www.RX7fb.com

Right, so the car's been "using" coolant. Or at least, it's going somewhere. I was pretty sure it's not waterseals, because there's none of the usual signs, no white smoke, not hard to start, all that. It does smell sorta "head-gaskety" when hot and been running for a while. When I got it, it was losing water and water seals were suspected but further investigation showed the union for the bottom rad hose was corroded, and cleaning this up and re-seating the hose stopped the leak. This one is something new. It's only a minimal amount, and up till recently I've never seen signs of an actual leak, but the other day I moved the car and there was a puddle of Halford's finest red coolant sat underneath. So, more scrutiny has found a bit on top of the engine where coolant's collected.

It's the sort of gulley formed where the inlet manifold meets the lip on the edge of the housings. There is a very small puddle of coolant gathering there, in roughly the area shown by the red arrowed box on this 'ere picktcher;


Sooooo, what's leaking there, then? It's been suggested that one or both of the coolant way O-rings has failed/is failing and the gasket isn't man enough to withstand the leak when it all gets hot. Does this sound likely? Stupid question, but what is the inlet mani gasket made from? If I pull it off to investigate, is it going to mutilate the gasket and I'll need a new one? Looks straightforward enough to just un-bolt the mani and pivot it up out of the way without even having to disconnect everything but I don't want to start this and then find I need to wait three weeks trying to find a new gasket that no-one make any more.

Opinions welcome, both on the cause and fix. Ta vurrah much

Lucky wrote:It's been suggested that one or both of the coolant way O-rings has failed/is failing and the gasket isn't man enough to withstand the leak when it all gets hot.

My 7 was using water with the same symptoms and when I whipped the old manifold off thats exactly what had happened.

It's pretty simple to unhook the couple of cables, two hoses and a couple of electrical connectors necessary to remove the inlet and carb completely. It'll make life much easier to clean up the gasket faces. If you do remove it then i'd say it's 50/50 whether the gasket will come off whole or not, its a paper gasket that will have gone rock hard. I'd probably get a new one ready, unless you're willing to bodge it with a bit of RTV silicone ( which is what i normally do )

my money would be on the o rings as well ... if one of those is weeping, the paper gasket won't hold the water back.
They are only about 7 quid for a gasket. I always smear some rtv around the o rings as well for good measure.

Ive not tried it but apparently if you print this pic full size the gaskets are the right size, you then have a template for the cornflake box.
I would buy them but it could get you out of the sh*t.

Balls

OK, where to get a 12A gasket from then? Mazda still do them? Save me from my Blue Peter hell trying to cut out round that photo

I got my last one from Rockauto... but you'd need to order other parts at the same time to offset the shipping costs.... the previous one I bought I got ordered from RX Motors thinking that they must use loads of them and would stock them. Turns out they didn't, they just ordered me one from Mazda so I had to wait for Mazda to ship to them before it got forwarded on to me.... and I had to pay their markup too.
It's probably worth trying your local maindealer Nik.

here's the part number...

viewtopic.php?f=14&t=68

If you do need gaskets made up, I could try and use the computer controlled cutter we use for vinyls - that way it would be an accurate cut at least

Mazda still do them.

Lucky wrote:. So, more scrutiny has found a bit on top of the engine where coolant's collected.

It's the sort of gulley formed where the inlet manifold meets the lip on the edge of the housings.

Sooooo, what's leaking there, then? It's been suggested that one or both of the coolant way O-rings has failed/is failing and the gasket isn't man enough to withstand the leak when it all gets hot. Does this sound likely? Stupid question, but what is the inlet mani gasket made from? If I pull it off to investigate, is it going to mutilate the gasket and I'll need a new one? Looks straightforward enough to just un-bolt the mani and pivot it up out of the way without even having to disconnect everything but I don't want to start this and then find I need to wait three weeks trying to find a new gasket that no-one make any more.

Opinions welcome, both on the cause and fix. Ta vurrah much

I'm absolutely definite on the cause Nik. It's one of the rubber 'O' rings that's failing.

I got my parts from Rotechnics last time (2006) £23.15 in total for:
Gasket, Exhaust Manifold (12a) (I was putting a Double 'S' exhaust on at the time).
Gasket, Inlet Manifold (12a)
Inlet Manifold 'O' Ring....qty 2
Post 1st Class

Sorry they didn't put any part Nos. on the invoice.

Rotechniks Tel is 0118 988 8555

Interestingly, within Rotechniks Cost Breakdown for their own internal use, the 2 'O' rings are shown as 'FD engine build parts'.
The rest are just 'Parts/Materials 1'

It's now a regular garage check for me to peep over the nearside wing into the area you've circled, looking for coolant.

BTW.....What a cracking engine bay. Beautiful ....

Cheers, guys. I've got around a zillion O-rings in the garage, must have two the right size in there. I assume that despite the no doubt astronomical price, Mazda O-rings are the same as any other common or garden O-rings lol. Hopefully that link with the part number Ian posted is for a 12A? I'm off to do battle with the local Mazda dealer in a sec, so I'm expecting to have to stand over them and explain in words of one syllable what I need like you would to a backwards child. In fact, I'm taking my four-year old as moral supprot (and cos he likes going out in dady's silly car) so I can prove that a four-year old can grasp the concept better than they do