Thread: 3.6 TDV8 bad overheating on hills towing caravan

No oil in coolant or coolant in oil so appears confined to a coolant problem.

Dragging brakes has been discussed but the combination rolls easily along on very light throttle with good economy and burnt linings would have been smelt each time he has had to pull up to cool.

The vehicle has travelled several remote and sometimes muddy tracks in WA and SA towing a camper trailer so mud caught in the fins is very possible even though hosing from the back hasn't revealed any mud.

The RRS engine bay is more cramped than the L322 with the same engine plus the RRS's active roll-bars add congestion behind the engine but since realising that the overheating did not initially occur, I expect that he will find the radiator is either externally or internally partly blocked. It has the same 2-radiator arrangement as the L322 so would be expected to handle some load.

Today's update - water pump and radiator removed for inspection.

The water pump looks to be as new. The main radiator was clear both inside and outside and back-flushing the radiator produced nothing. The aux radiator was removed and inspected just before Christmas and it too was spotless both inside and out.

Have to check the main hoses for internal delamination/collapsing as suggested.

Whilst the hoses haven't specifically been inspected for delamination and that they appear to be in good condition, its a good time to fit new ones and keep the old ones as spares, unless of course the overheating is overcome with new hoses. Coolant volume through the radiator increases as the need to dissipate heat increases and the increased flow could cause an internal split to be picked-up to at least partially block the hose.

To me it seems more like a fan problem air flow when working hard .
I don`t know what type of fans they run on these but typically a car will over heat with a crook viscous fan working hard up hills

Internal radiator inspection. You can only be sure it is clear by removing tanks.

The fan is driven by an ecu-controlled viscous coupling. The IIDTool reports both the fan speed and the pwm duty cycle for the coupling drive and both increase and decrease as expected for an engine that gets hot very quickly. All indications are that the fan is turning as required.

It appears that delaminated radiator hoses causing hose blockage is commonplace on vehicles generally as hoses weaken with heat/age. The sudden onset of overheating when this engine is worked could easily be explained by a hose becoming blocked as coolant flow through the radiator increases. Often the tell-tale sign of an affected hose is very slight weeping from the ends around the fibrous material due to coolant having worked its way from the split along the fibres. Obviously the top hose gets the hottest so more likely a culprit than the lower hose.

Originally Posted by theelms66

Internal radiator inspection. You can only be sure it is clear by removing tanks.

Can't R&R the plastic tanks on an alloy radiator but high volume flushing into the outlet showed no significant restriction. The quick escalation to overheated would require a high percentage of the tubes to be blocked, which is not supported by the flush test.

On your Original post you said top radiator temp was 113 and bottom was 103 . Sounds a little hot returning into the motor does it not . I dunno.

Originally Posted by theelms66

On your Original post you said top radiator temp was 113 and bottom was 103 . Sounds a little hot returning into the motor does it not . I dunno.

i was thinking the bottom was a bit hot gien that it was just cooled by the radiator. hence why i think the rad cooling performance is minimal.