why do an inline modification when they make a 180 degree stat now ???? The 180 degree stat has had MUCH success, without all the extra work and parts. K.I.S.

 

The inline mod seems to allow smaller temp swings than the weird stock design, and is far cheaper than buying another Rover stat. Remember, this design is a 50 year old Buick engine that was designed to work with an inline thermostat. That said, it is more work than just buying the TD5 stat. I do agree in this case that it isn't worth doing til they solve the overheating/bleeding issues.

Hay - that looks like a very good technique on how to bleed the system (the pressure tester to blow out air is brilliant), and I'm gonna have to buy one of those sight glasses.

Abran - I notice you haven't replaced the fan clutch. We've seen several people with clutch problems over the last year. The way you test it is when the engine is off and cold, spin the fan with your hand. If it turns more than one revolution it's toast.

When you bleed the system, keep at it for a while. I found that tapping on the hoses and moving them around helped express the air. Also, be careful with the coolant reservoir when you elevate it because you can easily snap the hard plastic hoses that plug into it. I have never been able to fully eradicate the waterfall sound, though my last bleeding session almost killed it. But my truck runs cool so I haven't worried about it.

Another thing I notice is no one has told you to download the RAVE. There's a link in Buzz's signature to download it for free. The RAVE is the service manual that explains how to do all vehicle maintenance for the Disco.

One last thing, the cheapest places to buy parts are ebay, amazon, and rockauto.

 

is your condenser fan motor running, it should be coming on around 210-215.?

 

I think you have it backwards, the existing rover design was designed to prevent temperature swings that could harm an aluminum engine.

I have the TD5 180 stat in my Disco 2 and it was the BEST mod to the truck. It will save it's life.

My existing stat was bad, up to 230F on a normal low RPM climb, as high as 250F at one time....still the guage was pegged in the middle (need to purchase an ultra-guage to get real temps).

Changed the T-stat, and now, even in the winter, the truck heats up to 188.6 and sits there. No swings. no weird stuff. Nothing. Plus, the new design allows for heated bypass to the heater. My truck blows heat (as soon as temp reaches 140F) within 5 minutes of a cold start, dead of winter.

Granted, I'm starting to creep up to 194 to 197. I'm still on a stock radiator and fan-clutch, so I'm going to change those in the spring.

In any event, for the OP, 220-230 might be normal for "design spec" (IE: fewer emissions while warming up), but it has been proven to be abnormal for head gaskets and aluminum blocks. Get rid of the stock T-stat, either Rover TD5 180F or the inline mod, either are better than stock.

Thinking of going inline if I get a P38, although looking at options of keeping the stock location, if possible..

 

We've discussed the weird stock thermostat before here, and the consensus was that its purpose was to make the heater work faster.

In fact, page 421 of the RAVE states "the cooling system used on the V8 engine is a pressure relief by-pass type system which allows coolant to circulate around the cylinder block and the heater circuit when the thermostat is closed. With coolant not passing through the radiator, this promotes faster heater warm-up which in turn improves passenger comfort."

Also note that it says "in cold ambient temperatures the engine temperature can be raised by up to 10°C (50°F) to compensate for the heat loss of the 10% exposure to the cold coolant returning from the radiator bottom hose." So the stock thermo automatically raises overall engine temp by up to 50 degrees when it wants to. Talk about temperature swings! This might explain why your temps are climbing now that ambient temps are dropping.

All I can say is my inline thermo stabilized my temps at 183 until the ambient temp get into the 90s. Then it creeps up the low 190s. I do think a higher volume radiator/fan is good idea on these trucks as the cooling system seems to struggle when it gets hot. I personally am going electric fan in the not too distant future.

I certainly agree that either 180 degree 'stat is better than the stock.

 

Thanks everyone for keeping this thread alive.

Slight update. Downloaded RAVE a while ago. Put a new fan clutch. Removed the water pump just to make sure(local mechanic said that once he had a D2 that was ultra pressurized and found the pump impeller was corroded) The cooling system still seems ultra pressurized. At operating temp of 221, the rad hoses get pretty hard. Have done all the hocus pocus I can think of to bleed. It seems that after bleeding the waterfall noise is almost gone, but after 15-20 minutes driving it starts to come back.

I will buy a new in line 180 t stat, but could I be getting air in the system via a mystic leak? Coolant tank, radiator, t stat have all been replaced.

It's these problems that makes my D1s look soooooo good!

 

"I think you have it backwards, the existing rover design was designed to prevent temperature swings that could harm an aluminum engine."

Ain't so, my friend; not good to spread rumors not based on fact, THAT ONLY SPREADS MISINFORMATION, CONFUSING ROVER OWNERS. It WAS designed for reason mentioned by another poster, PASSENGER COMFORT: "In fact, page 421 of the RAVE states "the cooling system used on the V8 engine is a pressure relief by-pass type system which allows coolant to circulate around the cylinder block and the heater circuit when the thermostat is closed. With coolant not passing through the radiator, this promotes faster heater warm-up which in turn improves passenger comfort."

The inline conversion takes the awkward bulky stupid design, done only to give more passenger comfort, back to the way it was originally designed for this particular engine, when it was designed and used by General Motors, and later when it was used on the earlier Rovers and in other British applications too, none of which did an ounce of harm to the all aluminum engine design.

 

Generally, when I hear "The cooling system still seems ultra pressurized," as it applies to Land Rover engines, I think that there almost has to be small, minute, cracking of the aluminum walls BEHIND one or more cylinder liners, causing combustion gasses to escape via that route, into the coolant system. Such condition is commonplace with this particular engine, following one or more overheating episodes; it directly causes an ultra pressurized coolant system, with hoses "pumped up," when it happens. When this happens, one can spend all the money in the world on all the things you have been, and still are, spending it on, without altering the condition. The only good, permanent way to stop that condition, is to tear down the engine, remove the liners, to get at the cracks in the thin aluminum walls behind them, TIG aluminum weld the cracks up, machine down the welding to fit in new liners, rebuild the engine.