I've just changed the headgasket on my Megane ('98 1.6 8v K7M engine). The job wasn't too problematic, and I spotted the headgasket problem very early, so I expected no knock-on problems with it. However, since I've started to run the engine since the repair the engine is sounding a little noisier than before. Sounds like some extra tapping sounds in time with the engine revs. I'm not sure whether it is just me being paranoid or there is something not quite right. Any ideas what is might be, baring in mind what has been done to the engine?
I also think there's a whiff of petrol coming from the engine, which I'm pretty sure I didn't notice before. There doesn't appear to be any weeping from the fuel rail, as I did have that off. So I'm not sure where that is coming from either.
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Hi Dave,
Although I don't have any experience of this engine, the first check I would suggest is to check that oil is getting to everywhere it should.
If you can, run the engine with the cam cover off. You may need to set up some means of catching the oil that gets thrown off the cam.
The reason I suggest this is that I remember building up a Cavalier engine which tapped a bit from the top end after a rebuild. I found that one cam lobe wasn't getting oil. Thankfully on that engine, you could get the cam out without disturbing anything else, so I cleared the blockage without much extra work, and before any damage was done :-).
number_cruncher
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I mananged to run the engine with the rocker cover off, and there was plenty of oil sploshing around. It's better to lift the revs a little otherwise the oil comes out like a geyser! It did seem a little lop-sided in the oil spraying, so I removed the rockers and blew though the little holes, which hopefully has cleared any potential blockages. It seems more even after that. I still haven't had the chance to drive it and give it a good listen since yet.
I was wondering whether the removal and refitting of the rockers maybe have slightly sent their clearences out of kilter. I might try and check them. I certainly feel less paranoid the noises are anything serious now.
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On my 1996 1.4 8v the tappets are adjustable, as per years ago. Mine had the head off following a coming together of piston & valve (broken cam belt) back in March before I bought it, and it's slightly tappy although it runs perfectly well. Could it be that you just need to adjust the tappets - but not sure if you have them on your engine. If you do have them, and you haven't adjusted them, then it's likely this is the problem.
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Davemar,
Many years ago, whilst refitting my Lotus twincam head I managed to slightly bend an inlet valve (whilst refitting the timing chain). The sound it made was exactly like a loose tappet, it took me many hours and 2000 miles to diagnose.
I also had a 2L Renault 25 with tappet noise, which I only managed to cure with a replacement cam, I could not see anything wrong with the old one.
Regards
GGH
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I had a go at adjusting the rocker/valve clearances last night, wasn't too difficult a job, though getting a spanner onto the crank pulley bolt to turn the engine was a bit awkward. Some of them were a little out from the spec, so I adjusted them. I just ran the engine for a couple of minutes in the garage and I think it did sound less tappy. I'll have to take it out for a proper spin to have a good listen from a normal driving position.
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Hi,
Don't, whatever you do, be tempted to overtighten the valve clearances. It is *much* better to have a bit of tappet noise than valves not closing properly.
number_cruncher
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I was pretty careful do to that. In fact some of the exhaust valves were a little overtight, so needing opening up a tad.
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