Just had my MOT and it has passed with no advisories but the tester found an oil leak and said it might be the rocker gaskets, had a look but all seems well, has any one any ideas where it could be coming from?
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The MOT Tester may be right about what he calls the rocker cover gaskets. (We don't have 'Rockers' though we still use the name for the Cam covers). The covers are pressed out of sheet steel and can deform upwards at the rear end if the aftermost couple of screws are overtightened. Running a straight edge fore-and-aft over the flanges should show any bending.
Oil inside these covers naturally runs over a small saddle in the head casting to the drain hole which is located along the back of the cylinder head. It pools in front of the saddle and will find a path under or over a loose gasket seal if it can. Tighten up carefully, because you may only bend the cover more. It mat be a cover off job to do a proper fix.
Leaks there can be hard to detect, for after shutting down a hot engine, the oil is thin enough to run down to the bottom of the bell housing without leaving much of a trace. A mirror and torch can help - look for a wetness on the cork gasket at the rearmost corners of the gasket, under the flange on the cam cover.
If you have a drip of anything on the bottom of the bell housing flange, I found that after wiping the side of the engine down, I jammed some dods of blue paper roll into any crack and crevice I could find. After getting the temperature up, I switched off. The Blue paper will turn dark blue with any wetness that appears, making it a good indicator - better than a rag. leaving it overnight will show up any slow leak, but be prepared to repeat this over a fair bit of time, as the paper can wick wetness out of metal to metal facings, misleading you into thinking that is a leak. The starter motor flange is an example, as is the oil pump and filter arrangement.
Some leaks can travel a long way and working back to the source can take some patience. For instance, I had a drip from the water pump hose - I think it was - and it had dripped onto the front of the head, ran along the head gasket seam, down past the oil pump and was dripping from the bottom of the sump gasket flange on to the floor. There was a time when the antifreexe wetness on the side of the head gasket seam had me really (and I mean really) worried, but what a relief to trace it further back and realise it was just a turn of a jubilee clip to do a fix.
I hope that helps,
Duncan, Skye -
When mine passed last week the tester called over to me and said 'you've got a slight oil leak under there - just an advisory' ..... i replied, 'thanks, that is two less than last year!'
.............AndyComment
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Try the silicone gaskets I have recently fitted these along with a few others on this forum. So far so good and no seepage from the cam covers so far, 150 miles done.
If you go down the replacement route either cork or silicone check the cam covers for splaying due to over tightening. Mine were slightly splayed on the drivers side by 3-4 mm.
MikeComment
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thanks for your replys yes it is one of the rocker gaskets when engine is hot it starts to leak slowly tightened it down and seems to be ok but I will order new ones on Monday.Comment
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Just one other point to look out for - At the front and rear of the camshaft casting there are rubber 'D' -shaped rubber bungs set into the casting. They can be a source of leaks also and a lot of people consider it good practice to change these at the same time. This is particularly true if the rubbers have gone a bit hard. In my experience (yes I tried to economise) the aftermost one leaked even though I had used a non-hardening sealer on it. The sealer hadn't taken to the aluminium, which I thought I'd cleaned. So I had to do the whole lot again.Originally posted by wb50 View Post
Lesson learned.
Duncan, SkyeComment
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