I've just bought a 180 Stat for my 4.7 and I've just seen a post on the forum that said to drill a small hole in the diphram before fitting it. This was on a 3.9 V6. Do I have to do the same when fitting it to the 4.7 V8? If so, why and how big?

Thanks,

Paul

 

you dont have to do it but it makes re-filling the cooling system easier... the air trapped below the t-stat has a place to escape with the hole. the hole does not need to be big at all, real small is all you need.

 

So, where exactly on the t-stat is this hole drilled? I've never heard of this procedure. 1/8" big enough if I do drill? I"m going with the 180 ASAP.

 

do an 1/8" hole and you'll have problems... 1/16" or smaller... remember it is just a bleed hole so air can escape during fillup. it does not need to be big at all...

 

If Walt Chrysler wanted a hole in the thermostat, he would have put one there.

 

hahahaha... good one. some t-stats come with it pre-drilled with a small plug that seals it when it's full... if your worried about drilling a small hole in the diaphram on the t-stat, then dont. I have drilled it for years and the only time I had a problem is when I used too big a drill bit... then it thru a code. real small is good...

 

Moe in Wichita,KS. I read a story about one time whenChrysler changed the co. that made stats for them. the new co. was used to making very close tol. valves, and the stats they made for Chrysler were air tight. to get a cooling system to filleasly Chrysler engeners said to drill a 1/8 inch hole around the outer edge. i have done this for decades, withno trouble.

 

i drilled a 1/8" hole, in the outer, solid flange, but as close to the center as possible. if you get too close to the outer edge it will be covered by the casting flange and be ineffective. no problems.