What does this plug?

[1995mtxsho]

The plug circled in red, what does it plug, Coolant or oil? It looks like it is in the water jacket because it is right by a freeze plug.

If it is a water jacket plug, would it be wise to mount a coolant gauge sending unit there?

 

[shomtx95]

loosen it and see what comes out, if it is coolant should be fine for a gauge, but i mounted mine in place of the factory sending unit

 

[Phoenix]

If I remeber correctly this plug is in brass , and coolant passes in it , and yes it would be a great idea to put in a sender unit.

 

[gmorrell]

It's a drain plug for the block coolant passages. IIRC, there isn't one on the engine front side, as the ****** for the oil cooler coolant loop serves the same purpose. I think it's 1/4" pipe thread, so it should work fine for a gauge sender with an appropriate pipe bushing.

I think the SHO engine is the only domestic car I've owned in over 30 years with a brass block drain plug from the factory. Every other domestic POS used steel plugs which become one with the block after a few years and have to be drilled out.

 

[K-Dawg]

Putting the sender in the stock sender location will give you a better idea of the coolant temperature coming out of the heads (hotter). If all you're looking for is a difference from normal, then I'd think that plug would be fine.

 

[Eric VerValin]

I would also sugguest having your temp read up near the aluminum. Thats the part that is going to warp if you have issues.

Also.. when doing a coolant flush... you should remove those, and flush the ENTIRE motor. Something most people never do.

 

[itwonder]

It's a drain plug for the block coolant passages. IIRC, there isn't one on the engine front side, as the ****** for the oil cooler coolant loop serves the same purpose.

There is a block coolant drain plug on both the front and the back of the block. I painted mine red so they are easy for me to spot. The front one is a bit hard to see.

 

[pjtoledo]

ditto on not putting the a temp sender there. thats at the bottom of the cylinder, the temps down there don't have the relevance of head or upper cylinder temperatures. 14mm if I recall correctly

 

[93rev2sev]

ditto on not putting the a temp sender there. thats at the bottom of the cylinder, the temps down there don't have the relevance of head or upper cylinder temperatures. 14mm if I recall correctly

14mm will certainly work...but it's gonna "technically" be a 9/16....I think.

 

[1995mtxsho]

Ok, so no-go on the block plug.

Any suggestions on how to incorporate a mechanical gauge sender into the system without losing the stock gauge?

Gauge uses a large calipary tip:


Heater Hose perhaps? Or a T at the temp switch? Will a T give accurate readings if the probe isnt directly in the stream of coolant?

Also is a T acceptable for the Oil pressure Sending unit and the aftermarket mechanical hose?

 

[K-Dawg]

You can use a T for both senders.

 

[itwonder]

Will a T give accurate readings if the probe isnt directly in the stream of coolant?

My experience with temperature sensors installed in various T arrangements is you will not get an accurate reading. it will read lower than actual.

I would install it in the block drain provided the probe does not block the passage.

 

[K-Dawg]

I just replaced the stock gauge sender in my last SHO. Didn't miss the stock gauge one bit.

 

[NotSoSlowSHO]

Also.. when doing a coolant flush... you should remove those, and flush the ENTIRE motor. Something most people never do.

Because SHOs have so many coolant related problems, right?

And explain to me please, how removing one brass plug that has nothing to do with the flow of coolant, is going to help a flush. The passage the plug is located is not a dead end.

 

[93rev2sev]

I can see how it would help evacuate debris. Little hunks of RTV, pieces of casting flash...there can be a lot of gunk in the crevices of a 100,000 mile block.

these things might not want to flow all the way to the radiator. They tend to get stuck on the way out. Having a hole in the block for them to flow out might help quite a bit.