Thank you all for the information. Now I can look at my options on what to do or not to do money wise.john.
On Mar 1, 5:23 pm, waterguy <[email protected]> wrote: > Regarding the manifolds, it all depends on your engine/manifold > combination. I have twin 440 Chryslers that were originally set up > with the manifolds as part of the closed (freshwater) cooling system > and the risers as part of the raw water system. Chrysler designed > their system so that the could be set up this way or with the > manifolds as part of the raw water system. > > Advantage to having the manifolds as part of the closed system: They > last nearly forever. Mine are 38 years old and as far as I know are > original ("CHRYSLER MARINE" on the original casting and the Chrysler > Marine tag under a bolt). > > Disadvantage to having the manifolds as part of the closed system: > Any failure of the cooling system (plugged intake, broken raw water > pump impeller, broken raw water or fresh water pump belt, whatever) > and your engine is overheated RIGHT NOW. A minute or two inattention > to your water temp gauges and you may have a seized engine. This is > due to the amount of heat a fresh-water-cooled exhaust manifold dumps > into the coolant. There's a very very thin margin for the failure > mode. With raw water cooled manifolds you've got a couple more > minutes before temps go critical. My boat has a light-and-buzzer > overheat/low oil pressure alarm in addition to the gauges for that > reason. > > Chrysler used two different plates between the manifold and riser: > one blocks water flow between the water jackets of the two, the other > permits it. The builder would use one or the other end plate on the > manifold depending on whether he wanted the manifold to be part of the > raw or fresh water systems. I expect most others are similar. > > As far as having your transmission heat exchanger plumbed into the > freshwater side, bad idea. An earlier post noted that my transmission > manuals state that they're supposed to operate between 170-180 deg F. > In closed cooling systems, Chrysler specified a 165 deg. F > thermostat. What that would mean if you cooled the transmission heat > exhanger with engine coolant is the cooling medium (the engine > coolant) would only be a few degrees cooler than the operating temp of > the transmission oil. > > With most systems, the raw water is pulled in and run through the > transmission cooler first. Even in the tropics, there's no place that > the ambient water temp is going to be more than 75-80 deg. F, so > there's a 100-degree difference between the cooling medium and the > transmission fluid. If you use engine coolant there's not enough > difference to pull the heat out of the transmission, and it's off to > Rebuild City. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
