Crossfire Thermodynamics Lab Course # CTL 102

Brian Hall
Classroom / Lab #172
Assistant Professor: Mr. Waldig
2 hours
Hands on Lab: Fabrication of stat modifications


The previous classroom discussion reviewed the thermostat operation and its construction. In this lab we will cover the physical construction and materials needed to complete the modifications for the crossfire.

The Stant stat needs to have two notches cut into the sides of body which will slip over the posts of stock housing. This can be done with a file or chassis “nibblers” to remove the material indicated in the photos ( about 1/8 inch per side ). This is a cut and fit step that the student will do several times to insure the correct amount of relief is needed.

The factory housing will also have to be altered by having the center locating pin removed with a burr or other cutter fit into a drill or grinder like a Dremel tool. The post is simply cut out and smoothed to reduce water friction. Refer to the photograph for the before and after images. It may be easier to purchase a spare thermostat assembly as they are less than 40$ and would allow you to do the work without being off the road or under stress while trying to do the work in a hurry.

The third item needed is a spring which clamps the thermostat body to the factory housing. I have found that a spring can be harder to locate than if would seem reasonable. To get around this problem, I found that Autozone has many LOWER radiator hoses within springs to prevent collapse. The photo shows one with the part number, it only needs to be about 1.75 inches in diameter to fit the housing. I have included a shot of the spring from several angles to give a feel for the shape and length needed. The hose will have enough material to make several springs if the first is not just right.

We are almost finished with the changes to use the thermostat except for the large washer on the back or top of the stat. I found that the correct washer is available at LOWES as shown in the photo. The smaller existing stant washer must be cut off carefully; I have done it proving that it is possible for those who wear glasses ( gods way of warning others: caution may attempt unsafe acts ) to do it.

Position the stat in a bench vise and start cutting the washer at a slight angle as illustrated. It is not necessary or ADVISED to cut through the washer. When completed flip the stat around and cut the opposite side in a similar manner. At this time the original washer can be bent back and forth several times to weaken it and cause it to crack and fall off. This removes the washer making way for the new larger washer’s installation.

One of the LOWES washers is placed on the stat after the center hole is enlarged with the Dremel tool of a hand “rat tailed” file. The hole only needs to be made large enough to slip over the post of the Stant thermostat. When the washer is installed it is held on the post with a 3/8ths JESUS clip. (The name comes about when using this fastener as they have a habit of going PING and taking off, when you say, (JESUS where did that go). See the photo to get a feel for the assembled stat, spring clamp and modified thermostat housing.

The thermostat is now complete and can be installed in the motor as the original one was. It will operate like the factory stat and provide the fast warm up but be fully open at about 172 degrees. The engine will still be at the original temperature setting, as the factory computer will reduce the fan motor speed to attempt to maintain the temperature at the same temp as stock. This will be taken care of in the next installment of the cooling system upgrade.

Questions are welcome, they improve my threads and assist those who don’t wanna ask, sorta like school. Enjoy, see ya next semester. Woody

Again the temperature of the engine is the balance of the heat produced and the heat rejected by the cooling systems. The thermostat allows more water to flow at a lower temperature, the fan has to be driven at a higher speed to actually blow this heat energy away, ultimately providing a cooler motor and the key to more horse power to the road.

I will be testing the effects of the stat and the fan motor controller on my SRT-6 with a three channel temperature monitor.

Stat body with post removed

Chassis nibbler used to cut my notches

Notch area of stat to fit houshing

First cut on stant stat washer with hacksaw

Spring for hold down view

Spring material source, hose at Autozone

Both cuts to stant stat before cracking washer off

Jesus clips and installation on new washer

Spring again, side view

Limited and SRT housings view

Stat reading, note the computer is holding the temp up by controlling the fan speed. With a resistor the fan is sped up and the water runs at 172 on a 90 degree day, more details to follow.

Woody

 

If I may be so bold as to add just one small thing to The Professor's excellent presentation:
when removing Jesus clips use a small blade screwdriver & gently pry off the clip making sure your finger, your hand, a rag, something you can catch the little devil with is right behind it or it will disappear! I hate those things.
Woody, I swear, if I find a decent round magnet I will send it to you. Your low tire warning lite is driving ME nuts!

 

Kindly let us know how it goes now that summer’s debilitating heat is upon us.

 

THX for the detail. I think I will try this as in SW Florida it is HOT!

 

How about making and selling one? Looks like a lot of that 4 letter word-WORK!

 

How much down? I'll pay the balance when the T-stat is finished. Thanks, mark

 

Woody, will any 172* stat work? Do you prefer a certain part number? I have no idea what chassis nibblers are What thermostat should I buy, SRT6 or the Limited?
A complete parts list with parts numbers for the dummies among us(read me!) would be helpful.