| Drbrown | -- 07-24-2014 @ 10:50 PM |
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Have '47 Ford. Car came with pressurized radiator cap on a rebuilt radiator. Cooling system works fine; Runs at btwn 180-190 degrees on open road; No overheating at gauges; Sometimes a very small amount of coolant comes out overflow tube. Need opinions/recommendations: Just read in Ford Book that Ford discontinued using their 4 lb pressurized cap in '46 without stating reason. Anyone know why ? Are plain non-pressurized caps available and should I use one ?
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| len47merc | -- 07-25-2014 @ 4:29 AM |
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Sounds like your system is working well. I run a 4 lb cap on an early '47 Merc (i.e., many fundamental similarities to '46 Fords) and experience the same temps on 90 degree plus days (w/original radiator). The original cap was non-pressurized but the rubber seals were long gone and needed changing so I went to the 4 lb (original style matching) to stop the spitting I was seeing after bringing the car back to life - it didn't address the issue. The real problem for me was overfilling the radiator tank. Once the level was optimized - for this vehicle about 1.5"-2" minimum below the top of the tank (not the fill neck) - the spitting stopped regardless of ambient and/or motor temp. The system was designed to be non-pressurized and the large tank at the top of the radiator was intended to have adequate headroom to accommodate expanding coolant. If you have not already tried this, lowering your level of coolant to only cover the top of the core by 1/2" - 1" may likely solve your problem. Btw - after getting the coolant level 'right' either the pressurized (4 lb) or non-pressurized caps work equally well on this vehicle. Steve This message was edited by len47merc on 7-25-14 @ 4:51 AM
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| Old Henry | -- 07-25-2014 @ 7:12 AM |
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The 47 radiator will reach its own maximum coolant level if you fill to the top. It will then puke out the excess when heat expands the coolant until it's at maximum level then stay there without any more puking. It will be about 2" from the top. This message was edited by Old Henry on 7-25-14 @ 7:13 AM
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| TomO | -- 07-25-2014 @ 7:12 AM |
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Plain, non-pressurized caps are available and I would stay with the 4lb cap for all driving. It will help with cooling and reduce the chances of coolant foaming. If you intend to have your car point judged, you MAY lose a 2 points for the wrong cap. Tom
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| Old Henry | -- 07-25-2014 @ 7:26 AM |
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A 4 lb cap will prevent boil over for 13° higher than non-pressurized. It makes a difference when climbing mountains in the heat like I did just yesterday. I could watch my temperature gauge and know that I had no worries up to 225° instead of the standard 212°. Still had to stop twice to cool down when it went over 225° but it would have been a lot more without a pressurized cap. (15 miles of 8% grade in 98° ambient temp. 2nd gear @ 25 mph or less most of the way.)
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| Drbrown | -- 07-26-2014 @ 1:17 PM |
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Thanks to each of you. Since obtaining the car in 10/13 I've seen the smallish coolant hick-ups on the garage floor mat. They happen after I park it and apparently while the engine is cooling down. And there has been a slow decline in the radiator coolant level, now down to about 1.5 to 2 inches below cap. Based on your comments, things seem okay and nightmares of about cracked blocks, heads and gaskets will subside.
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| carguy | -- 08-04-2014 @ 2:25 PM |
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I've been working with overheating issues on my '34. Is there a way to use a pressurized cap under my greyhound radiator ornament? Bill Brown '34 Cabriolet
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| TomO | -- 08-05-2014 @ 9:27 AM |
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You can buy a pressure relief valve from Skip Haney and install it in the overflow line and use your stock cap in good condition. The valve will allow up to 3# of pressure to develop. This may or may not help your overheating problem. I don't know of any way to convert your stock cap to a pressure cap. Tom
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