Bottom Crankshaft Bearing KG7

[Mark Quint]

Hello All,

I am replacing the oil seals because they are likely old. In order to get to the bottom seal, I need to remove the bottom crank shaft bearing. I imagine that my lacking mechanical skills will damage the existing bearing when I remove it. Therefore, I might as well try to find a replacement. However the bearing is a Fafnir 205K C1 … C1 Tight Clearance. Shall I try to special order or is a modern replacement available? My AI overlord says this: 205K‑C1 = legacy Fafnir number

 

 

• Today’s Timken equivalents:
  • 205K / P205K (direct lineage)
  • but 6205 series is the modern standard

 

 

• The only real gap is C1 clearance, which must now be special‑ordered or evaluated for replacement

 

[Tubs]

You can remove the bearing without damaging it. If you scroll through this previous thread you may find something of some value. https://www.aomci.org/forums/topic/mercury-kg7q/#post-317732

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

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Mark Quint

[chuckw]

I heat the crankcase bottom with a propane torch and the bearing fall out and then you can replace the seal.

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Mark Quint

[seakaye12]

chuckw wrote:

I heat the crankcase bottom with a propane torch and the bearing fall out and then you can replace the seal.

This.  It literally falls out.  If your existing bearing tests good I would not replace it.

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Mark Quint

[green-thumbs]

All the bearings, seals and gaskets are available from Ferguson Poole and. Best method I have  found is to heat in oven at 500 degrees, Bearings flall out or can be slammed out if if really stuck,

Heat may also be key to installing as the fit is TIGHT! I say may because seals may not stand too much heat, I understand there are heat resistant seals  at extra cost,

Bearing condition may be affected by wishful thinking. These bearings are available and reasonable new,

Louis

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Mark Quint

[DAVID]

freeze bearing to install

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Mark Quint

[Mark Quint]

Thanks All, good advice. I put the assembly in the freezer 30 minutes, took it out, held it upside down, applied propane heat to the Al casting and voila, the bearing and spacers dropped right on the padded floor… perfect.

[Mark Quint]

Here is a fun one… the oil seal that I removed has a hole drilled in it. Please ignore other damage. That seems like a terrible idea. That defeats the purpose of yhe oil seal a bit. Water could get thru that and thru the bearing and into the crank case. Why would someone do that?  This KG7H was raced for years so sometimes I find racer tricks… but this one? I plan to not drill a hole in the new oil seal, just curious about this finding.

[Tubs]

 

When you find a seal with the hole in it its usually the original. I’ve read that the small hole was to be aligned with the drilled passageway in the crankcase bottom to bleed excess oil from the crankcase at slow speeds. These motors don’t typicality spend much time running at slow speed  

 

 

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

1 user thanked author for this post.

Sam M.

[Author]

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