| len47merc | -- 02-09-2014 @ 7:31 AM |
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Changed all the original hoses on a '47 Merc (w/heater) as well as installed new 180 degree thermostats (original hoses were hard as PVC, original thermostats looked like something out of Buck Rogers and were stapmed '171'). After install the car now runs much cooler on the gauge than before (from just below 3/4 previously to between 1/4 & 1/2 on the gauge), takes much, much longer to warm-up and lastly after running at temp am having an overflow problem. Lowered the coolant level and still have an issue. Understood (perhaps erroneously) these systems were not pressurized like modern cars so am still using the original radiator cap. Does anyone have any experience with these caps, after installing new thermostats, being the root cause of slow-to-heat & overflow probs? Thanks in advance. Steve
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| TomO | -- 02-09-2014 @ 8:22 AM |
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Your thermostats seem to be open all of the time or you have the wrong thermostats and they are sideways in the hoses. The correct thermostats will stay in the openings of the heads when the hoses are installed. The 49-53 thermostats will go up in the hoses. Measure the flange on the old and new thermostats and you will see the difference. Most 47 Mercs came with a 4# pressure cap P/N 41A-8100. The cap was optional, but sold with most cars, because it raised the boiling point of the coolant. Ethylene-Glycol (Prestone) anti freeze tends to foam and go out the overflow in a non pressurized system, Propylene-Glycol (Sierra) is less likely to foam and overflow. Tom
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| len47merc | -- 02-09-2014 @ 8:53 AM |
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Thanks Tom. Thermostats came from Job Lot (James) and measure the same flange OD as the originals +/- .001" or so (just checked). It was d*mn tough to get the new top hoses over them and onto the head flange as the outer edges were somewhat crisp/sharp and pointed upwards, presumably to keep them from canting in the hose. Not sure how to validate whether this Merc has a 4# cap or a 'no pressure' cap as there are no markings on the original cap (such as a '4' on one of the 2 cap ears as I've seen at Van Pelt and others). Assuming, given the lack of definition on the original cap it is 'no pressure', (here comes a possibly stupid question) do you or others know whether a no pressure cap should have rubber seal? I've seen pics of caps with rubber seals and some without but the pics do not define the pressure rating. UPDATE - Tom, you were correct on the thermostats canting in the hoses. I measured the driver's side thermostat for the measurements shown above to confirm size; however, upon removing the passenger side hose I found the thermostat high in the hose. The dimension is accurate and consistent with the old thermostat, so I am not sure how to prevent this from reoccurring short of placing another hose clamp above the thermostat to ensure it stays in place - not an option I wish to pursue. Any thoughts from anyone appreciated. UPDATE 2 - Tested original thermostats in microwaved water of known temp (calibrated Fluke meter thermocouple). Opened at 170 degrees and were fully open at 180. Cleaned and reinstalled originals and placed hose clamp high with approx 1/5 of the width of the clamp above the hose flange to pinch the hose rubber in over the thermostat flange. Drove 25 miles after completion of reinstall and charging with coolant - no problems now. Original cap working fine. Long-term looking for better solution to ensure thermostats stay securely in the head tube versus the method just described - suggestions appreciated. Thanks again Tom - you're on the money as usual. Steve This message was edited by len47merc on 2-9-14 @ 1:34 PM
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| supereal | -- 02-09-2014 @ 3:20 PM |
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The usual way to hold the hoses in place is to put a hose clamp just above the thermostats on each side to clamp them in place. We use 160 stats rather than 180, but if they work OK, i wouldn't worry. A 4 pound cap will help contain the coolant as it expands from the heat.
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| len47merc | -- 02-09-2014 @ 5:05 PM |
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Thanks supereal - after pondering on this for a while earlier today as noted above your approach seemed to be the most logical though I wondered how this would score when I ultimately submit the car to judging. On the temp, these stats are so easy to change that here in NC I intend on running 180s in the winter and 160s in the summer/heat months, this once I employ your 2nd clamp recommendation. For a while today I was thinking my hoses were not designed properly to hold the stats down. Thanks supereal for weighing in with the good info. Steve
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