504 head identification?
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  1. #1
    1000+ Posts Wildebeest's Avatar
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    Default 504 head identification?

    I've been going over my collection of square port 504 / 505 heads checking the variations and the casting numbers and letters under the rocker gear.

    Head No. [1] marked 82 XNT. This one has pulse-air casting in the exh. ports and long manifold studs. Previously identified as a 505 head with unleaded valves. [Thanks Ray.]

    Head No [2] Marked 81 XNIT and XM7 T. other markings = 103731-3K1.
    Without pulse-air casting.

    Head No [3] Marked XNI 75. [1] [79], other markings= 103291. 0999.
    Without pulse-air casting.

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    The diameter of the combustion chambers are all identical at 88 mm.
    This is where I need answers. Head No [2] has two markings, XNIT and XM7T. Am I right in thinking that this head will fit both the 2 litre and the 1.8 engine, bearing in mind that they are both the "open block" type?
    By this I don't mean can be "made to fit" but is a factory fitting to both engines?
    Because the bore sizes differ ie 88mm = 2litre. 84mm = 1.8. You would imagine that there would be an overlap of the bore diameter and the head diameter, a bit like putting a six and five eight" hat on a size seven scone and vice versa !!

    I suppose the only way to put your mind at ease would be to have both blocks in front of you plus the two different head gaskets and see where or if the water jackets etc line up?
    Failing that, the word from a parts man in the know.

    Interestingly, all three heads suffer from severe corrosion around the water pump opening. The rest of the heads appear OK. A piss poor design feature this. I've wondered why they never incorporated a "sacrificial plate" into the pump design?

  2. #2
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    Hi Wildebeest,

    Can't help with the head ID, but the corrosion is probably because of cavitation, so a sacrificial anode would probably make no difference.

    Stu


    2003 PEUGEOT 206 GTi

  3. #3
    1000+ Posts Wildebeest's Avatar
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    Default 504 Heads ?

    Quote Originally Posted by Stuey
    Hi Wildebeest,

    Can't help with the head ID, but the corrosion is probably because of cavitation, so a sacrificial anode would probably make no difference.

    Stu
    Stuey,
    What I meant was a replaceable steel backing plate to the water pump.
    The early Toyota Corrolla for instance.
    The Peugeot practice of using the large core plug recessed into the head is the problem. This will erode away but the alloy surrounding it corrodes away at a faster rate.
    It would be preferable to replace a steel backing plate than a cyl. head.

    Even the PRV6 for all its faults had a replaceable backing [alloy] on their pumps.

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