98 S70 Overheats while idling

Post by **shaker_chi** » 27 Oct 2016, 09:05

This morning on my way to work I was sitting in traffic (I'm in Chicago) and my thermostat went from the 3 o'clock position to 2 o'clock. Once I accelerated it would go back to normal. At one point it was borderline red so I pulled over and coolant was being forced through the reservoir tank. I just put in a new radiator last week. My 1st hunch is the fan since it wasn't running when I popped the hood. Is there a way I can test the fan or the relay? I probably knocked something loose when I replaced the rad. Any suggestions would be greatly appreciated.

Eddie G

Sommerfeldt · Post by **Sommerfeldt** » 27 Oct 2016, 10:00

Still, or again? Does it do this every year?

- G

Post by **scot850** » 27 Oct 2016, 10:16

It may be the fan as you suggest has not been re-connected correctly, has dirty contacts or has failed. You can test the fan and the relay, but it may also be the temp sensor as this sends a signal to the relay to switch the fan on. I tested the system on an 850 recently using 2 cables I made up with smaller croc clips on one end and larger clips that could fit over the battery terminal +ve, and one that I clipped to the rear engine earth cable by the top toque mount -ve.

Firstly, though, is the car still doing this? It could have been air in the system which needed to 'burp'. Check the fluid level again and see if it is good.

This link may help somewhat that I did:

https://www.matthewsvolvosite.com/forums ... =1&t=77346

Neil.

Post by **shaker_chi** » 27 Oct 2016, 11:56

Thanks Scot. I'll check that out when I get home tonight. And yes, this is not the first time it has happened. Last time it turned out to be the thermostat.

Post by **sleddriver** » 27 Oct 2016, 12:52

+1 on rechecking all fan/relay/temp-sensor connectors. Also inspect the condition of the female temp-sensor connector itself. Mine was corroded and needed to be rebuilt to prevent recurring CELs. If you short those two pins, the cooling fan should come on.

Post by **shaker_chi** » 27 Oct 2016, 13:07

Thanks Sled. So if I jump those 2 connectors the fan should turn on?

Post by **bmdubya1198** » 27 Oct 2016, 16:58

Make sure that fan relay is connected properly. Like sled said, these connectors get pretty corroded. I know mine are pretty beat up.

Post by **shaker_chi** » 27 Oct 2016, 23:10

Tonight I hooked the fan directly up to the battery and it ran fine. Also, I grounded the 2 middle prongs on the relay itself and the relay did react. I assume one is speed 1 and one is speed 2 since they reacted differently, but the fan never turned on when I grounded the 2 center prongs. I grounded each separately and nothing from the fan, just a few clicks from the relay.

harryhendo · Post by **harryhendo** » 28 Oct 2016, 06:04

When the engine is cool, start the engine. Feel the upper radiator hose that runs to the thermostat housing on the top right side of the engine. It should be cool. Wait for the engine to come up to the 'normal' running temp (gauge is at center), and then feel the hose again. It should be hot, meaning that the thermostat is open and the hose is conveying coolant through the engine. If not, replace the thermostat.

Post by **shaker_chi** » 28 Oct 2016, 07:21

Thanks Harry. Yes, that hose gets hot once the car reaches operating temperature.