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6.5L Turbo Diesel 1992-00 6.5TD - Discussion forum for the 6.5L engine.

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Old 08-17-2009, 05:46 PM
jerry598 jerry598 is offline
Join Date: Aug 2005
Posts: 188
Default Tool for coolant drain plugs

My engine's out of the truck and I'm surprised that the threaded coolant drain plug requires some odd tool to remove it. The plug looks like it should be removed with a square 3/8" socket wrench, but my 3/8" is too big and my 1/4" is too small.

Does anybody know what tool will fit these plugs?

What I really want to do is remove the same size threaded plugs in the rear of the block in search of that spring-loaded oil cooler bypass valve. Just want to make sure that valve is functional before reassembling the engine and I figure its hidden behind one of those threaded plugs that match the coolant drain plugs.

The oil filter bypass valve was easy to check. With the filter adapter removed from the block it was easily accessible.
Black 95 6.5 929 block, 146k miles, 43k on IP, 22k miles on engine rebuild done myself in '09, 6 L&S Full-torque inserts in the outer main crank bolt holes, Clearwater heads, Fluidamper, rebuilt NV4500, 3" downpipe, 4" exhaust, no cat, dual T-stats, 9 blade fan, 180 degree clutch, Heath hi-flow spin-on water pump w/ restricted orifice, turbomaster, PMD relocated, OPS relay mod, Heath PROM upgrade (great performance boost, especially startups). Now us semi-syn Lucas 2-cycle oil in every tank which fixed a DTC 35 code.
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Old 08-18-2009, 09:40 AM
john8662's Avatar
john8662 john8662 is offline
Join Date: Sep 2001
Location: Lubbock TX, USA
Posts: 4,193

The valve you're referring to should have been removed during hot-tank and vatting.

The valve will be underneath a cup plug in the oil filter boss. The plug in question will be a 7/8" Diameter plug with a .060" hole drilled into it. Underneath that plug lies the oil cooler bypass valve.

No threaded plugs to remove to see that guy. Removing the plug mentioned above requires a threaded fitting on a slide hammer to remove. Yes, a pain...

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