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n7188u
Joined: 15 Nov 2015
Posts: 395
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 Posted: Fri Jan 05, 2024 4:48 am Post subject: Slight exhaust leak at cylinder head manifold joint |
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Hello Europa Family,
First of all Happy New Year together with hopes of a great year 2024! I also hope you had enjoyable holidays (I did have a very special one, which included a Europa related activity, and I will an expand on a following posting).
The reason for my posting today is that I’ve been having a slight exhaust leak through the #4 cylinder head joint to the manifold. I had this leak on my old engine and again on my new one so I can safely assume it is related to either pipe alignment or warped mating surface at the pipe. My other three pipes are not leaking. So far I have realigned the pipe multiple time to try to improve the seating of the manifold on the head with no success. I am afraid that if it continues like this it will eventually damage the head sealing surface.
I am sure that if CKT was still around I could talk to them and solve this issue (I should have done that earlier) but so it’s life. Anyone in the forum had this issue and resolved it hopefully without requiring new parts?
What occurs to me as possible solutions:
1.- Check if the mating surface in the joint is not warped (no idea yet how) and correct it (also no idea how).
2.- If the joint is not bad, lap the joint.
3.- Use an exhaust system sealant. Heide at CKT once recommended Hylomar EAP5 for the slight leak at the slip joint in the #1 cylinder pipe. I would think this could help but only short term as this joint probably moves a little.
4.- I read in the Rotax-Owner forum that CKT would sometimes recommend a sleeve to be placed in the joint (I think this is for a seriously worn cylinder mating surface). It would be nice if some sort of soft gasket existed for this joint.
I will check on the Rotax maintenance documentation but does anyone know what the specification is for the cylinder head exhaust port joint mating surface. I would think that the exhaust one should be slightly spherical to allow some misalignment. A lapping tool could be created to rectify the surface on the pipe but that could get expensive (I wish I still had my machine shop).
Anyway, I will await for our valued opinions on this subject.
Chris
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peterz(at)zutrasoft.com
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| Posted: Fri Jan 05, 2024 8:26 am Post subject: Slight exhaust leak at cylinder head manifold joint |
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Are these the sleeved ones? Or the “ball joint” looking rounded seal? I have the latter on my classic, and eliminated all my leaks by using genuine Honda motorcycle copper exhaust gaskets.
Cheers,
PeteZ
| Quote: | On Jan 5, 2024, at 11:18 AM, n7188u <chmgarb(at)gmail.com> wrote:
Hello Europa Family,
First of all Happy New Year together with hopes of a great year 2024! I also hope you had enjoyable holidays (I did have a very special one, which included a Europa related activity, and I will an expand on a following posting).
The reason for my posting today is that I’ve been having a slight exhaust leak through the #4 cylinder head joint to the manifold. I had this leak on my old engine and again on my new one so I can safely assume it is related to either pipe alignment or warped mating surface at the pipe. My other three pipes are not leaking. So far I have realigned the pipe multiple time to try to improve the seating of the manifold on the head with no success. I am afraid that if it continues like this it will eventually damage the head sealing surface.
I am sure that if CKT was still around I could talk to them and solve this issue (I should have done that earlier) but so it’s life. Anyone in the forum had this issue and resolved it hopefully without requiring new parts?
What occurs to me as possible solutions:
1.- Check if the mating surface in the joint is not warped (no idea yet how) and correct it (also no idea how).
2.- If the joint is not bad, lap the joint.
3.- Use an exhaust system sealant. Heide at CKT once recommended Hylomar EAP5 for the slight leak at the slip joint in the #1 cylinder pipe. I would think this could help but only short term as this joint probably moves a little.
4.- I read in the Rotax-Owner forum that CKT would sometimes recommend a sleeve to be placed in the joint (I think this is for a seriously worn cylinder mating surface). It would be nice if some sort of soft gasket existed for this joint.
I will check on the Rotax maintenance documentation but does anyone know what the specification is for the cylinder head exhaust port joint mating surface. I would think that the exhaust one should be slightly spherical to allow some misalignment. A lapping tool could be created to rectify the surface on the pipe but that could get expensive (I wish I still had my machine shop).
Anyway, I will await for our valued opinions on this subject.
Chris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=513018#513018
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n7188u
Joined: 15 Nov 2015
Posts: 395
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| Posted: Fri Jan 05, 2024 12:13 pm Post subject: Re: Slight exhaust leak at cylinder head manifold joint |
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Thanks Peter,
Not sure what the sleeved one is (the Rotax style?) but I have a CKT muffler purchased 3+ years ago. Just a ball(ish) or taper looking ring at the end of the tube.
What is this Honda copper gasket you use?
I looked at it again today and in reality the leak is very minor and no obvious gap is visible. But again I am concerned about deterioration of the aluminum surface on the head.
For now I ordered the Hylomar seal compound and I will thoroughly clean the surfaces and will reinstall with that.
I also heard something about Bud having a lapping procedure for this. I appreciate all advice.
Chris
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peterz(at)zutrasoft.com
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| Posted: Fri Jan 05, 2024 1:00 pm Post subject: Slight exhaust leak at cylinder head manifold joint |
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Ya, meant the rotax style. I have the same as you, ballish ring clamped with floating flange.
My heads were properly ruined with fretting and leaking, in addition to three cracked headers (one at a time) ….all due to torsional resonance with my original (heavy) three blade warp drive taper blade fixed pitch prop and the resultant pocketed gearbox dogs.
To rescue the heads I had to lap them with the an exhaust ball-end, but they would still leak due to the pitting. The Honda copper crush gaskets proved leak and trouble free.
P/N 18291-MN5-650 per the attached photo.
I did end up replacing my gearbox dogs (and thus the gearset sadly $$$), and upgraded to the super light wieght CS E-prop and all my issues have disappeared  . And the replaced dogs still look like new after 400hrs. I’m confident that the dogs were pocketed during Troy’s initial 250hrs
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Area-51
Joined: 03 May 2021
Posts: 372
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| Posted: Fri Jan 05, 2024 7:58 pm Post subject: Re: Slight exhaust leak at cylinder head manifold joint |
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Several possibilities; all treated differently.
The cylinder head sealing contact surface itself could require lapping. Best way to affect this is removal and bench lapping with 240g paper glued onto the exhaust header with contact cement; some kerosene as lubricant and rotate header back n forth about 50deg for a bit, then lift and rotate 30-70deg and repeat several times Not much pressure required. Easiest to clamp header pointing up and rotate head upon it; makes cleanup easier... can use valve grinding past as well... soot or bearing blue at the start and end can be used to check sealing surface for gaps. Sealing surface only requires 1mm cross section.
The 914 has part of the header extending into exhaust port; it is a very firm fit when new; long term slop flogs out this area in the head casting and requires sleeving insert to prevent leakage.
Copper compress rings can be used as mentioned and should be set centered and tensioned again when hot. This is a bandaid approach to rotax factory sealing method and may work totally fine. Have found copper rings on some engines.
Heat expansion of the header pipe may be causing movement at the sealing point and returning to normal once cooled down. Stainless steel pipes grow a fair bit when heated up. Some stainless steel exhaust systems on cars can grow up to 30mm... Try loosening off header at cylinder head and collector; give the header a few light taps with hide hammer and retighten just under spec and again once cooled down. Observe for outcome.
Check the clamping collar when tensioned; there needs to be a gap between the collar and the head; the collars bend quite easily when over tensioned.
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Area-51
Joined: 03 May 2021
Posts: 372
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| Posted: Fri Jan 05, 2024 7:59 pm Post subject: Re: Slight exhaust leak at cylinder head manifold joint |
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Several possibilities; all treated differently.
The cylinder head sealing contact surface itself could require lapping. Best way to affect this is removal and bench lapping with 240g paper glued onto the exhaust header with contact cement; some kerosene as lubricant and rotate header back n forth about 50deg for a bit, then lift and rotate 30-70deg and repeat several times Not much pressure required. Easiest to clamp header pointing up and rotate head upon it; makes cleanup easier... can use valve grinding past as well... soot or bearing blue at the start and end can be used to check sealing surface for gaps. Sealing surface only requires 1mm cross section.
The 914 has part of the header extending into exhaust port; it is a very firm fit when new; long term slop flogs out this area in the head casting and requires sleeving insert to prevent leakage.
Copper compress rings can be used as mentioned and should be set centered and tensioned again when hot. This is a bandaid approach to rotax factory sealing method and may work totally fine. Have found copper rings on some engines.
Heat expansion of the header pipe may be causing movement at the sealing point and returning to normal once cooled down. Stainless steel pipes grow a fair bit when heated up. Some stainless steel exhaust systems on cars can grow up to 30mm... Try loosening off header at cylinder head and collector; give the header a few light taps with hide hammer and retighten just under spec and again once cooled down. Observe for outcome.
Check the clamping collar when tensioned; there needs to be a gap between the collar and the head; the collars bend quite easily when over tensioned.
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