Odd Overheating Issue

[05GXPTriCoat]

So I searched and read and searched and read some more, but I cannot find the same problem duplicated. I have 74,xxx miles on the 05 and drive 23 miles to work one way. First, I noticed that when I got off the highway and started up the long hill to work that the temp gauge would climb (normal in most cases-low speed high load) but then it got to be when I slowed to exit the highway it would start to climb immediately. Changed the thermostat (found it was sticking), the water pump, belt and tensioner (pulley was rough when spun and belt was starting to shred). Great. Bled and drove seemed fine for a couple of days then acted as though the radiator was plugged. Drove it home and I could put my hand on the outlet side and it was cool to the touch. Changed the radiator and thought I had it bled. Kept squeezing the hoses to get all the air out and the whole rad now gets hot. Now it got hot while pulling a long hill on the highway. The weird part is that if I ease off on the highway, the temp gauge will drop back to normal. When i get off the highway it will start to climb again, but as soon as I can get the rpm's up it will drop right back down to normal. No rough idle at start up and no CEL. Plenty of power, runs great and heater gives plenty of heat. Doesn't seem like a head gasket because the temp will come back down.

Any ideas? Pressure cap? Blocked purge line?

Thanks!

[ddalder]

Have you checked to make sure your fans are working correctly and that the AC condenser isn't plugged with bugs? Since it sits in front of the radiator, if it's plugged there will be reduced air flow to the radiator.

[05GXPTriCoat]

Both fans work in low and high speed modes. The condenser is actually really clean for spending time in this climate. Checked the purge line and it is clear, gets hot when running just like it should.

[BBamm]

You said you replaced the water pump as well? Isn't the N* known to catch a pocket of air in there when they get changed? Could that maybe be part of the problem? I think I've heard that because of their location, the cooling system won't function properly because the air pocket won't let coolant past...

[CMNTMXR57]

When you say it "overheats", is it physically up to the red range and about to boil over? Or is it just seem to be running hotter than normal (or hotter than you would expect/like it to be)?

My guess is the later... I would say that's normal. When you're cruising along (not working it any), you have fresh air running through it and you don't have it under hard load... It cools. When you come to a stop, that airflow stops, and you will see it get warmer, until either you get the car moving again and/or the low speed fan comes on to assist.

But if you feel it something outside of normal airflow means, I'm gonna ask something so utterly profound, it's borderline stupid... It's along the lines of a customer service rep for a toaster company fielding a phone call that a new toaster doesn't work... Well... Did you plug it in?

Anyway, I really, truly don't think that there is a way to screw up the direction you drive that water pump seeing as though it's off on the complete opposite side of the engine, driven by it's own belt with nothing else being driven off that camshaft... But are you turning the water pump the right way?? Putting my flack jacket on. I know it's an absolutely absurd thought. But after a couple of drives, sustained drives, at that, any cooling system should purge itself by then. I seem to recall the umpteen times I drained mine that it took longer than other cars to purge, but within a few drives, it should be fine. I think GM states 15 minutes of closed loop idling to purge it.

Other thoughts;

- Coolant level.
- Possible bad replacement T-stat.

[05GXPTriCoat]

By overheating I mean it actually got to the red and gave me the Check Gauges/ Air Con Disabled warning message. However, it did come back down after holding it around 2000rpm's. The dropping temp was in a not-so-smooth manner. Kinda jerky on the way down like there were pockets of air then coolant passing the temp sender. The water pump is most definitely inserted and belted the correct direction.

The new tensioner is spinning smoothly and while revving I can look and see the pump spinning, it speeds up and slows down accordingly. A new bad part is rare in my experience, but that thought had crossed my mind as well. It's just that there are times like this mornings drive to work it sat rock steady at just a needle's width past 200, a touch lower than before the work was completed. On the way home after idling in 80+ degree weather through heavy, slow-moving traffic it stayed in the same spot. Now it did go up slightly on the highway part and I never really got into the loud pedal, but only to say 220-ish gauge indicated and then came right back down. Same for getting off the highway, went up and then came down. Odd see? The rise and fall seemed more like a sticking thermostat today as it was a rise to a certain spot then a quick fall back to where I'm comfortable with the gauge resting. No overheating though today.....I'm going to get a new cap just for insurance and it's 10 years old

[CMNTMXR57]

You've checked;

1) The shrouds/deflectors are in place

2) You've pressure tested the system and cap

3) The small hose to the overflow tank isn't pinched/kinked

4) water pump belt tension (this was also one of my thoughts when I originally posted)

If all of this checks out, and you're sure the replacement water pump is ok. The new radiator is ok, and that the thermostat is ok, I might start looking into electrical.

[05GXPTriCoat]

Thank you CMNTMXR57. I will start looking at a possible issue with the sensor and/or wiring in and around that. I was hoping for Capt. Obvious to appear and point at something dumb I overlooked, but I've run through everything like you listed and that's why I posted...appreciate everyone's input! Now that I have a regular schedule, I will make more of an effort to help where I can as well.

Thanks again!

[05GXPTriCoat]

Well it's the head gaskets.... I had a last hope of the cap being bad, pressure tested and failed. Replaced and drove it down the highway with no issues until I got on to some 2-lane roads and was driving a long hill and it headed straight for the red zone. It did cool back down though and I got it home without it going into the red. Just for grins and one last ditch effort, yanked the thermostat and drove it again. Stayed in the same temperature range as it did with the thermostat installed. Went up a hill and beeline for the red zone.

[300sflyer]

Well it's the head gaskets....

This is the cure... Worked perfectly on mine.

http://www.northstarperformance.com/sgstuds.php

[05GXPTriCoat]

Kit ordered...along with the necessary install items....it'll be nice to go ahead and get this done and not worry about it anymore.

[05GXPTriCoat]

How long did it take to get the kit? It's been a month since I ordered mine and the only thing I have received from Northstar is an email saying a shipping label has been made...a week and a half ago...

[300sflyer]

Have you tried calling on the phone? I had mine in about a week.

[05GXPTriCoat]

Yes, but it goes right to a recording stating they are all in the shop and busy making the kits. Finally got an email response and a shipping notification. I should have the kit Friday! Found a shop with a lift I can use too so I'm saving some cash too...nervous but ready to get back into my car. The 279,xxx mile 4-cylinder Camry just isn't the same...

[05GXPTriCoat]

So the tear-down began today. I finally got started around 2:30 and stopped around 6, but managed to get it ready to lift the body off the subframe without rushing and not breaking anything which is a win in my book. Working overtime during the week and the garage being 40 minutes from my house limits me to weekends. There aren't any super-detailed write-ups (found some for Cadillacs) so it was a learning experience as we went today. I'm taking pics too so hopefully I can post them with info when it's all said and done. Air tools, a lift and PB Blaster are making quick work of things.

Any tips or tricks would be appreciated!

[Juggernaught]

Good luck with the head bolt/head gasket replacement. I hope the entire operation goes smoothly. It's sad to see that even with the "improved" coarse thread head bolts in the 2005 N*, that the bolts and gaskets will still fail. How many miles are on your GXP? When you do the tear down, is there any way to see if the head bolts failed, or if it was the head gaskets? I'm just curious, because it sounds like all of us with a N* will have to go through this exercise sooner or later.

[05GXPTriCoat]

I have 73,xxx miles on it. I had hoped for about 20k more before having to do this job but once it's done it will only be the other minor annoyances to deal with to keep it on the road. As for the part that failed, the head gaskets usually fail due to the bolts pulling/letting go of clamping torque. I will try and find the culprit next weekend when I continue the tear-down. To be fair though, I have not been afraid to stomp the loud pedal. And yes, most of us N* owners will face this issue at some point and hopefully after going through mine I can provide some helpful information.

[havoc1482]

most of us N* owners will face this issue at some point and hopefully after going through mine I can provide some helpful information.

I've got 165xxx miles and nothing yet. *knocks on wood* haha

[CMNTMXR57]

Same here. I never had the issue.

Technically by '04, most N*'s had this issue worked out. It was early gen N*'s that this was a prevalent issue on.

[300sflyer]

I've got 165xxx miles and nothing yet. *knocks on wood* haha

Better knock twice...