mercedes vehicles, are filled through the cap, and methodically kept full, while the motor is tinkered with, and revved, and shook, or what have you... the motor will bleed and fill...

but the easy way to fill it, is through the upper radiator hose, until coolant exits the radiator, then reconnect, and finish filling through the tank, then squeezing the upper hose, until air is all purged...

KatM · #26 12-30-2014, 12:53 PM

Just started reading on here today and this one is very interesting. I just wanted to share a link to a phase diagram for water, in case any of you want to see it who are discussing whether or not water compresses, which may in turn be more of a disagreement on whether or not the volume changes with temperature and pressure. I love a good phase diagram...

http://upload.wikimedia.org/wikipedia/commons/2/2f/PvT_3D_plot_-_water.png

leathermang · #27 12-30-2014, 01:04 PM

Quote:

Originally Posted by vstech

Water does not compress......

It does compress some... all fluids do.... but thankfully not enough to make them useless in our brake systems...

Compressibility of water as a function of temperature and pressure

funola · #28 12-30-2014, 01:26 PM

Quote:

Originally Posted by Lucas

Ok I'm back to my original thought. Take an old radiator cap, drill a hole for a funnel, drop the funnel in the hole and fill with water.

Run car with heater on. Squeeze hoses and watch bubbles come out. Takes about 20 min.

And pinch off the overflow tube.

I don't get why you have to drill a hole in the radiator cap to put a funnel in???

Zulfiqar · #29 12-30-2014, 01:53 PM

Quote:

Originally Posted by funola

I don't get why you have to drill a hole in the radiator cap to put a funnel in???

me too

remove cap and you already have a nicely cast perfect round hole for a funnel to stick in it.

vstech · #30 12-30-2014, 01:54 PM

Quote:

Originally Posted by leathermang

It does compress some... all fluids do.... but thankfully not enough to make them useless in our brake systems...

Compressibility of water as a function of temperature and pressure

ok... it does compress, but not under the pressure that a water pump would impart... what is happening with the water pump spinning, is air gets displaced, and rubber expands...