D5 internal coolant loss - gasket or cracked block ?
 

I have an XC60 2014 D5 88K miles
Have had slow coolant loss for nearly a year but recently it has increased.
Exhaust is clear, no other problems, runs fine.
I had an independent garage pressure test the coolant and found no external leaks.
But when he stopped pressurising the system and held the engine at high revs the coolant pressure went back up.
He said this showed an internal leak such as head gasket.
As he is not a Volvo specialist he asked me to find out what were the usual problems with this engine.

I am reading about the risk of cracked cylinder liners.
I spoke to a Volvo main dealer who said that with a cracked liner the whole engine had to be replaced.
Please can anybody comment on what are the possible causes with this particular engine and which of those are most likely ?

Head gasket is a possibility, bit very, very rare.

Cracked block is even rarer with only one ever recorded on that engine on the forum to ny knowledge, and even then I don't recall the garage ever actually showing the poor chap any crack.

Liner problems afflict the petrol units, and even then usually only if abused or tuned tuned excessively. Not to say thats not what it could be, but it would be so unusual as to be almost unheard of.

Properly cared for the D5 motor defines the word "robust". Faults generally tend to be related to ancillary items such as turbos, swirl flaps, belt tensioners, etc, rather than within the motor itself. Never say never, but the odds are in your favour that it isn't something really nasty.

I guess your next step is to remove the head and see what can be found? Not a difficult job, just lengthy. With luck it's just HGF, although I'm a touch concerned there has been a fault for a year because water is effectivrly incompressible and can cause nasty problems if it should get into a high pressure area where it shouldn't be. Hoping that if it is HGF there are no consequential problem as a result of leaving it so long.

Fingers crossed for you, hopefully a new headset and youre all good.

Thanks for your reply. Can you confirm this -

If revving the engine causes an increase in pressure in the coolant header tank (as measured by a gauge attached to filler) then does that mean the problem must be one of -
- head gasket
- cracked head
- cracked block.

Is there anything else it could possibly be ?

Off the top of my head, yes - can't think of anything else that would cause pressurisation proportional to revs.

HGF seems most likely, but even that is very rare if the correct coolant has been used. Provided the engine hasn't been used long term like that, or even worse cooked, a new HG isn't the end of the world by any stretch. A ball ache for the wallet, but that's about all. I'm hoping that is what it is.

However, before getting too excited the garage should do a sniff test to comfirm that it is exhaust gases causing the raise in pressure. One can't just assume, although it seems likely from your description. Even the most back-street spanner jockey should be able to do that, so don't let him try and palm you off.

By the way, I presume you're doing the safe thing and not running the car in this condition?

Certainly on a D5 185 there is an aluminium pipe towards the back of the block. This is out of sight and fits the bill for your problem.

It's caught a few out on here as it is a slow , often not obvious leak.

Why not add some fluorescent dye to the header tank and see where it is leaking.

As already mentioned, head gasket and cracked block are virtually unheard of on the D5.

Read both pages of this thread.

https://www.volvoforums.org.uk/showt...t+leaking+pipe

That block has known issues with leaking headgaskets in fact there is room at one spot between the head and under block which expanses and contracts and after a number of years it starts leaking

See my post below. I had a mystery internal leak. Now fixed. Just giving it you for info as you asked.

https://www.volvoforums.org.uk/showthread.php?t=318347

Are you sure the radiator isn't leaking ? Usual place is the bottom corners of the radiator

Update on coolant leak - sounds like engine crack
 

Thanks for all the comments above.
Further advice would be much appreciated following the latest developments which suggest I may have to scrap the car after only 89K miles ! !

A Volvo dealer has now looked at it as follows -

- Coolant pressure fell from 1.5 to 1.3 bar over 15 mins
- No external leaks
- No exhaust gases in coolant (therefore they say highly unlikely it is HG)
- They say ERG leak is not possible on this model D5.

So a crack in the block is almost the only possibility they can see.
They want to take the head off to look.

If they take the head off and find a crack in the cylinder they say they are not allowed to simply put the head back on (I am in France).
A whole new engine is the only way forwards costing £11K.

The car runs fine today so I see no point in taking the head off, finding a crack and then scrapping the car !

Incidentally the rad was replaced 2 months ago.

My questions are -
- could the leak be so small they are missing it (falls 1cm per 200 miles) ?
- is it really impossible to repair a cracked cylinder liner ?
- could it be in somewhere like the heater pipes and so small I am not seeing damp or a smell - how do I take a look at those ?

I simply find it incredible that this car may be scrap and am looking for any possible alternative ways forward.

Sounds like you need to give this ^ a try.