exhaust tailpipes

[toms170b]

Can someone recommend a source for exhaust tailpipes P/N 0550157-4 and 0550157-33 page 89 of the parts manual?
How far should the stack protrude thru the cowling?
Mine stick out less than 1 inch and I think someone cut them shorter than original way back in the past.
Exhaust stack assembbly is in great shape, just need the tailpipes.
If someone can point me in te right direction it would be apprecited.
Thanks
Tom

[jrenwick]

If you can find some original Cessna photos to look at, such as in an owner's manual, you'll see that the pipes did not originally protrude more than an inch from the surface of the lower cowling. It doesn't sound to me like you really need to replace those pipes!

[hilltop170]

Tom-
Why do you think your current exhaust stacks need lengthening?

Are they leaving exhaust stains on the outside of the cowl? Is exhaust blowing back into the inside of the cowl?

What angle are the stacks cut? Are they square, angled to the front, angled toward the back, or angled parallel with the cowl?

The reason I'm asking is I have observed stacks angled in all different direction on several different airplanes which are cut short (1"), medium (2"), and long (4") and I'm still seeing significant exhaust stains behind the stacks on all of them.

Below are some exacmples.

Short cut stacks, one parallel to cowl, one angled aft, both soot cowl

Medium length, one parallel to cowl, one facing forward, both soot cowl

Long stacks, parallel to cowl, both still soot cowl but not as bad

[GAHorn]

The Cessna spec is for them to protrude 1.5 inches, and the "cut" should be parallel with the cowl. (They should appear to open forward/outward.) Some folks (unlike our former leader) who "inhaled"... imagine the relative wind somehow restricts the exhaust gases from exiting and reverse their tailpipes....which does nothing for exhaust pressures .... but does increase the heat and soot which impacts the cowl.

[toms170b]

Thank you everyone for the responses. The reason I am thinking I need to lengthen the stacks is fumes. I have always tolerated the exhaust stains on the belly and just assumed it was norm for the course. But I recently started taking my 2 young boys flying and both complained about exhaust fumes in the cockpit. I never really noticed in the 25 years I have been flying this bird but once the kids pointed it out it was obvious that there is a distinct exhaust smell in the cockpit. I always fly with both vents open, even in the winter so I guess I just adjusted.

The stacks are protruding about 1 to 1.5 inches and they are cut parallel to the cowling. They are cut open forward so I guess I have tailpipes conforming to Cessna's spec.

We did an extensive annual in first week of June and went completely through the exhaust system. No leaks, no cracks, everything tight and like brand new. But there is definetely some exhaust smell getting into the cockpit.

Other than lengthing the tailpies I really don't know what else to try. If anyone has ideas I am open to trying something.

Tom

[GAHorn]

Thank you everyone for the responses. The reason I am thinking I need to lengthen the stacks is fumes. I have always tolerated the exhaust stains on the belly and just assumed it was norm for the course. But I recently started taking my 2 young boys flying and both complained about exhaust fumes in the cockpit. I never really noticed in the 25 years I have been flying this bird but once the kids pointed it out it was obvious that there is a distinct exhaust smell in the cockpit. I always fly with both vents open, even in the winter so I guess I just adjusted.

The stacks are protruding about 1 to 1.5 inches and they are cut parallel to the cowling. They are cut open forward so I guess I have tailpipes conforming to Cessna's spec.

We did an extensive annual in first week of June and went completely through the exhaust system. No leaks, no cracks, everything tight and like brand new. But there is definetely some exhaust smell getting into the cockpit.

Other than lengthing the tailpies I really don't know what else to try. If anyone has ideas I am open to trying something.

Tom

This has been discussed in several threads previously but they may not be easily found.

THE LENGTH OF YOUR TAILPIPES HAVE NOTHING TO DO WITH FUMES IN THE COCKPIT.

The most common sources for exhaust in the cockpit (IN FLIGHT....ground ops may be due to simple prop-blast/drift due to surface winds) is:
1: Lower strut attach points not properly sealed. Use weatherstrip-edging on strut end, and use metallic tape to seal off the fuselage strut openings.

2: Land gear entry at lower cabin. Inspect the covers and use rubber cloth (or inner tube material) for gasketing beneath the covers.

3: Lower beacons and belly antennas, etc. Seal the beacons and antennas properly.

4: Inspect and replace door weatherstips.

5: Above/behind the hat-shelf the rear cabin usually has only cloth/headliner....no actual "wall" or bulkhead. Exhaust can be "sucked" up thru the tail and travel forward and enter the cabin. Sealing that area with sheet metal or foam instulation sheeting will reduce that.

Look closely at your exhaust "plume" (the gray streaks) and you can see where it is likely entering at the lower strut, upper gear legs, cabin doors, especially on the left side.

Get a CO-detector for your cockpit.

[n3437d]

I'll share a thought - related to fumes but not tailpipe but rather the firewall. One of the first things that my AI/AP who owns a 170 did was to look at the firewall and he used a hightemperature caulk and placed "dabs" on all the tiny opeings that were present on the firewall. As I am the last of four owners, anything and everything could have been the cause - in all there were about a dozen tiny holes that he sealed. With an active CO monitor I have recorded no leakage of fumes after 10 years of ownership. I'd be interested if anyone else has done this.

Joel
N3437D

[jlwild]

My mechanic did the same thing Joel's did.....seal all the holes on the firewall. In addition, during annual inspections, I noted there were lots of screw holes in the floor (baggage area to rudder pedal covers) that must have held down carpet and who know what. Anyway, I also sealed all those.

In addition the area's George mentioned have also been sealed with new gasket seals, etc. It all helps. Don't have a CO2 detector, but none have complained since everything was sealed.

[toms170b]

Thanks for all the input. I will get started on sealing up the cabin starting with the left landing gear where it enters the fuselage and is covered with exhaust plume.

[minton]

I have one of each side, new old stock for $25.00 ea.

[dave@doorsteward.com]

Purchased a 170A this summer and now doing its first annual since purchase. Removed left hand heat muff for the cabin heat and found exhaust stains in the heat muff and the entire length of the scat tubing from muff to firewall cabin heat valve. Initially thought the muffler had a crack in it allow exhaust to enter muff. After removal of muffler from the engine, thoroughly cleaned, inspected and pressure tested under water, there is no muffler leak. It appears that the muffler to exhaust stack connection is very sloppy and loose and exhaust is back flowing up the stack around the loose connection and up into the heat muff. Have others experienced this and is it related to stack length, orientation, worn stack or just need to seal that muffler to stack connection?

[Bruce Fenstermacher]

Well to answer your question, of course others have had this problem. The 170 exhaust system, both the original pancake style and the later Hanlon Wilson have multiple leaks when they are sealed well. Lookout when they get sloppy.

Before any advise could be given. We first need to know what muffler system you have. The original system for your A model is the pancake style. These are flat like a pancake. The later is the Hanlon Wilson round style and there is usually a plate with the name on the heat shield.

Then of course pictures of what your dealing with would help.

[dave@doorsteward.com]

It is the Hanlon Wilson Muffler. The exhaust stains inside the heat muff on the outside of the muffler has been cleaned, but I believe it still exist on the inside of the shroud around the muffler. I will try and provide photos tomorrow of that and of the stack to muffler fit. Dave

[cessna170bdriver]

Dave, do you still have in place the thick aluminum rings that seal between the muffler and the shroud? If the one on the bottom is missing, the normally loose connection between the exhaust pipe and muffler can leak exhaust into the shroud.

[dave@doorsteward.com]

There is only the clamp with alignment pin that goes around the top of the stack and to the bottom of the muffler. I saw no Aluminum rings on either side. Dave