96 Nissan Sentra... Overheating mystery... help please!
 

I have a 96 Nissan Sentra with a 1.6 liter engine and has 120k miles.
It recently began overheating and I had to turn on the interior heater
to drop the temperature down. Since I do most of my own work on the
car, I have done done a number of things to resolve the problem...
but, with no luck so far. I need some suggestions on what else I can
do.

Here is what I have done so far:

1. Brought the radiator to the radiator repair guy in town. He did
an informal flow test (put a hose in one opening and watched the
outflow out of the other). He said that in his opinion the radiator
had sufficient flow.... surely enough flow so that it shouldn't have
caused the problem I experienced.

2. Changed out the water pump and thermostat. I decided with 120 k
miles on the car, I wanted to do this anyway.

3. I checked the fluid in the radiator as the engine was warming up
and thought I saw bubbling. Additionally, I saw signs of vapor
coming out of the tail pipe as I was starting up. Lastly, it seemed
that my antifreeze levels had been coming down in recent weeks without
signs of obvious leakage. All this convinced me that I must have a
blown head gasket.

I brought the head to a automotive machinist in town and his
estimation was that the head did not show signs of antifreeze leakage
in the head combustion area. He indicated that the valve area of
the leakage would show obvious signs if such leakage occurred.


After all of this I am not sure what I should check out next. I need
suggestions. My first thought is that maybe I should change out the
radiator anyway just to eliminate that as a problem. What do you
think??

Al Kondo

On Fri, 07 Jan 2005 17:49:08 GMT, Al Kondo > wrote:
>I have a 96 Nissan Sentra with a 1.6 liter engine and has 120k miles.
>It recently began overheating and I had to turn on the interior heater
>to drop the temperature down. Since I do most of my own work on the
>car, I have done done a number of things to resolve the problem...
>but, with no luck so far. I need some suggestions on what else I can
>do.

>Here is what I have done so far:

>1. Brought the radiator to the radiator repair guy in town. He did
radiagor good

>2. Changed out the water pump and thermostat. I decided with 120 k
pump and thermostat probably good

>3. I checked the fluid in the radiator as the engine was warming up
bad head gasget

>I brought the head to a automotive machinist in town and his
>estimation was that the head did not show signs of antifreeze leakage
>in the head combustion area. He indicated that the valve area of
>the leakage would show obvious signs if such leakage occurred.


>After all of this I am not sure what I should check out next. I need
>suggestions. My first thought is that maybe I should change out the
>radiator anyway just to eliminate that as a problem. What do you
>think??

Check the fuel mixture and timing including timing belt alignment (not
off a tooth). Leave the damn radiator alone.
Plan on doing a valve job.

--
BBA

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"Al Kondo" > wrote in message
...
> I have a 96 Nissan Sentra with a 1.6 liter engine and has 120k miles.
> It recently began overheating and I had to turn on the interior heater
> to drop the temperature down. Since I do most of my own work on the
> car, I have done done a number of things to resolve the problem...
> but, with no luck so far. I need some suggestions on what else I can
> do.
>
> Here is what I have done so far:
>
> 1. Brought the radiator to the radiator repair guy in town. He did
> an informal flow test (put a hose in one opening and watched the
> outflow out of the other). He said that in his opinion the radiator
> had sufficient flow.... surely enough flow so that it shouldn't have
> caused the problem I experienced.
>
> 2. Changed out the water pump and thermostat. I decided with 120 k
> miles on the car, I wanted to do this anyway.
>
> 3. I checked the fluid in the radiator as the engine was warming up
> and thought I saw bubbling. Additionally, I saw signs of vapor
> coming out of the tail pipe as I was starting up. Lastly, it seemed
> that my antifreeze levels had been coming down in recent weeks without
> signs of obvious leakage. All this convinced me that I must have a
> blown head gasket.
>
> I brought the head to a automotive machinist in town and his
> estimation was that the head did not show signs of antifreeze leakage
> in the head combustion area. He indicated that the valve area of
> the leakage would show obvious signs if such leakage occurred.
>
>
> After all of this I am not sure what I should check out next. I need
> suggestions. My first thought is that maybe I should change out the
> radiator anyway just to eliminate that as a problem. What do you
> think??
>

cracked block! I would have performed a block leak test before removing radiator
or head -- you could remove the block - have it boiled and inspected for
cracks - or you could put the engine back together including radiator, etc, etc,
etc. then perform a engine block leak test!

BBA

A few places can also pressure test the system.. .You've hit all the
obvious issues.