Ermmmmm............that doesn't look right

[Knight Rider]

Recently my C70 has been losing coolant, new huge but enough to drop it to the minimum level in 3 months since top up. Also today when changing the headlight bulbs, on startup i noticed a hissing noise coming from the back left handside of the engine, sounds like its coming from the coolant hose, revved it and noise went away, but a light trail of steam or smoke came from what looks like the underside of the top engine mount. Any ideas anyone???????

Admittedly it has sat for the last 2 weeks, and turns over/starts fine, not issues with overheating etc..........

So, anyone any ideas at all ???

[T5frankie]

just sounds like a leak mate maybe a split pipe or a loose jubilee clip?

[Knight Rider]

Well had a good look today. can't see anything untoward, no puff of smoke from behind the engine mount - even took it for a little blast down to Baldock n' back can't see anything.
But there is still a constant hiss coming from the back of the engine near the brake servo - also followed the bottom of the coolant pipe from expansion bottle, can't see a split or hole but on each end of the pipe is a build up of white crust/gunk

[mds]

Check the "O" rings on the heater pipes at the bulk head

[bubba_1986]

I have exact same problem, light just came on yesterday. Struggling to find leak like yourself, if i have any luck will let ya know

[ajma]

I have a leak something like that too... nothing obvious / visible except the heatshield above the exhaust gathers coolant over time or after a hard run and the lower part of the brake servo looks like it's getting steam cleaned now and then.

I've already replaced the coolant bottle (which had some very minor cracks) and the hose which connects to the bottom. My next suspect is a very short piece of hose which attaches to a metal pipe heading towards the turbo - I can't see or feel any cracks but the ends of the hose are a bit swollen and there is some kind of deposit on the metal pipe round the connection.

The temperature has occasionally started to go down while driving so I suspect the thermostat will have to be replaced again (was done about 2 years back). Will change the short hose at that point too and see what happens.

[Flatout Phil]

The only coolant pipe failure I ever had on a T5 was the little coolant pipe (rubber) that runs up into the turbo. Not a huge job, but fiddly. Suffers from massive heat of turbo and exhaust as well, and sometimes, oil residue. It loses flexibility and cracks. Worth changing regardless - mine blew when I was 200 yards from home (thankfully).
Pipe from Rufe.

[Wobbly Dave]

the radiators tend to go on the plastic bits at either side. I know of at least 2 C70 including my own that have had this. Patent part radiator is about 70 quid IIRC or you could get one for less 2nd hand.

Good luck

[wegal]

Not totally sure on the braking system on these cars .. does it have a vacuum pump for the brakes ? If so, then the hiss could be a leak in the brake vacuum side. But i could taking ££££.

[siamblue]

On old W plate T5 classic, i too had a coolant leak, it was dripping near to the gearbox, so i took all of the airbox out and it wasn't the main coolant pipe where i thought it might be but the matrix pipe that goes to the side of the head, it had swollen like a balloon and wasn't far off failing big time,

Gary.