1998 v70 overheating, coolant circulation problem

Post by **Ozark Lee** » 23 Oct 2009, 16:07

I have replaced the water pumps on all three of my Volvos and I have yet to have a problem with the water pump not priming but that was been a huge problem on my daughter's Porsche and it was also a big problem on a Chrysler my wife had (I think it had a Mitsubishi engine in it) and both of them, like the Volvo system, is driven off of the timing belt. The Porsche and the Chrysler both had bleeder valves built into the upper thermostat housing but the small line from the top of the thermostat housing to the overflow tank should do the same thing.

Is there any chance that line is somehow clogged?

BSEE UCLA - I should have known based on how thorough you were. I got my BSEE from the University of Missouri.

...Lee

Post by **confused_al** » 23 Oct 2009, 16:49

That little thing in the front...

mikesail · Post by **mikesail** » 23 Oct 2009, 17:09

Ozark Lee wrote:I have replaced the water pumps on all three of my Volvos and I have yet to have a problem with the water pump not priming but that was been a huge problem on my daughter's Porsche and it was also a big problem on a Chrysler my wife had (I think it had a Mitsubishi engine in it) and both of them, like the Volvo system, is driven off of the timing belt. The Porsche and the Chrysler both had bleeder valves built into the upper thermostat housing but the small line from the top of the thermostat housing to the overflow tank should do the same thing.

Is there any chance that line is somehow clogged?

BSEE UCLA - I should have known based on how thorough you were. I got my BSEE from the University of Missouri.

...Lee

The line is ok, you can see spurts of water coming thru into the tank.

I've wondered if there is some way the system is not primed. Hard to imagine when the engine is being force fed by the garden hose though.

But with the water pump off everything looks fine, and I can use the hose to flow water in both directions thru the system.

Regarding the thermostat orientation from the next reply, why does it matter? The assembly is level so it should bleed regardless, right?

Post by **Ozark Lee** » 23 Oct 2009, 18:41

I don't think the orientation of the rivet matters but you took away my next question with the photo. I bought a couple of aftermarket thermostats and noticed that they didn't have the rivet that would allow air to vent so I just drilled a 1/16" hole in the diaphragm on the aftermarket versions so as to assure that it could vent. It may take another block or so for my cars with that modification to warm up in the winter but it falls into the "who cares" category.

I'm stumped.

...Lee

Post by **confused_al** » 23 Oct 2009, 21:09

Lee, wouldn't you think the air trapped in the up hose would limit (not block) fluid flowing into rad, if the same air can't vent out from the top of the thermostat?
In both write-ups;
http://volvospeed.com/Repair/thermect2.php
http://www.lakesidedp.com/volvo/Thermostat/
they all instruct to ensure the direction of the bleed valve, which should be located on the highest point (in the front) within the thermostat housing.

mikesail, why don't you put everything back together without thermostat, yes, let the cooling system run without thermostat see if fluid get through the rad or not.

mikesail · Post by **mikesail** » 23 Oct 2009, 22:54

confused_al wrote:Lee, wouldn't you think the air trapped in the up hose would limit (not block) fluid flowing into rad, if the same air can't vent out from the top of the thermostat?
In both write-ups;
http://volvospeed.com/Repair/thermect2.php
http://www.lakesidedp.com/volvo/Thermostat/
they all instruct to ensure the direction of the bleed valve, which should be located on the highest point (in the front) within the thermostat housing.

mikesail, why don't you put everything back together without thermostat, yes, let the cooling system run without thermostat see if fluid get through the rad or not.

I really can't see that the front of the thermostat is any higher, Does the volvo manual say to do this? ( I've only a Chilton )

Two things. One, as in my first note, the car was run without a thermostat so I could observe the water flow from the housing. It was negligible, thus my belief that the pump was not pumping. Secondly, the thermostat for these cars is a two part valve, the lower disc is the control for the bypass circuit, bypass circuit being the lower port in the thermostat housing. Without the bypass disc in place the water is free to recirculate directly to the pump and avoid the radiator. It would be hard to say which way the water will flow without a thermostat.

Post by **confused_al** » 24 Oct 2009, 10:21

All right, I'm confused (what else is new).
I finally got my VADIS pc up running, and find no mention of thermostat bleed valve. It feels like I'm adding feet to a snake.
Having said that, one thing is for sure that air in the thermostat housing will prevent the thermostat from opening properly. Also, if there is trapped air in the block it will disrupt proper water flow through the motor.

rmcmighty · Post by **rmcmighty** » 12 Nov 2013, 23:22

I believe i have the same cooling problem with my 99 V70 XC ... recently did the heater core, bought the car for $900 ... its in immaculate condition body and interior, knew it needed a heater core and possible thermostat. I changed both but ended up with what i thought was a nasty airlock .... today i drove it to work .... 3 km from my house with the expansion tank slightly vented at the cap in hopes to let some air out of the system. all was good except no heat, blowing cold and engine light came on lol.
after work i drove it home ... stopped at the local parts store on my way and bought some more coolant... topped up the system and parked in front of the house .... temp gauge spiked so i drove it around the block and give her some juice to see if it would cool ... it cooled i parked and shut it down .
about 2 hours later i go outside thinking .... hmmmm i have added 10 liters of coolant to that car since i did the heater core and haven't noticed any leaks ..... now i find .... slush (it snowed here recently) sure enough i have a coolant leak under the car somewhere .... I looked inside the timing cover and don't see any coolant. i also have that same hot upper hose and cold lower hose thing going on .... no heat off the heater hoses going through the fire wall either... any suggestions ? im thinking water pump or a hole in a hose nearby

Post by **98T5** » 21 May 2014, 18:02

So what is the conclusion here because I'm having the same exact issue with my 1998-V70 T5.

Volvich · Post by **Volvich** » 05 Nov 2014, 01:20

Anyone any updates?
I'm having the same issue... My heater core blew, I replaced it.
Now it overheats again, fan comes on at 102 Celsius but the coolant temp rises regardless. Radiator lower hose as well as the upper hose are cold...