Exhaust or petrol fumes in car

The Oily Bits S1 Specific Topics
1

The car is a motorsport bodied Elise, when driving after a period of an hour or so I am experiencing coughing fits and heartburn indicating fumes in the car, although there is no discernable smell, that is until I open the window and there is a definite smell but I can’t tell if it fuel or exhaust related. Anyone else experienced similar?

There doesn’t appear to be a fuel leak, i.e. nothing dripping under the car, the exhaust is relatively new Janspeed full stainless, again no evidence of a leak into the engine bay, which is something I did suspect, the fumes leaking through the motorsport slats and being drawn into the interior through aerodynamics.

I’m just wondering if this is a characteristic of the motorsport body and would not occur with the normal Exige engine cover.

Rather worrying as I have a few track days lined up and I don’t want to pass out at the wheel!!!

2

i reckon you deffo have a leaky zorst somewhere.

Do a search because someone posted similar recently, and IDG had this happen to him at Anglesey which is posted up here somewhere.

3

Thanks for the suggestion, did search and got some information, would point to a leaking exhaust but I can’t find any obvious leak. Interesting that the cabin is a low pressure area and would draw fumes leaking from the engine cover as I suspected.

4

Had that on ours when we got it. Turned out to be the tail pipe section which needed adjusting and tightening, no fumes since (well not any more than any other overfueling Exige )

5

Check for scorch marks at either end of the Cat/CRP, that’s where mine leaked from.

I’d say it’s also worth taking out the seats and sealing the holes in the bulkhead. Uldis is the resident expert on this front.

Ian

6

Thanks for the suggestion, did search and got some information, would point to a leaking exhaust but I can’t find any obvious leak. Interesting that the cabin is a low pressure area and would draw fumes leaking from the engine cover as I suspected.

Low pressure zone, exactly, especially when the windows are open.
Do a longer search (it’s an old subject) for details but parts where fumes come in through are:
-behind the seats to the insides of the clam. That should be sealed but many times it’s just a hole. Draws air straight from the engine bay.
-hole where the brake cable goes through. Draws straight from the tank area.
-several holes in the fibreglass bulkhead behind the seats, don’t know why they’re there but they are. Draws air directly from the engine bay.
-big holes in the dash to the sides, communicating directly with the side sills. Draws air through the sills from the engine bay. Gets hot too because air get warmed by the oil and water hoses.


BTW, I don’t think the MS rear cover is at fault here. And you should first find the source of the fumes: leaky exhaust joints, manifold not sealing well against the head, leaky flexi joint, cracks behind any weld, etc.
Suggest going around with a “stethoscope” listening for leaks when the engine is running.
A 1m piece of garden hose would do, and any leak would be pointed at very easily.

HTH

7

Thanks all for suggestions, will do a detailed examination of the exhaust joints, there must be a bad seal somewhere. Sealing all the cabin holes may well be a good idea to avoid a reoccurence, any suggestions on what to use, silicon sealant presumably.
Post on Pistonheads gleaned a suggestion that the petrol cap might be at fault, possibly not venting properly causing a build up of fumes.