New clutch and invisible fluid leak
Hi, I recently had my clutch (not fly wheel) replaced by a local garage on my 05 (facelift) 147 1.9JTD (80K miles). They also replaced the front brake pads and discs, front tires and re adjusted the rear brake callipers along with a standard service and change in gear box oil.
Almost immediately I noticed my average motorway fuel efficiency drop from ~48.5 mpg to ~44mpg on like for like journeys.
After 600 miles the clutch/brake fluid warning light came on while on roundabouts. The fluid level was below 50% so I took it back to the garage. The mechanic suggested it was the brakes bedding in but agreed the drop was excessive (unless they didn't top it up fully to start with). They topped it up to the top and over the next week / ~150 miles it dropped by another ~3mm.
They have since examined it and said there is no fluid leak anywhere (brake system, master and slave cylinders etc) and topped up the level again to monitor over the next week. They are at a loss to explain the drop in fuel efficiency. I have no reason to believe they are miss leading me and have been nothing but helpful so far.
So my questions....
Is 44mpg for a 1.9 147 JTD doing a steady 70 on a motorway unreasonably low. Did I have a super clutch before to get ~48.5 mpg. Tyres are inflated, A/C is off. As far as I can tell everything is the same.
Is it possible for clutch fluid to be leaking inside the clutch, perhaps onto the plate in such a way as not be visible and reduce fuel efficiency (perhaps through clutch slippage)?
Any other ideas on what maybe going on and what I can do to test it (Iím not a mechanic and have never worked on cars before)
I only replaced the old clutch as during an engine rebuild following timing belt failure at 68K a different garage said the clutch was looking very worn. It felt fine but and I didnít want to risk it failing and damaging the flywheel and gear box.
Iíve spent hours looking through various forums online but canít find anything to shed light on this. Any advice anyone can offer would be welcomed.