Over heating? water pump? ?????

[MandoScott]

Hello, I'm new to the forum. Although i have found very useful info from this forum in the past.. Here is my situation.

I Recently purchased a used "05" bonne gxp. I love most things about this car. but i am having a problem with the car either overheating, or not..
I'm thinking it is some kind of clog in the system. But not sure... Car seamed to stay around 200 for the biggest part. now it seams that it is overheating.. It is acting as if it were low on coolant. but levels are where they should be.. If i am at high rpm i get heat. but almost as soon as i go to idle air gets cold. temp goes up. it has reached about 270 (according to temp gauge)... But motor has never actually seemed hot. Im at a loss.. Don't know if the water pump is bad.. Or possibly a clog..
Can someone help give an experienced person some insight...? It is not a bad cluster according to the normal malfunctiones mentioned in previous post's... Could it possibly be a bad head gasket and I not get any symptoms of the problem? Doesn't smoke.. And runs smooth as silk.

Please give any suggestions... I'm open to any... As i said, I am experienced.. Just cant grasp onto what may be going on....
Thanks in advance.....

[CMNTMXR57]

Have you strolled down to this section?

http://www.pontiacbonnevilleclub.com/fo ... ered-cars/

It is a section devoted to GXP's and the Northstar V8 in them. In this section you cannot miss the many threads on cooling system issues, overheating, and other similar issues that plague the Northstar V8. You will get your answers here. Matter of fact, the one at the top IS a cooling system issue, where the owner was diagnosed with the infamous N* head gasket failure requiring restudding of the block and new head gaskets which is always the worst case scenario.

[J Wikoff]

Moved to the GXP section.

[maxi426]

Make sure the gauge is accurate. 270* is awfully hot to not "seem hot".

[CMNTMXR57]

The gauges on these cars aren't accurate to begin with. They work within a "specified range" and are more or less glorified idiot lights.

Best way to get an accurate temp is to look at the ECT readings if you have a scan tool.

[cougarcat454]

I just went through this exact same thing. Do a block test see if there are exhaust carbons in the cooling system. Rent the thing from autozone. The fluid to test it cost about 8 bucks and it is very easy to do. Had the head gaskets done on mine last week. www.midwestcadillacrepair.com . Would highly recommend him. Says he gets cars in all the time that have had radiator replaced, Water Pump replaced, thermostat replaced etc.. and it does not fix the problem. If the block test is positive for exhaust carbons in the cooling system your head gasket is bad.

[CMNTMXR57]

Ahh, so you're here in Chicago also?

[cougarcat454]

I am from Iowa. North of Des Moines about an hour and a half.
I put the car on a trailer and took it out to Palatine on Saturday.
Got on a plane flew out the next Friday and drove the car home just over 300 miles.
Local mechanic did not want to work on it. Called a place in Des Moines that would do the job, but the quoted price was horrible. I also don’t think they have done very many.

[CMNTMXR57]

Ahhh, ok. Just asking cause we've got a couple of us here.

[MandoScott]

Thanks Everyone for your input. i am gonna test block before i go any further...But i do have one more question... I think the radiator could be clogged..Should the upper hose inlet side of radiator be super hot and the other side of the radiator where the lower hose inlet, be a drastic temperature difference? Like, when i touch the plastic side of the radiator from left to right temp is night and day difference. I could possibly see a small degree difference. But i am talking like it is for instance...The left side is like 190 degrees and the right side is like actually cold....What is your opinion on that? I'm thinking the radiator is clogged.. Any suggestions????

[300sflyer]

A drop in temperature as the coolant flows through the radiator is normal. If it was clogged solid, you would be overheating continuously.

Testing the coolant for exhaust gasses, is the only real way to know what is going on.