Another coolant temperature thread

[mattd1205]

Hey everyone,

I’ve got a 91 245. I’ve developed some cooling issues lately. It’s been over 90 degrees lately and I noticed the temperature needle has been creeping up to 3/4 while idling in heavier traffic and when going uphill. Once I get going on level ground, it cools down quickly. The needle goes down to halfway between “normal” and fully cold before stabilizing a bit below the “normal” mark about 5 minutes later. The same goes for when going uphill. It gets up to 3/4 when going up hill and then it goes down to half way between normal and cold when going downhill before stabilizing just below normal about 5 minutes later. Running the AC in stop and go traffic and going through drive throughs have been problematic for as long as I’ve owned the car (8 years) so I’ve learned to completely avoid those scenarios. The temperature has been relatively stable when driving in normal traffic as well as driving at freeway speeds. The car never had any issues with hot weather even in stop and go traffic (provided the AC is off) or going uphill so those issues are new. I realize I’m way behind on cooling system maintenance but should I just fire the parts cannon and just replace everything that is cooling system related? Here’s the list of stuff that was done over the years.


• made sure the head gasket was ok via block tester and check for any visible coolant leaks (done today). No leaks were found.
• belts are tight and were replaced in 2020.
• Aisin standard duty fan clutch installed in 2020
• radiator was flushed and cleaned the radiator fins with garden hose in 2019. Block was also flushed
• thermostat (87c wahler), head gasket, water pump (hepu) were replaced in January 2017
• temp faker deleted in 2015
• radiator (nissens 2 row) and hoses were replaced in September 2008

Any input would be greatly appreciated

[PCH]

From everything you listed the temp should be staying in the middle. Is the radiator fan shroud in place?

[mattd1205]

Originally Posted by PCH

From everything you listed the temp should be staying in the middle. Is the radiator fan shroud in place?

Yes, it’s there and intact.

[c1800]

Radiator might be restricted , typical flushing won’t correct that. Not familiar with HEPU water pumps, but a cast impeller is noticeably more effective at moving coolant at idle than those with a stamped sheet metal impeller.

[dandeluca]

I can't offer much advise as to why/if your coolant is getting too hot. I just wanted to mention that I hooked the electric AC condenser fan on my 91 245 to a rocker switch on the dash. It rarely/never seemed to come on on by itself. Now I can switch it on to give additional cooling and peace of mind when creeping in traffic or idling in a drive through line.

[VB242]

How's the fan clutch?

[Urvanej]

Not exactly a parts cannon, but thermostat change is easy and cheap. New does not mean fully functional.

[rb92673]

Is the coolant cap sealing? If it is not holding pressure the cooling system will not work correctly. It's a couple bucks to replace.

Have you checked the temp at the outlet elbow with an infrared temp gauge?

It's pretty simple to check if the sensor is good by measuring the resistance in a pot of water. There should be two, one for the ECU and one for the gauge.

[PCH]

May be replace the thermostat and make sure it's not installed backwards at the same time (not 100% sure it's even possible on Volvo, but I've seen this done before)

[Mr. V]

I'm trying to recall, but shouldn't the little dohhickey on the stamped rim of the thermostat be set at a certain position (referencing hands of a clock) when installed?

Like maybe one or elven o'clock, something like that.

[PCH]

The little hole with some loose rivet in it needs to point up to minimize the air pocket in that location but it's not a major issue.

[dl242gt]

When I had a car with this type of symptom. I was caused by a marginal radiator. If you are behind in maintenance and the radiator is from 08. I'd consider a new radiator.

I would also consider using the 82C thermostat to help give you a bit more cooler under hood temps.

[hiperfauto]

Definitely pull the thermostat and inspect it carefully. They can fail in several ways.

Years ago I had the radiator rodded and replaced the thermostat on a customers 240 that was running hot. The car left running fine but a few days later she called and said it was running hot again. I asked her to bring the car back so I could check it out but she took it to another shop instead. They proceeded to have the radiator rodded (again) and replace the thermostat (again) which they said was defective. Since she wanted me to pay the repair bill (which I did) I asked for the defective thermostat to be returned. Sure enough the jiggle pin managed to get stuck under the plate holding it open a little all the time. I'm sure the second rodding of the radiator was unnecessary.

[mattd1205]

I’m going to pickup a new Vernet 88 Celsius thermostat tomorrow. I figure I’ll flush the system while it’s open. If that doesn’t work, I’ll probably get another Nissens radiator.

[dnordin]

I second Dave's opinion, I had similar symptoms and it was an inefficient radiator, the fins were corroded but I never noticed it, a radiator shop pointed it out to me.