1989 k2500 block coolant drain plug

[cgbude]

I am trying to locate the coolant drain plugs on my 350 v8. I think I may have found one shown in picture left of spark plug boot but not sure where other one is.

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[GoToGuy]

Should be same general area on both sides. Along lower block edge.

 

[GrimsterGMC]

Knock sensor is the drain on passenger side and there is a plug on the drivers side exactly opposite.

 

[Caman96]

If it’s a 454, there will be a knock sensor on each side and no “plugs”.

 

[termite]

If it’s a 454, there will be a knock sensor on each side and no “plugs”.

On the vortecs, maybe? My 1995 TBI 454 has a block drain plug on each side with a pipe plug in each.

 

[Caman96]

On the vortecs, maybe? My 1995 TBI 454 has a block drain plug on each side with a pipe plug in each.

Yeah I was thinking Vortec, but since he hasn’t let us know, we’re all guessing. I looked in his signature and didn’t see anything.

 

[cgbude]

It's a 350 tbi. And yes it has a knock sensor opposite of the bolt I found on drivers side.

 

[Schurkey]

If it’s a 454, there will be a knock sensor on each side and no “plugs”.

The TBI big-blocks may have had knock sensors in the block drain ports. I think I've heard that that's the case.

The Vortec big-blocks have knock sensors in dry holes, and regular pipe-thread block drains. I replaced my block drain plugs with brass draincocks.

Right side. Camera is looking "up", which gives the optical illusion that the block drain is pointing "up" and not "level"

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Left side. Kinda hiding around the oil filter/front driveshaft area.

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It's a 350 tbi. And yes it has a knock sensor opposite of the bolt I found on drivers side.

There's no "bolt". There's a hex-head, steel/iron 1/4" pipe-thread plug as installed by GM. Fairly common for there to be a "crust" of debris at the bottom of the water jacket that has to be broken-up with a Phillips screwdriver or awl, before the coolant will drain.

As you might assume, once you have removed a steel/iron plug, and the debris that's settled in place, you'd do well to replace it with brass plug, or better-yet, a brass draincock. I use Loctite/Permatex "592" as a pipe-thread sealant. Wonderful stuff. It also gets custom-packaged for GM with a GM part number; and I'm sure GM jacks-up the price accordingly. It's what the service manual recommends for a pipe-thread sealer.
www.amazon.com/dp/B0002KKTH2/?coliid=I2C34IAJPLZFEQ&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

The knock sensor has to be torqued into place--the actual torque on the sensor affects it's sensitivity. Follow service-manual torque spec so you're sure to get it right.

 

[cgbude]

Good to know I will have to get a new plug before I attempt to drain. Just to be clear, removing low radiator hose doesn't drain all the fluid from the block correct?

 

[cgbude]

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Clearer pictures with both sides.