Mercruiser Mark iv oil temperature issue
#41
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I agree. It does make sense to filter the hot oil and then send it to the cooler. Mine go through the cooler first then filter before returning to the block. They were rigged that way when I bought it. I think I’ll reroute my lines to your diagram when I reassemble them.
#42
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My hoses are routed exactly like this. My number 17 hose is my outlet and my number five hose is my return.
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Last edited by 35fountain; 06-21-2022 at 07:53 AM.
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Last edited by 35fountain; 06-21-2022 at 06:32 PM.
#45
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I just checked my hoses again. My oil flow path is correct as far as direction but it does go through the cooler before the filter. It must have been done this way from the factory because the hoses look to be original and my block exit hose is too short to move locations. My flow path: exits the block, enters cooler port side, exits cooler starboard, enters filter housing with arrow pointing towards center, returns to block adapter marked “in”.
The path works but it is filtering cooled oil.
The path works but it is filtering cooled oil.
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I will be rerouting and installing new hoses when I reassemble. I plan to route to filter first and then cooler. Just makes more sense to me. I would think hot oil would flow better through the filter. New cams, lifters and springs were purchased today.
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I was afraid someone was going to mention that. Lol. It’s a brand new oil cooler with less than one hour run time on it. I feel like I have to at least try to clean it. I’m thinking about removing it and maybe trying to pump diesel fuel through the cooler oil passages under a small bit of pressure. Basically plumbing it to a transfer pump.
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#50

Bold move cotton
If you are going to reuse the cooler I would put it before the filter so all the junk gets trapped, don't forget to buy a filter without a bypass. Call the manufacturer and see if they can re core it. In the words of my father " the cheap man pays the most".
Good luck
If you are going to reuse the cooler I would put it before the filter so all the junk gets trapped, don't forget to buy a filter without a bypass. Call the manufacturer and see if they can re core it. In the words of my father " the cheap man pays the most".
Good luck
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TomZ (06-23-2022)