VR 6 Acclaim - new thermostat trial

[Dunlop]

After noticing that the engine didn't seem to be warming up after driving up to the main street (850 metres) but that the top radiator hose seemed to be warm, I decided to buy a 91C high flow Tridon thermostat to see if I could fix the issue. Put it in last night with some high temp silicon and drove it up the street a short time ago after idling it for some minutes.

Drove up 850 metres to the main street and parked the car with the engine running. Opened the hood to check the engine temp - engine had warmed up nicely and the top hose was still cold - much better than yesterday when the engine was still cold and the top hose was warm - not hot. Air temp is about 30C now and I have to drive up a short rise of 80 metres on the road.

But when I looked at the gauge, it was nearly on half whereas in that situation it's normally only on less than a quarter... As you know, VR 3800's normally sit on a quarter on the gauge unless - in my case - I'm driving up a hill in warm weather. Drove out on the highway a few kms and the gauge dropped very slightly below half. I stopped and opened the bleed valve - that was ok - then drove off again back home - the highway goes uphill on two stages.
When I checked the engine block, it seemed to be really quite hot although the car was running pretty well - no uneven idle which can indicate running overly high.

When I called Dayco last year, I'm sure the tech told me that their thermostats are designed to 'crack' open before the engine reaches normal operating temp - probably a saftey feature. Thing is though in this area it gets damn cold in winter, so the car has been using up excessive fuel and this has affected the heater core which needs flushing anyway and also has a slight leak. Fortunately I don't drive very far so the amout of petrol I've used excessively could be worse...

The staff member at Supercheap told me the new thermostat only cracks open at 91C - not before.

So, does it sound like the engine is running too hot? Or could my radiator need flushing even though there's no indication of any gunk at all in the top - it's just clean green coolant?

Any advice much appreciated.

This is the new Tridon - curious thing is that the Dayco high flow is $28 and the Tridon is $36...https://www.supercheapauto.com.au/p/tridon-tridon-high-flow-thermostat---tt2003-195/299465.html

 

[Dunlop]

After noticing that the engine didn't seem to be warming up after driving up to the main street (850 metres) but that the top radiator hose seemed to be warm, I decided to buy a 91C high flow Tridon thermostat to see if I could fix the issue. Put it in last night with some high temp silicon and drove it up the street a short time ago after idling it for some minutes.

Drove up 850 metres to the main street and parked the car with the engine running. Opened the hood to check the engine temp - engine had warmed up nicely and the top hose was still cold - much better than yesterday when the engine was still cold and the top hose was warm - not hot. Air temp is about 30C now and I have to drive up a short rise of 80 metres on the road.

But when I looked at the gauge, it was nearly on half whereas in that situation it's normally only on less than a quarter... As you know, VR 3800's normally sit on a quarter on the gauge unless - in my case - I'm driving up a hill in warm weather. Drove out on the highway a few kms and the gauge dropped very slightly below half. I stopped and opened the bleed valve - that was ok - then drove off again back home - the highway goes uphill on two stages.
When I checked the engine block, it seemed to be really quite hot although the car was running pretty well - no uneven idle which can indicate running overly high.

When I called Dayco last year, I'm sure the tech told me that their thermostats are designed to 'crack' open before the engine reaches normal operating temp - probably a saftey feature. Thing is though in this area it gets damn cold in winter, so the car has been using up excessive fuel and this has affected the heater core which needs flushing anyway and also has a slight leak. Fortunately I don't drive very far so the amout of petrol I've used excessively could be worse...

The staff member at Supercheap told me the new thermostat only cracks open at 91C - not before.

So, does it sound like the engine is running too hot? Or could my radiator need flushing even though there's no indication of any gunk at all in the top - it's just clean green coolant?

Any advice much appreciated.

This is the new Tridon - curious thing is that the Dayco high flow is $28 and the Tridon is $36...https://www.supercheapauto.com.au/p/tridon-tridon-high-flow-thermostat---tt2003-195/299465.html

Just one other thing I've noticed - when I touched the bottom radiator hose, it seemed to be nearly as hot as the top one...

Does this sound right?

Thanks

 

[Immortality]

I think the person at SCA doesn't know what they are talking about.

A thermostat controls temperature by restricting coolant flow to the radiator. Thermostats are not a open or closed type switch, they open more as the heat increases and close a bit when the engine cools. All thermostats will open before their stated operating temp.

I think the gauge is about right. It's been a long time since I have driven a VR/VS with a stock thermostat but with a cooler 82°C thermostat I remember them sitting on about 1/4 or just above the first first mark on the gauge.

 

[Dunlop]

I think the person at SCA doesn't know what they are talking about.

A thermostat controls temperature by restricting coolant flow to the radiator. Thermostats are not a open or closed type switch, they open more as the heat increases and close a bit when the engine cools. All thermostats will open before their stated operating temp.

I think the gauge is about right. It's been a long time since I have driven a VR/VS with a stock thermostat but with a cooler 82°C thermostat I remember them sitting on about 1/4 or just above the first first mark on the gauge.

Thanks for that.
But what do you mean by the SCA staff member not knowing what they were talking about?

 

[Immortality]

Super cheap auto staff....

 

[Dunlop]

Super cheap auto staff....

I think he might have been right though - makes sense...

I have a Dayco 82C thermo that I fitted a year ago or so but I didn't think it made much difference to the older 91C Dayco - particularly in winter so I took it out after some months, I'm tempted to take the new one out and put this in again to see if it's opening too early.

I've noticed that most of the high performance thermostats for this engine are rated at 82C. Again the thing is that it gets so cold in winter here I really need the higher opening unit unless I can resolve the heater issue.

 

[Immortality]

I've had the exact opposite issue with thermostats, they end up running cooler than specified. Right now I have a dayco fitted, it should be 82°C but the engine will drop down to 79°C when cruising but then I've had the same problem using Tridon thermostats and one from MACE too.

 

[Dunlop]

I've had the exact opposite issue with thermostats, they end up running cooler than specified. Right now I have a dayco fitted, it should be 82°C but the engine will drop down to 79°C when cruising but then I've had the same problem using Tridon thermostats and one from MACE too.

That's curious - could be they set the actual opening temp lower for safety reasons... Can you remember what brand of thermostat you have now?

The reviews for the Tridon seem to be generally positive so far...

 

[Immortality]

I've used dayco, Tridon and the Mace supplied one. I also have one here from ZZP that I'm going to try next however all have done the same thing so I suspect it's not the thermostats. Mine is a L67 which is moderately modified. I have used 82°C thermostats in ecotecs and 3800 V6's and they seemed fine there.

When I bought the car it had the standard 91°C thermostat and around town it would operate at about that but out on the open road it would drop down to low 80s so this car/engine has always had some weird cooling quirks.

 

[Dunlop]

I've used dayco, Tridon and the Mace supplied one. I also have one here from ZZP that I'm going to try next however all have done the same thing so I suspect it's not the thermostats. Mine is a L67 which is moderately modified. I have used 82°C thermostats in ecotecs and 3800 V6's and they seemed fine there.

When I bought the car it had the standard 91°C thermostat and around town it would operate at about that but out on the open road it would drop down to low 80s so this car/engine has always had some weird cooling quirks.

Thanks for the info...

All I can do at the moment is to just drive around for a while and see if the thermostat 'loosens up' a bit. I put KYB Excel G struts on the front some months ago and thought they were too stiff, but on the last 90km trip they seemed to have softened up slightly so maybe the thermostat might do the same thing...