Coolant level/pressure

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Originally Posted by Blknight.aus

hang about isnt it a V8,, arent the v8s ment to be on ethyl glycol...

double check what coolant you have , the 2 different types do not like each other.

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You're right about it being a V8 Dave - hadn't noticed that.

However, just checked on Rave, and it says -

"Use Havoline Extended Life Coolant (XLC), or any ethylene glycol based anti-freeze (containing no methanol) with only Organic Acid Technology corrosion inhibitors, to protect the cooling system.

CAUTION: No other anti-freeze should be used with Havoline Extended Life Coolant.

Rave quotes the same anti-freeze for both TD5 and V8, both at 50% dilution - the only difference is the quoted volumes. TD5 is 4 litres of anti-freeze, total re-fill volume of 8 litres (13 litres from dry) and V8 is 6.5 litres of anti-freeze, total re-fill volume of 12 litres (13 litres from dry).

oops. well spotted Dave, i missed that too!

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Originally Posted by BMKal

You're right about it being a V8 Dave - hadn't noticed that.

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Yes, its a petrol V8!
Right, before I start on looking into this, I was speaking to mechanic mate of mine who reckons, before I start doing anything, to check with you guys that I have the correct expansion tank cap. He pointed me to an article that states:

"The radiator cap is more than a cap for your radiator; it keeps your engine cool by sealing and pressurizing the coolant inside it. It is designed to hold the coolant in the radiator under a predetermined amount of pressure. If it was not kept under pressure, it would begin to boil, and soon all the coolant would have boiled away. However, the radiator (or pressure) cap prevents this from happening by exerting enough pressure to keep the coolant from boiling. If your cooling system is under too much pressure, it can "blow its top"! To prevent this, the radiator cap has a pressure relief valve. The valve has a preset rating that allows it to take just up to a certain amount of pressure"

So that got me thinking. How do I know if I have the right tank cap? Does anyone have a part number or something I can check it against? (Year and model in sig).
With the motor hot, when I release the tank cap by hand, I get a lot of pressure release and the tank fills back up to where it should be, from looking like it was empty.

Might just be worth a try before I get round to draining and flushing...?

Cheers in advance,


..:: KIEREN ::..
2000 Disco II Auto V8

Here's a few things you could try based on my experience, and these should show up a fault with either the head gasket or the motor, doesn't hurt to try. Someone please correct me if i'm wrong about any of this.;)

1. In the morning or when the car is cold, release the radiator cap, no pressure to come out at this point, maybe a little suction.
2. Have the mechanic check for exhaust gases in the coolant, they should have or know of someone with the tester.

I have either a blown head gasket or a cracked block :mad: on my 4.6, when I release the pressure the coolant level rises back up to the normal mark. I also have pressure in the system in the morning. The temp guage also does not go above the halfway mark.

Stu