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Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4716
Experience:  Fully qualified / self employed garage technician in the UK
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All. I am new to posting on here so please bear with me! I

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Hi All. I am new to posting on here so please bear with me!
I have a v40 2001 1.8 petrol automatic. FSH. Just had new VVT, cambelt, alternator, water pump and exhaust. 120,000 on the clock.
Running very well until yesterday, stopped at traffic lights and it was idling really rough almost lumpy is the only way I can describe it, no warning lights, temp gauge normal. So I pulled over in a car park popped the bonnet and check the oil, no oil on dipstick, walked over to the garage and put oil in, started the car again, really lumpy. Drove it home no problems at 50/60mph only low revs and stopping.
Took to the garage this morning and they have done a compression test 3 cylinders are fine the 4th has low compression? No oil leaks from anywhere and the rest of the car is fine.
Does anyone have any ideas what this could be and if its viable to fix? I love my car!
Thank you for reading!
Hi.. Have they done a leak down test on the 4th cylinder? alot differant to a compression test! I asume there wasnt any prior issue before all that work was done? Any signs at all of blue smoke or even oil in the coolant or vice versa?
Customer: replied 2 years ago.
Hi. Not sure of the leak test but no problems at all just all needed to be done at the same time! The only issue it had was the vvt was making a grumbling noise hence having it replaced. No oil in water or visa versa and no blue smoke. Was running lovely until yesterday.
Hi.. Ideally they have to do a leak down test on that 4th cylinder - it means by ensuring that all valve's inlet and exhaust have to be closed..compressed air is continually forced into the cylinder..there a special equipment to carry out that specific test - and that will give an idea as to where that compression loss is going..normally if its a bent valve,either inlet or exhaust then you will hear the air escaping from the air box or from the exhaust tail pipe..if its leaking into the engine the compression maybe by a faulty headgasket then you'll hear it from the oil filler cap or even bubbles in the coolant...If it turns out to be a bent valve then id say its possible that could maybe of happend due to the bad VVT hub maybe put the cam to far out time and allowed the piston to somehow hit an open valve..but its pretty unlikely id say,you dont often hear of that the obvious being a setting up of the timing installation error...but Id say a leak down will verfiy either way what route you have to take on this and costing etc and if its viable - but in all instances above the head will have to come off..doing the test above will confirm before even stripping down the engine... a compression doesnt really give much bar the overall condition of the engine or cylinders...
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