I'll get the Felpro gasket kit and new bolts if I have to do the gasket. And I'll use The Right Stuff for the RTV.

Since the LIM gasket change 40k ago. I don't think there was an coolant loss from what the PO told me. And I've changed the oil and it looked good. But a shop recently told me that the LIM gasket is either leaking (must be external), or it was the old leak the prior shop didn't clean up. So, I was thinking of getting a steam cleaner to clean the engine up and then keep an eye for it leaking.

I do see some slime at the front of the engine under the power steering reservoir. Though I was thinking it was power steering fluid as the reservoir is wet from the cap leaking and it looked like the lower part of the return hose is wet as well.

 

GM switched over to the metal design ones in 2006 (the 3500 engine used in the 2006-07 Montes used them). At the time GM used FelPro, they switched over to a different supplier later but now they're back to FelPro.

 

Do you know if GM changed part numbers when they switched to the metal design? I've got a list of part numbers the dealer used when they did the LIM gasket back at the end of 06.

 

It should be part# 89017769

 

The gasket kit the dealer used was part #89017279. I'm betting it was probably the crappy kind. As I had read of some posts on other forums that were only a couple of years old. And they checked out the gaskets at the dealer and said they were crap compared to Felpro. They said the gaskets from GM still had plastic in them.

There is alot of sludge at the front of the engine behind/below the power steering pump. I've got to remove the pump in order to remove the spring clamp so I can replace the power steering return hose. So, while that is off, I'll clean up all of that sludge.

 

My experience is the high pressure power steering hose goes bad before the low pressure/return hose.

Before pulling the pump off, get some good engine degreaser, cover the engine with it and use a power spray at a car wash and hose it down. Just doing shoot water up the air box and you should be fine.

Then see where residue builds up.

My experience is. average LIM (Nylon) gaskets last for 80,000-120,000 miles. If you only have 40K miles on them, you should still be OK for a while.

BTW - This has been a thread talking a lot about LIM gaskets, what's the symptom again??

 

The original LIM gasket was already leaking at 40k miles as the PO noticed the coolant level going down. So the dealer replaced it. But I had it at the shop recently for some stuff, and they came and told me the LIM gasket was either leaking, or the prior shop didn't clean up the old leak. If it's leaking again, then it started not long after the gasket had been replaced as the new gasket so far only has around 30k-40k miles on it. It's also possible the dealer could have messed something up or not clean up all the old gasket stuff off or something.

But the only thing I've noticed is the coolant doesn't build up pressure as I can pull the radiator cap off when the car is at operating temp and no coolant comes out. And the upper radiator hose never gets hard. Every other GM car I've had the coolant would start gushing at operating temp with the cap removed.

It does have a slight stumble that you can feel and see when the RPM needle dips some on the stumble. I can feel it every once in a while when driving, but mainly notice it at idle. The shop I had it at called it a stumble.

And the engine is a little noisy when accelerating. The shop called it a gurgling sound and thought of air pockets. I don't think there should be air pockets as I've since flushed the coolant and bled it many times with no change in the accleration engine sound. As that is when they told me about the possible LIM leak. I did notice at idle every so often you hear a brief fast paced tap tap tap tap tap tap from the front exhaust valve cover area when I probed with my scope.

 

Valve ticking in the 3100/3400 is normal, a light ticking is expected. Are you noticing any lose of coolant??

As for the stumble, could be time for new plugs/wires (I think you were discussing doing that in a different thread). If that doesn't do it, make sure fuel/air filters are new. After that, I'd look into testing the coils and injectors. I don't have an injector test (but a shop with a GM Tech II scan tool can test them).

 

I just got it and started flushing the coolant a week later. I'll keep an eye on it to see if it loses coolant. It was full when I first checked it.

I put on a new air and fuel filter when I first got it. I do plan on doing plugs and wires. I plan on ohming the injectors if I'm able to in order to make sure they aren't dead. And I found another test to check for a dead cylinder: Part 2 -Cylinder Balance Test (GM 3.1L, 3.4L). Misfire Diagnostics.

 

That's an interesting link. Basically, it narrows down to your problem cylinder. At that point, you could still have an issue with an injector, spark plug, wire, possibly even part of a coil pack (but if you yield the same results on two towers of one coil, I'd suspect the coil at that point).
I've never heard of that method, but I see what they are going for. I may try that some day.

Here's something that might be helpful troubleshooting coils:
View topic - Comprehensive guide for troubleshooting Ignition coils : PontiacBonnevilleClub.com