CO level in cabin

[Steve Pierce]

Here is the longer tailpipe installed on Cathy's Tri-Pacer.

[Greg Adams]

I had cockpit CO levels that were reading as high as 300 ppm on my Pocket CO detector, which I believe to be pretty accurate. These levels started after a period of extensive work and upgrading firewall forward. Some of the changes I made that I think would have had an effect are new baffles and cowl seal, relocated the oil cooler from the chin sccoop to the back of cylinder 4 and plugged the chin scoop. I don't know what the CO levels were prior to doing all of that because I bought the CO detector while doing that work.

In attempting to eliminate the CO, I have installed a complete new exhaust and muffler from Knisely, extended the exhaust pipe, applied sealant to every opening in the firewall I could find, and done some work attempting to seal around the gear legs with foam tape.

I now have CO levels that are low double digits during climbs and descents, and in level cruise are 4-6.

My question is: how common is it to just put up with small amounts of CO in the cockpit, or is a zero reading the norm? I've looked through posts about CO on the forum, and where there is a conclusion people seem to be reporting readings of zero.

I'd like to get the reading down to zero, at least during cruise, but I'm running out of ideas on what else I can do to get there.

[Greg Adams]

I didn't mention what my plane is - PA22/20, 160 hp

[Steve Pierce]

Hi Greg, Here is a good thread on this topic.
http://www.shortwingpipers.org/forum...ight=Honeywell

[Jinkers]

Hehe... That's the link to this thread Steve

[Jinkers]

Greg, single digits in cruise and teens in slow flight sounds at least acceptable. These airplanes have lots of places that can let in exhaust such as the gear panels on the belly. by extending the exhaust pipe you have done what you can about that. I decided that once I got the CO levels below the alarm set pint on the detector it was good enough.

[Steve Pierce]

I merged the threads so all the information is together. I like the way the fairings were on my Clipper. They overlap on the belly unlike the Pacers and Tri-Pacers I have had.

[Bob Mac]

Carbon monoxide can have a wide range of tolerable dosage depending upon many things including physical factors and health issues of the person exposed, duration of exposure, medications being taken and so on.
Jinkers has stated it very well. Striving for the absolute minimal level possible is worth the effort. There seem to be plenty of potential fixes on this website.
As close to zero as possible should be the goal. And a worthwhile one.

[kloudking1]

Steve,
How much longer than stock is that tail-pipe you had made for the Tri-Pacer? I think I am going to give them a call Monday and see if they can make me one. When I am flying the Colt I think I smell exhaust, and my little stick-on CO monitor gets just a little bit darker I think, not sure. I've never seen one of those turn dark with CO so not sure what it should look like. My muffler isn't leaking, but you can see soot on the right gear leg and the tail pipe tip is just a little lower than the bottom of the boot cowl, so I think I might be getting some exhaust around the gear fairings.

[Steve Pierce]

I seem to remember them adding 2" to it but I have seen all sorts of different length tail pipes.