Thread: 3800 Series II non-SC runs hot after replacing lower intake gaskets and upper intake

Update #2 for today:


Used the block tester and test was NEGATIVE for blown head gasket...woohoo!!!


Refilled and re-bled the system again after following block tester instructions to remove 2-3 inches of coolant from tank prior to test. Stil running steadily between 210-235...


Upon inspection, now looks like cooling fans are coming on way too late (but they are coming on). Fuses look good, but haven't yet tested the relays. Are there any other factors contributing to the cooling fan automatic operations?


After all this, next step will be to replace the radiator.

That's usually pretty normal. You have pretty much tried everything else out except the ECT sensor below the tstat housing.

Thank you "luckyg817" and "The Guz"...The water pump is only about a year old, and I've swapped out a new ECT sensor twice to make sure the new one wasn't bad. The old ECT sensor was destroyed accidentally during the dis-assembly process.

Some have had bad luck with ect sensors being bad right out of the box. Do you have the torque app or something to scan the car with? If you do, you could cross reference what the gauge is reading vs what the scanner is reading and maybe you're just having a false reading on the gauge.

Originally Posted by luckyg817

Some have had bad luck with ect sensors being bad right out of the box. Do you have the torque app or something to scan the car with? If you do, you could cross reference what the gauge is reading vs what the scanner is reading and maybe you're just having a false reading on the gauge.

Could I have bad luck with two different ECT sensors? Maybe, but doesn't seem likely. My neighbor has the Torque App with the OBD reader that I can borrow for testing. However, when I have pulled coolant from the bleeder the temp usually reads same as what I see on the gauge.

Update #3:

Pressure tested the radiator, and it failed. Very difficult to pump up to 16psi and the pressure quickly drops. Radiator is leaking at top of engine side, on the driver's side, where the aluminum core meets the plastic. I know these plastic ended radiators are altogether not a great design and was hoping to not have to drop $$$ for a new one.

I bought a "lifetime warranty" radiator from an eBay vendor back in 2011 but it looks like they are long gone. Autozone has a Spectra Premium lifetime warranty radiator. Reasonably priced, has their "lifetime warranty", and I know I'll be able to find an Autozone for the warranty replacement if it breaks again.

Anyone have positive/negative reviews on the Spectra radiators?

Originally Posted by The Guz

I'm trying to remember what we did no my brothers 03. It was so long ago when we did the LIM. But I believe we taped the threaded part of the ECT and that fixed any issues he had with his sensor. I forget what brand he has. Perhaps something else you can try.

"The Guz" can you elaborate on this? I'm not sure how taping the threads of the ECT would help the situation. I assume you are talking about using something like plumbing thread tape...??? The ECT that I purchased already had thread compound applied on the threads out of the box...

To clarify: I don't have issues with the ECT leaking. I suspect that the new Duralast part that I have (which I bought a week ago, and have already replaced once since then) is producing a false reading causing an inaccurate needle reading on the instrument cluster, as well as causing the electric cooling fans to engage at 210-ish instead of the 185-ish temps that I have been used to seeing throughout the years.

Thanks.

Final Update...

FIXED!!!

I put in the new radiator AND swapped out the Duralast Coolant Temp Sensor with an OEM AC Delco sensor (AC Delco part# 213-815), and everything looks great after the first 45 minute warmup/test drive!!!

Coolant temps are staying right at around the 185-190 degree mark on the instrument cluster exactly as expected. Cooling fans also operating as expected and cycling on and off at the right temperatures. Also bled the cooling system as instructed in some of the above replies.

Funny thing now is that my A/C button light stays illuminated, so my A/C no stays on permanently. Not really that big of a deal since I'm in SoCal, but if anyone has any thoughts about that I'm all ears. Maybe it's vacuum-related...?

Lastly, I also ordered and installed new upper motor mounts. I also followed this YouTube video (https://www.youtube.com/watch?v=qAZJ4xxcLyI) to turn the dogbone mount to tighten up the engine movement, and the test drive was amazing! Soon, I'll be replacing the Transmission and Engine mounts on the bottom (when I'm ready to tackle the Oil Pan gasket replacement). The car really feels like new. It will probably be even better if/when I get around to replacing the front struts.

300,000 miles (and beyond) here I come!!!

Thanks for all the input and advice. I truly appreciate it.

BP