Thread: 3.6 TDV8 bad overheating on hills towing caravan

The only time my L322 has got hot was on a hot day during about 30 min of soft sand driving (high tide) in low range. I ended up stopping and letting the engine idle for a bit with the bonnet open.

I’ve never towed anything near 2.5T with my L322, only a couple of types of loaded hard floor campers.

I agree with Blade, the motor emits a lot of heat during normal operation. I took this to mean the motor is efficient at dispersing heat. I have wondered whether additional vents at the sides of the bonnet would be worth while. The shark fin vents are already pretty substantial.

Is it worth trying to flush the cooling system somehow and make sure there isn’t any sort of sludge built up.
Sounds stupid but you never know.
Mine always appears like the coolant is perfectly clean.

When you drive the car Graeme does it feel like your 3.6?
As in does it feel similar in power?
Just trying to work out if it’s got some issue and having to work harder to achieve the same power.
I also agree that maybe he needs to keep it reving more to keep the fan spinning faster.
But that also may mean turbos spinning faster and more heat being generated as well?

It would be good to attach the van to another 3.6 l322 and do the same hill test.
That would answer all questions very fast.

The coolant has been renewed several times.

Mine is a 4.4 L322 so quite different to a 3.6 RRS and I haven't driven his RRS anyway.

He test-drove my 3.0 D4 with the van attached before buying the RRS to see how well the D4 towed compared with his LS-equipped RRC. At the time he commented how the D4 didn't particularly like maintaining speed on a steep nearby hill although I thought he was asking too much of the engine. The D4 dropped gears until revs were rather high then maintained a slower speed. I would have dropped more speed to lower the revs. He's too far away to go for a run with him to see how he manages speed and revs.

Higher revs won't necessarily turn the fan faster as the ecm reduces the fan clutch engagement to avoid excessive fan rpm. Higher revs won't necessarily increase turbo heat either, indeed often reducing the heat generated as less boost is required for the same power o/p and less unburnt fuel exits the cylinders thus reducing combustion within the turbo. What does increase is the water pump speed which should increase flow through the radiator to some extent. However the impellor design is very open and more a high volume at low pressure than a high pressure pump so less able to overcome hose and fitting restrictions and therefore may not circulate fluid any faster at higher revs.

Well it seems that the problem has not always existed. My brother now recalls that it did not originally overheat and that it is getting worse. He used to be able to pass slower van-pulling vehicles up hills with ease whereas now it wont go up slight inclines without getting hot. This is good because it changes from a possible design short-coming to something that is no longer working properly so is fixable - water pump or radiator hopefully.

Not sure if it can happen on coolant hoses , but any possibility one of the hoses is collapsing under the extra load and restricting coolant flow ?

Remember the turbo hose on my TD5 did that when towing a caravan and it lost all power, never happened when the van wasn't hooked on , different hose but anything is possible I guess

Cheers Ean

i'll go with clogged radiator