DS head gasket
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Thread: DS head gasket

  1. #1
    Fellow Frogger! marc61's Avatar
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    Default DS head gasket

    About 6 months ago I fitted a new head gasket to my DS21, I had the head skimmed as it was quite warped and since then the carís done about 800 miles. Recently I noticed the water level dropping slightly in the header tank (about a cm every 200 miles) and a bit of mayonnaise in the cap. Also the water has turned from blue to cloudy brown. The other thing is itís lost/consumed about a litre of oil in 800 miles, which means it must be being burnt.

    The plugs are good, brown and consistent, the car drives fine but something is happening. I measured the compression earlier today and it was only 90-110 psi on 3 cylinders and 135 psi on the other, so Iím thinking head gasket problem? Iíve just drained the coolant, loosened and re-torqued the head bolts and will try again with fresh water.

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    But this isnít very good, can a head gasket fail that quickly? Could it be something else?
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  2. #2
    1000+ Posts forumnoreason's Avatar
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    Default

    combo of worn rings and head not being tightened down?

  3. #3
    1000+ Posts driven's Avatar
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    What procedure did you follow when tightening head bolts?
    Were bolt holes clear? If full of water / oil will fracture block and not be correctly torqued.

    Did you retighten after warming up and cooling again?

    Oil loss could be oil into sump as well

    Head was warped but did you check block deck as well?

    It is quicker to replace a head gasket a second time as I have found out

    BUSH MECHANIC AGAIN Can cause many tears
    Need to try and drive out water oil between head gasket faces.
    Take off cooling system pressure cap and warm up engine
    Drain water from cooling system, start engine run engine say 15 -20 ?? secs
    Pull spark plugs and let it all cool down
    Retorque
    OH YES, change oil, oil filter and fill cooling system

  4. #4
    1000+ Posts driven's Avatar
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    Default

    What procedure did you follow when tightening head bolts?
    Were bolt holes clear? If full of water / oil will fracture block and not be correctly torqued.

    Did you retighten after warming up and cooling again?

    Oil loss could be oil into sump as well

    Head was warped but did you check block deck as well?

    It is quicker to replace a head gasket a second time as I have found out

    BUSH MECHANIC AGAIN Can cause many tears
    Need to try and drive out water oil between head gasket faces.
    Take off cooling system pressure cap and warm up engine
    Drain water from cooling system, start engine run engine say 15 -20 ?? secs
    Pull spark plugs and let it all cool down
    Retorque
    OH YES, change oil, oil filter and fill cooling system

  5. #5
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    Default

    Quote Originally Posted by forumnoreason View Post
    combo of worn rings and head not being tightened down?
    Have the cylinder liners been disturbed when the head was off ? Was the engine turned over without the head being on .. maybe to check on bore wear or just to clean up the top ? If so, the paper liner gaskets "may" have moved or been disturbed. Paper gasket failure was typical of DS 23 engines.

  6. #6
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by driven View Post
    What procedure did you follow when tightening head bolts?
    Were bolt holes clear? If full of water / oil will fracture block and not be correctly torqued.

    Did you retighten after warming up and cooling again?

    Oil loss could be oil into sump as well

    Head was warped but did you check block deck as well?

    It is quicker to replace a head gasket a second time as I have found out

    BUSH MECHANIC AGAIN Can cause many tears
    Need to try and drive out water oil between head gasket faces.
    Take off cooling system pressure cap and warm up engine
    Drain water from cooling system, start engine run engine say 15 -20 ?? secs
    Pull spark plugs and let it all cool down
    Retorque
    OH YES, change oil, oil filter and fill cooling system
    And NEVER turn the engine with the head off. Unless you you retain the liners with a proper fixture.

    If a liner moves, all the sh1t in the cooling system falls into liner sealing area. And the liner will never seal again until it's removed, cleaned, and the seal replaced.

    I clearly remember Regans always replaced liner seals when replacing a head gasket on 404, 505 and 505 XN engines.

  7. #7
    Fellow Frogger! marc61's Avatar
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    Default

    I didn’t check the block for flatness, so guess that might be it. The liners were held down with bolts and big washers whilst the head was off. The bolt holes were dry and cleaned out thoroughly before I put it back on.

    Yesterday I retorqued it cold, all the bolts were tight and good before I set to. I checked compression before and after, no change (lowest is 93psi, highest 136psi). And then checked it with a little oil in the cylinder and the readings were only very marginally higher, so loss of compression isn’t piston related. I’ll warm it up today, take the water out and try re-torquing again.

    I’m thinking maybe the head might have cracks in it somewhere? Do they crack? I didn’t check that.

    Have bought another head gasket, somehow think I’ll be taking it off again later in the week.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  8. #8
    Fellow Frogger! ds21bvh's Avatar
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    Default

    Marc,
    The small change in compression when you added oil points to a valve sealing issue.
    Are the clearances ok?
    Also is there pressure in the cooling system when running, bubbles in the coolant are area dead giveaway.
    Cheers
    Mark...

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