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Discussion Starter #1
I use my '97 4.6L for inner city stop-and-go driving in the warmer days of the year.

I removed my thermostat a few weeks ago when I flushed the cooling system, and have noticed no real differences. What are the pro's and con's of doing this on the 4.6L? All opinions welcome.

ps. I did a search and found nothing specific.
 

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Judging by the pic in your avatar....you probably have bigger problems.

On a more serious note....you should have a thermostat. Its got a spot for it...it should have one. To me, thats like driving around with a spark plug out. Yeah, it'll move...but its probably not good for the car.
 

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Discussion Starter #3
wkenneth, thanks for your input.

So that you know, I have a mechanics backround, so I know that under normal conditions, a thermostat is a necessary component. However, I wanted those people who know the 4.6L engine inside and out to give me the scoop.

The car has been completly repaired, by me, and is awaiting some paint. It has been driving in 90-105 degree weather for two weeks now.
 

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Well Here are some thoughts.....without the thermostat the water will constantly circulate throughout the block and the radiator. The Thermostat keeps the water at a certain temperature..... When it reaches that temp it opens and allows water to flow into the radiator to be cooled ... yadda yadda yadda... I assume you know all that so the real questio is what else happens due to temperature in your engine..... Well I am no expert but I do believe that certain emission levels are attained by keeping the engine at certain temperatures.... Obviosly Less heat in the car the more HP your supposed to make.... BUT I'm not sure how the computer works in relation to the car water temp.... I have heard of Open Loop and Closed loop operation in dealing with the cars EEC... How this is effected by the temp I really cant say.... Here is what I GUESS.... Hopefully someone will enter with better knoledge than I and explain better. But I would assume until the car reaches proper temperature that the computer never really gets into its Open loop processing.... this may cause bad gas mileage and reduced power...... <- BUT TO BE HONEST I DO NOT KNOW......Someone who does please help........
 

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Sometimes the thermostat has an effect on the thermal balance of the engine.

A little true story: A few years back someone thought he could "improve" the cooling system of the 6 Cat 850 KW gen sets that keep McMurdo Station, Antarctica warm and running, by removing the 'stats and using the radiator fans to control engine temps. The thermal inbalance got so bad that 2 blocks cracked, and one had to be replaced at a cost of about $35k.

Now a 4.6 isn't a 1100+ HP diesel, but do you want to take the chance?

Another story from my stock-car racing neighbor, who removed his thermo, and the increased pressure blew his upper hose and took him out of the race.
 

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It only needs to be cooler than 192 degrees if you're running advanced timing and/or experiencing detonation. Even at that, you can install a 180 T-stat and get the EEC set up to turn the fans on sooner. Even if you don't have the EEC set up...the fans wont turn on til 192. So in stop and go traffic...it will still be the same temp. Unless its more go than stop. The warm up cycle is based on time, not temperature, so eventually, yes..it'll run 'normal'. Hot engines run better, not cold ones.
 

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Open loop is brought on by time not temp.

Since you removed your stat, your car never reaches operating temp. That means excess wear on everything. Your engine is designed with great research by engineers and computer modeling. So by never reaching operating temp you are out of spec in the expansion area. So basically your car not reach operating temp even on a long drive 3 hours+. Your fans should not ever come on either.

Put a stat in and it will be more effiecient in gas mileage.
Because you are taking too much heat away your effieciency is hurt.

No chip = 195
chip =180



It would be interesting for you to post your mpg I would guess them to be below 19

Aaron
 

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Cool thanks for the info about the Open/closed loop being time dependant....
 

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Discussion Starter #9
Thank you to everyone who helped explain the sensors and timing functions on the 4.6L. With this information, I replaced the original 190 degree thermostat into the engine.
 
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