The other day the gang i run with were trying to light a BB Chev for the first time.A high dollar computer injected engine that took about a year of constant work to get to the day we all waited for,you know the drill,add water,gas,trans fluid for the first time,and try to light it off.Well i made a statement of did any one drill a weep hole in the thermostat to help bleed air out,which i have always done to countless projects over the years with no bad results.One of the guys blasts me right away that you cant do that,aguy he knows burnt up an engine by doing that! I said something like WHAT! Like i couldnt believe what i just heard and he comes back with "ill argue over that".I replied OK lets argue, so not much else was said because sometimes its better to let well enough alone for the time being.Every one was on edge anyway with firing the engine and all.So any comments on this,one way or the other.I say not an issue and it cannot cause an engine to get ruined as he stated.
I drill a small hole (1/16" or less) in every thermostat I install. I used to drill 1/8" holes in them, but it REALLY slowed down the engine warm up. I got some heater complaints from cutomers that drove 10 miles or less. No complaints with the smaller holes. Larry T
I'm with you! No way will you burn up a motor by drilling the thermostat. Hell,tell him you can buy them with the holes already there!
Ask him to explain exactly how a small hole in the therm will burn up an engine. I've never heard of this trick to begin with, but it makes sense to me.
i drill a couple of 3/16" holes, the only time i have had an engine get warm on start up is if the thermostat doesnt open, a pocket of air traped under the thermostat keeps the water from reaching it, before i learned about drilling i have had engines boil over 10 min after fire up while trying to break in the cam, then i went to no thermostat at all on first fire up, then drilling, all is good now.
i drilled mine & it serves 2 purposes, It gets the air out & on my t bucket the radiator cap is lower then the block so i take the upper radiator hose off at the thermo housing & fill the rad thru the upper hose, i watch the hole in the thermostat & i can see when the waters getting up there.Works great jimv
Drilling a hole will surely do the exact opposite to burning an engine, it will allow some water movement right from the off. Now if the stat had no hole and was faulty and didn't open then there's every chance that the engine will burn. Or there was an airlock formed because the air could not escape and the engine ran hot. The way I see it the hole can only be a positive here.
The hole is really a convenience to prevent a huge burp of coolant. Even if you don't drill, an air pocket isn't going to cause the engine to burn up, because there's still some coolant circulating thru the engine.
Most OEM thermostats have a small hole in them nowadays. They use a vacuum system to fill the engine and rad on the assembly line, and they need the small hole to pull all the air out. A small hole will never cause and engine to get ruined.
FWIW I notice thermostats work alot smoother and closer to their rating with the holes. Perhaps the hole allows enough coolant to purge the cold stuff in the thermostat housing, giving the stat a truer engine temp during warmup.
I assume most guys don't have the small bypass passage hooked up. I prefer to have one so the hole only serves to help bleed air while filling. The hole/s also serve to allow the thermostat to receive real time heated coolant from the core of the engine so when the block is up to temp so is the thermostat and it opens right on cue. Take a typical GM V 8 with the bypass blocked. While the TS is closed there is no water flow around the block or past the TS bulb. The engine can reach way over the TS opening temp but the TS is still seeing way cooler water. I have watched engines blow water out while the TS never opened. Drilled a few small holes and everything was fine. Just my take on it.
I was at an R.V. show once and talked to a guy that did cooling systems--he said they drill 3 small holes--at 12:00--4:00--8:00 in the thermostat.He said testing showed it created a small vortex to help pull fluid and decresse cavitation.He sounded like he knew what he was talkin' about,so I tried it in one of my cars that had some cooling problems. I'll tell you--it worked! It warmed up better,and the temp gauge had always read weird,but no more.Better all-around cooling,too. Just my .02
I think you should drill a hole in his ass with your foot. Never had an issue with it, done it on all of my thermostats that didnt have one in it when manufactured.
Good post. I had never seen a thermostat without a hole in it, until reading this post. I haven't installed the stat in my 289 yet, so I looked at it, no hole. I'm not to worried however as the 289 has a bypass built into the stat housing. Definitely will have to drill a hole on engines without a bypass.
In fact it's the opposite, the motor won't warm up to full temp if it's cold out. We had one stick closed and overheat a truck; my buddy took it out as an emergency repair and I'm not sure he ever put one back in. Rollback with a 350, retired to a lot truck when it got replaced with a newer one. Still runs and goes -
We sell several quality stats and the normal operating range is 10-15 degrees and the Weir Brand advertises a 5 degree operating range, but at the trade shows the factory reps even commented that older cars with no heater or those with a heater and a inline valve would benefit from drilling a 1/16 hole as a "internal bypass" for , yep, you guessed it, air pockets.
Actual experience on a late 90's V-6 Camaro in 20 degree weather--about 5 miles driving with the 1/8" hole, about 2-3 miles driving with 1/16" hole before you could feel the heater start working. Not much difference? Tell that to the lady that owns the car! LOL Larry T
Tell your buddy he needs to go back to school and make up all those days he missed! Oh, and his hat and seat are in the corner...
aguy he knows... Did the same guy tell you about the Corvette for sale for $100 because 2 people died in it? Or was it the military motorcycles in crates, but you have to buy 100 of them?
Most engines have by passes! (Thats what that 3rd hole is on a chevy water pump where the bolts go thru). Its just that Ford decided to use a hose thats almost impossible to install & can blow out when your driving!! I think one car has one thats about a inch long & really impossible to replace.The By pass allows the water to circulate in the block when the thermo is closed, where as the hole allows the air to vent into the radiator tank. jimv
On first fireup i leave thermo out, fire engine dry and then add water. Having thermo out you'll see water circulate so that you know pump etcetc is working and if you have air pocket or not; adding water after engine is running will save a big problem if something isn't sealed proper. Did you know that a starter will develop enough power to bend a connecting rod on a cylinder that has some water in it? After everything is hunky-dorey i drill a small hole, and thanks to LarryT the hole from now on will be smaller.
Some small off road vehicles have have drilled stats from the factory to help bleeding, evacuate air and act as a bypass to prevent hot spots during warm-up. An additional advantage of holes - if your stat every fails and locks in the closed position, you'll have a fighting chance of saving your engine with the holes allowing some coolant through. I know because this has happened to me.
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