97 GTP Coolant leaking and Temp spike

[graham25]

I've recently developed some issues with my GTP that are very concerning. Initially it was just random coolant leakage where it appeared that smoke was coming out of the top of the radiator. Then there would be temperature spikes, but if I put the heat on in my car the temp would drop and stay around normal. Now the temperature spikes but the heat won't work. I'm not very mechanically inclined, but I'm not a complete idiot either. I've searched forums and found some similar problems but I'm still not sure on where to start. I would also prefer not to go to a mechanic. Any help would greatly be appreciated. Thanks

[Juanmiguel]

It's hard to tell for me, are you still having coolant leaks? I would start checking stuff in the following order:

Check the hoses and radiator for any leaks. Look underneath the car when it's hot to see if there's any cooland dripping or in your garage.

Check for coolant on the engine oil, the 3800s have a tendency to leak from the lower intake manifold gasket into the cillinders.

Check the driver compartment carpet and see if its wet or if it smells like coolant, the heater core may be leaky too.

Change the TSTAT for a 185°F it's cheap and easy to do and also change the radiator cap, that's also easy. Mine wasn't working and I was throwing away coolant all the time.

Purge the system with the purge valve locaeted in the TSAT housing to get rid of air bubbles in the system.

If the coolant looks like mud, you also want to flush it and put new coolant in it.

Also check if both fans are working when it's hot. If not, you have to check the fuses. relays and temp sensors related to them.

[graham25]

Today I changed the thermostat. I'll have to wait till I drive it tomorrow to see if that changes anything. There is a leak coming from the driver's side in the radiator. That was an off and on issue. But what concerns me is the sudden temp spike and the fact that the heat doesn't work now. When it does come on it lowers the engine temp. I do appreciate the help

[Juanmiguel]

Heat spikes could be caused by low coolant levels, it creates air bubbles inside the cooling system and there are times where there is no coolant flow in the engine and then the heat spikes until the water pump gets hold of some coolant and pushes it through the system into the engnie, then the temp goes down quickly again.

The only reason I can think of for the heat not working is either the heater core is not getting any coolant flow into it or the A/C ports not working properly and not being able to change from cold to hot.

If you have a leak on the driver's side, it could be the coolant tank overflowing (mine overflowed when the radiator cap didn't work properly), the hose at the top of the radiator or the radiator itself.