2001 Chevrolet Blazer, 2WD, standard transmission, 135k miles

My truck recently stopped wanting to start. The engine will turn as it normally would, but the vehicle won't start. It recently started taking 2 or 3 turns of the key: Turn the key, let the engine try to turn endlessly, stop.. turn again and the engine will start like normal.. and then a few days later it started sputtering on the second try but starting fine on the third. The truck wouldn't have any problems accelerating after it was successfully started, and once I thought I'd hit something, but considering the misfire that happened today (will explain in a few moments) I'm assuming is was a small backfire.

A. I noticed a coolant leak a few weeks ago and looked it up, and the most likely cause is the intake manifold gaskets need replacing most likely due to the Dex-Cool coolant inside (I specifically use Dex-Cool cause that's what the manual suggests, and I was ignorant about the problems it causes until I looked it up).

B. There was also a very, very loud humming noise heard if going a specific speed or higher, but would quit if making a sharp enough right turn, looking that up determined it's probably a bad wheel bearing

A. and B. are there to express the recent problems IN CASE there is information in there that is helpful. I haven't actually had these things looked at (I haven't personally looked to find the source of the coolant leak to identify it's actually the intake gaskets, nor been able to get the vehicle lifted to see if the wheel bearing was indeed bad or if the problem was something else).

Today when I tried to start the vehicle, it wouldn't start no matter how many times I turned the key. I figured the battery might be going bad because after the 5th or so turn the engine started turning over a little slower, so I attempted to jump start the vehicle with a friends car. The engine turned as fast as normal, still no starting, and once after the 8th or 9th try there was a giant backfire (sounded like someone slammed into the side of the car, or like threw a baseball pretty hard at it) and I could smell exhaust fumes, so I quit trying to start it and now I'm here.

In the past, when it was taking 2-3 turns to get the truck started, if I were to make a brief stop somewhere and try to start it again, it would start without any trouble. It would only become a hassle after leaving it sitting for 5+ hours

Any idea of what it could be? Is there anything I can do to check on the problem?

I searched through the forums and everything that comes up is head gaskets or intake manifold gaskets.

The misfiring is probably from water/coolant leaking into the cylinders.. there's no white smoke coming out of the tail pipe, but I am pretty sure there is water in the oil, and again I can smell exhaust fumes after trying to crank the engine 7 or 8 times. Is there an easy way to tell if it's head gaskets vs intake manifold? If I have to replace intake manifold, would replacing the head gaskets be just as easy since I have to take the top of the engine apart anyway?

 

1st check the starter. Pretty sure it's bad. Mine went out earlier this week, and I replaced it with help from this forum. As for the coolant leaker, check to see if it's leaking from the front of the engine block. If it is, you'll need to replace the water pump.