Oil Separator flame trap "Chimney"
Posted: Fri Feb 09, 2024 1:42 pm
I thought I would share a refurbishment I am doing on a tappet chest oil separator chimney from a spare engine.
This type of breather was used on the later Morris Minor 1098cc A-series engines and in the case of my car, the chimney is connected to a PCV valve on the inlet manifold.
A-series engines have a reputation for leaking oil. When I was a student this was a big problem because engine oil is expensive quite apart from the mess and environmental damage from oil leaking all the time.
Some years back, I refurbished the tappet chest chimney on the engine in my car. It was completely blocked with rust. After refurbishment, the engine does not leak oil at all. This is because the breather system is working as intended and relieving crank case pressure.
The chimney and pipe from the tappet chest cover are brazed in position. The chimney itself was originally filled with a mesh of wire wool. Unfortunately, this was not stainless steel and since blow-by gasses contain water the mesh rusts into a solid lump. The mesh both assists in separating out oil and acts as a flame trap. If the PCV valve was faulty and the engine backfired then potentially a flame could ignite the blow by gasses and even cause the crankcase to go bang.
Ideally, the chimney would be removed by heating and releasing the brazing. Then cleaned out, mesh replaced and brazed back together. I do not have the skills or equipment to do this so I poked down the chimney and got clumps of rusted mesh out and eventually after partially filling with water and shaking and more poking got all of the rubbish out. There are some clips that originally held the mesh in. With very long needle nose pliers these can be pulled out.
After cleaning out the can, the flame arrestor must be replaced and I used stainless steel pot scourer. It is tricky to feed this in but it can be done with patience. To ensure the mesh cannot fall into the engine (very unlikely), one of the clips can be re-fitted.
I hope this is of some use
Edit: I do actually have a torch that can get hot enough to braze with the right gas (MAPP) but no brazing rods at the moment. I may have a go because I am intrigued as to whether there is anything else inside and I would like to return the piece to better than original condition with stainless steel mesh and clips. I have never tried brazing but I do have experience with plumbing soldering.
Stephen
The chimney type tappet chest cover clearly showing how it is brazed together
Lumps of rusted mesh/wire wool
More rubbish from inside
The clips that held the mesh in the canister
This type of breather was used on the later Morris Minor 1098cc A-series engines and in the case of my car, the chimney is connected to a PCV valve on the inlet manifold.
A-series engines have a reputation for leaking oil. When I was a student this was a big problem because engine oil is expensive quite apart from the mess and environmental damage from oil leaking all the time.
Some years back, I refurbished the tappet chest chimney on the engine in my car. It was completely blocked with rust. After refurbishment, the engine does not leak oil at all. This is because the breather system is working as intended and relieving crank case pressure.
The chimney and pipe from the tappet chest cover are brazed in position. The chimney itself was originally filled with a mesh of wire wool. Unfortunately, this was not stainless steel and since blow-by gasses contain water the mesh rusts into a solid lump. The mesh both assists in separating out oil and acts as a flame trap. If the PCV valve was faulty and the engine backfired then potentially a flame could ignite the blow by gasses and even cause the crankcase to go bang.
Ideally, the chimney would be removed by heating and releasing the brazing. Then cleaned out, mesh replaced and brazed back together. I do not have the skills or equipment to do this so I poked down the chimney and got clumps of rusted mesh out and eventually after partially filling with water and shaking and more poking got all of the rubbish out. There are some clips that originally held the mesh in. With very long needle nose pliers these can be pulled out.
After cleaning out the can, the flame arrestor must be replaced and I used stainless steel pot scourer. It is tricky to feed this in but it can be done with patience. To ensure the mesh cannot fall into the engine (very unlikely), one of the clips can be re-fitted.
I hope this is of some use
Edit: I do actually have a torch that can get hot enough to braze with the right gas (MAPP) but no brazing rods at the moment. I may have a go because I am intrigued as to whether there is anything else inside and I would like to return the piece to better than original condition with stainless steel mesh and clips. I have never tried brazing but I do have experience with plumbing soldering.
Stephen
The chimney type tappet chest cover clearly showing how it is brazed together
Lumps of rusted mesh/wire wool
More rubbish from inside
The clips that held the mesh in the canister