merc 350 - what does an oil cooler do?

samm835

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My boat is closed cooler with an oil cooler. I've never had a boat with one. Its 1986 sea ray 260 merc, I am wanting to take it off today to make sure its clear of debris so was curious as to what it actually does and is it a pain to take off
 

alldodge

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I don't know if you have one or two coolers, being a 1986 I'm thinking just one. Either way its either the power steering (PS) or engine oil cooler or a combo of both PS and oil. The power steering cooler is on the return oil side of the pump so not much pressure. It will have two hose clamps holding the small hoses going to/from the PS pump and hydraulic ram.

If it has an oil cooler then it has high pressure lines going to/from the engine block and oil filter. Should use line wrenches to remove and replace the hoses.

If it is a combo one, then one end is the PS and other end is the oil cooler.

There is usually a bracket which clamps the cooler to the block. Only issue with removing is keep rags around to catch drippings.

In all cases there is the water hose clamps to be removed
 

samm835

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I only have one, it has a pipe coming from the transom ......does this oil cooler have raw water going through it?
 

samm835

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So when taking off, would oil keep spilling out? Im planning to take off this week to make sure it's debris free
 

alldodge

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If you only remove the water hoses, then there will be no oil.

If you remove it completely then yes there will be oil drain out of the small hoses. Most of the oil is in the PS unit, so suck the oil out of it first to reduce spillage
 

samm835

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Makes sense, thanks for the help. Excuse my ignorance, I need to flush it out to make sure there isn't anything obstructing it....so wouldn't I have to disconnect everything?
 

thumpar

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Are you chasing a problem? I would leave it unless you have restricted water flow and suspect it.
 

Bondo

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Excuse my ignorance, I need to flush it out to make sure there isn't anything obstructing it....so wouldn't I have to disconnect everything?

Ayuh,..... I'm guessin' it's a P/S cooler, rather than a motor oil cooler,....

If so, it's a piece of 3/8" copper tubin', inside that 2" brass housin',....
Not a honey-comb style oil heat exchanger,...

If ya pull the 2 big hoses, ya can probe it with a stick,.... Shine a light through it,.... a pretty Big hole,...

You can flush it by runnin' water from the other end of the forward hose, at the t-stat housin', to the other end of the aft hose, at the transom fittin',...
 

samm835

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Yes I'm chasing an over heating issue. So I am checking there now, I'm checking the heat exchanger now.
 

samm835

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The drive has been pulled, new kit, new circulating pump. I did the pump mainly because of the age of the boat (1986) and im slowly replacing as I look for the over heating issue.
 

Scott Danforth

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Did you pull the heat exchanger end caps as I suggested in the other thread?
There are a few styles of PS cooler depending on which company made them. All of the really simple designs
 

mr 88

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Yes I'm chasing an over heating issue. So I am checking there now, I'm checking the heat exchanger now.

That small cooler/heat exchanger would not affect your engines temperature. I would be looking at your thermostat or exhaust riser being clogged up and not letting hot water out of the exhaust manifold quick enough.
 

samm835

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Thanks for all the help, yes I pulled the exchanger and end caps and all was good. I haven't had a chance to pull tube that connects to the ps/oil cooler yet. At the same time I'm going to pull the risers to have a look. Just my mind wondering, but would cracked heads cause over heating issue? No water/antifreeze in oil though....doesn't burn oil either.
 
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