Mystery coolant loss - big puddle on drive
 

Evening all, hopefully a member might be able to shed some light on a coolant issue I have been having.

The coolant level on the Volvo has been up and down over the past few months.

A few times this year the coolant light has popped up. I have topped the car up but checking under the car for leaks I never found anything that would indicate a leak and nothing on the drive. Was initially concerned it was the HG - and was going to do a test.

Coolant light popped again last night, and this morning there is a big puddle on the drive.

Sliding under the car it appears that the leak is coming from the front of the engine block. So I am suspecting thermostat housing (gasket or crack in housing) or rad top hose (holed / split).

I am just going to start yanking parts, but to help me along can any members advise if the there is anything else coolant related that runs under the inlet manifold which might be of sight, but is know to fail?

Just trying to create a short list before I start yanking parts off the car and dont want to make work for myself!

Cheers

James

I'm not familiar with your engine, 5 cyl 2.0 diesel?

It might be an intercooler unit and will probably be buried around where the engine meets the gearbox area.

Top it up with fresh water and run it stationary, if nothing comes out rev and hold it to 3000 rpm for 30 seconds or so and then check again, it will most likely be a hose that's perished but not visible instantly assuming if there is an intercooler in that area it's not got a cracked housing or simply leaking, also look for coolant staining underneath, it normally dries out around the sump gasket sort of level of the block.

Perhaps don't be confused by air con water on the floor at this time of year ?

yeah ^ that one had me worried the first time

but if the coolant level keeps dropping and needing topup then there is clearly some issue to be located

I had a "mysterious" coolant loss some time ago. I would go for ages without losing any, then all of a sudden I would get the tank coolant low alarm. After refilling it wopuld go for ages without loss and then lose the tank again. After a lot of searching (including dye in the system), it turned out to be the thermostat housing gasket, which only leaked when the thermostat opened. I generally only do short journeys.

Thanks for the replies guys!

Sorry probably entered the wring engine code - its a 2005 2.4T5.

Its definitely not the AC drain, the puddle is huge and when I went to refill the car the morning after the light came on the coolant level had dropped from Min to full empty on the tank - think it was roughly 2L to fill it back to the right level.

MWMan - thanks for the advice, weirdly the coolant level has dropped before but also seemingly only on the short trips / hot weather.

Going to yank the thermostat housing and replace / new seal as a start.

I think there is a water hose under the intake manifold in that region that could be leaking but not easy to see.

Roy

Managed to remove the thermostat housing - I am now pretty sure the leak has been coming from one of both of the gaskets.

Also when disconnecting the top rad hose from the thermostat housing, some excess coolant came out and pooled exactly where the patch was the other day.

I had read a guide I had suggested removing the thermostat housing it could be done without moving the PS pump on a P2 V70.

Wasted a bunch of time trying then just slackened off the belt, unbolted the PS housing an with the hard boost pipe removed I could lift the whole assembly up and out of the way so I could unbolt the thermostat housing with ease. Also means I dont need to disconnect any PS pipe work.