It's back on the road

[biffa75]

Dmgrs is the place I bought the coolant cap from. Fitted my old one and you can notice a difference when fitting the cap. (New one seems to screw in a lot further and takes more effort) possibly down to the seals being new perhaps? Who knows.

Just been out for a drive in the car following earliers coolant bleeding session and...

Engine running temperature around quiet back roads of around 30-50mph engine temp hovers around 83-84°c.
Goes down to 80-81°c when going down hill.

Uphill reaches around 85-86°c.

Having the heater on or off makes no difference.

No more gurgling behind the dashboard
(Although coolant level tries to rise when hot/upto temp with the cap off).

Starting to wonder if the thermostat is faulty.

[stevestrat]

Originally Posted by biffa75

(Although coolant level tries to rise when hot/upto temp with the cap off).

Always will. As the coolant heats it expands, system normally runs under pressure. With the cap off it can't pressurise and the level will continue to rise until it overflows.

[roverbarmy]

As Steve says, let it cool overnight. Check the level in the morning. Top up to bottom of header tank (Max level) Run then park up and don't touch the cap. Allow to fully cool (preferably overnight) and then check the level. Checking when warm or hot will give a false level reading and could allow expanded coolant to overflow. It's not called an expansion tank for nothing and that's why it has a pressure cap. Many a motorist has been scalded by taking an expansion cap off whilst the coolant is hot and pressurised (normal running condition).

[biffa75]

Thanks for the information, it's much appreciated. I'm now havin to use the car for work so will keep an eye on the level an do as directed.

The engine running temp is around 83/84°c. The thermostat was marked 82°c but dips below 82 when going down hill. Will the running temps.in the low 80s be an issue?
Thanks
Rob

[SD1too]

Hi Rob,

If, with your original expansion cap fitted, the hose no longer collapses (as reported earlier) then that proves that the new cap is the cause. Return it to DMGRS for a refund.

Your running temperature is 10 degrees too low. As you say, that might be because the thermostat is opening too early (unusual on the V6) or that the cooling system isn't pressurising properly due to a poor seal somewhere (time consuming to find).

You can test the thermostat to some extent by activating the digital temperature display, starting the engine from cold and grasping the bottom radiator hose (that's the one with the bleed screw conveniently situated beside the battery box). It should remain cold until the thermostat opens. The display will tell you at what temperature this happens. It should be no lower than 86 degrees.

Simon

[biffa75]

Thanks for the reply Simon,

I had to use the car for work last night so was parked up overnight, checked the coolant level this morning and it had dropped a small amount so topped up to the max tab inside the tank.

Still with the original (old) cap fitted and the hose no longer appears to be collapsing (was as if the hose had been vacuumed)

Anywho, the running temp this morning over a 10 mile drive on mainly 30mph roads was around 81/82°c.

I will check the bottom hose as you have detailed, I can confirm that all hoses get hot and upto pressure as you'd expect and there is good keen heat from the matrix after about 3 miles. (Rough guess it was showing 70°c or just below).

On a side note, as I pulled up at a shop on my way home and selecting neutral the cars idle became irratic again and died. Started straight back up again and idled fine.. don't think this car likes me 😅

Thanks
Rob

[SD1too]

Originally Posted by biffa75

I will check the bottom hose as you have detailed, I can confirm that all hoses get hot and up to pressure as you'd expect and there is good keen heat from the matrix after about 3 miles.

Just to clarify, it's not a question of if they get hot, but when so please try the test I described and hopefully it will help us.

The matrix isn't under the control of the thermostat so ignore that.

Simon

[biffa75]

Not had chance to do your test yet Simon with top hose, had to use the car again today and after a lengthy drive and coming to a stop.. raising the revs from idle to circa 1500rpm the gurgle behind the dash has come back.

Add this to job relocation some miles away from home I'm not sure keeping the V6 is even viable now..

[biffa75]

Done the test,

Could start feeling the underside of the hose (wrapping fingers round the hose) could feel a small amount of water getting hot at around 82°c. By 85/86°c it was fully hot and starting to becoming difficult to squeeze as the hose was getting hard.

So when driving around, with the readout showing 81/82°c the thermostat is just partially opening or just about..

The original stat that came with the car also has 82°c stamped to it.

Also to add, before starting the car today, coolant level checked all normal. No gurgling behind the dash either so.. I'm going to drop yesterday's gurgling I heard and count it down as me being tired

[SD1too]

Originally Posted by biffa75

Done the test ... getting hot at around 82°c. By 85/86°c it was fully hot ...

Thanks Rob. MGR says that the thermostat begins opening at 88 ±2 degrees and is fully open at 96 degrees so yours is opening early. Ignore the 82 degrees marking on the housing.

Simon