Internal vs External Coolant Bypass

[Jocko_51_B3B]

If I understand the bypass systems correctly, the '48 - '50 model thermostats were designed to stop bypassing completely when the coolant is up to full operating temperature. But for the '51- '53 models I can't figured out how (or if) the bypass ever shuts off. I don't see a mechanism for shutting the bypass off. So, for internal bypass systems, does some amount of coolant bypass continuously? If it does, do those engines tend to run a little hotter than the earlier external bypass systems? I'm just curious.

[MBF]

Not sure, but I think the purpose of the bypass was to let a limited amount of coolant pass through the system when the vehicle was cold.  That way the rear cyls wouldn't get overly hot while waiting for the thermostat to open, and you'd have some heat out of the heater if so equipped.   I don't believe there was a difference between the two when the thermostats were open.   If I'm wrong-someone please correct me.

[Merle Coggins]

True, a small amount could bypass the radiator via the “bypass” port but it isn’t enough to cause any problems. 

[Jocko_51_B3B]

Merle,

Thanks, that makes sense. But "could pass" or "does pass"? Anyway, the internal bypass simplified things and saved money on parts so I guess that's why it was adopted. I'm sure, during the initial testing phase, the Chrysler engineers back in 1949-50 measured the temperature carefully to see what effect the new system would cause. Be fun to know what temperature difference, if any,  they measured. It's not really important now, just a fun fact to know.

[kencombs]

17 hours ago, Jocko_51_B3B said:

Merle,

Thanks, that makes sense. But "could pass" or "does pass"? Anyway, the internal bypass simplified things and saved money on parts so I guess that's why it was adopted. I'm sure, during the initial testing phase, the Chrysler engineers back in 1949-50 measured the temperature carefully to see what effect the new system would cause. Be fun to know what temperature difference, if any,  they measured. It's not really important now, just a fun fact to know.

I think could or does depends largely on the radiator condition and thermostat flow.  A perfectly clear radiator would likely accept all the flow without causing backpressure that would reroute the coolant through the bypass if the opening in the stat allows.  Not all replacement stats  the opening dimensions and not all radiators are perfect so the answer is  there is the : maybe.

[Jocko_51_B3B]

Ken,

I'm talking about the internal bypass only. It looks to me like the internal bypass system bypasses a small amount of coolant constantly unlike the external bypass system which has a thermostat that ideally transitions back and forth between full radiator flow and full bypass flow. So, as far as I can tell, the internal bypass does bypass constantly, not could bypass. I know it's a fine point. I only brought this up because I believe it's good to understand how things are working. It's also interesting to investigate these matters to get a handle on what the engineers were intending to achieve. If I'm not understanding the internal bypass correctly, please clarify. Thanks, Jocko.

Edited March 14, 2019 by Jocko_51_B3B

[kencombs]

1 hour ago, Jocko_51_B3B said:

Ken,

I'm talking about the internal bypass only. It looks to me like the internal bypass system bypasses a small amount of coolant constantly unlike the external bypass system which has a thermostat that ideally transitions back and forth between full radiator flow and full bypass flow. So, as far as I can tell, the internal bypass does bypass constantly, not could bypass. I know it's a fine point. I only brought this up because I believe it's good to understand how things are working. It's also interesting to investigate these matters to get a handle on what the engineers were intending to achieve. If I'm not understanding the internal bypass correctly, please clarify. Thanks, Jocko.

I understand what you are saying.  It's just that the water flow will always take the path of least resistance.  No resistance in the radiator path would result in all water going that route..