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[Amego52]

Ok, Monday I replaced my water pump, cured that leak, today I replaced the HBV which was an obvious leak. The car runs absolutely fine but now I have a leak at the back of the engine somewhere, it is finding its way to ground further back than the bellhousing and I can hear the sizzle of water dripping onto a downpipe.  I have re-checked the HBV and all is well and I cannot see where the water is coming from. The car did have a boil up the last time it was used nearly a couple of years ago. Is it sounding like a crack somewhere or a head gasket? The car is a 98 V6 and I am now at a crossroads as I am trying to prepare it for a life abroad. Any help appreciated.

[Kevin Wood]

There are drains from the air conditioning evaporator back there. Are you sure it's coolant and not water? Does it still leak with the air conditioning turned off?

Kevin

[Amego52]

Hi Kevin, I'm pretty sure it's not that as the air con isn't working yet. The water in question is dripping hot.

[Brucie1946]

Hello,

could be your oil cooler top plate leaking, mine did, just replaced with completely brand new, might be a worthwhile upgrade especially if you have the old style oil cooler.  Can also be the coolant bridge, which feeds water to the heads, these often leak too.  Replace with dowty seals instead of crappy seals from vauxhall.

Just a possibility mind you!

Dean

[Amego52]

Hi Dean, based on what you said, I have just had a look by torchlight into where the cooler is, It all seems to be dry at the front and back. Also I had the cooler changed some time ago and it has only done about 20000 miles since. Cheers.

[Amego52]

Sorry, just giving this a bump before it goes to page 2 

[Amego52]

Right, I'm stripped down to the oil cooler and bridging pipe, the top plate seems to have a weeping spot at the front end, not the sealed bit but on the top face of the plate in the middle of nowhere, is this common (bearing in mind the water leak is coming from the back somewhere). Can you buy just the top plate or am i going to need to do the whole cooler which seems a shame as it hasn't done much work since it was fitted.
Also where can i get these dowty seals from.
Can the system be pressure checked before I carry on other than razzo's way in the how to section, like get somebody else to do it.
I must admit i am a bit nervous of going any further as a mechanic I am not!
I am still convinced that something more sinister is going on like a cracked head or something.
Thanks in advance chaps.

[Kevin Wood]

Oil cooler plates have been known to hole due to corrosion. Maybe someone on here breaking a car would be able to supply a good used one?

Other ideas - '98 V6s have been known to leak water from the rear of the head gasket...

Only other possibilities I can think of are the O ring where the transfer pipe from the bottom rad. hose meets the back of the block or perhaps the heater matrix if it's coming out of the aircon drain holes?

EDIT: If it;'s been laid up with poor coolant could it have frozen and popped a core plug round the back somewhere?

Easy to pressure test: Get an old coolant tank cap and fit a schrader valve to it (a tyre outfit will probably be happy to give you some old ones).

With the engine stripped as you have it, block the two ends of the throttle body coolant feed pipe and pump it up to 1 BAR with a tyre pump. Watch for leaks.

Kevin

[Amego52]

Plenty to think about there Kevin, thanks.
Its last journey two years ago ended The HBV leaking, resulting in a good boil up which fried the water pump seal, causing it to leak badly.
It has sat outside with no coolant (just water) until Jan this year when I pulled the water pump off. Sounds like every chance it could have done a core plug or worse then.
Is the O' ring on the bottom rad hose easy to get to?

[Amego52]

Right then, I have constructed a means of pressuring the water system thanks to the how to, and it works really well in case anyone needs to know.
It turns out that Kevin was right, as well as the oil cooler top plate leaking slightly, there is water coming from the drivers side air con drain pipe, but, it is water from the main system.
Does this mean my heater matrix is shot? If so is it a nightmare?
Cheers everyone.

[polilara]

I seem to have same kind of problem (see my "coolant leaking both sides of the gear box... from today) Did you already find the O-ring - was it difficult to get to ?
This is strange. Nothing is leaking and this red coolant is coming from somewhere

[Amego52]

Hi,
the only O'ring i'm aware of on the back is where the radiator bottom hose pushes on. As yet i have not had to deal with that.

Hopefully a knowledgable gentleman (or lady) will be along to put me right.