Exhaust fumes in cockpit

[tedtaylor]

Please help. Car runs perfectly, very original and unmodified (except Everest chip) even down to original exhaust system.
Under normal driving, no fumes, no problems.
Under hard acceleration, high revs, flat out racing to high speed, sudden exhaust fumes fill cockpit interior of car. This has happened with top down open air driving and with top up, windows up.
No odd sounds. I know my muffler has the baffles out, but overall still whole.
at first i thought it MIGHT be just blowing back into car from tail wind turbulence at speed, but with top and windows up, that's not possible.
Any suggestions on where to look or what might be causing this?
turbo boost overflow blow off valve dumping into front engine compartment and seeping into interior from there???
anyone?
thanks

[CalElan]

Are you sure it's exhaust?
Had a similar experience where the CAS was seeping oil at high revs which was then burning off and coming into the cab.

[tedtaylor]

Thanks CalElan, but my CAS o-rings have been replaced 2 years ago and i have no oil leaks, nice dry engine.
It's not an oil burning smell, but definitely exhaust fumes.

[Brit-Car-Nut]

Just a thought: The heater fresh air tubing in the wing is connected to the plenum by a foam "sock". The foam has probably deteriorated and you are now getting engine compartment fumes into the cockpit. It doesn't take a lot of fumes to seem like exhaust. If it was exhaust from the muffler, with the hood down, the fumes would not go into the cockpit. With the hood up you might have a bad vent in the boot (there is one on each side called "Cabin Air Outlet Vent" A100P6015F), but since it is bad WITH the top down, I would expect it to be coming in from the engine compartment.

CAS o-rings don't last all that long and well used engines might be starting to ooze and smoulder after two years. You say it doesn't smell like oil burning, but it is such a tight / hard to see area, it would be prudent to look closely again.

[HJ2]

I had the same, and with me it was the turbo seal on it's way out.... So I would check there as well

[tedtaylor]

turbo seal? what's that? what should i look at?

[steve matthews]

Ted, sure sounds like an exhaust leak. Is it enough to burn your eyes? Then it would be a large hole or leak.
Put it on a lift and examine each joint.

Steve

[HJ2]

Hi Ted,

More info from (unfortunately) my own experience over here:
viewtopic.php?f=31&t=25030

[steve matthews]

HJ2 I don't know that Ted has enough miles on the turbo to cause this type of problem.

But he can pull the inlet hose and do a visual of housing and turbin.

[HJ2]

Yes he can

But a visual check and a spin on the shaft does not tell you everything. At least, that's what I learned.
When spinning from static, there is no axial force, forcing the turbine against any crud built up
When operating under boost, the situation is a little different and the problems start.

Also check for smoke at heavy acceleration and suddenly lift the throttle completely.
If the CAS seal is now a viton one, there is no need to worry. If it is the standard stuff, yes, it will fail within approx. 2 years again. But this does not give exhaust fumes in the cockpit imho.

Good luck with troubleshooting!

[chrisP]

I have a very similar problem and have never really got to the bottom of it.
Items that i leave in the boot (trunk) come out smelling of exhaust fumes and on long runs the cockpit also has a slight smell of exhaust gas. My engine is dry and the exhaust is fully sealed.
My thought was that the aerodynamic shape of the car was sucking in the exhaust gases through the vents in the boot lid and then through the ventilation flaps that are in the holes where the soft top cover / boot lid hinges are.
I would be interested to hear if you find the answer
Chris

[Stevthom1]

Just wondering if there was ever a solution found to this problem of fumes in the cockpit? I have exactly the same problem, my car is running a Bailey dump valve but I also get anything that is put in the boot smelling of exhaust fumes as well. The car just went through its MOT with no issues around the exhaust system, the only thing I have noticed is that the tail pipe doesnt stick out very far from the body work so I wondered if its a combo of the dump valve fumes coming into the cockpit or slight leak on one of the boost pipes plus fumes pulling back from the tail pipe into the boot?