R10/Caravelle sump oil leak - head gasket flipped?!?
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Thread: R10/Caravelle sump oil leak - head gasket flipped?!?

  1. #1
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    Default R10/Caravelle sump oil leak - head gasket flipped?!?

    Hey Gang,

    I have a serious oil leak from my Caravelle - appears to be flowing from both ends of the motor despite multiple attempts at re-sealing the sump. I did re-build the motor some time ago, but have done very few Klms - wondering if I might have put the head gasket on upside down and blocked something?!?

    When I blow into the dip-stick tube, it does build pressure and hisses out on release. Is this normal?

    Any advice would be much appreciated.

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    George :-)

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    Haemorrhaging oil on those motors can be caused by a few things:

    1) Lack of use of the vehicle, the seals have shrunk from minimal oil exposure. This can happen with older type seals and modern type oils. Modern seals generally are more stable when exposed to oil, and don’t change size.

    2) In association with the above, the new seals may have been placed in the same place as the old seals, and are running in the worn area of the crank pulley and seal running area at the rear main bearing at the flywheel end of the crankshaft. A speedy sleeve or a new crank pulley can fix the former, and when replacing the rear main seal, place it in about 4mm further in than where the old seal was – this is the Renault factory method to get the new seal running on a previously unworn area of the crank.

    3) The timing chain cover and crank pulley seal may have been replaced before being centred by the crankshaft pulley, therefore the seal may not be running centred on the pulley.

    4) When replacing the sump, the tongue was not held in the right place when the front and rear neoprene sump gaskets were replaced. The tongues on the neoprene gaskets work in conjunction with the fibre (or cork) sump gaskets. If they are not placed correctly, or the wrong neoprene seals have been used (gasket sets contain a few of the neoprene gaskets to suit the different motors) a leak can result. A reasonable amount of care is needed to make sure things line up nicely.

    5) The crankcase is pressuring up from either a blocked breather in the rocker cover, or the rubber breather hoses and connections being sludged up, or the motor is breathing and pressuring the crankcase due to not being run-in and compression pressure escaping via the rings into the crankcase.

    The headgasket is fairly difficult to get around the wrong way, so I’d say the chances of that are minimal. It may be best to clean everything off to try and ascertain the source of the leak, I’m thinking the sump gaskets at either end have not been seated quite right – they can be tricky to get exactly in place, and don't like sealing again if they have been previously squashed.
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    Well put Simon.
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    Thanks very much for the well thought out and executed reply! I think the crankcase pressure is less of a problem (did another check, and it doesn't seem to hold much pressure). I think the culprits may well be the main seals. These have not been renewed, my rebuild started as a head reco, that then went to a 'rings and bearings' which became a pistons and liners and bearings (because the pistons and liners were as cheap as rings only), but the main bearings and seals were left untouched. The car is now over 50 years old, and I suspect still has the original main seals.

    Thanks again, I will continue with my inspection now that the motor is out of the car!

    G:-)

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    1000+ Posts alan moore's Avatar
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    Quote Originally Posted by Fireblade View Post
    Hey Gang,


    When I blow into the dip-stick tube, it does build pressure and hisses out on release. Is this normal?


    George :-)
    If you blow into the dip stick tube there should be no pressure build up. The air should come out the breather on the tappet cover, which should be routed back to the air cleaner.
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    Quote Originally Posted by Fireblade View Post
    Thanks very much for the well thought out and executed reply! I think the crankcase pressure is less of a problem (did another check, and it doesn't seem to hold much pressure). I think the culprits may well be the main seals. These have not been renewed, my rebuild started as a head reco, that then went to a 'rings and bearings' which became a pistons and liners and bearings (because the pistons and liners were as cheap as rings only), but the main bearings and seals were left untouched. The car is now over 50 years old, and I suspect still has the original main seals.

    Thanks again, I will continue with my inspection now that the motor is out of the car!

    G:-)
    Were those seals leaking before the head reco work? If not, why would they start now?

    Is there oil getting up to the rocker gear? However, even if the head gasket were incorrectly installed (unlikely but possible) it wouldn't cause a bottom end leak, as the oil pump relief valve will control maximum oil pressure anyway.

    What IS the oil pressure?

    If oil is "flowing" out, I'd suspect the sump gasket and neoprene bits and reassembly. If done correctly, they don't leak a drop. If not, they can leak a lot. It can be done successfully in-situ (I know from experience) but, as Simon says, it must be exactly right.

    Good luck.
    JohnW

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