Discussion
Gents
I know I'm not the only one to suffer from this but on my '92 Precat if the roof is up and you're 'at speed' and you then open the windows you then get exhaust fumes in the cabin.
I've measured the CO with a meter and the limits are as follows:
30ppm safe ( although this stuff rots brain cells so I'm not sure it can ever be classified as 'safe')
300ppm dangerous - leave room turn off gas etc etc
900ppm ACHTUNG, leave area immediately and seek medical attention
Inside it can be as much as 150ppm......
If you close the windows and use the fans to provide 'fresh' air it clears down to 0ppm
Now the exhaust doesn't leak (checked by pressurizing system with airline), but I've noticed the 500's have longer tailpipes than the precats so I'm wondering is there some weird aero effect dragging the fumes back into the cabin? And TVR's fix was longer exhausts?
Also the boot seal on mine is a little bit ragged around the edges would this have a similar effect?
waddya think?
Matt
I know I'm not the only one to suffer from this but on my '92 Precat if the roof is up and you're 'at speed' and you then open the windows you then get exhaust fumes in the cabin.
I've measured the CO with a meter and the limits are as follows:
30ppm safe ( although this stuff rots brain cells so I'm not sure it can ever be classified as 'safe')
300ppm dangerous - leave room turn off gas etc etc
900ppm ACHTUNG, leave area immediately and seek medical attention
Inside it can be as much as 150ppm......
If you close the windows and use the fans to provide 'fresh' air it clears down to 0ppm
Now the exhaust doesn't leak (checked by pressurizing system with airline), but I've noticed the 500's have longer tailpipes than the precats so I'm wondering is there some weird aero effect dragging the fumes back into the cabin? And TVR's fix was longer exhausts?
Also the boot seal on mine is a little bit ragged around the edges would this have a similar effect?
waddya think?
Matt
I have the same on my 96 5lt, and have extended my tailpipes, but the problem still occurrs, a new boot seal I think will definately help, but seem to think after talking to jools at trackcar solutions that a lot of the problem is due to the aerodynamics at the rear of the car, and somehow it gets sucked back in when you open the windows, I can`t remember all the technical terms, but I`m sure he`ll be along soon to share his wisdom!
This has cropped up recently... From my understanding...
With roof on, air needs to be vented to the boot (SH once made noises about making sure the speaker vents were free flowing IIRC) This can be over the rear wheel arches or thru the speaker/vents into the boot space. Behind the tank the boot is vented to the outside just behind the diff. Now I assume this is necessary to stop the hood etc popping when the fans (or blow thru from road speed) are pressurising the cabin.
With the roof off???? does this mean that the pressure sucking from the boot pulls air from under the car and into the cabin, or are you suggesting it rolls over the boot and rear roof section (folded down) and into the cabin. Either way I cant see the boot lip seal being of any consequence BTW. I do think it is essential to identify which route the CO is taking to the cabin before you can address the problem.
I dont get any smells, but I have played with fixing a 'deflector' to the rollbar behind the seats and it did make the cabin more comfortable. In the cold light of day it was not worth the effort so I didnt bother making one tho.
Dave
With roof on, air needs to be vented to the boot (SH once made noises about making sure the speaker vents were free flowing IIRC) This can be over the rear wheel arches or thru the speaker/vents into the boot space. Behind the tank the boot is vented to the outside just behind the diff. Now I assume this is necessary to stop the hood etc popping when the fans (or blow thru from road speed) are pressurising the cabin.
With the roof off???? does this mean that the pressure sucking from the boot pulls air from under the car and into the cabin, or are you suggesting it rolls over the boot and rear roof section (folded down) and into the cabin. Either way I cant see the boot lip seal being of any consequence BTW. I do think it is essential to identify which route the CO is taking to the cabin before you can address the problem.
I dont get any smells, but I have played with fixing a 'deflector' to the rollbar behind the seats and it did make the cabin more comfortable. In the cold light of day it was not worth the effort so I didnt bother making one tho.
Dave
That Daddy said:
Brings a new meaning that traffic coppers favorite line,is this your car sir?are you driving while intoxiacated
sorry, not much use really am i?
Checkup at Hospital for CO poisoning may be required Simon! Snot disslexxyar 1ts fewmes frome youre eggzorst sorry, not much use really am i?
Spelling Copper
spend said:
That Daddy said:
Brings a new meaning that traffic coppers favorite line,is this your car sir?are you driving while intoxiacatedsorry, not much use really am i?
Checkup at Hospital for CO poisoning may be required Simon! Snot disslexxyar 1ts fewmes frome youre eggzorst sorry, not much use really am i?Spelling Copper
i have altered post for you,,,,,HAPPY NOW,,,,
Thats a surprise Clive... It is notable that you say you get the problem with the roof up ~ I was under the impression most people had reported it with roof down. I have kind of perplexed over the back end air flow... I do run with a reasonable rake and have a wide splitter ~ neither of which I can see being to the detriment of said problem. I had at one time wondered about adding some diagonal splitters under the doors - solely in terms of having a nice vacuum at the rear to suck the engine bay clean.. I do think the boot lip & bumper lip on the Chim must help in breaking up the rear air flow and any attachment. Some Chim owners have reported similar problems in the past tho, I think.?? Are you sure in your case the fumes are coming from the exhaust rather than the engine bay?
Dave
Dave
spend said:
Thats a surprise Clive... It is notable that you say you get the problem with the roof up ~ I was under the impression most people had reported it with roof down. I have kind of perplexed over the back end air flow... I do run with a reasonable rake and have a wide splitter ~ neither of which I can see being to the detriment of said problem. I had at one time wondered about adding some diagonal splitters under the doors - solely in terms of having a nice vacuum at the rear to suck the engine bay clean.. I do think the boot lip & bumper lip on the Chim must help in breaking up the rear air flow and any attachment. Some Chim owners have reported similar problems in the past tho, I think.?? Are you sure in your case the fumes are coming from the exhaust rather than the engine bay?
Dave
cheers dave, no the exhaust is 100% sealed up, so not sure where it comes from to be honest, its one of those jobs that needs investigating at some point, but gets put on hold for other stuff, and then you get reminded when a thread like this starts up!Dave
That Daddy said:
blah..blah..Flaming hell Spend,is their nothing sacred with you aroundi have altered post for you,,,,,HAPPY NOW,,,,
Not until you buy an English dictionary, unlike Americans I understand Favorite to be a certain make of car.... i have altered post for you,,,,,HAPPY NOW,,,,
OOh Booger, I'm the Spelling Policeman in this one...
Isn't Microslop capable of supporting an English spell checker?
Edited by spend on Wednesday 18th July 19:01
rev-erend said:
Matt - why not use the CO meter to check what area the CO is coming in..
Do the test on the move !
Good idea, although the testing has all been on the move so far as this gassing out doesn't happen until you're at speed. I'll recruit my not-so willing assistant to be gas location checker...Do the test on the move !
I should point out that my car has no vents to the boot (as yet anyway) and this only occurs when the roof is on and the windows are open slightly. Close the windows and the CO slowly drops away.
There probably is a leak path through to the boot somewhere though.
Bear in mind that you can't smell this stuff either, you smell the rest of the stuff in the exhaust but this is the nasty bit.
Whereabouts is the vent in the boot floor then?
Matt
The rear speakers were originally vents (not speakers!) IYSWIM. At the side of the boot over the wheel arches there is a large cavity which links to behind the door locks ~ this is vented as well. They vent the cabin to the boot, so the hood / cabin pressure is equalized I guess. The boot is vented to the outside at the bottom behind the petrol tank, you need to get under the car and you can see/feel a row of holes facing the back of the diff. I think there may be some different revisions of the holes, not studied it but they seem to look a bit different on cars I've seen on ramps.
Normally when moving air is forced thru the front wings, whether the heater blower is on or not, and will pressurize the cabin. My view was that it was essential to vent this thru the back of the car, particularly to stop blowing the hood out. Hence the back of the car (well where the vents are behind the diff) should be a low pressure area & suck air out.
It seems 2 of you have now reported that opening the window slightly is reversing this.. I wonder if your front wings are blocked, or your heater box seals better than others?
Dave
Normally when moving air is forced thru the front wings, whether the heater blower is on or not, and will pressurize the cabin. My view was that it was essential to vent this thru the back of the car, particularly to stop blowing the hood out. Hence the back of the car (well where the vents are behind the diff) should be a low pressure area & suck air out.
It seems 2 of you have now reported that opening the window slightly is reversing this.. I wonder if your front wings are blocked, or your heater box seals better than others?
Dave
Mines a 97 500 and I have never had any of these problems.
There is a very low pressure area over the boot once the speed builds up, this is why if the boot lid catch isn’t sound the lid pops around 70 mph.
I do have a good boot seal and the boot has vent holes in the floor in the front corners, can be seen easily from underneath, not so visible from the boot with all the trim fitted.
The boot also vents into the cabin through the two standard round grills, some cars have speakers fitted in these.
There are also two vents along the back edge of the hood these go from outside above the boot lid through into the cabin. This is where some water leaks can come from if not correctly prepared and some may be completely blocked with sealant, can only be checked by lifting the hood frame. I’m not sure if these are the same on the earlier cars. I my opinion these vents should have a small dam of sealant to stop water running through whilst allowing air to flow over.
Cheers,
Simon.
There is a very low pressure area over the boot once the speed builds up, this is why if the boot lid catch isn’t sound the lid pops around 70 mph.
I do have a good boot seal and the boot has vent holes in the floor in the front corners, can be seen easily from underneath, not so visible from the boot with all the trim fitted.
The boot also vents into the cabin through the two standard round grills, some cars have speakers fitted in these.
There are also two vents along the back edge of the hood these go from outside above the boot lid through into the cabin. This is where some water leaks can come from if not correctly prepared and some may be completely blocked with sealant, can only be checked by lifting the hood frame. I’m not sure if these are the same on the earlier cars. I my opinion these vents should have a small dam of sealant to stop water running through whilst allowing air to flow over.
Cheers,
Simon.
spend said:
Normally when moving air is forced thru the front wings, whether the heater blower is on or not, and will pressurize the cabin. My view was that it was essential to vent this thru the back of the car, particularly to stop blowing the hood out. Hence the back of the car (well where the vents are behind the diff) should be a low pressure area & suck air out.
It seems 2 of you have now reported that opening the window slightly is reversing this.. I wonder if your front wings are blocked, or your heater box seals better than others?
Dave
My front wings aren't blocked as I get a good blast of air when travelling down the motorway and the windows do 'bow' out a bit at speed,It seems 2 of you have now reported that opening the window slightly is reversing this.. I wonder if your front wings are blocked, or your heater box seals better than others?
Dave
So my plan of action is to double check exhaust for leaks, perhaps by running engine with both tailpipes blocked... as maybe the exhaust box under the car is cracked.
It seems by opening the windows and relieving the pressure inside the cabin this then allows the fumes to flow in from somewhere, either under the car or from the torn boot-lid seal
I'll also add the boot floor vents as this seems like a good idea for a 1st step
Ta
Matt
had a good check around in the boot this afternoon, and found the problem staring at me in the face, but hadn`t noticed it before as I didn`t look up and see the condition of the inside of the boot lid!
you could clearly see where the black exhaust gases had come in where the boot edge goes along the back of the car, with further evidence of this being the soot on the carpet boot lid lining, then looking on either side , in the boot, the same colour stain in the carpet on top of the wheel arches, this being a vent area through to the cabin down behind both doors.
I applied some vaseline to the boot seal along the front edge and closed the boot, and suprise, suprise, none was transfered to the underside of the boot lid, so have found some thickish sticky backed draught excluder, and stuck this to the underside of the boot lid, which seams to seal the gap.
I think the boot seal is not so effective along the rear edge of the boot as when fitted it doesn`t sit vertically enough to be compressed properly when the boot is closed, it sits at more of a 30degree angle, I will try a new boot seal, but may leave the draught excluder inside the lid just to make sure.
you could clearly see where the black exhaust gases had come in where the boot edge goes along the back of the car, with further evidence of this being the soot on the carpet boot lid lining, then looking on either side , in the boot, the same colour stain in the carpet on top of the wheel arches, this being a vent area through to the cabin down behind both doors.
I applied some vaseline to the boot seal along the front edge and closed the boot, and suprise, suprise, none was transfered to the underside of the boot lid, so have found some thickish sticky backed draught excluder, and stuck this to the underside of the boot lid, which seams to seal the gap.
I think the boot seal is not so effective along the rear edge of the boot as when fitted it doesn`t sit vertically enough to be compressed properly when the boot is closed, it sits at more of a 30degree angle, I will try a new boot seal, but may leave the draught excluder inside the lid just to make sure.
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