Thread: D4 Cooling system differences?

Originally Posted by INter674

Sounds like a thermosyphon effect..as if there's no themostat..ie sudden rush of water displacement as the hot water is displaced by cold. Monkeys whobtemive thermostats cause this to occur thinking it improves cooling. It does not.

I flushed and replaced the coolant some months ago so I live in fear there’s some internal air lock even though the bleeders are flowing and I’ve done 20,000km since.

I’m keen to replace the thermostat due to age.

Both times it happened I was in low range and revving hard 3,500rpm on soft beach sand in sand mode driving with a strong wind. When you turn into the wind the problem does not reoccur.

My radiator and condenser fins are very clean.

Im tempted to up shift to keep the revs under 3,000 in the future or stay in high range. There’s a seperate argument on what’s better for the car screaming in lr or lugging in hr.

Lr is perfect for 0-20kmh but I’m not so sure when you are hitting the 40kmh suspension lowering limit.

Originally Posted by PerthDisco

I flushed and replaced the coolant some months ago so I live in fear there’s some internal air lock even though the bleeders are flowing and I’ve done 20,000km since.

I’m keen to replace the thermostat due to age.

Both times it happened I was in low range and revving hard 3,500rpm on soft beach sand in sand mode driving with a strong wind. When you turn into the wind the problem does not reoccur.

My radiator and condenser fins are very clean.

Im tempted to up shift to keep the revs under 3,000 in the future or stay in high range. There’s a seperate argument on what’s better for the car screaming in lr or lugging in hr.

Lr is perfect for 0-20kmh but I’m not so sure when you are hitting the 40kmh suspension lowering limit.

I think I would replace the thermostat and have the radiator tanks taken off and the tubes prodded out.
Cheers

Originally Posted by gavinwibrow

Yep, you picked it.
"Spoilers" are an ARB bar, including under-protection and a Runva 11.5 Top mounted winch. No extra lights, but numberplate straddles the two lower horizontal openings.
I think I'll start with putting/dropping the numberplate down to cover the fairlead on a hinge as per my LSE TD5, and see if that improves the airflow, plus I'm still very interested in applying the recent post for an additional ATF? cooler that I saved the details of.

Well, I've dropped and hinged the numberplate, and will check out the towing for any improved cooling when we go to the Manjimup Cherry Festival in a couple of months.

Should expect some improvement with the plate removed from the grill area.
You can see where the top of the plate used to be by the two screws just below the winch box. The original position was almost as high as in the upturned pic - to access the winch cable.

Gav, my setup is the same w/o the flip up plate, no cooling issues at all towing, car full of kids etc.

I think you may have a dodgy thermostat.

Did you 'burp' the system after your flush? There's a little rubber hose piece sealed with a plastic screw cap just next to the coolant outlet, run the engine to temperature and slowly unscrew the plug, this let's out any air in the system. There's another plug at the rear of the engine on top of the dross over pipe, bleed that one too, but I'd also suggest to replace that plastic cap with a brass one, about 10bucks from supercheap (btw thanks Dazza td5 for that gem).

Anyway, I'd be checking thermostat first.

Originally Posted by Eric SDV6SE

Did you 'burp' the system after your flush? There's a little rubber hose piece sealed with a plastic screw cap just next to the coolant outlet, run the engine to temperature and slowly unscrew the plug, this let's out any air in the system. There's another plug at the rear of the engine on top of the dross over pipe, bleed that one too, but I'd also suggest to replace that plastic cap with a brass one, about 10bucks from supercheap (btw thanks Dazza td5 for that gem).

Anyway, I'd be checking thermostat first.

I definitely did these two points using the pressure of a warm system as a final purge.

To note the brass plug definitely needs some thread sealant as try as I might to get the taper to bite I had a tiny leak until thread sealant was used.

Originally Posted by PerthDisco

I definitely did these two points using the pressure of a warm system as a final purge.

To note the brass plug definitely needs some thread sealant as try as I might to get the taper to bite I had a tiny leak until thread sealant was used.

Fit an oring to the brass plug if it didn’t come with one.
The hose has a small rebate for it to seat to.

Originally Posted by Tombie

Fit an oring to the brass plug if it didn’t come with one.
The hose has a small rebate for it to seat to.

But given the taper it doesn’t bottom out like the plastic LR ones do. They have a slot in the plastic thread to allow bleeding escape once backed off the o-ring.

Originally Posted by Eric SDV6SE

Gav, my setup is the same w/o the flip up plate, no cooling issues at all towing, car full of kids etc.

I think you may have a dodgy thermostat.

Did you 'burp' the system after your flush? There's a little rubber hose piece sealed with a plastic screw cap just next to the coolant outlet, run the engine to temperature and slowly unscrew the plug, this let's out any air in the system. There's another plug at the rear of the engine on top of the dross over pipe, bleed that one too, but I'd also suggest to replace that plastic cap with a brass one, about 10bucks from supercheap (btw thanks Dazza td5 for that gem).

Anyway, I'd be checking thermostat first.

G'day Eric. Will ask DazzaTD5 to check the thermostat in her week after next service, but suspect its just that I'm asking so much pulling 3.5T of high wind resistant block of flats/brick that the old girl is on the limits.

Dazza does all my work and he would have ensured full bleeding after replacing the plastic overflow tank and again after the engine oil filter block leaked and impregnated the coolant. I'm pretty sure I was not booked for the full hours he then spent flushing the various bits.

Also, in non tow running she is pretty cool and certainly within normal temp parameters. Going to Margs next week with no tow and only 2 passengers/luggage, so will get some normal running stats then.