Starting to Run Hot

My 97 GTP is starting to run hotter then normal. I pulled the cap on the radiator last night and my worst fears were realized. Starting to see some sludge buildup in the radiator. I'm wondering what would be the most likely culprit, the intake manifold or a head gasket? I'm seeing a loss of about 1 qt of oil every 4k miles. Not bad I didn't think but considering it never use to burn any, now I know where it is going. The motor has 165k. Anyone have any suggestions on whether I should have it rebuilt or should I do a piece at a time. I think it would be cheaper in the long run to rebuild. What do you think? I've already decided I am keeping the car for my boy to drive some day. He's only 6 now. LoL!!

Have you checked the engine oil and coolant for cross contamination? Any coolant loss?

The oil consumption doesn't sound that bad for being a '97 GTP and having 165K miles.

It is up to you whether you want to rebuild the engine but I would start by replacing the lower intake manifold and all supercharger gaskets and o-rings. It is cheaper. If you suspect a head gasket then a compression test may reveal something.

When was the last time the cooling system was flushed and new coolant put in?

BTW - Both my sons are 18 and 20 y.o. They can get their own GTP. I'm keeping mine. I've had it for well over 8 years.

Its time to flush the coolant. I have not done that for about 40k miles. I am changing the oil this weekend so I will be checking that as well. Thanks for responding. I will consider pulling the manifold. I helped a buddy change the gaskets on a 3.1 not to long ago. I'm sure it wouldn't be that much different other then the SC. I was checking out some of your links last night on pulling the SC. That doesn't look hard at all. Do you recommend anything to run through the radiator to help clean it out?

I would recommend using Prestone Super Flush additive and let it run a few days through the system. A lot of us canned Dexcool and went to the Prestone Extended Life coolant (yellow bottle) which is fully Dexcool compatible and based on the same OAT technology. I would flush before doing anything else.

The easy part of doing intake gaskets is getting the fuel injector rails/injectors and supercharger off. Then it becomes more tedious but definitely a DIY job. We may have some old posts on doing a LIM job on a L67 SII 3800 or NA which would be similar. And procedures on coolant flushing. Good luck.

Since you are changing the oil, you may want to consider doing an oil analysis unless you are going to go ahead and do the gasket job now. Cost is $20 at blackstone-labs.com.
I also noticed my GT running a little hotter than normal a few months before the upper gasket started leaking. I removed my radiator and had a shop do a cleaning and repair but it is a hassle removing and reinstalling.