[flamecycle]

Hey quick questions as I'm greasy and in the middle of what I thought would be a quick change...

I'm trying to change the thermostat on my '96 4.0. Went on a trip to a hot place last week, and started having the engine temp drop way too far when, for example, going down the pass I just climbed. In fact, the temperature dropped all the way to the bottom of the gauge. Then the climate control would freak out and go into fault, etc etc, but I believe the thermostat as the root cause, because climate control works fine until the temperature drops too far too fast.

All the classic signs of a stuck open thermostat.

So anyway, I've got the ball on my workbench with the thermostat inside, and napa had a listing for a thermostat, so I got that. But what am I missing to get into the ball and swap the existing thermostat for the new napa one? Is the whole unit the official LR thermostat? I'm trying to figure out what I'm up against before I completely disable my truck because I trashed the housing. If it's not going to open nicely, I'm going to put it back as is until I get the entire replacement.

 

[flamecycle]

I'm starting to find several listings on Rover specific sites that show the whole housing as the part. I'm slowly learning that Napa, while nearly always spot on for my American trucks, doesn't have nearly the batting average on my British truck...

And here I though LR had engineered this cute little pod that would open up to reveal the same thermostat like every other vehicle on the planet. But NOOOOOO.

LOL

Oh well. A bad day in the garage still beats a good day at work. :thumb:

 

[RRToadHall]

Yes indeed the little Jarvik heart is the thermostat. They rarely fail if the coolant has been maintained. I would toss it in a pot of water, heat it up on the stove and see if it is operating. A couple of denture cleaning tablets in the hot water do wonders for cleaning up a stuck unit.

 

[kmagnuss]

Lol... Jarvik heart.

 

[p38arover]

I don't know if Tridon parts are available in the USA but from another thread:

Re the original thermostat, the Tridon site shows their replacement for the P38A is the TT440-180P which has an opening temp of 180 deg F / 82 deg C. Note they show the moulded carrier so they must have it right.

See http://www.tridon.com.au/partfinder/default.aspx

The RR workshop manual says:

The thermostat is closed at temperatures below
approximately 80 °C (176 °F). When the coolant
temperature reaches between 80 to 84 °C
(176 to 183 °F) the thermostat starts to open and is
fully open at approximately 96 °C (204 °F). In this
condition the full flow of coolant is directed through the
radiator.