1948 8N new knocking sound??

[Webster11]

Hey all,

Ive owned my 8n for 3 years now. Rebuilt the carb, replaced the distributor, new points, wires, and plugs, changed oil, kept up with routine maintenance. Anyways, I had it out plowing snow in my driveway about 2 months ago. It was about 20 degrees that day. I'm plowing snow and running along just fine and all of a sudden I see puffs of smoke start coming out of the oil breather tube and immediately start hearing a new loud knocking sound. Oil pressure maintained 30psi like always. I was close to finishing up the driveway and decided to put "ol red" away. I waited until warmer weather came and decided to start it up and run it again. Same thing. Smoke from the breather tube and knocking. No smoke at all from the exhaust pipe. Fast forward to last week, I decided I would change the oil and filter, since it was about time to do so anyways in preparations for my spring garden. The oil contained no fine metal shavings but I did find two 1/4''-1/2'' long pieces of metal in it. I will take pics of the metal and upload. I'm not sure, but I think these may be pieces of a cracked sleeve. After the oil change, the oil pressure is still good (30-35psi), but it still knocks and smokes a bit out of the breather tube. What do ya'll think? Sleeve? Valves? Tappets? Something else?

Many thanks!

 

[Jim L WA]

I think you are right. Either a sleeve or could even be a piston. Time to tear him down and see whats going on.
Welcome to the forum by the way.

 

[Eman85]

Pull the spark plugs and see what they look like. Do a compression test. Parts in the oil, knocking and smoke from the crankcase I'm thinking expensive internal engine problem.

 

[Webster11]

I think you are right. Either a sleeve or could even be a piston. Time to tear him down and see whats going on.
Welcome to the forum by the way.

Thanks pal, I am planning to take the head and oil pan off at the very least, but I figure I am looking at a complete rebuild over the summer months. When I bought it, the motor was said to have been rebuilt around 2012 but I know for certain when I gave it the first oil change that it was extremely sludgy and dense.

 

[Webster11]

Pull the spark plugs and see what they look like. Do a compression test. Parts in the oil, knocking and smoke from the crankcase I'm thinking expensive internal engine problem.

Yeah, thats what im afraid of. I plan on tearing the motor down and looking further into it after a compression test.

 

[HarryVanderpool]

Remove the tappet covers and observe motion 1st.

 

[Webster11]

Remove the tappet covers and observe motion 1st.

Will do! Thank you

 

[bob p mn]

Sounds like it dropped a sleeve, our 48 did that a couple times years ago. If the pieces you found look like they could be parts of a sleeve I would pull the pan 1st. The fix was to bore the block and install the thick walled sleeves that came in the later N's. I did ours in 1976 and it's still going strong.