no pressure in radiator hose

[kinito22]

Heys,

I got the classic my-engine-is-overheating problem. I was checking out the engine today and it noticed that as the engine got more and more hot, there would be no pressure in the radiator tubes. When it got super hot, the upper radiator hose would get hot, but i'm guessing it was from the steam, cause' there was no water pressure inside.
There's this constant grinding noise coming from the area of where the water pump is. I ruled out that it cannot be the thermostat, because I just had it changed a week or so ago. Now as the engine gets hot, the fans do not turn on at all. Not even when I turn on the A/C.
*Also, the heater does not blow any hot air at all.

I'm fairly new to all this auto stuff, but is it safe to assume that it's the water pump that needs to be changed?

[tblake]

well, its not that hard to take the waterpump off to find out. you say you had the thermostat changed a week ago? did you do it yourself? did you properly bleed the cooling system of air?

[kinito22]

Got the thermo changed at the mechanic ...
actually, my dad took it there and they did the job. The mechanic did bleed the system to take all the air out.

Now this waterpump task, I'll be doing myself tho. I'm just worried that I'm barking up the wrong tree .... trying to solve the issue by fixing the wrong thing. Thus, my main concern is that I change the waterpump ... and the problem is still there.

But I'm thinking ... if there IS coolant in the system, and a new thermo, BUT no pressure in the radiator hose, then it outta be the pump ...

am I wrong to think that?

[jeffcoslacker]

The impeller may have come off the pump shaft, and is just rattling around in there. I've seen it happen once or twice. They won't deliver any flow through the radiator that way.

[LikeAChampion3]

I don't know about the pressure in the hose, but as far as that grinding noise, I took in my lumina last week and the mech said that it was a bad water pump (I had the same grinding). So I was changing the water pump today, but it was clean. Turns out it is the A/C compresser making the noise. So i would suggest checking that out as well..

[kinito22]

alright, well i'll get cracking on switching the water pump.
even if it isint the pump (Which at this point, im 90% sure it prolly is) the car is definitely due for a new one ... it's at 300,000km, was almost totally driven on the highway before my dad bought it.

the chilton manual i photocopied gives fairly rough guidelines for changing the pump.

someone told me that if i change the waterpump, i also have to change the timing belt .... is this true, or can i leave the regular belt in there?

[richtazz]

If your car is a 3.1, it doesn't have a timing belt, if it's a 3.4 DOHC, it has one, but it has nothing to do with the water pump. Changing the water pump on these engines is a 45min job (removing serp belt and 9 total bolts). Make sure you bleed the air out of the system afterwards. That can be more difficult and time consuming than actually changing the pump.

[kinito22]

it's sitting in the mech shop right now, my dad called one of his old co-workers who runs a garage.
so it should be back in an hour or so
it would have been way too hard to remove the pump myself, the bolts were corroded and hadn't been touched since the car was most likely made.

yup, my first question for the mech will be: did you bleed the system?

im happy ^^

hmmm .... any suggestions for a car name anyone
my nissan sentra is called: 'The Box'
my friend's dodge caravan is called: 'Eleanor'

[kinito22]

Arrgh!

Alright, just walked down to the garage ....

When I get there I see them working on the car, steam coming out from around the bottom of the radiator cap...
The mech had told me dad that he would replace the pump and that it was definitely the cause of the problem.
When I get there to pick up the car, the mech's boss comes up and tells me that it's STILL overheating....

He shows me the old waterpump, says that it definitely had a problem and had something loose in it, but continues and says that the fans dont turn on.

He showed me that the relay switch to the radiator fans was working, but that something from the computer to the relay wasn't processing and the fans would'nt turn on.

guys, does this make sense, or are they trying to rip me off?

I remeber many times before that when I was driving, the fans would be working like mad even with the temp at high. Whenever I checked it and the car was parked, the fans wouldnt come on....

*sighs*

input, anyone?