Questions and Answers
Pontiac Grand Prix Leaking Coolant
Q. Vince: I hope I got the right email address for auto questions. Your web site is great with lots of information and also easy to understand. I have a 1993 Pontiac Grand Prix, 3.1 liter V-6 that just started pouring coolant out somewhere on the back side of the engine. Because of the way the engine is in the car it's almost impossible to see where it's coming from, but I don't see any hoses or fittings or whatever back there.
There is some kind of electrical sensor plugged into the back of the block very near where the coolant is coming from. My Haynes manual says it might be a crankshaft position sensor, but I'm not sure. The manual also mentions a knock sensor and says it's "screwed into" a coolant passage, which I assume could leak.
My mechanic (on the phone) said it sounds like an intake manifold or head gasket leak, which I hope it's not, because I assume either of those will be big bucks to fix. Anyway, the coolant pours out at a fairly steady stream. Got any ideas?
Thanks for your help and your web site,
A. Sounds like you need to have it put on a lift and pressure tested to find the source of this leak and fast. You will pay a little up front but will know for sure what it is. The crank sensor will not leak coolant. The knock sensor is screwed into the coolant jacket but never saw one leak there. This engine is big on intake manifold gaskets and the quick connect fittings for the heater hoses.