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head gasket problems


mattgagan

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Hi. Very confused and some advice would be much appreciated:

Spit 1300 mkIII 1970, engine stamped FDxxxxxHE (sorry, can't remember the xxxxx)

Had the car 1 year now, inherited it, and it has run perfectly reliably until recently. Since I took it there has been oil staining of the bulkhead (rear) end of block on distributor side, suggesting a VERY slow leak bet. cyl head and block in that corner (never showed significant change on dipstick in the time).

Recently overheated after long (70m) drive. When cool, new coolant added to rad - immediately starts pouring through end of water pump, just before pulley. Checked interface to housing etc and all was sound, so definitely blown seal on water pump. Visible oil via dipstick and rocker box still appeared unpolluted by coolant, and vice versa. Replaced pump with new one. Engine restarted after much turning over (several minutes worth - is that how slowly fuel is pumped through the lines?), but apparently not firing on all cylinders. Inspection reveals there is oil visibly leaking out of earlier noted problem area bet. head and block (actually at the rear, but slightly to the distrib. side).

New gasket set ordered and delivered. Head off. Clean up (including some recent looking carbon on front 3 cyls, while rear cyl has more whitish residue). Block seems to have narrow recesses around each cylinder bore - is this a "recessed" block, which I've seen mentioned in forums but NO manuals mention as far as I can tell? New gasket doesn't have "top" marking or anything - seems perfectly symmetrical. Reassembly seems to go smoothly though I'm surprised at how many iterations of head bolt tightening I go through, with reduced torques at the same bolts each time around. Have I fitted the wrong gasket type?

Try to restart - turn over for ages and ages. Flat battery. Charge battery. Turn over for ages. Slight cough from a cylinder somewhere.... etc etc eventually fires up bit by bit. Running unbalanced, and won't climb up revs other than with very slow throttle increases. Seems like it's running on 3 cyls at best. Visual check reveals oil bubbling out of same place as before - rear of engine bet. head and block, slightly to distrib. side. Stop engine before any more trouble starts. Looking over/feeling engine after the few mins running: there is heat at and around the rear 2 cylinders and the front is cool. Is that normal?

Many thanks for reading all of this and for any help or advice.

Matt

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Recessed block is really easy to spot with the head off.

Non-recessed is a perfectly flat surface with 4 big holes in it, and a sharp edge where they meet.

Recessed block has a step that you can see and if you run your hand over definitely feel - it's only a couple of mm deep/wider than the bore.

With the recessed head gasket one side is marked TOP and the other has a copper 'ridge' around each hole.  This fits in to the recess in the top of the block both locating the gasket and also making a good gas seal.

A recessed block won't like having a non-recessed gasket (which is what it sounds like you have ATM).  A recessed gasket on a flat block and the head just won't sit down on the block properly.

I'd get a recessed gasket and see if that fits - sounds like it will.

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OK. Thanks for that. Will pursue... word on the street is that Payen gaskets are the way to go (God only knows what mine is) - any confirmation or otherwise? Recommended supplier(s)?

I had seen elsewhere in other forums that Spit mkIV onwards and from certain engine codes on had the recessed block, so discovering that my mkIII is recessed is rather a surprise!

Thanks again. Matt

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The oil leaking out the back of the head may well be unrelated to head gasket problems. It is pretty common, and appears to be a bit of a design fault. Almost impossible to cure, somebody even blocked up the oilway to the rockers where the problem is usually thought to arise (used an external feed instaed) and it still leaked a bit. Think it was Mr sideways?

Anyway, an oil weep is undesirable but most of us live with it. Very little is lost, its just a bit messy.

As to recessed bores, FD is a MK3 head and shouldn't be recessed BUT some people have the bores recessed at overhaul time. Maybe gives a better seal?? But you will need a recessed gasket to match, and yes payen is king. Ring around until somebody has them (canleys and the usual suspects!)

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