jstantherprsn

Hello Everyone,

I have the most oddest question. Some time ago (about 2 months ago) I bought an 193 T-stat. Anyways I saw that the part stores carries the high flow/high performance T stats. The stat from the pics definitely has more open area. I saw that the performance stats are the same price as the regular stats. Since I already have the stat and no longer have my receipt. Can one just drill out little holes to increase the flow area. I saw that the outer ring flange area is quite large. Maybe drill some holes there. Wondering if anyone knows anything about this. I want better flow and am willing to drill a few holes and salvage it instead of dropping another 10 bucks and 10 min drive to the store for the high flow.

spahr69

a thermostat opens and closes to let coolant in. and keep coolant out. wouldn't drilling holes keep a constant flow of coolant? i dont see this being a good idea. but someone contradict me if im wrong.

gpXJ

^^^ x2 I think you would be bypassing your thermostat by doing this and would constantly flow coolant, even when it was closed.

ol"blue

I don't suggest what you're describing. As stated earlier, it could impede t-stat operation and cause an overheating condition. IMO
On the other hand, I've drilled a 1/16" hole as an air bleed in the flange (to be installed towards the top) to eliminate an air pocket behind the t-stat to prevent overheating. (Take that for what it's worth. JMO)

91 limited owner

It will take a lot longer for the motor to reach operating temp. Instead of drilling it out. Just pull the whole thing out. When it gets colder out. And your motor is in need of it, to Even reach operating temp, Put it back in.

djb383

I've always drilled one or two 1/16" holes (180 degrees opposite of each other) in the flange of every t-stat I've installed (cars, motorcycles, etc.). Some t-stats come with a 1/16" hole, some don't. No t-stat seals water tight when closed, some water always passes by/thru it.

djb383

You are kidding, right?

Bustedback

Bad advise. Never pull the T-stat out completely. It can cause over heating issues, and driveability issues. A 1/16 hole is fine to keep out any air pockets, but never run without one.

jstantherprsn

I did more homework and realized I opened a can of worms. The overall consensus that I got from other auto forms was to leave the jiggly hole thing in but to drill 1/16 or 1/8 holes at 12 and 6 o clock and this will get the air out. My aim was to just increase the flow. I see that the drawback for the high flow t-stats is that there is no where to drill to get the air out. With that being the case you give up air pocket pass through for having a high flow t-stat.

I saw that somewhere it was recommended to get a 91 T-stat housing and put an additional bleed valve in usually another drain p-****. I know this is a side note but relates to cooling. Anyone ever put in a coolant filter? I know its popular in larger trucks.

5-90

True - in probably "four nines" worth of cases.

I have had three vehicles that simply would not run properly with a thermostat in place - they'd all overheat within ten minutes. And I know everything else in the cooling system was up to scratch, since I'd flushed the engine and ended up replacing everything else - including the damned heater cores!

The vehicles?
- 1985 Chevvy Cavalier, 122ci I4
- 1980 Honda Accord, 1800cc CVCC I4
- 1988 XJ, 242ci I6

I still haven't figured out what was going on in there - but none of those three would run properly with a thermostat in place. Period. Overheat in ten minutes or less. Fans worked, fan clutch worked, CTS pieces worked, everything else was just fine!

Considering the number of engines I've dealt with in varying repair capacities (from tune-ups to full overhauls and machine work,) those three are really a small percentage of the sample. I can probably add about four more in collected "reports from the field" - so figure that's seven individual examples out of probably a couple thousand vehicles in the last thirty years.

So, it would be incredibly rare - but possible.

As far as drilling - drilling two holes 1/16"-1/8" in the thermostat flange is no trouble. There's a bypass passage in most thermostat setups anyhow, and a small bypass near the water pump, to prevent coolant stagnation before the thermostat opens. So, the seal isn't total.

However, I don't see why you'd want to drill out the flange just to increase coolant flow. If you want to increase flow, just get a larger port in the centre of the thermostat. No reason to do anything else that I can think of...

hubs97xj

Stant Superstat. Accept no substitutes. I don't know how many times I heard/read that, and I finally gave in. It does actually run cooler, noticeably, but not too much so. Under $9 with tax. What gets me, is that it's running cooler on the highway in 80 degree temps than it ran on the same highway in freezing temps. No modifications except for the new 'stat.

djb383

Is that according to a known accurate aftermarket temp gauge or the factory dash gauge?

91 limited owner

A cooling system works by sending a liquid coolant through passages in the engine block and heads. As the coolant flows through these passages, it picks up heat from the engine. The heated fluid then makes its way through a rubber hose to the radiator in the front of the car. As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air stream entering the engine compartment from the grill in front of the car. Once the fluid is cooled, it returns to the engine to absorb more heat. The water pump has the job of keeping the fluid moving through this system of plumbing and hidden passages.

robertj

Redneck with a drill <> engineer that designed thermostat.

Do yourself a favor and get a factory Mopar replacement thermostat.

djb383

You've never seen a t-stat that came from the factory with a hole in the flange? The engineers that designed those type of t-stats didn't lazy out, went a step further and designed a good way to bleed air from the cooling system without effecting/slowing the engine coolant warm-up process.

Redneck and engineer in the same sentence, that's a good one. Put a Stant SuperStat and a Mopar t-stat side-by-side on the bench and you'll understand better why Chrysler is in trouble.