Pontiac Montana Wont Idle after intake gaskets replaced

[sh]

The heat in my minivan goes on for about 4 minutes then cools down. The temp gauge goes up and down. The more I drive the the more it goes up and down. The add coolant light goes on and off but it has coolant (which in the housing reservour is very dirty and in the radiator hose it is very gritty, grimy). What could be the deal other than the thermostat needing to be replaced?

[Bob4]

You could have a sticking or stuck thermostat.
All the grime in the system may have the radiator or heater core plugged or restricted.
If you remove the heater hoses on the core, you can flush it with a garden hose. Full force in both ends of the core for a minute or two.

[jsnider]

I recently replaced the head gaskets on a 3.4 in a montana and now it will not idle and
When you hold your foot on the gas it seems to run ok until you allow it to come to an
Idle then it starts misfiring badly and will not run also sounds like its popping thru intake

[ProTech]

You could have possibly installed the pushrods in the wrong locations. The intake and exhaust pushrods are different lengths and if installed in the wrong spot, you will experience a rough idle. Also, if the rockers were not tightened properly, or if one or more slipped off the top of the valve stem, this can happen too.

There also has been many cases of over-tightening the rocker bolts which leads to them stripping and pulling out of the head causing a misfire condition on the affected cylinder.

Since this seems to have only happened after you did the repairs, you might want to recheck your work.

[Konnichiwa]

2002 Montana 3.4 losing coolant found head gasket was torn.
Took the heads in pressure checked resurface and valve grind new seals.
Put everything back it does not idle. Sometimes a popping noise check engine light said random misfire.
I had heck of a time putting the rockers and push rods in as I did it after I put on the intake, found out later on your pages your suppose to put on before the intake. Anyways I knew the push rods were different lengths so I did put them in order that they came out, but I did not torque them down I just snug them on so they don't come loose.
All the wires, sensors are self explanatory I did double checked them.
The popping noise tells me valve timing could be too tight? Making eng not idle.
This is not a nice job, but I'm gonna take it apart again and check push rods are in right place, u say that the short one is intake? What else should I be looking for? Any input will greatly appreciated.

[ProTech]

Yeah, you really need to go over your work....it sounds like something is definitely wrong after the repairs were made. The short push-rods are indeed the intake pushrods, so make sure you have everything in the right place. You should actually torque the rocker arm bolts to be sure you don't over or under tighten them. The spec for that is 31 ft. lbs.

Yes it CAN bend the pushrods if installed in the wrong position and do damage.

I'm sure you'll find a problem once you get it apart again...