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Is this temp gauge reading normal? see pic

20K views 19 replies 8 participants last post by  iCajun 
#1 ·
Driving down the road about 60-65 mph for 30 miles 84 degree day in Missouri. Is this what the gauge sould be reading or is it a little high!
96 Impala 117,000, k&n, 2 1/2" exhaust, 3.55 gears

 
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#2 ·
Are you running a stock PCM program? Also what's the temperature of the thermostat?
 
#5 ·
I was moving 60-65, have bleed system several times. car was running hot, so I changed the T stat, no change, flushed the complete system, and bleed 6 times or so. had a cheapy pressure cap on it and it was boiling over after i would shut it off, so I bought a gm cap and put on today, then drove 33 miles home( highway). quit boiling over but temp runs where it is in pic after 20 miles or so, could it be plugged rad. just started doing this Monday
 
#6 ·
have bled the car 6 or so times, when it gets fairly warm (towards halfway) i'll open bleeder and a little air comes out then straight fluid, so i shut and do it next time I drive it.
 
#7 ·
You may still have some trapped air from the bad cap and the Tstat R&R. Warm it up, shut it off, let it sit a couple minutes, then pop open the bleeder screw.

Also, with the car running, disconnect the ECT sensor at the water pump to check your fans. Both should come on within 10 seconds or so, and both should move enough air to push firmly against your hand. If not, you've got a bad fan motor or relay.
 
#8 ·
Yeah it certainly seems like it's running warm if you're seeing that temperature while driving.

I've installed a mechanical gauge in the cylinder head, and the F-Body 3 wire sender in the water pump. I can tell you that with both thermostats I've tried (160' & 180'), the operating temperature typically runs 12'-14' hotter than the thermostat rating temperature.

Looking at your gauge pic, I'd guess your seeing temps ~240', which is quite warm for a moving car.

FYI: Per the manual 2 of 2, page 6E-388

The PCM will command fan 1 ON at 107'C (225'F) and OFF at 103'C (218'F) and, fan 2 ON at 111'C (232'F) and OFF at 107'C (225'F)
 
#9 ·
The gauge was showing almost that high when I got out to my dads shop earlier, and I raised it up on the lift to take off starter(it has been draging when hot for awhile now) I forgot to read the temp with the IR thermometer as soon as I shut it off, so it was about 10 min. after I shut it off and it 190* at the sensor on front of the wp, could my gauge be reading higher that it should? I'll have to wait till I get the starter back on to test the gauge with IR thermometer. It has quit bubbling and over flowing with the new cap. I also bled some more air out after I shut it off earlier.
 
#11 · (Edited)
Sorry I don't have more to add - the suggestions given are all good. But you have proven one important point......the coolant cap is critical and is often overlooked or ignored. It is a replacement item and vital for proper pressurization which affects cooling ability. Easy and cheap to replace. Also - is new therm correct LT1 type? Not generic Chevy 350 type?
 
#12 · (Edited)
If I remember the math right, your gauge looks to be indicating about 230F. The next mark would be 239F, assuming the sender and gauge are deadly accurate, which I doubt. I've only seen my gauge that high once, while pulling my boat on a long uphill grade near Colorado Springs while running the AC. It normally runs just above the quarter mark, roughly 185F I suppose.
Thanks,
Alan
 
#13 ·
How long have you owned the car? I assume you don't have a lower gauge reading that it used to read to compare to this reading to clearly illustrate something is not right?

Could it be his radiator is clogged or something like that?

I've been doing a lot of flushing on my 95 9C1 to try to get all the rust out of the cooling system.

I've drained and filled it about four times so far, and each time bleeding the air out and getting it to run cool has been simple.

I took out the factory bleeder screw and replaced it with a 1/8 NPT ball valve with a 1/8" hose barb on it. I hook up a piece of clear tubing to the hose barb, and it is simple to bleed and is running super cool in 90 degree weather.

I also had a bad primary cooling fan, and with only the secondary fan turning, it was still running well below the red zone on the gauge, with the AC on. Admittedly, the AC was blowing warm air at lights before I could get a new fan, but it was still running only about 1/2 on the gauge sitting in traffic...

Lee
 
#15 ·
Thanks guys, I didn't drive it this weekend (crazy weekend) drove the yukon! On the way to work this morning it was about 65* out and it was running between halfway and the next dash up on the gauge after about 25 miles or so, then when I got to work I let it idle for about 3 min. and the temp droped down below the halfway mark, and i check the jug and front of WP with IR thermometer and they read 185* - 195* when the gauge was below halfway. Seem the gauge is not to far off but I think I need the radiator clean out, since it runs hotter going down the road than at idle!!
 
#17 ·
Kinda what im thinkin, not sure how old the WP is, looks nice and clean, the opti was replaced before I got car with an MSD unit, you think he would of replaced wp also but you never know. called radiator shop in Saint Joseph and he said that they don't boil them out anymore, they pull one tank and run flat bars down through the tubes (wrought out) or something he said, but it's $75.00. :eek: O well has to be done!!!
 
#18 ·
Pulled radiator today and had it cleaned out, He pulled the tank off and said that 2/3rds of the ends of the tubes where crusted shut with mineral deposits. I was only cooling with a 1/3rd of my rad!!! It does not even get past the quarter mark now, it has never ran that low, I am EXCITED, and it only cost $55 Thanks to everyone that had suggestions and I hope this helps other people in the future
 
#20 ·
Many years ago I started using distilled water instead of tap water in most of my engines. Haven't clogged a radiator since. About 88 cents per gallon at the grocery store. Come to think of it, guess I should change the antifreeze in the cars this summer as it has been a long time.
Thanks,
Alan
 
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