WTF??!! Why can't I find this?

Discussion in 'Classic Mustang Specific Tech' started by CornerCarvin67, Jun 30, 2005.

  1. I'm looking for a 16lb VENTED radiator cap. I have a regular 16lb cap, non-vented.... and believe the vented one would be better for my system. I was at the local weekly show last night and noticed a few old mustangs running the vented cap. NOT the cap with the lever on it. It looks just like a normal cap... but it reads VENTED on it. I assume this is to release air build up. Anyhow... I can't friggin find them. Any help would be appreciated. Thanks!!
  2. Amazing... 47 hits and not a clue. Dang! :)
  3. Boxed #: 18231
    Carded #: 28231
    Pressure: 16 lbs. vented
    Cap Type: OE style
    neck: 3/4" deep

    Would that work for you? If so, check
  4. When you get into the 16-20lb range, you're getting close to what the freeze plugs will handle. We run a 13lb cap on our early cars, even the track cars.


  5. ya

    maybe explain what car this is going on and why you want it???

  6. Excuse me for being thick, but aren't they all vented? The system gets to the rated pressure, say 13psi, and the cap then vents off any I missing something?
  7. Man... it just seems like this one won't go away. I've been chasing this one for
    about a month already. So I'll go one last time at this. I have an over flow tank
    on my car... not a return resevoir. So once the pressure builds up past the cap
    pressure.. it dumps in there... and stays there... until I hit the valve on the bottom
    and drain it out. Well there wasn't a hole in the tank to vent out the massive amounts
    of pressure building in the system... so I blew both my upper and then my lower
    radiator hoses within two weeks of each other (old hoses... but still). The pressure
    was such that the hoses were solid. So I got the idea of drilling a pin hole in the
    top of the over flow tank to relieve the pressure. That seemed to work. But then
    I'd get water coming out of it after some spirited driving. I had a 13lb cap on it. I
    put a 16lb cap back on so it wouldn't be so easy to blow by the cap and dump into
    the over flow tank. But then I see that some guys have "vented" caps. What
    the heck is that all about? Do they bleed of air pressure before dumping fluid?? So
    I recalled some of the reading on line I did and was hoping I just needed to find
    the "happy level" of coolant for the system. So I drove a couple times and drained
    water from the tank each time.... down to the point where it looks like the coolant
    level is just too low when looking in the filler neck. Is there a point where you can
    run too little coolant? I guess that would be noted when the car is running too hot.

    Well that's the kicker.... NEVER thru this whole testing procedure has the car run
    too hot. It never breaks 190... even idling on a hot day. (I put in a SPAL electric
    fan). I also bought a quality Autometer gage to be sure.

    So now I'm to the point where I'm going to go out and drive the piss out of it and see
    where my water level ends up... and if my car runs too hot because of the amount
    of water level it ends up at.

    I'm just getting tired of this...
  8. what year and model car? Also what engine size?

    Maybe your hose clamps weren't tight enough.

    I have 13 lb cap on my 65 that I just bought - it is a stant with the lever. Don't think the lever does anything except let the pressure out through the overflow line instead of steam burning your hand when you twist off the cap. It prevents the cap from turning until you pull the lever up. I like it. I've done the rag over the cap thing too many times.
  9. on my 73-302 the liquid level is just above the coils, i used to think that this was too low, but every time i'd fill it to the bottom of the filler neck it would just wind up blowing it out of the cap.......i've heard that this is commen


    i just left it get to the level where it was happy and have never had a problem with overheating
  10. my 302 is at the top of the neck. if I remove the cap. when the engine is running and watch the fluid comes up a little. not alot. I never build up that much pressure so my hoses are hard so it leaves me to think there is someting wrong with your system. I dont know if I have a sealed system that draws from the tank or not I have to go look now. just my 2 cents.
  11. Why are you running such a high rated cap? Mine is 7 lbs, I run the same catch can as you, with a 'closed' system, and I have no problems. My hoses don't bulge or feel like they have much pressure in them, and my car gets up to 210 degrees on occasion.

    Did you try running the overflow hose to the bottom of the catch can (with the valve open), and just leaving the top hose open? This would release built up pressure and still catch the coolant.
  12. You're describling more of a "recovery" system with the hose on the bottom. It's an "overflow" tank. With the hole in the top of the overflow tank... the only difference in the two is where the hose from the radiator neck is connected... top or bottom.

    I'm just chalking it up to one of those unique situations that I have to search and destroy to whatever works best for my car.

    I'm gonna go beat the hell out of it and see how the system reacts. That's the only true test I can relate to. I don't want it happening in the middle of an autocross event.
  13. I had a brand new 13lb cap on there... but it seemed like it was way too easy for the system to over come that cap and dump water into the overflow tank. I didn't mind so much... until I noticed the water was below the top row of fins in the radiator. It wasn't running hot.... but it was making me worry. I thought the 16lb cap would raise the boiling level and also keep the fluid in the radiator for that extra 3lbs. The cars I saw at the show all had 16lb caps. I'm just chasing my tail...

  14. I'll take a stab at this. You shouldn't have that much pressure so we need to figure that part out. How old is the thermostat and is it installed the correct direction. I know it's not running hot; I'm thinking there is a restriction somewhere not allowing the coolant to flow freely through the engine. What about the water pump? Another problem could be incorrectly installed head gaskets blocking the flow. It just seems that something is blocking your system from flowing and causing excess pressure. If you free it up, you will most likely have a problem with running to cool. Wouldn't that be cool? :D
  15. I did put a new thermostat in it late last summer... I suppose the chances are 50-50 that I put it in backwards. Which way shoud it be pointing again?
  16. I THINK the pointed part goes in the housing and the spring facing the other way but don't take my word for's been a long time since I changed mine. Somebody help us here.
  17. Are you running straight water or water and anti-freeze? If running straight water, I can see the pressure building up some, because of its lower boiling point, though 16 psi still seems high. If running water and anti-freeze, the boiling point should be high enough so that there is only some slight pressurization, assuming your temps are less than 200 or so. I can't see how 16+ psi is being generated in the cooling system by temp alone. I too am thinking that there has to be something somehow adding pressure to the system. Thermostat, head gasket, something.....

    PS. for the thermostat, the spring end goes into the intake, pointed end goes towards the radiator.
  18. I think 302 coupe might be onto something. I had mostly water in my system and had problems with overflowing when I shut the car off - even when the temp gauge wasn't past halfway.

    I just did a cooling system flush (and flush and flush and flush until the stuff coming out resembled clear water) and then emptied once again and put in 1 gal of the green stuff and about a half gallon of water. It runs much cooler now and there is little to no pressure in the cap even when hot.

    Get a thing of prestone radiator flush and get the system super clean, then use 70% antifreeze and 30% water and see if your problem is fixed. The car might appreciate that more than getting the hell beat out of it too.

    Could possibly go 100% antifreeze couldn't you? What do you think folks?

    (By the way - did I miss something lately??? The price of antifreeze is about $8-$10/gallon. And I thought gas was getting outrageous!!!)
  19. Ok I think its time for basic lesson in how the cooling system works and what exactly it does.

    We need water and coolant in our cars year round (usually a 50/50 mix depending on type of antifreez) the antifreez protects against freezing in the winter, protects the internals of the engine and rad against corrosion and keeps the boiling point at a managable level all year round, Too much antifreez and it wont cool proper and not enough it wont do its job.

    As the coolant gets hot it expands and this is why there is a need for a pressurized system so it doesnt just evaporate on us.

    there are 2 types of radiator caps/overflow systems that i know of, the old school type that merily dumps fluid onto to the ground, which i belive you have and the newer cap that blows it to a tank and when it cools down sucks it back in.

    with the old school type cap your level of coolant when cold will be lower then the top of the rad, 1 inch 2 inchs maybe more it just depends on the car.

    with the newer style the level should be at the very top of the cap or right near it when cold.

    I say leave the 13ib cap on there, make sure you dont have a cooling system leak (pressure test or merely drive it) put in the proper mixture of coolant fill it right to the top, go for a good long drive heat it up fulley, let it blow out what it wants to. then let it cool and go for another drive and let it cool do that oh say 3 times. Ill bet by the 3rd drive it wont be blowing out any more coolant :rolleyes: and when you check the fluid level (when cold) its down a couple inches :) (which is fine)

    youve got a good temp gauge that is good :banana: