Engine Temperature Problem?

[m00t]

Our LS400 had been sitting in the front of our house for a while without use, so we decided to dust it off and make sure it was good to go just in case.

Everything was fine... except that the temperature needle went above the standard 'middle mark'. It went up one full tick mark, in that it stopped halfway between the tick before the RED tick and above the tick above the middle mark. When running 'normally' it stays at that position, with no signs of going any further.

We thought it was something cloggin' up the coolant pipes inside. We washed it out with cleaner fluids and still, no change.

We changed the sensor. No change.

We checked the radiator to find that yellowjackets had built mud nests onto the radiator. We cleared them out and vacuumed a bunch of grass and dirt at the bottom.

No progress.

What seems to be the problem? Is it a peripheral problem or an internal problem with the engine itself?

[SteveLS400]

Our LS400 had been sitting in the front of our house for a while without use, so we decided to dust it off and make sure it was good to go just in case.

Everything was fine... except that the temperature needle went above the standard 'middle mark'. It went up one full tick mark, in that it stopped halfway between the tick before the RED tick and above the tick above the middle mark. When running 'normally' it stays at that position, with no signs of going any further.

We thought it was something cloggin' up the coolant pipes inside. We washed it out with cleaner fluids and still, no change.

We changed the sensor. No change.

We checked the radiator to find that yellowjackets had built mud nests onto the radiator. We cleared them out and vacuumed a bunch of grass and dirt at the bottom.

No progress.

What seems to be the problem? Is it a peripheral problem or an internal problem with the engine itself?

Hi

Did you follow the correct fill procedure? You will find it included in this link http://www.lexls.com/tutorials/cooling/coolant.html

This is the only way to correctly fill the system to capacity. Try it and report back.

[Redsteve]

Hello mOOt,

I have had a similar problem after a day off roading.

As you can imagine the radiator gets caked in mud during the day. If I just clean the mud off the front of the rad the trusty old Hilux runs a bit hot. What you need to check for is the mud that has been pushed between the fins in the rad.

Get a hose pipe and make sure you can squirt water from the front of the rad through to the back (don't use a pressure washer as you will flatten the fins, they are quite delicate).

The radiator relies on air passing through it (not just over it) to cool the engine, and the LS has a big engine so it needs big air to cool it.

It has always worked for my Hilux, good luck for your LS.

Steve.

[m00t]

We washed the radiator; nothing. A note on the temperature rise- it happens right from the starting of the engine. It steadily moves to that point when idle and in park, and quickly, when moving, of course. It remains there, even when driving relatively long distances.

[SteveLS400]

We washed the radiator; nothing. A note on the temperature rise- it happens right from the starting of the engine. It steadily moves to that point when idle and in park, and quickly, when moving, of course. It remains there, even when driving relatively long distances.

Hi again

Having had the opposite problem, I would now suggest fitting a new sender unit. Make sure you get one with the right connection.

[m00t]

I'm sorry, I'm not familiar with vehicle part jargon- a 'sender unit'?

[m00t]

Okay, update. Thermostat changed, sensor changed, coolant reservoir changed. We are thinking that there's something wrong with the needle. concur?

[lexynik]

not really-as its been sitting a while (you didnt say how long) and the car isnt overheating persay just running hotter then usual i would say you have a blockage of built up sediment or air in the system somewhere - apply some radflush stuff then do a reverse flush with the thermostat removed - (cheap fix if it works)

[m00t]

A reverse flush?

[lexynik]

yup,basically remove a hose from somewhere ie the rad and the thermostat- work out which way the water travels round the system usually from the waterpump and flush the opposite way - put a garden hose in the hole where the hose came off with a bit of rag wrapped round so it bungs the hole up and flush clean water in one hole until only clean water comes out-replace thermostat and antifreeze - youll know if it needed it from the amount of crud that comes out

[lexynik]

err-just reread your post - are you saying that from cold the needle goes straight to the hot position or does it happen as the car warms up ?

[SteveLS400]

err-just reread your post - are you saying that from cold the needle goes straight to the hot position or does it happen as the car warms up ?

I would also ask "does it go up immediately the ignition is turned-on?"