Anyone know the size of the block drain plug above the engine mount?

I would like to take the plug out and put a temp gague in its location, the only problem I have is that I am not sure what size is used to take it out, I tried a 1/4" but that was to small and a 3/8" was to big. I'm not looking for the NPT size of the plug, im looking for what size square to put on a ratchet to use to take the plug out.

onesic6 said:

I would like to take the plug out and put a temp gague in its location, the only problem I have is that I am not sure what size is used to take it out, I tried a 1/4" but that was to small and a 3/8" was to big. I'm not looking for the NPT size of the plug, im looking for what size square to put on a ratchet to use to take the plug out.

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It takes a 5/16" square tool. I got one from Snapon tools a few years back. That plug had a sealer applied to it that setup very hard. Pipe size is 3/8" NPT.

techno1154 said:

It takes a 5/16" square tool. I got one from Snapon tools a few years back. That plug had a sealer applied to it that setup very hard. Pipe size is 3/8" NPT.

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awesome just the info I was looking for, thank you very much

techno1154 said:

It takes a 5/16" square tool. I got one from Snapon tools a few years back. That plug had a sealer applied to it that setup very hard. Pipe size is 3/8" NPT.

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I knew about the 5/16" square (you can make a tool from a cheap 5/16" or 8m/m hex key in about five minutes with a little grinding - did it for my Peugeot transmissions...) but I've been wondering what size thread. Thanks!

When I get mine out, I'll put in a valve instead...

onesic6 said:

I would like to take the plug out and put a temp gague in its location, the only problem I have is that I am not sure what size is used to take it out, I tried a 1/4" but that was to small and a 3/8" was to big. I'm not looking for the NPT size of the plug, im looking for what size square to put on a ratchet to use to take the plug out.

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Forgot to mention - that probably won't be the best place for a temperature sensor anyhow. You're likely to be in a "pocket" down there, won't get constant flow, and won't get an accurate reading.

Better, if you've got RENIX, would be to get a 1991-up thermostat housing and use that - it's also drilled & tapped 3/8" NPT, so you're using the same sensors (if you need to adapt down to a 1/4" NPT, use a bushing instead of a nipple. You want the sensor tip to have as much exposure to coolant flow as possible.)

If you're doing this because you want a backstop to the OEM gage on later models, put an adapter in the upper hose - you can find them at various speed shops, and in a few sizes at Summit Racing or Jeg's. If you're doing this because you don't have a gage, let us know what year your rig is and we'll let you know what you need to swap to a gage cluster instead of idiot lights.

what do you do, just install a petcock/spiget in place of the drain plug?

Pretty much what I was going to do - either a street ell or an ell with a close nipple to point the thing down, a brass/stainless ball valve, and put a hose barb fitting on it so I can direct the drain into a container somewhere.

A brass-bodied ball valve with a CRES (stainless) ball will work - the PTFE wipes shouldn't have any trouble at all, and the thing won't seize with heat or time (when I replace service valve or hose spigots in houses, I use ball valves for those as well. Same reason. For hose spigots, I just put a ball valve on and then put a hose bibb adapter on it after.

(That way, I don't have to deal with packing leaks, washer leaks, valves that don't turn fully, and if I need it on or off in a hurry, I can do that. One-quarter turn get all or none of the water - problem solved.)

I have a 96 XJ. I was doing it because I have the cluster with the idiot lights and wanted an actual gauge. I actually ended up buying a gauge cluster from someone online today and I will be getting it by the end of the week hopefully. I was wondering if anyone had a different part number besides the mopar number for the coolant temp sensor. The part store by me can not cross reference it and when they look it up it by year make and model it comes up with a few different sensors but does not say which is for the light and which is for a gauge. I am trying to pick one up at Advacned Auto Parts, they carry GP Sorensen and BWD brands if that helps.

BWD website has a handy application look-up section: http://www.bwdbrand.com/web_app/catalog/catalog.aspx

Note that coolant temp sensor (WT3027) is the ECU sensor that goes in the thermostat housing. The gauge sending unit is WT430 described as sender-temp-with gauge.

Don't you have the sensor for the idiot light in the rear driver side of the head? The WT430 sensor just replaces the sensor for the light. Be careful when removing the existing sensor so as not to break it off.

Pelican said:

BWD website has a handy application look-up section: http://www.bwdbrand.com/web_app/catalog/catalog.aspx

Note that coolant temp sensor (WT3027) is the ECU sensor that goes in the thermostat housing. The gauge sending unit is WT430 described as sender-temp-with gauge.

Don't you have the sensor for the idiot light in the rear driver side of the head? The WT430 sensor just replaces the sensor for the light. Be careful when removing the existing sensor so as not to break it off.

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sweet that is just what I was looking for, seems like the guy at the parts store was looking up the coolant temp sensor and not the coolant temp sender. thanks very much for the help, now I can go and pick these up!