Farm Equipment - 615 (D15 SII), engine knock?

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615 (D15 SII), engine knock?

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Category: Allis Chalmers
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=156012
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Topic: 615 (D15 SII), engine knock?

Posted By: Dean (West MI)
Subject: 615 (D15 SII), engine knock?
Date Posted: 29 Nov 2018 at 7:12pm

My 615 has the same gas engine found in the D15 SII (160 ci). At idle, it has a loud knocking noise coming from the rear, top of the engine. Using a screwdriver as a listening device, the noise seems to be originating from the top region of the head at the rear of the engine, right about where the valves are on the exhaust side. I adjusted the valves while the engine was warm, but the noise still persists. As the idle increases, the knocking is less noticeable, and cannot be heard at 1/3 to full throttle. But it may be the other engine noise is drowning it out.

I do know that someone tried to pull start the tractor while it was hydrolocked, but have no idea if that may be the cause or do to the shuttle clutch, the engine may not have even turned over.

Any idea what the knocking noise could be?

Replies:

Posted By: wekracer
Date Posted: 29 Nov 2018 at 9:10pm

We had a d17 with a stiff wrist pin. It made a knocking noise like you describe when the piston skirts slapped against the sleeve. Could be the connecting rod is bent causing the same issue

Posted By: Acdiesel
Date Posted: 30 Nov 2018 at 10:47am

IGNITION TIMING BEING OFF WILL CAUSE A IGNITION KNOCK IN THE TOP END

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D19 Diesel,D17 Diesel SER.3
2-D14, 2-D15 SER.II WF/NF
D15 SER.2 DIESEL
D12 SER.I, D10 Ser.II
2-720'S D21 Ser. II

Gmc,caterpillar
I'm a pharmacist (farm assist) with a PHD (post hole digger)