When a diesel engine runs too cold???

Anonymous-0 · Feb 6, 2011

I'm trying to get a better understanding of what's happening........ With me running without a tstat, I'm slobbering gunk out the filler breather tube and there is condensation/foam in the filler neck. I'm loosing coolant somewhere also. Now, if there was a thermostat in place and the motor was running as hot as it should, would the hotter temp cause things to expand. I got this picture of things slightly expanding and making things tighten up making a better seal in places like head gasket and the ctlinder seals and just run better.

Feel free to bust my bubble if I'm wrong.

Dave

JMS/.MN · Feb 6, 2011

There is a logical, practical reason for the thermostat system being developed. Yes, things do need to expand for efficient operation in a variety of ambient temps. It is a basic system of protection for the engine, not just some wild engineer"s idea that was included, because it could be. Why does your house heating system have a thermostat? Efficiency, uniform comfort, etc. Some other things they thought of......maybe not so needed, like changing things just for the sake of change, rather than improvement.

Anonymous-0 · Feb 6, 2011

The thermostat keeps the engine at an even constant temperature. Without a thermostat the temperature can vary quite a bit which isn't good for the engine as you have found out. You would do good to have a shop pressure test your cooling system to see where your coolant is going. Although $300 is ridiculous for a thermostat, it is way less expensive than an engine overhaul (or worse) from not running one. A thermostat is a very important component to prolong the life of an engine. Dave

Jerry/MT · Feb 6, 2011

Running an engine without a thermostat means you won"t get it to the proper operating temperature and then menas that you won"t heat the oil to the proper tempertaure and the condensate and volatiles won"t evaporate throught the breather tube. Your fuel econmy will suffer and the clearance on the rings will not be correct and you "ll load your oil up with unburnt fuel residue, etc.. Sludge will form in the crankcase and wear will increase. the exhaust system wil get a case of the "slobbers" from unburnt fuel. If you want that to happen, keep running without a thermostat.

Anonymous-0 · Feb 7, 2011

100% right.

Anonymous-0 · Feb 7, 2011

Your slobber is most likely that lost coolant. And getting it up to temp will probably not burn it off.

Just for your info, coolant will eat away at the bearings. Soon you will have oil pressure issues followed by catastrophic failure.

MarkB_MI · Feb 7, 2011

You need to check for a blown head gasket.

ASEguy · Feb 7, 2011

Thermostats establish MINIMUM operating temperatures not maximum operating temps. Running without a thermostat just doesn't make economical sense. Older cars from the 60's and 70's ran cooler thermostats and the result was shorter oil change intervals, excessive cylinder wall wear, as evidenced by the ridge at the top of the cylinders which had to be cut out to remove the pistons, and rich mixtures which hurt fuel economy and emissions. Gerard

Chris(WA) · Feb 7, 2011

Consider your bubble burst.
If she is losing coolant there is a gasket or crack to blame.As others have said a stat only controls minumum temps. If the stat is missing things have not gotten warm enough or it was remove in an attempt to cool things down in a over heat situation.
Best pressure test and be ready to tear down. Sorry...

Anonymous-0 · Feb 7, 2011

You can get it to run hotter, faster, if you put a piece of cardboard over 1/3-1/2 of the surface area of the radiator. If you are only using it for short periods of time, this may help with the condensation, and slobbering blow by pipe. Loss of coolant is another thing, leak somewhere.

RodinNS · Feb 7, 2011

Jerry described what happens when you run without a thermostat... Engine can't get hot enough to evaporate out the condensation that naturally occours.
That said... if yours is losing coolant beyond a nominal amount that they push out to find their level in the rad.... then I'd say you have a head gasket issue or crack somewhere. Is this the engine you had half rebuilt 8-12 months ago?

But to answer your question... generally speaking, the closer you keep and engine to 190 F, the better it will run.

Rod

Mike in Mn. · Feb 7, 2011

Right on!!

trucker 40 · Feb 7, 2011

What a thermostat does is that it gets the whole engine warm at about the same rate.It kind of balances the heat,and makes the engine work better,especially a Diesel.You are right about it being hotter and sealing better.
Now,what are you having a problem with?Loosing coolant?You dont say why you dont have a thermostat in it.You dont say if you can see where the coolant is leaking out or if it is.
You could put a thermostat in and see if that fixes it.You could see if you have any water leaking to the outside,or into the oil,you could pull the exhaust manifold off and see if one of the ports is clean which would mean its getting water from that cylinder.
Diesels run better when they are about 190 degrees like somebody else said.Since they dont have spark plugs it takes heat to ignite the fuel,and at 190 degrees is how they are made to operate.

Ferd · Feb 7, 2011

Don"t know what tractor you"re working on, but I had a similar problem and it turned out to be the liners leaking. The antifreeze hadn"t been maintained with additive and the block was so pitted from cavitation that it couldn"t seal the liners. Former owner had filled it with stop leak which eventually failed.
I wouldn"t run without a thermostat as others have said.

When a diesel engine runs too cold???

Anonymous-0

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JMS/.MN

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Anonymous-0

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Jerry/MT

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Anonymous-0

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Anonymous-0

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MarkB_MI

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ASEguy

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Chris(WA)

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Anonymous-0

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RodinNS

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Mike in Mn.

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trucker 40

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Ferd

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