Engine Running without thermostat 2

[kmpillai]

Hi all,
If somebody running an 4 stroke engine without thermostat, will it harmeful to the engine.

KMP

 

[SomptingGuy]

Before CFD took over in head designs, coolant flow and the resulting local HTCs was largely guesswork. Some got it right; some go it wrong.

- Steve

 

[Thecardoc]

I really don't have much to say about what causes some components to fail as compared to what might be occurring in another group of similar components. The downside of working as a tech has always been we have to figure out a failure, fix it, and then go right onto the next repair in as little time as possible. Basically that leaves us with almost no time to spend on many of the "whys".

Realize too, a particular component could have a known high failure rate but for a tech working in the trade that could still amount to only one exposure to it in a given technicians career. So to that technician, the appearance is that it is not a common failure.

 

[Azmio]

during durability tests where we forced the prototype engines with few hundred hours of rated speed, we simply took out the thermostat from the engine.

 

[Tmoose]

Azmio wrote = "we simply took out the thermostat from the engine"

why ?

 

[GregLocock]

That's a funny test.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

The dyno cooling water supply was probably very accurately thermostatically controlled to a stable temperature outside the engine for accurate reproducibility at the cost of not accurately representing typical real world conditions.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[GregLocock]

Yeah but for durability you normally want to test all the components under real life conditions - we had a corrosion problem caused by cavitation that would not have shown up if we arbitrarily changed the pressure/flow characteristics.




Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

Greg

That was the implication in my last phrase of my last post.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[jerry1423]

pat primmer and Greg ...

Why do you have "See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers for professional engineers" in each of your replies? Is there something wrong here with the postings?

 

[patprimmer]

No, it is in all our replies to direct any member, but especially new members to the FAQ as it can be helpful for them in getting the most out of the site.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[dicer]

For a nondyno nontest deal. You never want to run your car/engine without one. Kinda like driving around with no airfilter, or torsion damper.

 

[jcd06]

The fluid in the cooling circuit is under pressure to raise the boiling temperature.
You all saw the 0.9bar or whatever psi on the cap of the expansion vessel or the rad.
There is more than that.
The thermostat, even being 100% open at normal working temp still acts as restrictor.
At high RPM, pressure will build up inside the engine because the pump flow pushes against the thermostat.
I measured about 2bar while the rad cap is rated 0.9bar.
This helps in avoiding steam pockets forming around hot spots eg. between spark plug and exhaust valve seat.
You take a risk when removing the thermostat.

 

[Lou Scannon]

Good points. Though it's not my area, I recall truck engine cooling systems are designed for ~60psi operating pressures.