The V8 Owners Forum -

odd prob, fitted, built and owned rv8's for years but never had this before!
just got a m reg(1994/5) discovery auto/aircon with a 3.9 v8i, but not origonal engine it has a later cross bolt block engine fitted about 5-6 years ago by land rover. got it cheap cause prev owner was convinced it had cracked block/liner.
it looses a tiny bit of coolant but never gets above the half on temp gauge and doesnt push water out.
BUT the top hose is bulging out with pressure after short trip, the other hoses seem to be ok i can squeeze them but top hose is always swollen and hard as rock.
i have fixed a couple of small leaks on the lpg hoses, hopfully accounting for the small coolant loss.
i drove this back from northampton to derby at full chat up the m1(with plenty of spare water in the back!) and it didn't loose any coolant or get anywhere near hot, surely if it was cracked/porus block it would have got hot and used coolant!
he says he has changed head gaskets viscus unit and thermostat(i presume it has an 88 deg, havn't looked yet) and it looks like it has a new 15psi rad cap on the expansion tank. have bled system as i could hear air bubbling in the heater matrix.
i also cant see any sign of bubbles in the coolant just this excessive top hose pressure, it also reaches temp quite quickly.
sorry for the long post any ideas?

Does it still do it when running on petrol? I had an internal leak in the vapouriser which passed LPG into the water jacket and pressurised it and made it gurgle.

Chris.

The entire cooling system will be at the same pressure.


Are you sure the top hose isnt just ready to fail ?

i thought about the vapouriser but it was replaced as part of lpg service in january(got recepts to prove,), i suppose it could still be faulty though, i have another top hose on order as i thought the same thing, the main bulging is near the stat housing, the whole hose expands alot though i would have thought a hose fail would be a localised weak spot. it is the type of hose that is routed very high, much higher that the expansion tank, crap design.
had the stat out today and as i thought it is an 88 deg, going to swap for a 74 or 78 as a preventitive measure against block cracking. see what happens when new top hose fitted if thats all it is i've got a bargain (£300) but knowing my luck it'll be more serious!

stevieturbo wrote:The entire cooling system will be at the same pressure.


Are you sure the top hose isnt just ready to fail ?

Actually not so

if the rad is blocked for instance the pressure at the inlet will be far greater than the outlet

For this reason placement of the pressure relief valve / cap could make a difference in a kit car.

Once engine is off then yes pressure will be the same around the whole system

Ian

Ian Anderson wrote:

stevieturbo wrote:The entire cooling system will be at the same pressure.

Are you sure the top hose isnt just ready to fail ?

Actually not so

if the rad is blocked for instance the pressure at the inlet will be far greater than the outlet

For this reason placement of the pressure relief valve / cap could make a difference in a kit car.

Once engine is off then yes pressure will be the same around the whole system

Ian

Are you sure about this Ian?

The pressure in the system is to do with the heat and expansion of the water, not the water pump, so should be consistent throughout the system. Ok it will be slightly different, but not so much that could be felt by squeezing the top hose.

I have read it can be as much as 5 - 10 psi different at different points in the system

This also helps account for the massive difference in poundage on the pressure caps from about 7psi to over 30psi

Ian

right, replaced top hose and yes it was tatered and giving a false impression of pressure i have also caustic flushed the system as the rad was slightly blocked and fitted a 74 deg stat. done a compression test and all cylinders excellent 150psi plus, BUT system is getting hot spots, it is not using water or getting hot on the temp gauge but is boiling in the top hose and expansion tank the rest of the engine seems ok.. checked water pump and is fine begining to think the block is indeed cracked behind a liner, time for the ironite block seal! unless anyone has any more ideas?

Is your pressure cap sealing?

If not you lose the ability for the fluid to get above 100 without boiling

Ian

its had a new cap(at least prev owner says it has, looks new!) but will replace it anyway, its not pushing water out though, i would have thought it would loose water through the cap if it wasn't sealed. i am begining to wonder if a crack behind the liner is putting a stream of bubbles in to the system and creating airlocks/hot spots at high points. cant see any bubbles in the header tank though. the aircon is cutting out as well which it supposed to do if the coolant temp gets to high, the gauge always reads about right though, and now slightly cooler since 74 deg stat fitted(just under 1/2 way).

problem now solved! chucked in the ironite and now no problems, i have also changed the rad as i was not convinced it was completely unblocked, after a few short runs and a long one all seems fine and dandy!
cheers everyone!

sorry to hijack but i am having exactly the same issues 98 disco 1 3.9 efi auto

what it irontite is it somthing that locates small leaks and blocks them?

Thanks
Si

http://irontite.com/store/index.php?mai ... ducts_id=1 available in the UK from here http://www.p38spares.co.uk/commerce/ind ... umber=1010 and probably lots of other places.

thats handy to know cheers marki

Tried and tested on my leaking rover block Kalimex K-Seal
worked a treat and i've not lost a drop of water so far
http://www.kalimex.co.uk/