Still running hot
Thread Starter
Instructor
Joined: Apr 2011
Posts: 127
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Update: Removed the screen. Cools off to about 205*, but still running hot at anything under 2000 rpm. For example, if I run a constant 65 mph in 6th gear, it'll stay at about 207*, if I drop to 5th gear and maintain the same speed, it'll run at about 203*, but if I hold 65 mph in 4th gear, it'll drop to, and hold at 198*. Still scratching my head...
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Update: Removed the screen. Cools off to about 205*, but still running hot at anything under 2000 rpm. For example, if I run a constant 65 mph in 6th gear, it'll stay at about 207*, if I drop to 5th gear and maintain the same speed, it'll run at about 203*, but if I hold 65 mph in 4th gear, it'll drop to, and hold at 198*. Still scratching my head...
I would see it first on the Analog followed by the Digital... then one day all hell broke loose and I had steam out the pipe. after fixing the heads I ran about 190-195 at 70, recently my Radiator started leaking so I installed the Dewitts, and now 188 on a 105 day. I would shoot the the engine and verify the gauge befor getting to deep.
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
o2 sensors causing a lean condition?
Hi adtbrown,
Given ththe challenges with coolant temperature continues (per your other posts over the past few months), aside of the problem maybe being with your new radiator (as the other poster suggesting -- based on others with clogged tubes albeit new), and appear to be getting worse,
might it be time to look elsewhere?
Have you checked for a clogged catalalytic converter?
Have you replaced the o2 sensors?
Remember the computer only knows if the engine is rich or lean based on what the 02 sensors tell it. If they are tired or failing and incorrectly reporting a rich situation, the computer will lean the mixture, possibly to the point of causing the engine to run hot and sadly, the computer will not realize this and just continue running the engine overly lean, likely causing the engine to run hot.
One easy way to tell this might be with an emissions tester. If the engine has nearly zero emissions at idle and at 2k, it could imply the o2 sensors are a bit off.
Given ththe challenges with coolant temperature continues (per your other posts over the past few months), aside of the problem maybe being with your new radiator (as the other poster suggesting -- based on others with clogged tubes albeit new), and appear to be getting worse,
might it be time to look elsewhere?
Have you checked for a clogged catalalytic converter?
Have you replaced the o2 sensors?
Remember the computer only knows if the engine is rich or lean based on what the 02 sensors tell it. If they are tired or failing and incorrectly reporting a rich situation, the computer will lean the mixture, possibly to the point of causing the engine to run hot and sadly, the computer will not realize this and just continue running the engine overly lean, likely causing the engine to run hot.
One easy way to tell this might be with an emissions tester. If the engine has nearly zero emissions at idle and at 2k, it could imply the o2 sensors are a bit off.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 195
From: folsom california
If the cooling system was that bad, you probably knocked off enough corrosion, mud, rust, build up, whatever, from around the sensor or from the sensor itself to allow it to register an accurate reading. Remember, a lot of that crud, besides restricting flow, also acts as an insulator and restricts heat transfer.
Thread Starter
Instructor
Joined: Apr 2011
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Update: I replaced the radiator with an even higher capacity aluminum radiator. While the temps are barely better, it still creeps up and runs about 210* below 2800 RPM. Gonna try a 3rd thermostat, and plug in to the computer and do some searching on here and compare my O2 sensor readings with what it should be. Other than that, I'm out of ideas, unless I somehow got a bad water pump.
BTW, if it was a plugged cat, it would overheat more at high RPM's. Mine runs COOL above 3000 RPM's, even better with the 2nd new radiator.
BTW, if it was a plugged cat, it would overheat more at high RPM's. Mine runs COOL above 3000 RPM's, even better with the 2nd new radiator.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Originally Posted by adtbrown
One more confession to make... Under the advice and supervision of a GM tech, I thoroughly cleaned and flushed the cooling system (including the heater core) and refilled it with Dex Cool. ........
I'm confident that the cooling system is clean.
should perform just fine.
In your first post (cited above) you mention that the system was thoroughly flushed, but did not mention if the two knock sensors located in the bottom of the block were removed for flushing.
No flushing is complete if the knock sensors were not removed.
With all the contamination you experienced, it could be reducing coolant flow in the knock sensor area. If you haven't replaced the knock sensors, it is recommended you do so...... much cheaper than radiators.
Thread Starter
Instructor
Joined: Apr 2011
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THANK YOU, seabright for the suggestion to pull the knock sensors!! When I previously did the swap to dex cool, I did pull the sensors, but I am not sure, now, that I did as much of a drain out, as I did a clean out. Il still anxious to see how it does on the road, but like I said, it sure did a whole lot better idling yesterday than it has in years.
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