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[grifter]

3.2 elite

Last couple of months I've been loosing coolant, got to top it up after say 50-100 miles back up to level, usally when light low coolant light comes on. After a run the other night had a good look underneath, left it sitting for a while on my drive, couldn't see any drips anywhere, had a good scour around engine bay with torch no sign of anything. Done block test last night and nothing showing, not that I suspected HG but just ruling it out.

Last year replaced rad, oil cooler, hose from block to heater radiator also replaced the top rad fan switch, still got the lower one to do, also replaced the aux water pump under the coolant bottle as it was leaking, that was last Year too. Also checked the floors for any water ingress, bone dry. Only thing I can think is maybe leak from oil cooler plate and it's running down the back of the box or something and I can't see it. Made sure I used the right sealant and that everything was clean and torqued up properly so be surprised if it's the oil cooler plate leaking, although if it was that then perhaps it is dripping out when the car is moving and then pooling somewhere in the V when stationary, then pouring back out when I'm moving so I don't actually see the leak.

Hopefully get in on the ramps at the weekend and get right under it. HBV is quite new so not suspecting that either.

[YZ250]

........
HBV is quite new so not suspecting that either.

I wouldn't completely dismiss the HBV, as my original on my 3.2 lasted around 80K miles but it's replacement lasted less than 5K miles. The replacement was purchased from a main dealer and the box had the hologram on it. The second replacement was still OK when I sold it. Worth checking using the max high temp, max low temp method. 

[TheBoy]

Carefully check the plastic parts of the main rad for leaks as well.  IME, you won't see a puddle under the car, and probably won't see much in way of steam either.  Its hairline cracks that close when the pressure drops.

I had a spare cap with a shrader valve in, and pumped up to about 8PSI, then used a torch to locate mine.

[TheBoy]

........
HBV is quite new so not suspecting that either.

I wouldn't completely dismiss the HBV, as my original on my 3.2 lasted around 80K miles but it's replacement lasted less than 5K miles. The replacement was purchased from a main dealer and the box had the hologram on it. The second replacement was still OK when I sold it. Worth checking using the max high temp, max low temp method. 

There did appear to be a duff batch a few years ago, a few people, myself included, got caught out

[Migv6 le Frog Fan]

Heater matrix is also a possibility. I currently have similar symptoms due to a small leak at the matrix.
Which reminds me, I really must get off my arse and replace i soon.
Only use it occasionally, so havent been desperate to do the job.

[TheBoy]

Heater matrix is also a possibility. I currently have similar symptoms due to a small leak at the matrix.
Which reminds me, I really must get off my arse and replace i soon.
Only use it occasionally, so havent been desperate to do the job.

I would have thought you would have smelt it if it was heater matrix?

[grifter]

I just got my coolant pressure test kit in there so put it on and pumped up to 15psi, I can see water dripping down the back of the engine, just forward of the heater matrix pipe sort of down onto the back of the box.

Will need to strip out the plenum and stuff to investigate further.

Thanks for all other suggestions so far. Will have a check round other bits while I'm at it with the test kit.

[grifter]

........
HBV is quite new so not suspecting that either.

I wouldn't completely dismiss the HBV, as my original on my 3.2 lasted around 80K miles but it's replacement lasted less than 5K miles. The replacement was purchased from a main dealer and the box had the hologram on it. The second replacement was still OK when I sold it. Worth checking using the max high temp, max low temp method. 

There did appear to be a duff batch a few years ago, a few people, myself included, got caught out

I did get 2 new ones a couple of years ago with GM numbers on them, hopefully mine's isn't one of the duff batch.

[Migv6 le Frog Fan]

Heater matrix is also a possibility. I currently have similar symptoms due to a small leak at the matrix.
Which reminds me, I really must get off my arse and replace i soon.
Only use it occasionally, so havent been desperate to do the job.

I would have thought you would have smelt it if it was heater matrix?

So would I , but I didnt. Its only a small leak though. 

[Nick W]

........
HBV is quite new so not suspecting that either.

I wouldn't completely dismiss the HBV, as my original on my 3.2 lasted around 80K miles but it's replacement lasted less than 5K miles. The replacement was purchased from a main dealer and the box had the hologram on it. The second replacement was still OK when I sold it. Worth checking using the max high temp, max low temp method. 

There did appear to be a duff batch a few years ago, a few people, myself included, got caught out

I did get 2 new ones a couple of years ago with GM numbers on them, hopefully mine's isn't one of the duff batch.

The other snag is that although they're unused, they are still just old.

[grifter]

Will need to strip out plenum and stuff to get in there see what is leaking exactly before condeming anything.

[Steveh]

By coincidence my 20l has had a similar coolant leak this week (I know its not like your engine) took mine for mot and it was dripping man refused to do mot got it home no dripping even though still had coolant and engine hot. Even pressure test with compressed air it took some finding it was a pin hole in hose under intake manifold managed to get to it by taking alternator off. Cut about 15mm off pipe and managed to seal.

[Steveh]

Funny at last years mot it developed a leak at mot place but it was the water pump then don't think it likes mot's lol

[robson]

Also had this  problem it was the  water pump.

[Ricky043]

If the leak does turn out to be caused by something that is a big job (i.e. BHG) or if you cannot trace the leak, don't rule out the possibility of sealing it using an engine leak sealer. The modern ones are miles better that the old Holts Radweld which never lasted  very long and I found caused overheating anyway.
WHen putting my dad's old omega v6 back on the road I remembered it had a leak but would never reveal itself. I was told it was a BHG and quoted £1300 to fix. I used a leak sealer and it hasn't leaked since (in about 15 months). No problems with overheating either.

Had a similar problem with my Rover P5B. Could never trace the leak until we took out the engine and transmission this summer to replace the oil seals on the BW35. When we separated the engine and trans, one of the large core plugs on the rear of the engine inside the transmission bell housing, was rusty and pin holed, which would have been squirting the coolant into the bellhousing - not the most obvious place to check for a water leak. The coolant sealer I used was particularly recommended for the vauxhall v6. Cannot remember the name, but still have the empty bottle in the workshop if you want to know.