Thread: Defender Tdi300 cooling system

I'm also pretty wary of high temps on my 300tdi. 1998 with a recently new AMC head, recently rebuilt injection pump and new timing. Valve clearances reset regularly. Disco 1 auto by the way

I have dual temp gauge - digital - which I bought through Rover parts. The AMC head had a few spare bolt holes (used for if fitting alternative inlet/outlet gaskets and pipes to a rebored and restroked 2.8l kit), perfect for attaching one temp probe. I haven't actually fitted the second probe, but I'll probably fit it to the sump or bottom of the block. I also have a low coolant alarm, ordered through aulro.

Summer in North QLD - can sometimes hit 105deg on the head up one of the long hill climbs. Usually on the highway, I'll sit on 90-95kmh and see the head sit around 95 deg. That's an auto with lockup and in 4th gear. I'll usually do the same as you - crack the heater on if its getting a bit too warm. I'll try get the second probe on the sump and take her out for a run this weekend - let you knw

1998 Disco 1 300tdi no edc no abs
1995 Disco 1 v8i dual fuel RIP

It's not leaking oil, it's bleeding power.

Just a thought but could it be possible that the oil cooler is heating the coolant in the radiator and not the engine temp. I was thinking that it only gets warm when the turbo is working at full capacity and that the oil running through it must get pretty dam hot. Another interesting factor, I have a oil pressure gauge and as the engine is under load, the oil pressure can drop as much as 170kpa (cold motor 390kpa down to 220kpa when the engine temp gets up to 3/4s) I would have thought that the oil viscosity wouldn't change that much but I guess clearances change and don't know so much about turbo temps and the oil temp being released back into the sump from the turbo. Another consideration, is it possible that the bottom radiator hose could be collapsing and restricting water flow from the radiator to the pump. A common problem with the old holden sixes but Im not sure if this has ever been a problem with the landrovers??


cheers

The factory gauge is (as you presumed ) normalised
Mid level reading is for coolant temps at the head of about 65-100degrees
If the guage moves your coolant temp is over 100

Many options as to why you are overheating
Start at the top and keep working

Steve

Originally Posted by swivelrat

.... I have a oil pressure gauge and as the engine is under load, the oil pressure can drop as much as 170kpa (cold motor 390kpa down to 220kpa when the engine temp gets up to 3/4s)....

I got a D1 Tdi.
Note sure on engine history, as I've only had it for about 6months.
Head has been redone at some point tho.

My oil pressures are: cold 60-65psi(440-ish kPa) which slowly drops to 53-48psi(350-ish kPa) at normal operating temp(83 degrees) at about 2000 RPM on an easy cruise.
Never really checked at idle tho.
This is now with Penrite's full synthetic 15W60.
No idea what oil was used when I bought it, but it was (literally) just serviced the week prior when the owner got the RWC for it.
Oil pressures with that unknown oil were much lower.
Mid 50's cold at cruise and high 20's to low 30's at operating temps.

Basically changing from whatever oil it had(at about the 6000klm point that I owned the car) to the Penrite, gave the car roughly 5-10 extra psi in oil pressure.
2000klm later the values are still basically the same.

Have you got bull bars,spotties,winches etc in front of the rad?,is the shroud fitted?,is the engine tuned up?.Check the fan with a paint brush,change the thermostat with a genuine one,are the hoses ''ballooning'' when hot,do you have the correct coolant mixed correctly. Pat

Thanks Pat303, yes to winch, spotties, bull bar but it didn't get hot previously with these on so Im more interested in what's changed under the bonnet. New radiator, hoses, pump, third fan and third thermostat with no change to creeping temp.


However, I now have new theory. The heater is fed with coolant unrestricted from the head, through the heater and then feeds into the bottom hose and back into the pump/engine. When the engine is at operating temp, thermostat open, bypass closed, depending on what flows easiest there is nothing to restrict the coolant coming straight from the head through the heater and back into the bottom hose potentially recycling uncooled coolant. Most heaters are operated by an inline valve but the defender only blanks off the air going through the heater matrix. Tomorrow, Im going to block the heater flow and see how that goes. Could make all the difference.

I suggest not to block the heater flow.
It is an important part of the head cooling.

make sure the 3x 1/4 hoses from the rad/thermostat/res are clear and free flowing.

It does sound a bit like a partial blockage but I could be wrong.

Listen to jboot51 tho. Do NOT block the heater circulation on a 300tdi! It is needed to safely get the engine up to temp before the thermostat opens.