Radiator Cap - urgent scientific question

orfeo
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orfeo
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Joined: March 8th, 2011, 6:45 pm

November 28th, 2015, 4:03 pm #1

:whistle My 1995 3-cyl Metro LSi hatchback comes with a 13# radiator cap, but the neck on the aftermarket all-aluminum radiator from Radiator Classic causes all 13# caps (have tried several different ones, all brand new) to release @ <9 lbs, causing my coolant level to be low. Due to this, my car overheated and blew the head. $800 dollars later, I find that the 16# cap holds well, and doesn't release until 16# of pressure (like it should). I have also learned that racers use higher pressure caps on many different model cars for more efficient cooling. Is there any downside to my using the 16# cap? Does 3 extra pounds of pressure make enough difference to possibly cause a problem in our Metros? I really can't afford another catastrophic engine failure. Many thanks! :banghead

Sorry for the double-post, but I didn't know where to put this! HAPPY THANKSGIVING !!
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Stubby79
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Joined: January 6th, 2013, 3:45 am

November 28th, 2015, 4:10 pm #2

i dunno, but i ain't gonna buy an aluminum rad, knowing this.
(besides which, throwing money at an economy car defeats the purpose)
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pdqrunner
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Joined: April 27th, 2009, 3:13 pm

November 28th, 2015, 4:12 pm #3

I'm not sure that cap caused you problem. You may a blockage in the system causing the lack of cooling.
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David95237
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Joined: July 14th, 2013, 1:18 am

November 28th, 2015, 5:01 pm #4

I found that the aluminum radiators take the older style radiator cap which is deeper.
Half of being a mechanic is knowing where to hit and what size hammer to use.

Learn from others mistakes, you'll never live long enough to make them all your self

"To know what to do is wisdom. To know how to do it is skill. But doing it, as it should
be done, tops the other two virtues."
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Metromightymouse
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Joined: February 19th, 2013, 9:09 am

November 29th, 2015, 1:13 pm #5

David95237 wrote:I found that the aluminum radiators take the older style radiator cap which is deeper.
Yep, they went with one size fits all. It was pretty obvious that the late model cap wasn't going to work on mine, early cap works perfectly.
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orfeo
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orfeo
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Joined: March 8th, 2011, 6:45 pm

November 29th, 2015, 7:16 pm #6

It WAS the cap (Yes it takes the older style cap). Every time I checked the radiator, it was low, while the overflow was full. But I didn't check it often enough, and I blew the head.

The Metro guru here (he's a forum member) said it was a defective neck on the radiator causing the 13# cap to release pressure at 7 to 9 lbs of pressure. We tested a half-dozen new caps and they all released too low. Tried a 16# and VOILA, it releases at 16#. . . Now I'm not losing any coolant wahtsoever. :rocker

However, I am concerned about whether a 16# cap could cause harm? Thoughts? Opinions?
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orfeo
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orfeo
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Joined: March 8th, 2011, 6:45 pm

November 29th, 2015, 7:24 pm #7

Stubby79 wrote:i dunno, but i ain't gonna buy an aluminum rad, knowing this.
(besides which, throwing money at an economy car defeats the purpose)
I hear ya, but it was pretty inexpensive. As I recall, not much more than OEM-style, larger capacity, and lifetime warranty against leaks. In hindsight, I would stick to OEM, but it seemed like a good idea at the time, and had several endorsements from the guys on here as being GTG. . . Really my own fault for not paying closer attention to the coolant loss. :banghead
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orfeo
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orfeo
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Joined: March 8th, 2011, 6:45 pm

November 29th, 2015, 7:26 pm #8

I have also learned that racers use higher pressure caps on many different model cars for more efficient cooling. Is there any downside to my using the 16# cap? Does 3 extra pounds of pressure make enough difference to possibly cause a problem in our Metros?
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Murf 59
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Joined: July 2nd, 2009, 9:49 am

November 29th, 2015, 7:27 pm #9

I run one of the alum radiators. Love it. It came with a cap. I run that one. Have never had any issue with this rad.
A 13.5 to 1 G10. With GTi twin cam pistons. Performance head package work sponsored by our friends at 3Tech.
A set of 4.38s set up as a 4 spd. MSD ignition, and a Weber card on top. It has a SRD header on the bottom side.
I run a Glow shift tach, and a HF vacuum gauge.
This engine is still in the works. I have all the pieces, but am not able to get the energy to assemble it.

This is what it looks like running at Bonneville from the front seat of a Geo Metro
http://www.youtube.com/watch?v=rOcWzyzyjPw
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