V6 Oil Leak Under Rocker Cover....? Deeply confused

[BongoBonkers]

We had a misfire on our V6. To cut a long story short, we've changed distributor cap, rotor arm, spark plugs and HT leads. Whilst doing the spark plugs I found one plug well (passenger side, rearmost)had 1/2 cm or so of mystery fluid in it (oil or water, hard to say which in the circumstances). Whilst investigating this I have now found where this fluid is coming from and it doesn't look pretty.

If you pull off the centre spark plug cap on the passenger side and look into the plug well you can see a cut out in the casting. If you look through the cut out, there is a cavity which is full of oil (I think). I am fairly certain that it is this fluid that is occasionally overflowing the reservoir and dribbling down the plug well. I think this cavity should be bone dry (as some of the other similar cavities in other plug wells are...).

Does anyone know where this fluid may be coming from and how I would go about fixing it? It's a disaster at the moment as we have about 3000m to do this Xmas which was gonna be in the Bongo....Not happy to take it at the moment. Any suggestions gratefully received......

[haydn callow]

Sounds as though the cover gasket is leaking ...try tightening all the bolts a bit....may have to fit a new gasket.

[BongoBonkers]

Thanks for the reply. Have already tried nipping the bolts up on the rocker cover gasket. They weren't very tight but perhaps they aren't meant to be.....

[haydn callow]

New gasket then.......the bolts are not meant to be really tight.

[BongoBonkers]

I would normally call Fred and Jerry at Discount Trucks to deal with this kind of problem but as I am short of time we got our local garage to have a look today. They are decent chaps and kindly obliged at such short notice. Basically, they have given it a good clean up and tightened all the rocker cover bolts (they said they were really loose....). They reckon that's it sorted and it's fine to use so we're off to Scotland tonight (or tomo morn most likely as rain and traffic awful here) and then hopefully on to the alps next week. Fingers crossed!

If anyone's interested I reckon I now have a clear picture of my recent mis-fire problems I've been posting about. I think the rocker cover gasket has been slowly leaking over a long period (it was replaced one year ago) and dribbling oil down the plug holes eventually building up enough to cause a mis-fire. Sadly I didn't work this out before replacing dis cap, rotor arm, HT leads and plugs but that's the way it goes sometimes!

Thanks all for your help on our recent troubles. Hope we're in for a trouble free period now....Happy Xmas!

[mikeWalsall]

The same thing used to happen on a Vauxhall 2.0 16v DOHC 4 cylinder ecotech I once owned ..

The four plugs where not only deeply recessed into the cylinder head, but where covered over with a 'cosmetic' cover so well hidden from view.

Even when I replaced the 'rubber' cam cover gasket the plug recesses still filled up with oil .. I found the reason to be .. although it looked like alloy .. the cam cover was actually made from plastic .. which had slightly twisted/gone out of shape ..

Rather than buying a new cover .. I put a thin bead of silicone sealant in the gasket groove then the gasket .. with the extra 'thickness' it stayed sealed ..

Oh ... on that Vauxhall .. the TDC Camshaft Position Sensor gave a few problems, with the engine management light coming on, and the engine going into 'limp home mode' ..

[A1tony]

I checked mine when there was some leaking of oil and the bolts were barely finger tight. Seems to be a common theme on the v6.

[waverider1]

Hi, does anybody out there have a service manual for the petrol V6 2.5L J5 Bongo (2002) and know what the torque setting for the nuts on the rocker cover gasket are supposed to be? thanks

[g8dhe]

3.5-4.4N/m or 35-45kgf/cm

[waverider1]

Thanks for the Rocker cover torque specs, that's great am guessing it's a 14mm socket? As the torque's so low I suppose a bike torque wrench would the way to go maybe? Just didn't want to over tighten them! Cheers