D4 3.0 Cooling system service

[DiscoJeffster]

Hey,
So at 243,000km and 7 years I decided it was time to do a proactive cooling service. I replaced the water pump, coolant bottle, water outlet (common failure point, top of engine, joins the v into the top of radiator hose), replaced the top of radiator hose that had a cut line from the engine cover, and also replaced the thermostat - as in I removed the thermostat casing and put in a new thermostat unit, and what a pain in the backside that was!!!! Trying to get the five or six hoses off that unit to remove and replace the thermostat under the car, in situ was a right PITA! A high level of regret was experienced.

Anyhow, hoses aside, all mechanical failure points have been addressed. Nice fresh coolant. Fingers crossed for tomorrow when I'll have an opportunity to take it for a drive. Parked/trapped in the garage today, idling the best I could get the temp to was 76 degrees so the thermostat hadn't opened. Tomorrow I'll get a road trip to get the temp up and get the last of the air out.

[PerthDisco]

At what age would it be smart to replace the radiator/ tranny cooler?

On holidays and mate has a 90 series Prado Diesel in exc cond. 02 model he has had since new and now keeps at his holiday house to run around the beaches and tracks. Two days ago it pumps all its tranny fluid out conveniently in a beach car park nearby rather than a remote track we often use. We tow it back (using his other Toyota so no photos) and find that the tranny oil hose has separated from the bottom of radiator. Tranny cooler all integrated into radiator. There is a fine thread aluminium fitting that screws in to the bottom tank that the pipe attaches to. The fitting has a steel washer and a stainless washer. It looks like the steel washer has rusted and swollen effectively pulling the fitting out until the thread was damaged and the fitting popped out under pressure. The oil trail was only about 20m till the car stopped. Looking on internet same problem, same part on radiators in Honda’s and other makes sharing same radiator maker.

Changing the entire radiator assembly at 10 years appears to be the wise choice.

[DiscoJeffster]

At what age would it be smart to replace the radiator/ tranny cooler?

On holidays and mate has a 90 series Prado Diesel in exc cond. 02 model he has had since new and now keeps at his holiday house to run around the beaches and tracks. Two days ago it pumps all its tranny fluid out conveniently in a beach car park nearby rather than a remote track we often use. We tow it back (using his other Toyota so no photos) and find that the tranny oil hose has separated from the bottom of radiator. Tranny cooler all integrated into radiator. There is a fine thread aluminium fitting that screws in to the bottom tank that the pipe attaches to. The fitting has a steel washer and a stainless washer. It looks like the steel washer has rusted and swollen effectively pulling the fitting out until the thread was damaged and the fitting popped out under pressure. The oil trail was only about 20m till the car stopped. Looking on internet same problem, same part on radiators in Honda’s and other makes sharing same radiator maker.

Changing the entire radiator assembly at 10 years appears to be the wise choice.

So the Discovery setup is slightly different with coolant directed to a second heat transfer unit that’s situated under the forward engine / radiator cover. In fact that’s one of the places you drain the coolant from for a drain and refill. There was a post in the transmission sticky where someone recently replaced this heat transfer unit as their gearbox specialist detected coolant in their gearbox oil and that’s the only place that could occur.

I’m not seeing many threads on rads failing etc so I think the Disco setup is pretty good quality from the factory. Keep the coolant in good health and you should avoid crud build up as well.

I replaced my water pump and thermostat because they’re a nightmare to change on the road so I’d prefer to know they’re in good health. Saying that, new parts aren’t alway good so I also run the risk I’ve played with something that would never be a bother.

[DiscoJeffster]

In case it helps, here are the part numbers for the components used.

LR013164 - Water pump (no known issues)
LR073372 - Coolant housing (known for cracking)
LR095544 - Hose to engine (hose gets damaged by engine cover)
LR020367 - Coolant bottle (known to have issues with built in level sensor when coolant changed)

TH45682G1 - Repackaged genuine thermostat unit, made in Germany as per the original (open the existing housing and insert new unit)

[discorevy]

So the Discovery setup is slightly different with coolant directed to a second heat transfer unit that’s situated under the forward engine / radiator cover.

Disco 3 has trans cooler integrated in radiator and while not prone to failure , there have been a few. The d4 with its separate matrix appears not to be immune from cross contamination either, but again its rare.

[DiscoJeffster]

Saying that, new parts aren’t alway good so I also run the risk I’ve played with something that would never be a bother.

And there we have it. Coolant low messages since replacing the bottle, to avoid that damn problem! I went with an aftermarket version thinking how hard can it be lol. For now I’ve tried swapping sensors between the old bottle and the new but I suspect I’ll end up buying a new genuine bottle. We’ll see.

[DiscoJeffster]

And there we have it. Coolant low messages since replacing the bottle, to avoid that damn problem! I went with an aftermarket version thinking how hard can it be lol. For now I’ve tried swapping sensors between the old bottle and the new but I suspect I’ll end up buying a new genuine bottle. We’ll see.

So far the original sensor in the new bottle is working fine. FYI, the sensors aren’t submersed and click into the bottom of the bottle so it’s simple to replace by simply undoing the two bolts and lifting the bottle slightly to remove and replace. No need to drain the bottle etc.

[LRD414]

I removed the thermostat casing and put in a new thermostat unit, and what a pain in the backside that was!!!! Trying to get the five or six hoses off that unit to remove and replace the thermostat under the car, in situ was a right PITA! A high level of regret was experienced.

Would you do this task differently next time or is it just a case of it's difficult no matter how it's attempted?

Scott

[DiscoJeffster]

Would you do this task differently next time or is it just a case of it's difficult no matter how it's attempted?

Scott

Hmmm. Well there is a complete hose set which includes the thermostat which would be easier I suspect, but it’s very expensive. Next time I probably wouldn’t replace it. It was only the cost and the fact I’d already bought it that I persisted with changing it. I haven’t heard of many thermostat issues hence I probably overdid it

[Ld4]

Did you have a problem with the o- ring at the front of the thermostat when trying to slide it back on cause I'm sure my o ring isn't sitting right because it still leaks?