tmcolegr

I have read through every post on this issue and still have some questions about installing the sending unit for the water temp. gauge. To begin with, I have purchased the CDC dash gauge pod and am planning on installing Autometer Cobalt series electric water temp., oil & fuel pressure guages. I am planning on keeping all the factory gauges operational as well. The oil pressure gauge is a no brainer - just tee into the existing oil pressure sending unit location. The water temp. gauge is where I need some assistance. Where is the factory sending unit located? I would like for my water temp. gauge to be as accurate as possible. I have looked over the entire engine and it seems to me the most logical place would be in the water manifold at the front of the driver's side cylinder head. There is a plug already at that location with a 1/4" square drive to assist in R&I of the plug. I was seriously considering drilling and tapping the plug for the Autometer sender which I believe is 1/8" NPT. Since my gauges haven't arrived yet, I'm not 100% sure about that size though. I assume this plug serves to allow the cooling system to be manually vented when refilling the cooling system to avoid an air pocket. This would also be (in my opinion) the most accurate location to mount the sending unit. Please see attached picture of the plug I'm referring to. I have noticed some others have mounted their sending units in the block on the driver's side. Not sure why - perhaps someone can enlighten me. If any of you have already installed gauges, your advice would be greatly appreciated.

2L8IWON

I just put a mechanical water temp gauge in my Mystic, but haven't touched my 05 yet.

TTT for you.

PS I notcie that you work for Cat in Orlando, my uncle is a parts manager for them, his name is Curt.

MTAS

Todd - been there, done that - it leaks Drilling and tapping it might work though. I didn't do a vast search on an adapter to fit the sensor, so it's possible that one exists, but not from Autometer. I ended up putting the sensor in the block which may not be the most accurate, but it's the only place that would readily accept the Autometer adapter and sensor. I don't know where the computer senses the coolant temp, but would also love to know. Good luck!

tmcolegr

So George let me be very clear on this. The heated coolant returns to the radiator from the engine through the manifold/hose which is on the passengers side front of the engine? What happens when the thermostat is not open? George I am not questioning you - just want to make sure I understand the coolant flow through the engine (both with the thermostat open and closed) and radiator. Does the coolant not circulate in the engine but not through the radiator prior to the thermostat opening? Is the attached picture the location your referring to? Is the sending unit 1/8" NPT? A picture of your installation would be great!

If your suggestion is correct, the temp. gauge should indicate a gradual temperature rise from when the engine is first started (cold) until the thermostat opens. The gauge should monitor all of this including the initial temperature drop when the thermostat first opens. Then when the thermostat is open, the gauge should read about 5-10 degrees max. above the opening temperature of the themostat if everything is working correctly. Do you happen to know the opening temp. on the OEM thermostat?

Another question: where is the thermostat on this engine? Is it located in the manifold where all the hoses connect just below and behind the P/S reservoir? See attached picture.

I'm sure I am not the only one with these questions - George if you or anyone else knows please respond. I want to install this sender in the correct location.

PS: When I was installing my Steeda Charge Motion Delete Plates I noticed a sender on the passenger's side of the engine directly under the intake manifold. With the intake manifold installed it is impossible to see. Could that be the coolant temp. sender for the factory gauge cluster? Let me offer my sincere appreciation to those that know the answers to my questions and are willing to respond.

MTAS

Todd I can answer 2 of your questions: Yes the pic on the left is the thermostat housing. It is a 180*F thermostat (so it opens at 180*F?). I'm very interested in this as well. I put the sensor in the block because it was easy to get to and with the Autometer adapter it screwed right in. My predator tune is set to kick the high-speed fan on at 190*F, and shut off at 180*F. My Autometer temp gauge stays pretty consistent at just above 190*F once she's up to operating temp (but it's still a heck of alot more accurate than the factory POS). If drilling and tapping that spot on the left side of the manifold is more accurate, then I'll go that route too.

tmcolegr

Dave I appreciate your input and it sounds like George may have some additional information on how this cooling system works. I PMed him this morning asking him to post his reply to my questions. I am knowledgeable on cooling systems in general as I have been a Caterpillar tech for 25 years (started my 1st job working on Caterpillar equipment when I was 16 and never looked back) and for the life of me this system is like nothing I have ever encountered. The rest of my information is factual based on my experience.

I want my gauges to be an accurate indication of what is really going on with the engine. The factory gauges read cold & hot temperature and low & high oil pressure. What I want to know, as do most others, is what is cold or hot and low or high. That is why I am installing them. The factory gauges are better than just a light but not much.

If you look very closely in the center of the attached picture you will see the sending unit under the intake manifold I was referring too. I believe that is the sender for the factory gauge cluster. I apologize for the quality of the picture but I had to use 2 lights and a mirror to get enough light in that location to even get the picture - took an hour to set up. If you look from the driver's side of the vehicle, behind the alternator but below the intake manifold you will see the sending unit I am referring to.

I hope someone can answer these questions.

PS: I asked 2 different dealer techs these same questions and got the "deer in the headlight" look. I'm sure someone could have answered my questions but not the 2 I asked.

tmcolegr

George what brand gauges did you install? Autometer?? What size hole did you tap into the water manifold? 1/8" NPT?

One last question and I'll leave you alone. If the cooling system is continually bypassing some quantity of coolant back to the thermost housing to be recirculated as you stated, wouldn't a sending unit in the plug on the driver's side water manifold accurately reflect the temperature of the coolant even when the thermostat is open? Keep in mind I am not questioning you but looking for a clearer understanding of the coolant flow through the engine/radiator both cold & hot.

Unfortunately my infrared heat gun is at work. If we were to monitor the temperature of both sides of the water manifold from start-up (cold) to thermostat open that should tell us. Your thoughts??

tmcolegr

George I took your advice and installed the water temp. sending unit in the location you suggested. I unbolted the coolant reservoir leaving the hoses attached and lowered it down to a level below the water manifold outlet to the radiator. I then removed the coolant outlet hose from the coolant outlet manifold on the engine. Much to my surprize, the coolant manifold was empty. Just to satisfy my curiosity, I raised the reservoir above the level of the coolant manifold, and the coolant level rose as the reservoir was raised. I inserted a clean shop towel folded in the form of a trough in the coolant manifold outlet to catch all the drilling and tapping chips. I then very carefully drilled the manifold in increasing increments until I reached 21/64". Slowly I tapped the hole* with a 1/8" NPT tap, removing the tap frequently to clean the tap flutes of aluminum chips, and checking frequently to make sure I did not tap too deeply with the tapered pipe tap. I cleaned all loose chips, installed the Autometer sending unit, reconnected the coolant outlet hose and remounted the coolant reservoir. Prior to starting, I removed the plug with the 1/4" sq. drive on the opposite side of the coolant manifold, to release an air pockets in the cooling system. Here are the results.

*PS: a very good friend of mine is a machinist. He gave me a tapping oil made by Tapmatic specifically formulated for tapping aluminum. He said it is the best product to use. As you tap aluminum, friction and heat are created and when the tap is removed, it is very easy roll a thread and damage the piece you just tapped.

Vegasjay

Nice job. What is the part # of that tap oil?

tmcolegr

Here is a link to Tapmatic's website:

http://www.lpslabs.com/Products/TDS/DA%20Plus%202.pdf

Here is a picture of the sending unit for the electric fuel pressure gauge. I'll post pictures of the remote mounted oil pressure sending units for the factory gauge and Autometer gauge when I am finished.

tmcolegr

Remote mounted factory O.P. gauge sender and Autometer O.P. sender

tmcolegr

Still plenty of room for the Zex NMU (Nitrous Management Unit)

tmcolegr

Installation is complete. Sorry for the quality of the picture.

legend05

Todd, that is awsome!!!!
Thanx for the step by step.
Can you P.M. me the exact material you used
for the remote O.P sending units (braided hose, that blue tee etc...).
Going to go that route.

tmcolegr

It will take me a little while - but yes I will. Do you want Russell or Aeroquip part numbers?

pittperson

Todd, what was the total cost of your setup? I'm looking into doing the same thing to make up for my lack of IUP.

Also, was the installation pretty straigh foward?

legend05

Whatever you used is fine
Thanx