Redbrown looking residue at the bottom of the expansion tank

[El Padrino]

Thank you Luxobarge and ITSv40. As the thermostat is fine, I'll leave it and have the new OEM thermostat and sensor as a spare.

I thought something was not quite right as I started to fill with coolant. So far, I've added 2 litres of genuine Volvo coolant and 1 litre of de-ionised water. Waited for a few minutes to let the mix go down, but it stayed at the max level without dropping. I was expecting to be able to put the full 7 litres (capacity for a turbo system) of a 50/50 mix in straight away. I got her up to temperature after 10 minutes but the level didn't go down. At this point, I kept saying there's not enough coolant mix in. Went for a short drive and as you rightly said Luxobarge, the low coolant level light came on. Once home, I lifted the bonnet to cool the engine and could see the expansion tank was near empty. I'll fill it up again once the engine has cooled.

[Luxobarge]

Yes, pretty much my experience. Do that once or twice more and you'll be all good. Bit of a pain, but you'll get there.

[El Padrino]

Originally Posted by Luxobarge

Yes, pretty much my experience. Do that once or twice more and you'll be all good. Bit of a pain, but you'll get there.

Thanks Luxobarge, the coolant level looks fine now, after a second top up test drive. Now I've actually got my hands dirty and done a coolant flush and renew, I know what to expect for next time.

Thanks to everyone's contribution on this thread. The information has been a great help for me and hopefully for others.

[El Padrino]

Checked the coolant level yesterday (which was fine) but was disappointed to see a bit of brown/rusty water residue at the bottom of the recently cleaned expansion tank again I think I know the cause. When I swapped out the two old expansion tank hoses, I noticed that the pipes they connect into had brown/rusty water marks on their tips (one pipe by the thermostat housing and the other behind the engine). The rest of the piping looks fine.
Expansion tank hoses.JPG
This must be where the residue I'm seeing is coming from. When I flushed the old coolant, I didn't see any of the residue in it, so that means I don't have sludge elsewhere in the system ie the radiator. I guess that the pipes on these P80 V70s are now old and rust gets here and there.

When I have time, I'll release some of the new coolant I added, disconnect the two expansion tank hoses and clean the tips the hoses connect to. What do you suggest I use to clean the rusty water off the tips? Can I reuse the bit of drained coolant again if I did the slight drain in a month or two (as it'll be quite fresh and new) or should I flush it again completely and add brand new coolant?

[Bob Meadows]

Hi:~
You could use a turkey baster and just empty the header tank to include the residue if possible- is this sediment or a stained tank?
Once the fluid is removed I would replace it with the same amount as removed and to the correct antifreeze mixture.

It is quite a short period since you have done the last flush so why not give it a little more time to see if anything is still being removed from engine internals, it can take a few flushes to clear everything due to the way the engine waterways are constructed.
Rust on hose ends providing the rubber isn't weakened in any way should be OK until you can repeat the flushing process again- hose clips ok?

I would initially do the header tank as suggested- see how it goes after doing more mileage- then repeat the flushing process as my previous post- allow this descaler to work by bringing the engine up to temperature, leave it as long as you can & repeat as much as you can (days will do no harm)
Do the full flush again & hose change at the same time if you think they need it.
Otherwise I don't think that you have any real problems.
Good Luck.
Bob.

[El Padrino]

Originally Posted by Bob Meadows

Hi:~
You could use a turkey baster and just empty the header tank to include the residue if possible- is this sediment or a stained tank?
Once the fluid is removed I would replace it with the same amount as removed and to the correct antifreeze mixture.

It is quite a short period since you have done the last flush so why not give it a little more time to see if anything is still being removed from engine internals, it can take a few flushes to clear everything due to the way the engine waterways are constructed.
Rust on hose ends providing the rubber isn't weakened in any way should be OK until you can repeat the flushing process again- hose clips ok?

I would initially do the header tank as suggested- see how it goes after doing more mileage- then repeat the flushing process as my previous post- allow this descaler to work by bringing the engine up to temperature, leave it as long as you can & repeat as much as you can (days will do no harm)
Do the full flush again & hose change at the same time if you think they need it.
Otherwise I don't think that you have any real problems.
Good Luck.
Bob.

Hi Bob, thank you for contributing to this thread again. I'll get a turkey baster to remove the coolant in the expansion and try that first. At the bottom of the expansion tank is rusty sediment. I thoroughly cleaned the expansion tank of any stains that were there, before adding the new coolant mix. It's not the actual coolant hoses themselves that have the rusty water ends, as I put brand new ones on with brand new hose clips. It's the steel piping forming part of the coolant system that the two expansion tank coolant hoses plug into, that have the rusty stains. They look like this colour but the pipes are not rusting away (not my actual pipes).
Rusty coolant pipe.JPG
I'll give it a bit more time and mileage until I do another flush with the central heater cleaner again. I suppose I could gently rub/brush away the rusty stains from those two pipes next time too.