Thread: YAY!...now im overheating! :(

Dave

"These engines use what's called a map thermostat. It's a fairly simple design.
The electrical connector on the thermostat is for a little electric heating element that's inside the thermostat. With no power applied to the connector, the thermostat acts like a normal thermostat on any engine. When engine demand and load is high, the heating element inside is activated to open the thermostat earlier and allow the engine to run at cooler temps.
You'll need a Land Rover specific factory or aftermarket scan tool to read those temps. "



Just make sure the electrics are still connected or not loose !

Also the many people will get a lower temp thermostat 85c, the standard L322 runs at a very high temp around 100c ; the reason for this was emission control readings. Is a bit of mucking around , but well worth it !

[ame]https://www.youtube.com/watch?v=qK0JjuCXHJA[/ame]

Laurie

Hi Laurie,

Thanks very much for taking the time to reply.

I guess initially my concern is why do i have such a big temp difference between the upper and lower hoses, and also such a if temp difference between the upper and lower parts of the radiator.?

My experience shows that this was was generally an indication of a faulty thermostat, but these cars are a lot more complex than what i'm used to working on.....especially with the electronically controlled component.

What happens if the electrical plug is disconnected from the thermostat?. Someone else has suggested to me that it them just reverts back to operating exactly thew same as a regular thermostat.??

Why would i have not seen my other thermostat start to open in the boiling pot of water?.

Like i said, the system doesnt seem to be building up a large amount of pressure (although it may have when i was in the car and then inside before the tank cracked). But after i put the new tank in and ran it.....it seemed to boil within a minute or so, and no real pressure in the system. Bottom hose was definately cool.

Dave

G'day Dave,

Everything you've written points towards a failed (stuck closed) thermostat. The temperature difference between top and bottom hoses observed and the thermostat not opening in boiling water (especially that last one). This is just a typical wax-stat type thermostat with an additional heating element allowing the vehicle to 'trick' it into opening a bit earlier under certain conditions. In boiling water it should open (like all thermostats).

I think you've diagnosed your problem. Hope that sorts it.

hi guys,

just wanted to check in and update this.

before going ahead and buying unnecessary parts, i decided to put it back together with a spare overflow.

I posted this overheating issue on rangerovers.net as well, and someone replied there suggesting that perhaps it was just time for the overflow bottle to split, and that everything else is expected.

I replaced the overflow tank and bled the cooling system correctly, and the car has been running fine since. The "boiling" i thought i heard (and felt) was in actual fact air running through the system.

The top hose being hotter than the bottom hose seems to have stabilised somewhat. Even though there is still a temp difference, i think this is normal (as someone else mentioned).

So - all in all it seems to be fine. Ive left it running in the driveway for hour after hour, and taken it for a number of good drives........and no issues.

Dave

I've just ordered one of those thermostat mod kits from Prague. I'd like a cooler running engine instead of 100 deg on the freeway and 103 in traffic.

I've started fitting the kit.

The original thermostat is a 105 deg C unit.



Getting the housing off isn't too difficult but in my case the thermostat heater plugged was stuck. I ended up pulling the heater connector out of the thermostat. When I finally got it apart, it had been severely corroded and stuck. One of the pins pulled half way out Coolant had, apparently, been forced past the sealant in the thermostat heater into the plug/socket. I suspect the wiring in that area had been corroded away and perhaps the heater was non-operational.

Sorry I didn't take a pic of the thermostat before cutting it up.

The two legs which hold the thermostat were cut off with a hacksaw but not too close to the sealing surface to avoid damaging it. I then used a Dremel with a sanding drum to remove the remaining bits of the legs.

Note there is a lot of tension on the legs and they will go flying across the room when they part.



The central part of the thermostat just pulls out.



Here you can see the thermostat that will be fitted to the old housing.

The car is running at 90-93 deg C now.

If I were to do this again, I think I'd go a different route.

Having seen the issue with the coolant getting into the plug, I'd go this route: fullfatrr.com - View topic - 4.4 Thermostats - could it be this easy for a lower temp ?

Look especially at the pics on page 2

Originally Posted by fisha

I promised some pictures of the stats:

Old 105?C BEHR on the left, new VEMO 88?C on the right:

See some similarities?

There are some reports of coolant wicking up the thermostat heater wiring into the engine management system - a bit like the oil in the Td5 injector harness. This housing would avoid that!