110 overheating

[showbag]

my landy keeps overheating only when i sit on 100km, iv relaced the thermostat, viscus hub and fan, flushed the radiator and replaced the coolant, the head gasket is fine and the presure tank cap is fine, what else could cause it to overheat.

[one_iota]

First post! and welcome. :)

Just a bit more info required for the brains trust here:

What year, engine and mileage?

[wrinklearthur]

my landy keeps overheating only when i sit on 100km, iv relaced the thermostat, viscus hub and fan, flushed the radiator and replaced the coolant, the head gasket is fine and the presure tank cap is fine, what else could cause it to overheat.

Hi Showbag

As one_iota has asked, just a tad more info about the model and engine please.

Common causes to all over heating problems in all vehicles, check the following;

that nothing is draging, load, transmission binding, seized brakes etc.
tyres at correct pressure.
air flow through radiator is unrestricted, no mud or chaff in the fins.
air lock in the cooling passages, coolant should be seen straight away when the plug on top of the motor is released.
engine timing or mixture is wrong.

less likely;
is the thermostat stuck closed , they usally stick open if they fail.
restriction to the coolant flow, cauld be something like a internally collapsed hose.

Sometimes conditions can play a part, for example, a following wind and the fan cant get enough air flow to cool the radiator.
And if you are really unlucky, a crack in the cylinder head or a porous block.
Cheers and welcome, Arthur

[abaddonxi]

Condition of radiator hoses? Fan working? Radiator blocked beyond ability of flush to clear it.

Cheers
Simon

[one_iota]

Having the radiator rodded by a radiator specialist might be a good place to start as flushing won't necessarily get the crap out.

[JDNSW]

You need to confirm it really is overheating. A high temperature reading can result from a faulty earth on the gauge. This can be checked by seeing whether it changes when the dash lights are switched on and off, bearing in mind that the gauge has a very slow reaction time.

John

[nice1guv]

Since its happening at speed, I'd be looking at the radiator being partially blocked or the water-pump not working properly.

[PAT303]

Flushing the rad is pointless,it's rodding that does the job. Pat

[wrinklearthur]

Flushing the rad is pointless,it's rodding that does the job. Pat

Hi Showbag

As Pat has said, rodding is the way to go for making sure the radiator is clear, has this been done already?
Another thing, that is a possibility, not long after I purchased my Defender flat tray, the water pump on the 300TDi motor started squeaking.
Thinking that it was the bearing failing, I replaced it with a new one that had a stainless steel impeller, I also replaced the 'P' gasket and the waterpump bolts at the same time.

But the old pump was not leaking through the seal and the bearing was good????? :confused:

The squeaking problem was caused by the cast iron impeller, which had rusted badly and the rust was rubbing on the inside of the waterpump housing. :o


Have you had a chance to look at your water pump impeller yet?

Cheers Arthur