so i have stated before the problem with the temp spiking to 240-250 for 5 min at start then dropping to just below 200 then stays around 200-220 so I went to check my coolent level and the top radiator hose looked like it was squished together it was almost flat when I took off the radiator cap it was under vacuum and the top hose expanded back to a normal size. I have added about a gallon of coolent so far and it is still doing this and is low on coolent again. there is also a hissing sound coming from the radiator cap wile its running and up to temp. it has a new radiator and watter pump. any idea what causes this? oh and I also hear a watter rushing sound on the pass. side inside the cab when I first start it up. I just dont want to take it to a shop yet and dont want to throw parts at it.

 

Replace the radiator cap. If you already have...... then take it back, and make sure you get the right one.

The water sound inside the cab is an indication of air in the system, need to burp it really good.

 

maybe your radiator or the t-stat is clogged.
did it do this before the the new radiator and water pump?
was your coolant a rusty color before?
that water sound in the cab is just water going in the heater core.

 

the radiator and watter pump was done before I bought the truck but they look new prolly only a month or so old the coolent seems clean no smell of oil and the oil has no smell of coolent and it doesnt smoke

 

Sounds like a stuck t-sat. The pump is sucking but very little water is making it back to the rad so the hose gets sucked shut.

 

Re-read the original post. The TOP hose is getting sucked flat. Bottom hose is suction side.

The radiator cap does two things:

1. Maintain a max of 16 PSI in the radiator when it is hot.

2. Allow the radiator to draw coolant back in, as it cools off when you shut off the engine.

His isn't doing number 2. So, you build a vacuum inside the cooling system. Lower hose has a spring in it to prevent collapse, upper hose does not.

replace the radiator cap.

 

You're right, my bad.

 

No Soup for YOU!

 

Now that I thought about that a little, I still could be right. The t-sat is on the engine end of the hose so the hose could get sucked flat if it was stuck. If the t-sat was on the rad end of the hose you would be right.

 

It should still get water thru the bypass.