No burp hole on thermostat

I bought a new thermostat for my 91 XLT 4.0 L. I noticed a few mentions on here of having the burp hole in the 12 o'clock position. The thermostat I got from the auto parts store doen't have a burp valve. Will this cause a problem or am I ok without it?

You can always drill a small hole and place it at 12 o'clock. I wouldn't go over 1/8" for the hole diameter. It'll help the air escape when you refill the system with coolant.

If the part wasn't manufactured with one, there must be some reason why. I wouldn't worry about it. Just install it, and try it out. Who makes it? Was it a name brand? Maybe some no name brand company might not make them as the same quality of a name brand with the bleeder hole.

I believe the burp valve is a check valve for the heater core. I believe its purpose is to relieve pressue in the heater core and to relieve air bubbles. I believe that I would get another t-stat that has the burp valve.

I don't think I've seen a burp hole in one of my explorer t-stats in quite a while.

I switched to "stant" thermostats and have been very happen with them. I do run the 180 in the summer (it gets really hot in southern az) which helps keep it somewhat cool in stop/go traffic when its 105F out.. and sometimes I change it to a 195 in winter, but I may stop doing that as the 180 still warms up the truck enough and it doesn't get that cold here (mid teens is a low as it gets).

Our neon never had a weep hole and a 180 tstat would take it out of closed loop. I started to use a 198 degree thermostat and drilled a 1/8" hole in it which helps as a bypass. It helped keep the neon cooler in the really hot days.

~Mark

My t-stat that I replaced had a burp hole. I put one in that did not have one. I now wish I had!!!! I now get a temp gauge that rises up past 1/2 way then will sellte down to 1/3 position. I read a really good article where ASA mechanics were drilling a 1/8" hole in t-stats that don't have a weep hole. Why? Because there is always some air in your cooling system. If you get an air bubble at the temp sensing bulb on your t-stat, it will not open at the proper time. A hole will allow the air to circulate out and away from the bulb. I bought a Stant brand and now am not happy that it did not already have the weep hole.
By the way, I know that I do not have a cracked head. I did a combustion gas test on the coolant, several times. It came up negative every time. I originally thought this to be the reason the temp gauge was rising way up then dropping.

Mark

I'm sure that the auto parts store will exchange it for another one with the hole if you tell them that you just bought it, and have the receipt. They might have another brand, like Hypertech, or Motorcraft that they could exchange.

Our '92 thermostat doesn't have a burp hole and the temp is pretty steady. With the 180 tstat in the temp stays right at 180 (the n in normal) and sometimes will go up to the o in stop/go traffic with the a/c on which is < 195 (195 is between the o and the r in normal on our truck)

Once the thermostat is in I put in I add my antifreeze/coolant and water (30-40% mix max). I then put on the radiator cap, but I don't put it on completly.. Just enough so it won't fall off. I then start the truck and wait for the upper hose to get hot. Once hot I pull the radiator cap off (be careful) and then top off the radiator. If I have time (e.g. going to work on something else) I let the truck cool. I then do the same procedure once more and find that this time when I take the cap off that I'm only about 1" below full. I add a little more coolant/water and then put some into the overflow, install my radiator cap completly (I use a stant 16lb lever cap) and all is fine.

If your radiator cap can't hold the pressure, it is possible that the system is loosing pressure which will cause the coolant to boil earlier. If I remember correctly, each psi raises the boiling point about 3 degrees. That means with a 16lbs cap and pure water (which I won't run) we will have a boiling point of 260.

I also found that if the fan clutch is weak the temp will jump all over the place when you accelerate. I run a HD thermal fan clutch (the fan is loud most of the time now, but the fan is really pulling air now).


~Mark

I have some questions. If you use straight water with no antifreeze, will the engine get hot faster, stay hot longer, and be harder to cool down to a lower working temperature while driving?

Water has better heat transfer properties than anti-freeze/coolant BUT anti-freeze/coolants also does a few things you need/want

1: Lowers the freezing point of your coolant mixture
2: Raises the boiling point of your coolant mixture
3: Lubricates the water pump
4: Provites Anti-Corrosion materials

If for some reason you Can't use anti-freeze (e.g. like in a motorcycle you take to the track) you can use "water wetter" to help change the heat transfer property of the water and I "think" it also gives you the lubrication and anti-corrosion, but I'm not positive (I haven't looked into it in a while).

~Mark

So basically you have more of a chance of overheating running straight water? What about running straight antifreeze? Will that stay much cooler in the summer time with the A/C on?

Neither is really good...

Straight anti-freeze won't transfer enough heat out of the water fast enough and you might overheat.

Straight water (forgetting about corrosion and lubrication for a second) will transfer the heat better, but the water may boil too early. You can compensate for some of that with a higher pressure cap (16psi).

Your best bet is to run enough anti-freeze to give you the lubrication and some boil protection, but not too much to cuase heat transfer problems.

I've read 30% minimum for corrosion protection but can't remember where I read it.

~Mark

Other than environmental factors (toxicity), is there any other advantage to propylene glycol over ethylene glycol? I know that they are not compatible, since they say not to mix them.

That I can't answer.. I've never looked into the less toxic one..

I believe the peak coolant website talks about both though.. so that might be a start for your research.

~Mark

Thanks for the tip. Here are a few things on their Q & A section:

A. Why is it important to mix antifreeze with water?
Antifreeze contains chemicals that protect your engine against rust and corrosion, as well as freeze-up and boil over protection. Water is required to activate the chemicals in the inhibitor package. Furthermore, adding water to antifreeze actually increases the freeze-up and boil over protection provided. For example, a mix of 40% antifreeze and 60% water provides freeze-up protection down to -10°F and boil over protection up to 259°F. In comparison, a mix of 70% antifreeze and 30% water provides freeze-up protection down to -62°F and boil over protection up to 270°F. However, we do not recommend adding more than 70% antifreeze. This would limit the corrosion and freeze up protection and heat transfer capabilities of the antifreeze.

B. Can I mix ordinary tap water with antifreeze?
Yes, tap water is commonly used for mixing with antifreeze, however, deionized water or distilled water is preferred. Do not use water softened with salts to mix with antifreeze.

C. Why does my vehicle owner’s manual recommend a phosphate free antifreeze?
Some European car manufacturers recommend that phosphate free antifreeze be used in their vehicles. The reason is that the water in Europe has an extremely high mineral content. If you mixed an antifreeze containing phosphates, which are part of the corrosion inhibitor package, with the water they have in Europe, the phosphates in the antifreeze may “drop out” and form deposits in your cooling system that can lead to corrosion. However, this is not a major concern in North America, since our water is lower in mineral content, or softer, than European water.If you are interested in a phosphate-free antifreeze, Old World Industries offers PEAK® Global LifeTime™ Antifreeze and SIERRA®, the Safer Antifreeze.

D. What makes SIERRA Antifreeze safer?
SIERRA Antifreeze is a premium quality, propylene glycol (PG) based antifreeze that provides engine protection comparable to that provided by premium conventional ethylene glycol (EG) based coolants.

However, because of its PG formulation, SIERRA Antifreeze is less toxic than conventional EG based antifreeze and, therefore, safer to pets, people and wildlife in cases of spills, leaks, boil-over, or careless disposal.

E. Can I mix SIERRA Antifreeze with an ethylene glycol based antifreeze?
SIERRA Antifreeze is compatible with ethylene glycol based (EG) antifreeze. If they are accidentally mixed, no damage to the cooling system will occur. However, due to the toxicity of the EG antifreeze, mixing antifreeze will eliminate the safety advantages of SIERRA Antifreeze.

Antifreeze mixture percentage chart: