Does anyone have any advice regarding a cracked manifold. I have a Enuos Roadster 1.8S Special from Japan. I assume the exhaust system that it has is standard on that particular model (but not a standard UK MX-5 exhaust according to my local dealer), it's stainless steel, unfortunately the welding on the manifold has cracked. So I'm faced with a problem. Do I try and get it re-welded. This seems to be a difficult thing according to all my local garages, mainly as it cannot be welded while attched to the engine, and once removed, would have to be put into a jig to stop it from changes shape, and therefore not fitting back on correctly. Do I try to get a new manifold. What are my chances of getting one that fits the rest of the system, or are they standard sizes. My last option, which is one I am seriously considering is, replace the whole exhaust system. I have been looking around and like the stainless model MOSS UK produces. Does anyone have and recommendations?? (1/00)

Others can advise on exhaust system, but regards manifold of "headers" I'm told the Jackson Racing headers are about the best there is. You shouldn't have to change anything except the headers and the gasket to the rest of the system.

I'd make a temporary patch with some of the exhaust bandage stuff while you get some quality headers. (1/00)
My ceramic coated JR header (the late 95/early 96 variety) cracked after 60 k miles hard use. FWIW (1/00)

1/ it is probably not the original exhaust .. a lot of these cars had replacements fitted by enthusiastic owners - does it have the heat shield with the embossed 'hot' symbols on it .. very thin steel but formed around the manifold/header and in two parts?

2/ 1.8 Roadsters from '93/'94 were fitted with 1.6 catalytic converters; this means the manifold/header is 2" longer than the UK version. I do not know if this practise was carried on beyond '94. The back of the cat is still in the same place so this does not affect cat back aftermarket systems.

3/ You really need to take it off to reweld it - there is no access in situ to confidently weld it. If it cracked it will be a fitting/vibration issue .. it may well crack again if this is not resolved.. it could be resonating. I cannot believe that it will distort with ordinary welding - the shape is far too complex ... and how hot do they think it gets normally? You do need to get to a stainless steel TIG welder to do a good job .. this is not the same as MIG and is normally more of a specialist thing to do .... definitely not back street garage stuff ... look in yellow pages under steel fabricators specialising in sheet steel work. (1/00)

The stainless steel "headers" "extractors" whatever, may or may not distort noticeabley. It would depend on where and how long the crack is. It also depends on how skilful the welder.

All that needs to be done is for them to be clamped to a solid flat plate, and kept there until again cool.

Personally, (and depending on how old the headers seem to be) I would go for a weld job first. Remember, as long as you can get them back on the engine with the gasket taken up and the other end plugged into the remainder fo the pipe the headers will self anneal and take up whatever "set" you have them bolted into. (1/00)

1.8 Roadsters from '93/'94 were fitted with 1.6 catalytic converters; this means the manifold/header is 2" longer than the UK version. I do not know if this practise was carried on beyond '94.

Great care needed with aftermarket bits, then. (1/00)
Yep, I got a cat replacement pipe from Magnex, for a '92 1.6, when it came it was 2" too long, so I had to exchange it for a 1.8. Even then it has a small stub connector for the cat overheat sensor (which UK cars don't have) and needed blanking off. (1/00)
Just to let you know that if you are thinking of replacing the manifold. Check that you have the sensor on your existing pipe (it's just before the cat). If you don't have one (like me) then you will need a plug for the hole in your new exhaust manifold which you will probably have to ask for, or get a sensor (can't remember the techie name for it).(2/00)
Before the MOT I had a quick check of the car, the exhaust manifold heatshield is cracked - is it ok to remove that one? (something rattles at certain revs, I assume thats it) (2/00)
My exhaust manifold heatshield is also cracked...rattles at 3600 rpm...really annoying.. can you let me know if you get any info on it...I'd like to remove mine, if it doesnt heat the engine bay up to much. (2/00)
The heatshield has to be removed as part of the 1.8 Supercharger kit anyway. (2/00)
Are we not talking about 2 different heat shields here??? (2/00)
Could be, I think in retrospect the supercharger one is the one near the cat. (2/00)

I'm amazed at the suggestion that something that Mazda obviously considered necessary for the car - effectively an inherent safety feature - could be removed without considering the potentially serious consequences (note I've also read all the responses to date (24/2/00 21.00)). After all, Mazda aren't going to be throwing money away fitting something deep within the engine for cosmetic reasons, are they?

If the heatshield is removed and a fire results, I would hope that the garage repairing the car would report to the insurance company that the heatshield had been removed, and that the insurance company would refuse to pay out as a consequence. Why should I have to suffer increased insurance premiums because of reckless behaviour by others in disregarding safety issues?

This certainly seems an inherent fault with the MX-5. At my car's 36,000 mile service before I bought the car, the garage reported "rattle from exhaust front pipe: requires new front pipe because heat shield has broken off". Then at the 42,000 mile service it reported "Heat Shield around Front Exhaust pipe broken". Again at the 60,000 mile service the report was "Down Pipe Heat Shield Weld Broken". At the 66,000 mile service the garage notes "Rectified Rattle from Exhaust Down Pipe Heatshield that was loose" - why it wasn't put right earlier is a mystery, unless of course it's been recurring, but at least the garage reported it each time. It's been fine since I bought the car. (2/00)
The heat shield is cosmetic to clean up the engine bay .. stops you seeing the rusty exhaust manifold .. and also for countries with 32C day time temps .. not the UK! (2/00)
I've removed my CAT heat sheild already, Im thinking about the manifold heat sheild. (2/00)
Isnt this cured by a jubilee clip being secured around the offending heat shield - I had this and Oxford Mazda did this mod but there is still something that rattles sometime at 3.5k revs. (2/00)
Its probably the heat sheild thats still rattling or the jubilee clip now rattling ont he heat shield!! ;o) Mine resonates at exactly 3600 rpm.. quite useful sometimes as I know how fast Im going without looking...but overall really annoying!! Would the list suggest removing the entire heat sheild..what about the metal around the manifold leading to the zorst and not just the shield? (2/00)
So my initial thought was right, and this is the heat shield I have removed. (2/00)