Hi guys,
Got a disco 1, 3.9 v8i, non air con model

Bit of a run down so you know the background-
Bought the car with an overheating issue. Flushed the rad, changed the thermostat (stuck closed), everything else seemed fine so topped up the coolant slowly to avoid air traps (i know they have a self bleed but wanted to be certain)

So, took the car on its maiden voyage- bubbling noise from the engine. Was fine for 5 miles until i hit the motorway when the engine temp rocketed and i safely pulled over at 7 miles from home.

Engine was overheated so got recovered back to base

The general consensus was headgasket failure. With the rad cap off i would rev the engine and bubbles would come out of the radiator filler hole, did this a few times to see if it was just trapped air to no avail.

So before i stripped the engine i was reccomended a product called steel seal. Thought it was worth a go, followed the instructions to the letter and put two bottles in the radiator- ran for 60 mins then left to cool.

So came back to the car- when i rev there is still a bubbling sound from behind the dashboard. Still bubbles from the rad (when i press and release the throttle) put the rad cap on and watched the coolant circulate in the expansion tank- appears to be no bubbles in there.

I don't want to test the car again on the motorway as my nerves wont take it and i have limited recoveries with the RAC.

Idling the car doesnt overheat, it sticks pretty steady apart from minor rev fluctuations (revved high today when i started it)

I know it is possible the steel seal didnt work (at £40 a bottle nearly i now need a breakdown or garage report to say it didnt work to get my money back!)

Has anybody got any idea at all what might be wrong or where to even look?

Ohthe tranny fluid is a low but dont think that would cause bubbling when i revv or accelerate.

Please help!

Don't think that the Disco1 is self bleed for coolant ...

sound like heater matrix has some bubbles of air in it ...

Could this cause overheating? I have read just about every article i can find on it, only one suggests it could cause overheating. The only bleeding process i am yet to try is using a pump to create pressure in the system and force air out

Dippypud said:

Don't think that the Disco1 is self bleed for coolant ...

sound like heater matrix has some bubbles of air in it ...

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300 series D1s have a sealed engine cooling system and is self venting like all modern cars and yes if there's a bubbling sound behind the dash that is air in the heater matrix. But the question is why.

It is possible that air is getting into the system still via a faulty head gasket or worse

gregat273 said:

Could this cause overheating? I have read just about every article i can find on it, only one suggests it could cause overheating. The only bleeding process i am yet to try is using a pump to create pressure in the system and force air out

Click to expand...

There's 15 psi when the coolant heats up, is the level normal when cold?

The usual suspects for overheating are fault a radiator, thermostat failed closed and a faulty head gasket.

Is it the same or different on a v8? Because i have bled it and bled it and bled it until i have started bleeding!

I am hoping that the steel seal worked, i have been unable to find a test kit to test for combustion gasses in the coolant but the oil seems fine, no milkyness or discolouration that i can see. Would i see evidence of this on the spark plugs maybe or is there a cheap and easy way to testfor head gasket failure without buying a compression tool?

Yeah the level is pretty stable when cold, havent noticed any fluctuation and there are no leaks that have made themself known yet. (The passenger floor is mouldy but it is near to being under the passenger seat not under the dash which makes me believe this is just down to faulty door seal or a nice rusty hole somewhere?) saying that, the glove box was damp.... Leaky heater matrix?

gregat273 said:

Is it the same or different on a v8? Because i have bled it and bled it and bled it until i have started bleeding!

I am hoping that the steel seal worked, i have been unable to find a test kit to test for combustion gasses in the coolant but the oil seems fine, no milkyness or discolouration that i can see. Would i see evidence of this on the spark plugs maybe or is there a cheap and easy way to testfor head gasket failure without buying a compression tool?

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eBay no 181253391968 - less than £15. Nothing to do with me before anyone asks. Don't know if it would fit a V8 but comes with adapters, so I assume so.

Would hardly break the bank and handy to have anyway.

Best way to tell for HGF though is a sniff test. You should be able to find a local garage or mobile mechanic that would be able to do one for you without breaking the bank.

It does sound like a heater matrix full of air though if the gurgling is coming from behind the dash.

Whats a sniff test?

flatline said:

Whats a sniff test?

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I'm not entirely sure how it works, but essentially it's a test for combustion gases in the coolant. Done with some sort of clever probe thingy that can 'sniff' the relevant chemicals in the coolant. Used to detect head gasket failure in the early stages (before mayo in the oil or bubbling out of the expansion tank or what have you occurs).

Cool,I imaginged some old bloke they keep in cupboard and only gets let out to sniff the coolant tank.

You say that but I imagine there is somebody somewhere with such mystical 'powers'!
Only problem is being self employed and having already spent a fortune on this damn thing £15 is alot of money at the minute anda garage would defo break the bank.

I think I will try change viscous unit and try some bleeding methods I have come accross (getting the rad higher than the matrix etc)

Pretty sure the bubbling isn't the only reason it is overheating and I have heardloads of good stuff about steel seal for me to say it hasn't worked without the proof

Ok so we have to assume that this product has worked, but there's another reason for over heating, air in the heater matrix won't cause the engine to over heat only poor heating in the cab possibly, it's not the primary engine cooling system.
You can do a practical test on the viscous coupling ie. try and move the fan blade when cold and then the engine is warm but even the sound of it will give u an idea of it functioning correctly.

U don't have to touch the rad, just Jack the front up or face up a slope, air will then travel to the expansion bottle with the system under pressure and engine running.

I have no knowledge of the V8's, but could it be a faulty water pump, damaged/corroded impeller causing low coolant flow ?

Yeah the cab heater works pretty well. I'm going to take her to my local garage see if they come up with anything. Said they had a few things they could check and only charging £40