318SixPack

(Too bad I cannot figure out how to edit the subject line: Gotta Check that Therm Housing Temp)

It seems like my gas mileage has dropped since replacing radiator and thermostat. Gauge shows it somewhere in the 195ish kinda range all the time. Checked if O'Reilly had an IR thermometer to check it in the lot. No dice, guess I am springing for a Harbor Freight one (on sale for $18 until the end of the year). Not really sure on those gadgets what 12:1 vs 20:1 means, besides more expensive.

Gas getting and fluid checking day is tomorrow, so will be starting a proper mileage check then too.

If that housing is not getting over 195 (thermostat checked good at about 195) then I guess I'm springing for an ACDelco 205F thermostat and might as well replace the housing and bolts.

Red1992XJ

Just curious, how much did your mileage drop? I notice when the switch to winter blend fuel from summer blend occurs, I will usually lose about .5-1 mpg. Then again, its such a small difference, it's kind of odd to deal with.

I don't think that 195 is that bad of an operating temp. Have you made any other changes lately?

318SixPack

Haven't started measuring yet. Just seems like I am refilling more often than before.

As noted, replaced radiator (hoses too) and thermostat. Also un-deleted the air cleaner box and filter. Had removed those years ago and never did what I was going to do there. Replaced battery cable terminals. Fixed a long time vacuum leak.

I have the stock original gauge in my dash, so can't really tell if I am at 195, or under. With old radiator I was always sitting close to 210 so it was easy to tell I was in the right zone.

And I finally found out what the 12:1 means on the IR thermometer.

lawsoncl

It's the ratio of the size of the spot it measures to how far away you are. 12:1 means at 12" away, it's measuring an area of 1" diameter.
https://www.grainger.com/content/qt-...d-thermometers (scroll down to "accuracy")

318SixPack

Checked it with an IR but might not have been using the best technique.



It is usually not reading quite that high, but close. That was around lunch time. Was targeting the laser on the thermostat housing in front of the thermostat, but it is a little dirty there. Later I tried up the neck near the upper radiator hose and that got over 205F

After work I tried measuring the brass of the sender. That was over 200F also. So, for now concluding that thermostat and sender are fine, it is just warming up slower and staying cooler than what I was used to with the old replacement radiator, original cap and thermostat combination.

Filled up with gas today, noted mileage to the tenth, checked oil and coolant. Everything is fine. Will see at next fillup what the mileage looks like.

PatHenry

That temp looks perfect per the gauge.

I also get lower than "perfect" temp in my 95. I've got a Mopar t-stat that I'll be putting in at some point which will hopefully give me constant running temps exactly as pictured.

cruiser54

It's fine........

318SixPack

Everything seems ok now. Pulled the battery from IR thermometer and stowed it away.

bluejeep2001

Don't change the t-stat.. The sender in the housing feeds the computer which changes the mixture based on temp. Get the jeep up to operating temps then shut off and quickly remove the connector off the tstat sender and take a reading...should be up around 1000 ohm.There is a chart to check out that sender...I will find it tomorrow but my sender in a pot of boiling water reads 675-800. As it cools-the resistance goes up...cooler temps give more fuel . The best calibration is to put in a pot of boiling water...then you know the exact temp...Can you take readings with an obd scanner even though you have obd 1?...If you can then in the morning on a cold car...your inlet air temp should be the same as your coolant temp but I cant remember what you can access with obd 1

318SixPack

I do not have an OBD scanner.

bluejeep2001

Ok for a 95...if you throw your sensor in a pot of boiling water.....should 640-720 at 195 ...it should be 840-970....anything near these are ballpark ok......if your resistances read much higher than 1100 then your sensor is off and you are dumping too much fuel because the computer is thinking the engine is cold......OR your thermostat and gauge sensor is bad and your engine really is cold

bluejeep2001

Remember that on a 95 your temp on the gauge comes from the sender on the left side of the head near the back...the sender in the housing only feeds the computer for fuel scheduling...they do not have to be same temp but should be similar-ish

downs

Then you're basing your actions on basically no data at all. Without actual mileage data we have no idea what you are actually getting or if it's out of the norm and all you're doing is blowing money and time for no reason.

318SixPack

Thought I qualified that up there with "It seems like" at the beginning of the statement. That began the suspicion, now I am checking it closer.

Back to the main topic, found in the IR thermometer instructions the issue of Emissivity. I have not adjusted it for the emissivity of oxidized aluminum (0.30), where I am checking the temp. Need to clean that housing up, make the adjustment, and try again.

The gun instructions do not show oxidized brass, like the sender, where I can also read temp, but this reference shows it as 0.61:
http://www-eng.lbl.gov/~dw/projects/...missivity2.pdf

318SixPack

OK looks like gas mileage is as fine as it was in 1996. 15.4 MPG in town. 354,712 miles now.

Two weeks between fuel stops and my commute is about 6 miles each way and top speed limit is 45 for only about one mile.

Oil looks good. Still close to the top of the safe line after adding a quart a couple of weeks ago, and clean.

Noticed this weekend it is not impossible to get temperature up to 210, but I have to sit and idle for a good 10 min to get it up there on a 70 degree day. I think it is the first time since I changed the rad ant thermostat a couple of months ago that it exchanged any fluid with the overflow tank.