Thread: Runs hot!!!

extract from RAVE, TD5 cooling system;

" General.
The cooling system used on the diesel engine is a pressure relief by-pass system which allows coolant to circulate around the engine block and heater circuit when the thermostat is closed. With coolant not passing thru the by-pass or the radiator promotes faster heater warmup which in turn improves passenger comfort. A coolant pump is mounted on a casting behind the PAS pump and is driven from the PAS pump at crankshaft speed by the auxiliary drive belt. The pump mounting casting connects with passages in the cylinder block and pumps coolant from the radiator thru the cylinder block.
A viscous fan is attached to an idler pulley at the front of the engine. The fan is attached to a threaded spigot on the pully with a left hand threaded nut. The fan draws air thru the radiator to assist in cooling when the vehicle is stationary. The fan rotational speed is controlled relative to the running temperature of the engine by a thermostatic valve regulated by a bi- metallic coil.


Thermostat housing
A plastic thermostat housing is located behind the radiator.The housing has 3 connections which locate the radiator bottom hose, top hose, & coolant feed pipe.The housing contains a wax element thermostat & a spring loaded by-pass flow valve.

Thermostat main valve
The thermostat is used to maintain the coolant at the optimum temp. for efficient combustion and to aid engine warm - up.The thermostat is closed at temps. below approx. 82 degrees C [ 179 degrees F ] . When the coolant temp. reaches approx. 82 C .The thermostat starts to open, and is fully open at approx. 96 C [ 204 F ]. In this condition, the full flow of coolant is directed thru the radiator. The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from the radiator bottom hose on the other side.
Hot coolant from the engine passes from the by-pass pipe thru 4 sensing holes in the flow valve into a tube surrounding 90% of the thermostat sensitive area. Cold coolant returning from the radiator , cooled by the ambient air conducts thru 10% of the thermostat sensitive area. In cold ambient temps. , the engine temp. is raised approx. 10 C [ 50 F ]to compensate for the heat loss of 10% exposure to the cold coolant returning from the radiator bottom hose.

By-pass flow valve
The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up.When the main valve is closed and engine speed is below 1500 rev/ min. , the coolant pump does not produce sufficient flow & pressure to open the valve. In this condition the valve prevents coolant circulating thru the by-pass circuit and forces the coolant thru the heater matrix only. This provides a higher flow of warm coolant through the heater matrix to improve passenger comfort.
When the engine speed increases above 1500 revs/min. the coolant pump produces a greater flow and pressure than the heater can take. The pressure acts on the flow valve and overcomes the valve spring pressure , opening the valve and limiting the pressure in the heater circuit. The valve modulates to provide max. coolant flow thru the heater matrix and yet allowing excess coolant to flow into the by-pass circuit to provide the engines cooling needs at higher engine rev/min.

There you go, quite simple, really........ Bob

That's great bob10, read it a number of times. As you say quite simple, really.

My issue, and issues experienced by others is the temperatures running hot on the V8. Simple–too hot!

This is why I looked at the cooling system mod, then found information on a lower temp stat.
The bypass system is only for when the stat is closed, engine not up to running temperature.

M

[QUOTE=diesel;1676528

My issue, and issues experienced by others is the temperatures running hot on the V8. Simple–too hot!



M[/QUOTE]

Yeah, I've read quite a few threads here about overheating, and often wonder if the Gulf Spec Discos , sent to Saudi Arabia and a few other places in the Middle East , had their cooling systems upgraded. I know there is a grill, called the D2 Saudi grill [ mesh ] , also fitted to limited edition vehicles [ Trek, Kalahari, Gulf spec], which the makers say deliver more air to the radiator, especially for V8's. Makes you wonder if Gulf spec D2's have a great deal of difference in their cooling systems, Bob

I've just found a scrap piece of woven 1/2" stainless mesh and will be hitting the local sheet metal shop next week to start on a stainless replacement "Saudi" style grille.

Originally Posted by diesel

They do run very hot to meet EU emission standards. Mine runs hot, too hot in my opinion. The electric fan is on 75-80% of the time. This is normal driving, no towing or weight carrying–I don't even have a tow bar...
I will be carrying out the cooling system mod, from what I've read it gives a more consistent temperature during all driving conditions.

M

The electric fan comes on with the air conditioner. You're hot if you turn the engine off and the fan continues to run.

Originally Posted by diesel

My issue, and issues experienced by others is the temperatures running hot on the V8. Simple–too hot!

M

What evidence is there for this?

I read somewhere that there is the thought that the head gaskets blow and so to reduce the coolant temp to fix this, but I can't see evidence for the relationship. Perhaps it has to do with the changes in the engine manufacture, exhaust manifold merge, perhaps it is related to injection and timing. The temps run in the Thor and Storm are not uncommon. One thing that I suspect affects the liners is high combustion temps - but I don't believe that is coolant temp related. The liners are marginal on thickness anyway.

Wrong thread

Gulf Spec Discos , sent to Saudi Arabia and a few other places in the Middle East...

I have seen that grill too bob10, I'm sure a competent trades man would be able to knock one up from an old grill.

The electric fan comes on with the air conditioner...

This is true Slunnie, if your aircon is on.

What evidence is there for this?

Experience & understanding. Good old 'know your vehicle'. (see below. Hot!)

Another update:
I emptied & flushed out the 'strawberry cordial', replaced with 'Monster Energy' green... Great news is, my fan never came on once. This is great considering I had the long weekend at Lavuka, using the tracks & having fun. I can even touch the bottle jack! This is true, I could not remove the jack previously until it had cooled.

Standard vehicle with all options, Good Year factory tyres (low on tread), no CDL... unstoppable, only the black mud on a steep slope and a bad decision to go through a deep mud hole stopped her. Impressive.