Have you noticed any puddles or spots on the ground? Any coolant on the serpantine belt or anywhere else in the engine bay? This would be a sign of a bad water pump.

Otherwise, without checking it with a coolant pressure testor, there isn't much else to look for.

Hopefully it's nothing major. Those 3900 Monte's are kinda rare (and cool ).

 

bummer man! I thought the 3.9s were pretty reliable. You'll have to keep us updated for sure.

 

Check your water pump for leaks. I had mine replaced at about 65K miles and I think its a common failure for 3.9 and 3.5. Its a quick 30 min job if it is.

 

I haven't really had any problems for 2 days now, but I'm keeping an eye on it and will do a pressure check on it this week! I do think that the termo is sticking, top hose is hot and bottom is not very hot compared to the top. I really haven't seen any leaks from it though.......Thanks for the suggestions, I'll keep this updated.

 

HMmm did a Google seach and looked like you don't have to worrie about LIM leaks on the 3900 becuase it no longer goes throught the intake and have a coolant crossover pipe like my 3.5 twin cam intrigue, like the intrigue I would not be suprised if that is leaking, ours has been leaking for probably a good year I just keep topping it of uses about 1/2 a gallon every 3-4 months

 

referring to this maybe^^^^^^^



Thanks Justin for the response man, I'm just in between worrying or not about it. My buddy who is a great mechanic does side work where he works and said just keep an eye on it for now......

 

As others have said, you should NOT be losing coolant, it's going somewhere, which means you have a leak. My 3.5L (which is similar to your 3.9L) had a leaking water pump at 65K. Got it replaced and all has been good since.

 

If I get the t-stat changed and that's not the exact issue then I may need a waterpump most likely? Should I just get the t-stat and waterpump done at the same time?

Will a coolant pressure test tell me if it's the t-stat? I have already mentioned that the lower hose is cooler than the upper hose once the car is warmed up. From what I've read online that is a t-stat sticking closed issue. If I get both done it will save $$ on buying coolant if it does turn out to be the pump?

 

It looks like what I said earlier also affects the 3.9. I would advise checking for leaks and to see where it is leaking. FWIW, I have seen the coolant pipe issue more than the head bolt one.


coolant pipe



head bolts