Run Without Thermostat? - Page 2 - PeachParts Mercedes-Benz Forum

MB-Owner-in-ind · #1 12-29-2007, 05:05 PM

I run the next step up in temp 85c in my cars. never a sign of overheating. I think the cars has excess capacity for the radiators. Diesel doesn't generate that much heat anyway. Try to warm one up when it is -10f outside. The temp guage wo9n't rise until you start driving. The heater core dissapates enough heat to keep the engine cold.

MB-Owner-in-ind · #2 12-29-2007, 06:01 PM

If you change the t-stat then loosen the bolt on top of the housing and add antifreeze in the overflow tank until it comes out of the bolt hole. This will purge the housing, very important.

hofler · #3 12-29-2007, 10:37 PM

Just my 2 cents,
I had persistent overheating poblems and after having the radiator cleaned and rodded and leaving a new thermostat for the garage to install, still had over heating poblems. I took it upon myself to check the funcionality of the installed thermostat and when I pulled it to check it (place it in a pot of boiling water) I discovered that it had been installed backwards. I simply flipped it around (spring towards the engine) and it worked like a charm, down to just over 80c. I guess the garage installed the new one the way they found the old one.

Get your hands greasy, it will surprise you how cheap it is, and what you will find out that the professionals don't know who you have paid to do it "right".

R

xtreme barton · #4 12-29-2007, 11:23 PM

ill throw my two in also .. the thermostat actually helps slow it down a bit too.. in return the coolant has a little more time to get cooled rather than a fast flow with a little amount of time to cool

JimFreeh · #5 12-30-2007, 09:27 AM

MB thermostats act as a flow deflector.

That is, when the engine is cold, they encourage the flow to bypass the radiator and go directly back to the water pump.

As the coolant heats, the t-stat spring moves the bocking plate to open the passage to the radiator, and closes the short circuit to the water pump.

By eliminating the t-stat, you allow the coolant to have unrestricted access to the water pump, which will encourage the coolant to NOT go through the radiator. Simple fluid dynamics. The flow of coolant will take the path of least resistance.

You need a t-stat in your coolant system to get maximum heat rejection from the radiator. Simple fluid dynamics problem.....

Jim

KarTek · #6 12-30-2007, 11:28 AM

On a related note, running a higher temp t-stat should not lower the vehicle's ability to handle higher ambient temps. A cooling system is designed with a capacity that matches the output of the engine up to a limit regardless of the which t-stat is installed. The temp of the t-stat simply maintains the operating temp of the engine within a certain "band".

If a vehicle overheats, it's not because the t-stat is too high, it's either because the output of the engine has been modified in excess of the radiator's capacity for the given ambient temp or the radiator flow is restricted by crud or a malfunctioning pump or t-stat. It can also result from a poorly designed cooling system where the radiator has no reserve capacity and the higher temp t-stat will run it so close to the limits that any unusual load or higher ambient temp will push it over the edge. This is the case on my beater Chevy. I swapped in a 350 into a V6 truck and kept the smaller radiator because I'm to cheap to swap it out for a bigger one. The only time it's a problem is when it's idling with the AC on in the direct sunlight in the summer. Still, it gets pretty hot but it never boils.

An 80C t-stat wide open will flow the same as an 85C. A common mod on Ford Diesel pickups is to run a 203F t-stat to pick up a little power and maybe a MPG.

In any event, like the others said, it's not a good idea to run without a t-stat...