So I am trying to get my cooling system running good and decided it wouldn't hurt to replace the thermostat in the truck, when I checked prices I noticed there were 3 temps available (160, 180, and 195) so my question is which one should I get and why the 3 choices? also if someone could save me some time and tell me where it is, I know where it should be but just looking from the outside I couldn't see a housing for it.

another question on a side note, twice yesterday I heard a new sound, about 5-10 seconds each time and both times during acceleration from a stop I heard a hissing sound coming from what sounded to be under the drivers side dash or on the drivers side under the hood. It was loud enough for my wife to hear it. I thought maybe a little loss of power to go with it but it didn't happen enough to say for sure. Anyone have any thoughts on that?

 

I realize you live in Arizona and you want things to stay cool, but I would still say a 180 is as cool as you should go.
Also check your mechanical hub clutch as well as the 2 electric fans to make sure they are all working OK.

Also, what color is your coolant recovery bottle, if it is black replace it also, they were super-ceded years ago for the new white bottle cause the black one is always having seam failures.

 

Follow you're upper radiator hose to the opposite end from the radiator. It clamps to a silver aluminum neck which is held on by 2 bolts. drain coolant, remove hose, remove 2 bolts, pop cover off. If it hasn't been off in a while, may take a little persuasion. When you get the thermostat, tell them to give you a fel-pro #12994 if you don't like messing with perma-tex or other liquid gasket makers. Works perfect.

The hissing sound sounds like a vacuum leak. Where you're describing it coming from, check the line that goes to the brake booster, from the intake plenum. Or it could be in the intake hose itself(from the air filter to engine).

 

to mike, I replaced the bottle I think early last summer from the black original to the white (hose connector broke off while bleeding the system) viscous fan clutch (I am assuming thats what you are talking about) I don't think works right, the fan turns when the engine is on but it spins pretty free by hand when the engine is off, not really sure how to tell but I don't hear a noticeable difference from hot to cold in the sound of the fan. as for the electric fans, 1 of the 2 is currently out waiting to be repaired, I decided since it wasn't working I should at least remove it until it is working, it will be back in and working by next week. I thought I would do the e fan first since I know that isn't working, then the thermostat because it is $5 and usually an easy job, then if it still feels like the heat is putting a strain on the truck I will do the viscous fan clutch last.

to Kenk: I was just out there looking at the truck and the conclusion I came to on the location was exactly as you described. as for the gasket I will do that, my last liquid gasket leaked and made my job 2X as hard as it should have been! so thanks for that. and for the hissing sound, I only heard it those 2 times making it difficult to pinpoint and troubleshoot, but I will keep looking and repost to this thread if anything else comes up.

 

The fan clutch will have some resistance turning when you first shut it off if it is hot. You should hear it engage, a whoosh when you first take off in hot traffic, and then feel it release when it cools down. Any chance that is what you are hearing?

One electric fan makes a difference. My a/c was weak (95 degrees here) and would climb a little in traffic. I replaced them and I can hang meat again. No fluctuation in temps either.

 

most of the time the truck is great with no problems, when it gets really hot out above 100 degrees, the A/C is on high, and I am driving in traffic, the temp gauge goes up to about 2/3 of the way up the normal temp bracket. When this happens I can feel the engine is struggling, a slight quiet knock under acceleration, fluctuation in the A/C temps. once it hits that point nothing will change it except getting home and letting it sit for a few hours. however turning off the A/C immediately brings the temp gauge back to normal.

 

yup, change the fan

keep in mind that any fluctuation in the gause is a lot in real temps. Just because you aren't in the red doeasn't mean you aren't doing damage..

 

I agree although it sounds pretty stupid to me, why not just adjust the gauges range or the output of the sensor. Many people rely on those gauges to tell them if something is wrong and that gauge can easily be misconstrued. Any time mine goes above the bottom of the temperature symbol I take immediate action to correct the situation.

 

at least there is actually a gauge and not some stupid light. Look at the oil pressure. It trips a 9PSI. You can do a lot of damage before 9 PSI..... Mechanical gauges are still the best way to go. I have a gauge pod that mounts to the a-pillar. I have a temp gauge in and I am waiting to install an oil pressure gauge. I dont have it mounted yet, but after holding it up, it should blend in ok.... I have a spare piece of trim that I may just fiberglass in and paint.

 

that's how I'd do it!