[steve500]

I'm beginning to feel as if I may have a very minor head gasket leak on my frontier... Why?

Well, back before winter rolled around, starting up the truck, I had a bit of mist coming out of the exhaust while warming up, not real bad. I then had an odd coolant problem, this was after a coolant flush that nissan did... I had a lot of air in the system causing the truck to overheat only when idling, I bled the air out and added coolant to the normal level. 10,000 Miles later (few weeks ago), it hasn't overheated, but the fan turned on only when idling, it would shut off when accelerating, even with defrost/AC turned off. So I checked the coolant in the morning, lots of pressure released, although it was not low, but this stopped the fan to turn on when idling. Another thing, now that winter is here, when this truck warms up, like most trucks, it has quite a bit of white smog coming from the exhaust, only... from my truck it seems to linger around in the air a lot longer than my girlfriend's 08 colorado does. When accelerating it is worse. After about a mile of driving, it will die down.


How can I test to know for sure that my head gasket may have a leak?

I can hear a hissing sound @ idle on the left side of the engine on top under all of that plastic, someone on Thenewx.org said it's completely normal.

I was also told that you can test this by opening the oil cap while idling, hold your hand over the oil cap and feel for air pressure. I'm just unsure if its good on the engine or not to run it with the oil cap off.

Also, one of my pre-cats are starting to fail... I'm at 30K miles, how could this be?.. Nissan has an appointment for me to get the cat's replaced next week under 80K mile 8yr federal emissions warranty.

Also, is it normal for coolant to want to pour out of my radiator when started in the morning with the cap off? ...

I'm out of warranty.

Any help is appreciated.

 

[bimmernut318]

You can have the coolant tested for exhaust in coolant. Hissing sound is normal as the head gaskets wont make that kind of sound. If the head gasket were real bad you would have oil in your coolant and you would find water in your crankcase. Other thing to watch for is either a cold running truck or overheating badly. To me it doesnt sound like a head gasket problem unless you are having these problems.

 

[NissanPowerBaby!!!]

Two tests you can do:

1: Simple compression test: remove the plugs and check to see the compression in each cylinder. If any one cylinder is out more then 10%, that's considered too low. If after injecting some oil into the cyclinder, the compression doesn't come up it's either your valves not sealing or a fubar'd head gasket.

2: After doing the compression test (or before), with all plugs removed blow air from a blow gun into the spark plug hole. The valves in this cylinder, along with the valves in the adjacent cylinder should be closed. If air comes out of any other hole BUT the one you're blowing it into, then you definetly need a new head gasket.