You only need a small hole-- 1/4 inch should be enough. That should not affect anything-- in fact, many vehicle mufflers have a small hole --like 1/8 inch-- that helps get rid of the moisture, so the exhaust will last a little longer.

 

I agree with jc completly. Most people put them right at the bottom of the stack where it bends to go straight under the truck

 

there really isnt a need for the hole or "weeper" valve on a diesel. The reason being the exhaust quickly heats to over 1000 degrees, evaporating water very quickly. Drilling a hole negates any protective coating that is present, so unless you have 316 stainless pipes you are opening your exhaust up to fairly rapid deterioration. The biggest concern is getting your rig dirty, and as long as you dont floor it right after start up you should be fine. Realistically you will not get enough water in the pipes to cause starting issues.
One other problem is that the holes often cause a "whistling" sound (not the expected turbo whistle).

After helping a number of my friends install stacks I personally wouldnt worry about drilling a weeper hole.

 

lol, the exhaust gets nowhere near 1000°F at startup or idle, only when crusing, and then the pressure is so much the reason you put a hole in htem means nothing because the shit just blew out the top.

Also it would take tons of rain, I mean a shit ton to ever cause a starting issue..

As for a hole, No need, but if you do, you only need like 1/8th inch or even less, a 1/4 inch is way too big.

 

What about alot of rain for you boys with stacks?

 

I know it rains/Snows in the North East, They just had 2 feet of SNOW, and you do not need 6 inch of water sitting in the pipe overnight. Drill a small 1/8 hole at the lowest point. And get a small plastic pale to cover the stack when parked overnight. That will also help.

 

Oh and if you are worried about rain getting your truck dirty you might as well skip the idea, because the suit from the stack will make a mess all the time rain or shine lol. Better have a very clean tune and even then,my bed will still get a little dirty.

 

im thinking more of blowing 5 inches of water built up in the stack all over the back of my truck after starting it after a bad rain. we just got almost 2 feet of snow here and its not uncommon for a lot of rain too. im sure there wouldnt be a problem with startup, just dont want to get the truck completely trashed every time it rains.

 

i live in northern MI and we get a ton of snow.. i keep a small plastic bucket underneath my tool box in my bed. i put it over my 7" stack every night after i plug it in(on a timer).. seems like a hassle, but it becomes routine and is worth it in my opinion. no hole and no mess!

 

or just run a side exit exhaust lolcats