1988RedT2
1988RedT2 UltimaDork
4/28/18 2:26 p.m.

I've got a J-D L-100 plain Jane lawn tractor.  Had it since 2003 and it's been flawless.  Engine is a B&S Intek 17.  Single cylinder.  It's been treated pretty well.  Oil stays surprisingly clean between changes.  Runs like a champ and always has.  What I'm noticing lately is this, and it's getting worse:

When I shut the engine off, the last few revolutions produce a definite clunking or knocking sound.  As the engine spins down, the knocking gets louder, and the last one is the loudest.  Lately, it seems I can also detect the clunking for the first couple revs on startup, though not as loud.  Idle is smooth, as is running.

I'm thinking this engine will be easier to rebuild before the rod pokes a hole in the block, if that's even what it is. 

Is there a common failure with this engine?  I've heard about the head gasket thing, but mine seems fine. 

TIA

stanger_missle
stanger_missle Dork
4/28/18 3:34 p.m.

Are the engine mounting bolts tight? Thats the only thing I found after a quick search.

Curtis
Curtis PowerDork
4/28/18 3:38 p.m.

Look at an exploded diagram of it.  Is there a centrifugal weight on the camshaft?  Some of those have an automatic compression relief system where a little side cam engages to hold the exhaust valve just barely off the seat during cranking, then at idle and above the weight swings it out of the way for normal operation.

Sometimes they fail and make a clunk as the trashed metal bumps into the lifter.

81cpcamaro
81cpcamaro Dork
4/28/18 5:23 p.m.

The Inteks are counterbalanced, and sometimes the counterbalancer fails. Unfortunately only way to check the counterbalancer is to take it apart. There is a good bit of info on youtube on them, might help narrow it down.

Fueled by Caffeine
Fueled by Caffeine MegaDork
4/28/18 6:06 p.m.

I’d check to see if the blade was rubbing or a loose mounting bolt first. 

underpowered
underpowered New Reader
4/29/18 11:14 a.m.
stanger_missle said:

Are the engine mounting bolts tight? Thats the only thing I found after a quick search.

This.  Engine mount bolts are loose.

1988RedT2
1988RedT2 UltimaDork
4/29/18 1:31 p.m.

C'mon guys. 

Engine mount bolts are tight.

Fueled by Caffeine:  I never start or shut down the tractor with the mower engaged.  Not mower related.

I'll look into the counterbalance thing. 

 

Thanks!  Anything else?

Fueled by Caffeine
Fueled by Caffeine MegaDork
4/29/18 5:41 p.m.

In reply to 1988RedT2 :

Well that’s perplexing.  I wonder if not the counterbalancer, valve train?

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