Discover Land Rover Discovery Serpentine Belt Routing Maintenance Tips

The fan "cupped" sides of blades goes toward engine block. It is easy to reverse blades on a D1, much harder on a D2.

 

Well I did some driving today. It appears everything is perfect below 55, after 65 things get warm. I remember reading in one post that the front fan is speed sensitive. Once I slow back to 50-55 or so the temps drop.

Looks like belt routing is right.

Any other suggestions?

 

Same thing happened today. Below 55-60 everything is fine. Above 65mph she runs hot. Is there nything speed related involved in the cooling system?

 

Thas a new one. I would be inclined to say the sensor, but dont quote me on that. If everything os picture perfect, then it has to be the sensor.

 

If AC is on, electric fans should be on until you get to 62.5 mph IF outdoor temp is over 82F. It should cut off if temp is below 77F as well.

Now if the act of the fan turning off at 62.5 mph is making things warm up that you can see with a scanner, that would make it seem like you are running at the edge of the performance of the system.

You should be able to verify that the electric fan is making that much difference by driving at 50 mph, but unplug the fan fuse.

Now for the purpose of the discussion, let us assume that the electric fan running does indeed make the temp go down at 50 mph - 60 mph. So what are some things that could reduce cooling? Here's a list to ponder:

Serpantine belt route? Serpantine belt contaminated with degreaser (slipping)? Water pump not making enough flow (2.64 gallons per minute into a five gallon pail at 1000 rpm)?

Themostat not Land Rover brand? There have been posts of after market not opening at right temp. Stat holes full of trash (top leg from "T")? Heater core restricted - can test by bypassing it as a loop?

Radiator clogged - since new this might be shipping peanuts, shop rag, etc. Still may want to check top to bottom on fins with IR thermometer for more than 10F difference. All the horizontal tubes are pressure fed and should be about same temp, if bottom is a lot colder something is blocked off.

AC condenser and oil cooler(s) have mud or trash or plastic in fins? Check with bright light behind them. Speaking of AC, does temp drop a lot when AC is turned off at 65 mph? Freon levels can make a difference in the heat on the condenser.

Products of combustion gas in coolant? Chemical test can show that. Might be that block crack only opens up at higher stress on engine.

Coolant temp sensor could be tested by removal, keep plugged in, and immerse in coffee cup of hot water. Compare scanner to another gauge. Sensor could be off "calibration".

Steam pocket at top of engine where the coolant temp sensor is. Perhaps at higher speed this finally moves away and lets sensor enter water, instead of just steamy air.

Plumbing route changed - see flow chart attached.


BTW, I can see why all those working on this are scratching their head.

 

Thanks guys.

I will try on Saturday to drive under 50 with no fan and see what happens. I am still trying to find my IR thermo to check the radiator.

I pretty much always have the a/c on, so I haven't tested with or without a/c on. I can check that easily.

The new thermostat was LR brand, not motrad.

The belt was new a few months back, when I was checking the routing I don't notice any obvious contamination. I will check again though.

I washed all the fins and everything appears to be clean. Do I need the shop to check the frein levels? Or is there a way for me to check it?

Can I pull the coolant temp sensor without introducing air into the system?

Thanks again for the ideas. I figure by keeping this thread going it might help someone else down the road.

 

The things that come to my mind...

Headgaskets; are you losing any coolant or is your coolant system still pressurized after the vehicle has sat for a few hours and cooled off?

Clogged Catalytic Converter; at highway speeds they need to flow more air. Does your Disco fall on it's face if you floor it from a dead stop?

It's running lean under cruise; are you getting an misfire codes or hear pinging?

 

Thermostat bypass w/ 180* thermostat and a new Hayden or four seasons fan clutch for a 99 - 02 disco 2 - you will also need a junkyard fan - you will have 180* engine temps instantly.

 

Just do the by pass....and put a chevy 180 t-stat on there.. Problem solve: Here is what u need: Meziere WN0072 Inline Thermostat Housings... Also need a lower radiator hose from a bmw 330i from a 2002

 

It would seem that the delicate balance of the current thermostat system is the issue. If there was no stat at all you'll get like 140-150 F temps in summer (at least with a D1). The in-line stat gets you back closer to a conventional in-the-block stat, you'll still want a small weep hole in the stat so coolant can circulate and get to the stat (like 1/8 inch). Fan clutch could be an issue, if it spins when warmed up and engine off, more than a partial revolution, swap it out. But bad fan clutch more frequently shows up as poor cooling when slow moving.

One owner took his three hose stat out, and poured hot water from a teapot in it at a known temperature to verify operation. If those little holes in top leg are blocked, temps would be higher. Enlarge slightly?

The way that bypass stat works is below operating temp when main stat is closed, the bypass disk can descend and allow coolant flow for heater. Once warmed up and opened, the main stat forces the bypass disk back into parked position. The flow thru the metering holes brings hot coolant from the "T" to the main "mixing chamber", where mixed with return water from the radiator. This warmed up water controls the opening of the main stat. So if anything changes the size of those little holes, stat won't get to operating temp as soon or as often. Block will be hotter, but stat thinks it is doing the job it was designed to do. The double wall chamber lets water leave through slots and out the side hose port to the intake of the water pump.

What can block holes? Sludge, trash broken loose from cooling system work, stopz leakz, shipping peanuts from new parts, shop rag, etc.

Note: If holes too big, some D2 (perhaps more often with SAI) have a sensor on the bottom of the rad that detects too small a difference between top and bottom, and thows a code for a stuck open thermostat. Same for weep holes on an in-line.

In a lot of cars and pickups there are bypass stats. I have seen more that are mounted with bypass disk on the bottom, which might account for less trash settling on them. Of course, this whole design is the work of engineer Hermann "Deep Fried" Fritz, a silent partner in the head gasket business....