Thread: Cooling System - 1980 3.5lt Range Rover

Have a situation where the cooling system is pressurising when motor is running forcing coolant into the expansion tank but not drawing it back as motor cools. Noticed the problem after seeing discharge from the expansion tank overflow pipe dripping on shed floor.

When you release the expansion tank cap the following day you can loose up to 1/2 a litre of coolant through the overflow pipe.

Vehicle starts and runs well through appears to run hotter on the guage than one would expect when warmed up.

Problem surfaced about a week ago after towing a trailer with 3/4 tonne of hay onboard.

Any ideas of cause or how to resolve ?????.

Thanks
Dunno

Originally Posted by LukeV

Sorry guys, it is a 3.9i.

I've been worrying about it being a slipped liner for a while now. The head guy said the heads have been machined 5 times!

I have replaced the cap with a non-recovery system type cap. I am pretty sure it is 15 or 16psi.

Is there any way of determining a slipped liner? I had a good look when the heads were off but I imagine it is hard to see if they have been moving.

I'm still hoping it is just an air leak somewhere causing an air lock, forcing the water out of the cap but then sucking air back through the leak rather then the coolant out of the expansion tank. The radiator did have a slight leak between the RHS tank but that has seemed to stop after I did the heads (was off the road for 3 months :P )
The coolant seems to pass through the cap when at 90-95+ degrees, which seems to indicate the system is either getting pressurised either through trapped air or leaking gasses from the engine (slipped liner, gasket, cracked block, etc).

Thanks guys,

LukeV

G`day Luke

It`s very hard without being on the spot .

A slipped or moved liner is fairly easy to see if you have an idea what to look for , not just peering at but using a magnifying glass and feel the right bits but also before removing anything getting an idea which side and cyls to be looking at .

For yours to be a liner problem i would expect that you`d have seen something when the heads were off .

The liner problem will tell like a head gasket fault allowing pressure past and into the coolant system but this occurs in the later stages of the problem .

Generally but not always the engine need to have been overheated , for some engines once is enough , others a couple or three , some it won`t matter , there`s no telling just like lotto so none is best .

In the early stage there would have been coolant loss without external signs , one reason if it is an overheating 94mm engine ( 3.9/4.0/4.6 ) that it is important to fix any external leaks no matter how minor .
( Since yours had a leak in the radiator it`s hard to measure loss where a liner is concerned ).

Another sign is rust or strange coloured sparkplugs specially if any of the middle cyls , 3,5,4,6 , the 4 end cyls are harder because they are all near where the coolant passages are in the heads but none of the middle ones see any coolant that can get into the cylinders .
Some may suggest that a crack in the head could allow coolant into the mid cyls and they`d be right if it ever happened .

The only Rover head i`ve heard of doing this including ones that have been hot was one and only one that had been modified from factory and had the ports opened up too far so was nothing to do with a fault in the head but that it had been releaved too far so the wall between the port and passage failed .

Another sign of a liner problem is on first start up from cold and normally only from cold , is excessive moisture coming out of the tail pipe . ( untill later stages then it doesn`t matter hot cold or otherwise )

When the engine is shut down and is cooling , the pressure in the coolant system is still enough to push through the block cracks past the liner into the chamber .

The cracks are usually far enough down the block that the combustion pressure holds the coolant at bay while running , in the first stages in the last stages the combustion pressure makes it way into and pressurises the coolant system .

Most of the above will be signatured

The best way to know if you have an air lock when refilling is to use measured bottled with the right quantity for the L/R manual , this way if you don`t fit it all in you need to find out why not .

With the engine started and the thermostat open , with the cap/plug off/out of the radiator run it up to and hold around 1500 - 2000 rpms .

When or if the level lowers top it up and let the revs fall fluid may be lost , run it up again , do same , let it idle till it settles , the radiator should be full .

Always fill and check level at/in the radiator . Top up at the tank but check radiator .

If it has any leaks it can suck air and will be impossible to get rid of air till the leak is repaired .

If at idle for 10 or 15 mins and it starts to overheat could be air in system ( though generally show sooner ) or could be the cooling fan isn`t working as should . Could be a blockage and other things also .

If at speed it overheats under load ( trailer acceleration ) but not at cruise/steady gentle pace 100kph could be air , gasket liner etc .

Only suggestions and too much to take in i know .

Cheers

ADD........... just to make it longer .......
Our RR has falcon fans on it , i`ve fitted an idiot light so`s i can see when the gauge rises that they are working .

They only come on at a temp set by whoever sets/fits them .

The Viscos work at a different range of temp which is why the gauge doesn`t tell when it works . They do there thing before the gauge knows about it .

I didn`t like them when i first fitted them but being used to how and when they work now and knowing that if fitted correctly with a shroud that draws from the entire area of the radiator and is sealed properly and fitted so`s no damage can be done to the radiator tanks etc , by vibs etc , i think they are a good thing , they move more air than viscos , they allow under bonnet work with the engine running easier and they allow the engine to be heard easier etc .

For piece of mind a know working Viscos fan is also good , if going bush for more than a couple of days the visco would be my choice but for road and economy the electric .

Also i have a 110 amp alt which is part of electic upgrade ? The electric draw alot of current when working but they should only be working at lower speeds or something no right .