Manifolds

[Vauxy]

Quick question, be kind I'm a newbie. I had a facelift MR2 that I unfortunately had to break after 9 months ownership due to severe rust. Just picked up a pfl and was wondering if I can swap out the manifolds to get rid of these precats? Car has done 110k miles precats still in as far as I'm aware.

[Iain]

Yes its a fairly standard swap out. Theres a few brands on the market all pretty similar. Ive had a 'gravity' one fitted for a few years now and had no problems.

[Carolyn]

These work well and are good value.  However the gaskets are rubbish use OEM head to manifold and OEM crush rings for manifold to cat.

https://www.ebay.co.uk/itm/204135729654?itmmeta=01JM7CQ10HE1QXK3J9J1J73XM1&hash=item2f877009f6:g:0kUAAOSwpstjXW92

[McMr2]

I'm in the process of fitting one of these, the gravity version. The cat pipe to manifold joint needs some fettling as there doesn't appear to be a recess for the two stubs that sit proud on the cat pipe flange.

[Joesson]

I'm in the process of fitting one of these, the gravity version. The cat pipe to manifold joint needs some fettling as there doesn't appear to be a recess for the two stubs that sit proud on the cat pipe flange.

The OE manifold without precats is on my 2, so no direct experience of after market manifolds, but, I have  a suspicion that the "two stubs" may be to locate the crush washers.

[McMr2]

The OE manifold without precats is on my 2, so no direct experience of after market manifolds, but, I have  a suspicion that the "two stubs" may be to locate the crush washers.

Indeed they are, but on the OE manifold there are recesses to accommodate them when the flanges are brought together. Doesn't appear to be the case on this manifold.

[Joesson]

Indeed they are, but on the OE manifold there are recesses to accommodate them when the flanges are brought together. Doesn't appear to be the case on this manifold.

Have you compared the relevant tube diameters? Just maybe the stubs go into the flange.

[SurreyMR2]

I'm in the process of fitting one of these, the gravity version. The cat pipe to manifold joint needs some fettling as there doesn't appear to be a recess for the two stubs that sit proud on the cat pipe flange.

I had same issue with standard & Zero sports cat fitment. Zero adapted the manifold and and now it fits as it should.

[Carolyn]

Indeed they are, but on the OE manifold there are recesses to accommodate them when the flanges are brought together. Doesn't appear to be the case on this manifold.

The  crush rings will still do the job

[Joesson]

My thoughts:
There being no recess in the flange there is nothing other than the stubs to locate the crush washers. So the stubs will determine the distance between the flanges when tightened and that protrusion must be less than the thickness of the crush washers. To machine a recess is another operation that a fabrication shop may not  have the machines to produce and the stubs are a less costly way of locating the washers.

[McMr2]

The  crush rings will still do the job

Unfortunately they don't seem to be in this instance - they are almost sealing but there was still a small leak. To be sure I'll order a set of Toyota rings (although I'm almost certain the one I used are genuine).

My thoughts:
There being no recess in the flange there is nothing other than the stubs to locate the crush washers. So the stubs will determine the distance between the flanges when tightened and that protrusion must be less than the thickness of the crush washers. To machine a recess is another operation that a fabrication shop may not  have the machines to produce and the stubs are a less costly way of locating the washers.

An easier option might be to grind the stubs back a little, it won't be neat but they're out of sight. A couple of mm would be enough to let the crush rings do their job.

[McMr2]

Have you compared the relevant tube diameters? Just maybe the stubs go into the flange.

That's what I had assumed but the holes are too small. Had both parts on the bench to make sure I wasn't missing something.

[Carolyn]

These are OEM rings.  Pale green in colour with a single groove around the outside edge and a lip around the inside edge.

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[Carolyn]

I don't know about the Gravity one, but I've fitted a few Toyosports ones and never had an issue.

[Iain]

Never had an issue with my gravity one. Used genuine crush gaskets and bolted it up nice a tight. Been fine for over 3 years now.

[McMr2]

I don't know about the Gravity one, but I've fitted a few Toyosports ones and never had an issue.

Never had an issue with my gravity one. Used genuine crush gaskets and bolted it up nice a tight. Been fine for over 3 years now.

Have to assume there is something different about my cat pipe then. The stub sits proud of the crush ring by about 0.5mm. As-is, there's no way it's going to seal, no matter how much the bolts are tightened.

[Joesson]

Have to assume there is something different about my cat pipe then. The stub sits proud of the crush ring by about 0.5mm. As-is, there's no way it's going to seal, no matter how much the bolts are tightened.

Given that, and if it was sold as  suitable for your 2, I would think that it is unfit for purpose and should be replaced with a correct item or a full refund and return cost.

[McMr2]

Given that, and if it was sold as  suitable for your 2, I would think that it is unfit for purpose and should be replaced with a correct item or a full refund and return cost.

I've let them know, but I'll have the same problem with any similar item that has a flat face on the flange. Just odd that other members with the OEM cat pipe haven't had this. It won't take much for it all to come together, it's a pretty tidy thing for the money.

[Joesson]

I've let them know, but I'll have the same problem with any similar item that has a flat face on the flange. Just odd that other members with the OEM cat pipe haven't had this. It won't take much for it all to come together, it's a pretty tidy thing for the money.

Good luck and a steady hand with your adjustments.