1999 V70 Temp Needle overheat, fans on, car doesn't ACT hot.

voom8 · Post by **voom8** » 29 Mar 2015, 16:51

Hello!

Observations:

1. start car up, after it starts to warm up...~ 3 minutes
temp needle goes immediatley up to the red and fans come on.
2. No temp sensor codes issued.

3. I Replaced the thermostat thinking that that was it (stuck closed) and filled up the reflow bottle.

4. Still Does the same thing.... But the car does not act HOT... the reflow bottle doesn't over flow... and the hose leaving the thermostat is only luke warm. (it's 30 degrees outside) The bottom one remains cold. They both however do not seem to be under any pressure when the temp needle says HOT. (this is a new themostat.) Car seems to have power.

5. Just after the temperature goes upto red.
I stop the car, and immediatley measure the ECT with an ohm meter
... it measure 800 ohms.
If I wait a minute or two... it measures 1.2K
cold it measures around 2.2K

My questions are:

1. Is there another temperature sender on the engine? I am measuring with ohm meter the one right under the thermostat.

2. Does anyone have a table of values ohms versus temperature?

3. How likeley could it be that the impellar has fallen off of the waterpump?

Post by **abscate** » 29 Mar 2015, 18:10

Courtesy of Mike ...(precopster)

As problems began more or less once a thermostat was fitted have you gone back to no thermostat for another test.

What brand are:

1) temp switch
2) thermostat
3) 2 speed relay

As these 3 items closely determine coolant temperature they should be OEM. The temp switch may be out of range and can be tested in a pot of water. Here's a table of correct values for the temp switch

0 degrees - 5740 Ohms
10 degrees - 3700 Ohms
20 degrees - 2450 Ohms
40 degrees - 1150 Ohms
80 degrees - 318 Ohms
100 degrees- 184 Ohms

voom8 · Post by **voom8** » 29 Mar 2015, 18:40

Hello, Thank you very much for your reply.

The problem occured before the thermostat was replaced.
The thermostat was replaced after, and the problem has the same charachteristics.

Since it is so easy to remove, I will take out the thermostat next and run it for comparison.

Since I only measure 800 ohms at the very least, I am troubled as to why the needle shows hot and the fans turn on.

Perhaps the computer is misreading the sensor? I would expect that an open circuit from the sensor to the computer would cause a fault code to be issued... but I did not read any the other day.

I will try to also re-read the codes tomorrow.

Post by **rspi** » 29 Mar 2015, 20:27

I have found an impeller lying in the block on one of my Volvo's. How old is the water pump?

Post by **abscate** » 30 Mar 2015, 05:25

You should be able to feel flow in the upper radiator hose to confirm the water pump is pumping.

Turn heat on high and confirm that hot water is flowing through heater core giving continuous heat. I think you can also take off the cap with the engine cold and confirm flow in the reservoir too.

My gut feel is your pump is ok and your sensor, wire, gauge is giving you a false overheat ....but you sure do want tread carefully here.

voom8 · Post by **voom8** » 30 Mar 2015, 18:06

no codes for the ECT in the computer.

I removed the thermostat and just put in the rubber gasket.

Turned the car on COLD and removed the upper radiator hose from the thermostat coupler.
Hardly any coolant is coming out.

Just a trickle at IDLE when cold.

The reflow bottle is full.

Could it be that the engine has no coolant in it, and yet the reflow bottle is full?

Post by **misha** » 30 Mar 2015, 20:11

voom8 wrote:no codes for the ECT in the computer.

I removed the thermostat and just put in the rubber gasket.

Turned the car on COLD and removed the upper radiator hose from the thermostat coupler.
Hardly any coolant is coming out.

Just a trickle at IDLE when cold.

The reflow bottle is full.

Could it be that the engine has no coolant in it, and yet the reflow bottle is full?

Sounds like you have a bad water pump.Could be that it failed internally.

voom8 · Post by **voom8** » 30 Mar 2015, 20:38

thats what I am thinking. I did it two years ago... timing belt/tensioner/pulley/waterpump
I saw a write up here replacing waterpump without removing timing belt... but my car is a V70
I would think If I could relieve the tension of the belt, yet keep it zip tied to the camshaft pulleys and not let the belt shift with respect to the crank pulley.... that I could get the waterpump out.

Has anyone done that succsesfuly?
I am out in the open here outside, no garage... and it's still a very cold spring.

- Brett

Post by **abscate** » 31 Mar 2015, 04:18

Don't fret about getting the timing belt back on, plenty of help here. Just make sure you read the right thread, the 99 on needs to be preloaded unlike the 98 and earlier.

Glad you found it before ruining a good engine.

PM me with location in case I'm driving by, for moral support.

voom8 · Post by **voom8** » 31 Mar 2015, 19:23

I ran it again today from cold...

I removed the upper radiator hose (No thermostat in place), and the coolant comes out as a trickle...

With the hose back on the radiator,
I asked someone to REV the engine and
could not feel a difference in the upper radiator hose while they were reving the engine.
Could it be that the impellar is loose on the shaft?

I am going to drain the coolant tomorrow and remove the reflow bottle and move the power steering pump aside.

This is a 1999... so the tensioner is different then the one write up I saw.

1. I am going to try mark the timing belt at the crank and zip tie the timing belt to the camshaft pulleys.
2. relieve the tensioner and then remove the waterpump and inspect.