April 22, 2012 at 3:24 am #83763
The slip joints on the turbo systems on most twin Cessnas need to be inspected every so often like every 25 to 50 hours when the oil is changed as the slip joints can rust up tight due to rain water and exhaust heat. The cooling louvers are just above the exhaust system and rain can fall onto the slip joints. If any of the slip joints rust up, that puts extreme pressure on the rest of the exhaust system and can crack an exhaust component at a weak spot with bad results. I use Mouse Milk on every joint every 25 hours. I bought a metal squirt can dedicated for Mouse Milk so it is easy to oil up all the joints. The regular Mouse Milk container is a pain to get the stuff on the joints without making a mess. There are three slip joints on each side of each engine–two between the down headers and one aft of the headers. I also Mouse Milk the ball joints just aft of the aft slip joint as the ball joints are made to move also. It only takes a few minutes to do both engines as only the side cowls need to be removed. This is good preventative maintenance an owner can do. Mouse Milk is available from Spruce and Chief’s. No it is not mined from mice!April 22, 2012 at 10:05 am #95879
Thanks for that advise. Just replaced RH engine LH bank and that’s practical advise on preventative maintenance.
AndrewApril 23, 2012 at 9:23 pm #95881
Here is a picture of my exhaust slip joints. You can see where the joints move about 1/8″ when going from hot to cold. You should see this moving mark to be sure your slip joints are actually “slipping”.
The slip joint aft of the headers moves about 1/4 to 3/8″ from hot to cold. I will post a picture of that on the next post.April 23, 2012 at 9:29 pm #95882
Here is the pic of the aft slip joint which may be different on some engines as there are two different types of slip joints and ball joints depending on the modification. Those AN3 bolts with springs and castle nuts should be snug and not loose and rattling around. You may have to add one or two #10 washers to snug up some of the bolts and springs.April 24, 2012 at 12:17 am #95883
The springs need to be 0.51 inches -0 + .03. Excellent tip on the exhaust slip joints. I do the same. Also, put mouse milk on the wastegate shaft from both sides.
The original style Cessna slip joints are a horrible design. It is much harder to see if the are moving, they have an internal seal that sticks more easily and when it does you will not get it free. The simple inner/outer design like you have is the best – because you can verify it is moving.
If the slip joints are not moving then your engine is putting pressure direct on the turbo mounts and engine beams. This is the primary reason why those parts crack.
Slip joints are widely available and not that expensive. Worth checking yours at every opportunity.
Thanks for bringing this one up. One of the biggest returns on the invested time. (Also look at the exhaust wastegate elbow between the fins for cracks)May 1, 2012 at 8:57 am #95951
Went and got some mouse milk and carried this out today, not that easy with the standard bottle it comes in! I used a brush to get it in. Do you usually wipe the excess off, or just leave it?
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