Here's a little background on the Ford Powerstroke thermostat...
Until 1996, all 7.3L Powerstrokes that were manufactured used an International
water pump and an International short stem 203o thermostat . In 1996,
Ford changed to a lower degree 195o thermostat. They changed water pump designs
at this time as well. The new pumps required the new long stem 195o thermostat in
place of the short stem to properly seat the bypass disk. All 1996-2003 Ford
PSDs now come equipped with a long stem 195o thermostat.
WHY IS 203o BETTER THAN 195o?
Diesels run most efficiently at approximately 200o. A 195o thermostat will start to
open at approximately 165o-170o. The Powerstroke has such an efficient cooling
system, that this low flow when the thermostat is slightly open is normally enough to
keep the engine cool. The downfall to this is that the engine -- when our trucks are
not under load --never begins to reach its optimal operating temperature. Our 203 o
thermostat begins to open at 185o. This brings the operating temps up from about
170o to about 185o. This is closer to the operating temperature range that is
preferable in our trucks for optimal efficiency.
When our trucks are under load and are producing higher combustion
temperatures the 203o will allow the engine to run even closer to its optimal
operating temperature. If the truck is under load and reaches the 203o setting, the
thermostat is then fully open. This means you are at the maximum coolant
temperature that the truck will reach. Your maximum temperatures are only a few
degrees higher than in stock configuration, but these are degrees that you want for
better performance. The best benefits come when the same truck is under a light
load and would have a hard time reaching this optimal temperature. As stated
above, you will never reach this optimum temperature with the stock 195 o
thermostat. The end result of installing the 203o thermostat should be slightly better
fuel economy, less smoke, and maybe a few extra "ponies" to go along with it.
WHY A LONG STEM AND NOT A SHORT STEM?
Although International still uses a 203o thermostat in some applications and that
thermostat is available at most auto parts stores, it is the wrong part for the
1996 - 2003 Powerstroke. DO NOT USE THIS! It has a shorter shaft and will
not shut off the internal pump bypass. This will cause inaccurate coolant flow
direction through the engine.
The thermostat in the Powerstroke not only controls operating temperatures, but
properly directs the flow of coolant through the engine. As the thermostat opens, it
proportionally closes the bypass. With the thermostat fully open, the bypass
is mostly closed, and vice versa. With the International (Pre-96 Ford) thermostat,
this cannot be controlled properly because of the shorter bypass stem. The shorter
stem of the IH(pre-96 Ford) thermostat allows the thermostat to be fully open while
the bypass is fully open. This means the coolant can travel in any direction available
-- whatever direction it chooses. It can either travel through the radiator or simply
make the shorter, less restrictive path back through the front of the engine. This will
cause uncontrolled overheating in the back cylinders of the block, with absolutely no
signs of danger showing on the water temperature gauge in the cab. It is possible
that the back of the engine can have no coolant flow at all yet the thermometer in
the outlet of the water pump shows all to be normal. Multiple things can happen at
this point. Cylinders can seize, freeze plugs can fall out and other normal symptoms
of an overheating engine may occur. Worst case is a blown motor and it won't be
covered under warranty.
We know the warranty departments and engineers at Ford have verified engine loss
due to the short stem thermostats in previous cases where people were sticking into
their trucks to increase their operating temperatures. As soon as they see the short
shaft thermostat -it's your problem. Our 203o thermostat will not encounter these
problems! It's designed to work as the OEM unit did WITH the long stem for bypass
protection.
WHY USE THE DIESELSITE 203o THERMOSTAT?
Higher optimum operating temperatures reached safely by using our thermostat with
the long stem for bypass protection. It's that simple. We've combined the two units
to bring you a safe alternative. Now you can have the optimal operating
temperatures without risking the chance of uncontrolled overheating in the back
cylinders of the block due to an uncontrolled bypass.
WARRANTY INFORMATION:
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90 days on manufacturing defects and workmanship only.
There are no other warranties, written or implied.
Improperly or poorly maintained systems can lead to failures in thermostats.
As with all cooling system modifications, a water temperaure gauge is a
highly important tool in monitoring the system.
As with the OEM thermostat requirements, we recommend that you change your
thermostat out once per year to insure proper functioning of the unit.
-----------------------------------Frequently Asked Questions:
--Question: Does your thermostat have a way to bleed air from behind the valve?
Answer: Yes. There is a small calibrated "V" notch cut into the side of the disc for
air bleeding. Do not drill a hole in the disc as this can change the opening
temperature of the thermostat. Our thermostats went through extensive durability
and flow testing to make sure they were perfect.
-Question: Why do I want my truck to run warmer?
Answer: You want the engine oil/water temps to be warmer so you get a cleaner,
more complete combustion. This can actually bring exhaust gas temperatures
DOWN. Diesel ignites from heat of compression. The idea is to compress the air
charge to build enough heat to light the fuel, but if it's fighting against a low engine
heat, the fuel will ignite, but not as complete as if the cylinders were just a bit
warmer. The more complete the combustion, the cooler the exhaust temperatures.
Diesel fuel combustion tends to work best at temps above 210 oil temps. Water
temps are usually about 10-30 degrees cooler than oil. An added benefit from using
the 203o thermostat is better working cab heaters in the cold months. Another added
benefit is better fuel economy. We have seen everywhere from 1-4mpg
increases. This depends on climates, driving habits, etc.
-Question: Will I need any other parts or o-rings to install the Dieselsite 203o
thermostat?
Answer: Each DIESELSITE.COM 203o thermostat comes with a new o-ring. We
recommend a new thermostat housing when installing a new thermostat if your
vehicle is over a year old. Many are rusted too badly to properly seal. We sell the
OEM housings for 1999-2003. We also offer a billet aluminum thermostat housing in
several colors. You can purchase your OEM housing at your local dealer as well.
-Question: What can I do to insure no leaks during the installation?
Answer: Be sure to start with a clean, very dry surface. Most installation errors are
caused by those who did not wait for the surface to dry or they did not clean and dry
it well before installing the thermostat. Although it is not needed if you start with a
clean, dry surface you can use regular RTV sealant during the install.
-Question: What temperature should I be seeing on the factory gauge in the cab
after installation?
Answer: The factory temperature gauge is not a true temperature gauge in that it
does not show actual temperature. It has three settings: cold, normal and
overheating. Cold is when you first start it up. Normal is anything that the
computer thinks is normal operating temperatures. This can range from 90o to
220o. Overheating is just that. The gauge is not designed for measuring your actual
water temperature it is designed to tell you whether you are in the normal operating
temperature or overheating. There is no in-between. With that in mind, the gauge
on your dash may stay the same, may go up or may go down slightly. It is NOT an
indication of what the thermostat is doing. If you want to know your actual water
temperature, you must put in an aftermarket water temperature gauge.
--Question: Does the thermostat affect my engine oil temperatures as well as the
coolant temperatures?
Answer: Yes it does. In fact, that is the whole point. It raises engine oil
temperatures proportionate to the coolant temperatures. The engine monitors oil
temperatures and our thermostat does not raise the oil temperature out of the
normal acceptable range. It only raises it to a more desirable range for the diesel
engine.
-Question: Can't I just block off part of my radiator to achieve higher coolant
temperatures?
Answer: Yes, but this is an uncontrolled situation. You have effectively reduced the
size of the radiator and if more cooling were needed for higher loads, the engine
might overheat. A higher rated thermostat is the only safe way to raise operating
temperatures.
-Question: Does my thermostat really need to be replaced every year?
Answer: This is like any thermostat. There is no magic. Its design is identical to any
OEM thermostat with only the opening temperature rating as its difference. A
thermostat is a heat reactive spring that changes shape every cycle. The more
hot/cold cycles the thermostat sees, the faster is wears out. So, depending on the
driving conditions a truck is under, a truck may see years of dependable operation,
or may see as little as a year. This is common. We decided to run a test and wait for
it to fail to see how long we got out of our personal company truck. The thermostat
has been in service for almost three years now. The thermostat finally reduced it's
max opening size not allowing as much coolant to pass, so temps ran a bit higher
than normal. It didn't actually "fail" , but merely failed to operate within design
specs. We tested the thermostat in a pot of boiling water to confirm the problem. We
installed a new thermostat and all is fine again. So, in closing, follow your Ford
recomondations to check and replace your thermostat when needed.