Hot Rods Thermostat modification

This is simple to do, but after having a few thermostats stick on old cars now I do this, which is I drill three holes 3/8" around the center so even if it sticks it flows. They make restrictors instead of thermostat but this to me works better especially in winter you still have heat. Thoughts?

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With that large of holes you may as well just remove the guts of the thermostat and run the washer part. I've done that a lot with my 48 when I was towing a camp trailer with it in the summer. It still got up to a decent running temp and stayed at that temp the majority of the time. Not the greatest in mid winter when it was 20 degrees out and my heater wouldn't put out much heat though.

 

(3- drill holes on a 3/8 drill hole pattern)?

What diameter are the drill holes?

 

I drill 2 1/8" holes in the thermostat of SBF's so I can eliminate the bypass, but multiple 3/8" holes seems excessive.

 

Agreed...too big a bypass hole.
1/8" has been the hole size to use for many years.
And only one or two of'em.

Mike

 

The one or two 1/8 " holes are used to let the air out so the stat doesn't air lock. It still lets the stat control the engine temp. I always use a working stat. No stat can cause excessive engine wear, if the engine never gets up to operating temp.

 

Ran just the disc with guts out for years . As stated not so good on a cold day , you just have to determine the right size piece of trash cardboard for heat control ! My old Cummins has 2 giggle valves for better words with about 1/8 inch holes has worked like a champ for many many workin hard miles

 

Doesn't drilling a hole, or holes, in a thermostat sort of defeat the purpose? If a hole was needed they would have included it.

 

It does defeat the purpose, but bad news when they don't open. I'm thinking maybe three 1/8th inch holes would be better.
A new Chevy van I ordered years ago the stat stuck on way home from dealer with less than 50 miles on it. I knew later I'd have trouble. Sure enough heads were warped. Thanks.

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Have had them get "lazy", and not close when they get some miles on them, never had one stick open. That's a bad deal there for sure. Definitely not a part to cheap out on either. The 2 buck chuck import examples on the shelves these days especially.

 

I don't think a 1/8" hole will defeat the purpose of the overall function ,and it does work well. I can't swear to this but I think i remember seeing it on a stock thermostat somewhere.

 

"It does work well" ... works well for what though? So, Stant, and the rest of the industry, for the last hundred years or so has been making them wrong?

 

Seems that way

 

buy a FAIL SAFE type....if it fails it does it in the open position...

 

How do you figure that? If you drill a hole in a thermostat so small that it "won't defeat the purpose of the overall function"; how is this same hole large enough to prevent damage from overheating?

I thought the purpose of drilling a hole was something to do with coolant flushes and air pockets. It's my understanding thermostats already have a slight clearance or an engineered "hole" for this purpose. Like I said, they've been doing this for a hundred years, and nowhere in the manuals or "service literature" does it suggest we need to drill any holes. See where I'm goin' with that?

 

Drilling a hole , a little 1/16 hole changes it enough to throw a code on a late model. Code says warm up time excessive. You can get a t stat with a wiggler to let air bleed if you want to pay for it. T stats do stick but it's 99% of the time in a neglected cruddy ancient anti freeze or leaky coolant system. They have a wear schedule and do need changed.

 

Been doing the one 1/8" hole for years and it works. In fact a couple of the more high end brands have a hole from the factory, some put a bent cotter pin in the hole.

 

No, you drill a bunch of holes in the thermostat because your radiator is clogged, or your electric fan doesn't come on.

 

I take the thermostats out and leave them out.

 

This ^^^^
I run them on my race engines [Road Racing]

 

"I've been doing it for years, with great success"; what does that even mean exactly? The home-trepanning people claimed the same thing. What is the problem we're trying to solve?

Near as I can tell from scrubbing the intertube search motor and the automotive forums there are only a couple different strategies or problems this is supposed to cure. The first seems to be running hot, or overheating. The OEM and stat makers go to a LOT of trouble to get those things engineered right. Thermostats set the minimum operating temperature, not the high side. Drilling holes should not be necessary.

The second one, trapped air bubbles and "burping" the coolant system, makes some sense. But -surprise-! the thermostat makers already thought of this and engineer a calibrated hole, or "jiggle" valve or other ways to accomplish this, and may not be apparent at a glance. Aftermarket thermostats may look different than OEM. That doesn't necessarily mean you need to bust out the Black & Decker. If air pockets are an issue why not crack a heater hose, or loosen the upper radiator hose and pre-fill there during a flush?

Another trick, that was apparently in a Ford TSB, was to jam open the thermostat with a piece of hard candy. This would allow for coolant flow long enough to purge any air bubbles, candy dissolves, thermostat works as normal. It does sound like the OEM used some kind of vacuum fill on the assembly line.

One thing amazing about reading the automotive forums is all the problems I never knew I had till someone 'splained it all.

 

Maybe I'm weird... I buy them and put them as is, no extra holes, nothin'. I always buy a name brand like Stant, think I have a Moroso one in my Ford.

 

You might not have noticed the hole?

 

F.D. I was on years ago had a thermostat stuck closed on an ambulance. Took out a 454 and peeled the inlet side tank off the radiator.

 

The weight holds it open for air to escape
Once it sees The water pressure, it's forced closed.
Little bit more sophisticated than a hole, or 3 holes at 3/8"

 

I'm pretty sure I read this thread in detail but I didn't see a single poster mention the fact that some aftermarket intake manifolds do not have the option for the bypass hose to the water pump if you know what I mean. This little bypass keeps water flowing through the block and helps Purge air pockets and keep a stable temperature throughout the block. Without that little bypass there can be stagnating Flows in the block. I'm a Believer in the little holes in the thermostat just for the heck of it. In a really really cold conditions it would seem that you would want some flow during warm-up just to avoid a hotspot somewhere inside the block. But that's just me.

Correction correction correction I nearly forgot that it's my aftermarket water pump that does not have the bypass fitting on it not the intake manifold. Sorry I'm in a hurry and failed to edit that first paragraph. That's why I drilled 3 3/16 holes in my thermostat and it works just fine.

 

"Have had them get "lazy", and not close when they get some miles on them, never had one stick open."

Is there a difference between "not close" and "stick open"?

 

I wondered the same thing. .

 

H.A.M.B proofreaders come through again! Yeah obviously I meant stuck closed.

The idea as I understand it is that the thermostat stays closed to aid in a fast engine warmup to normal operating temperature. The whole point of a thermostat is to keep the engine at a certain minimum temperature. Boils off sludge and crankcase condensation quicker, and reduces cylinder wear. Generally the engineering says the faster the engine reaches normal operating temperature, the better.

Once someone starts drilling holes in a thermostat, all the calibration and thought that went into that particular temp selection and flow rate just went out the window.

Doesn't the waterpump circulate coolant inside the engine during this time anyway? Drilling holes only slows warmup. If you have a 180° thermostat installed, and want to drill holes in it, then it's no longer a 180° thermostat. Why not just install a 170° thermostat?