unfortunatelly I have to sell my truck to get a 3/4 ton and i have this wierd problem i cant get to go away so I am going to list everything i have done recently and what is happening and i would appreciate your input because i have searched and asked a mechanic friend and the answers are alll over the place.

my truck is a 95 1500 when i got it it had brand new transfer case and rebuilt trany k&n air filter msd igntion holley double barrel throttle body the cats have been cut off and its running straight flowmaster pipes, recently i put a new air filter, did distributor cap, rotor, wires, and new plugs gaped at .38 also replaced all the vacuum lines new battery, new rotors pads calipers shoes drums, brake booster, 3inch lift...

heres the problem....every once in a while it hesitates for a second and then itss fine....usually when i stop at a stop sign and go it does it or when im on the highway and i heavy accelerate it hiccups for a sec then its fine. other than this it runs perfectly and i cant pinpoint what is going on. the only thing ive noticed lately is the heat hasnt been very hot and somewhere i am losing coolant but its not leaking anywhere so i suspect its evaporating somewhere. i felt the lower passenger hose after i had been driving for a while today and it had no pressure in it and when i opened the radiator cap it has no steam/pressure, im suspecting maybe the thermostat is bad and getting stuck and possible the water pump is bad but can this cause hesitations like this or coolant loss/evaporation somewhere? or do i need to look further? the only other thing i can think of is after about 2,000 miles on an oil change i start to lose oil presure and when i start my truck in the morning it sounds like its reallly sucking air so possibly the plenum gasket is bad but i dont know? or should i look into mabe fuel pump/filter? other than what i have listed it looks as if everything else is original or old so im not sure as to the age of some of the parts. since i am selling this and have put so much into it i want to fix this so i can get max dollar for my new truck so where do you guys think i should start? i apppreciate in advance your help with finding out what is going on because it is driving me nuts and i just dont wnt to start throwing on sensors and pumps and **** because i am stumped!!

 

How do you know you're losing coolant? The reservoir will of course fluctuate with engine warming/cooling. Coolant will not evaporate (at least under normal conditions...) If you are positive you are losing coolant and that there are no leaks, you should start with a block tester and check the coolant for exhaust gases. If the test shows a positive for exhaust gases you likely have a blown headgasket or cracked head.

Pull the throttle body, clean it all up including the IAC, and check the plenum (pool of oil at the back of the intake).

 

If you don't have pressure on the system after driving for a while, you have a leak. It may not be readily apparent, but, it's there. Finding it is the fun part. (might be as simple as a new radiator cap....)

For hesitating off idle, I would look at TPS, and fuel pressure.

 

about every 100 miles the reservoir is empty and its not dripping anywhere i can see, my jeep had a radiator once that leaked out of one of the seams and just evaporated so i could never see where it was going, i looked and ran dye and came up with nothing on this. my mechanic said he suspected blown head gasket too :/ i was hoping not for that guess i'll have him test for that thank you...can i just buy a test kit at carquest or oreilly?

 

Any auto store should have it. It might be called a combustion leak tester depending on where you go..

 

Mine was doing the same thing.... I would lose coolant, but, no evidence of where it was going. At least, until the seam in the radiator completely gave out.....

 

You could also bring it to a shop and have them pressure test the system (they sell pressure testers at auto stores too). Putting pressure on it will make a leak more evident.

 

For a while my truck was slowly loosing coolant but would never drip down. When I replaced my thermostat I found my leak. . . It was slowly coming from the bypass hose and drying onto the front of the engine. Definitely pressure test the cooling system and see of it holds pressure at 16psi (that's what they system is rated at.) also test the cap.

 

Is there any noticeable smell of burnt antifreeze from the engine compartment? I've mentioned this before but here goes: look closely at the timing cover upper corners for coolant leaks.

 

These seem to have an uncanny capacity to leat at thermostat housing...right where you cannot see it. ANd it may dry before you ever see it drip underneat.

+1 more on pressure test and combustion testing.