New Owner '85 4Winns, 175 horse 4 cylinder.

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chuckm51

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Jun 24, 2010
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Hi fellow boat lovers,

I was recently given this '85 4Winns, Horizon 170, 170 horse Mercruiser powered runabout. I've known this boat and its 2 owners since the boat was new.
I can't beat the price and the boat has had a lot of work done to it, including new engine, lower unit, recovered seats and floors.
I also received a Clymer's stern drive shop manual for 62-85 models., along with all shop records, repair invoices, etc.
I am pretty clever with my hands and own lots of tools and know how to use them. But for the life of me I cannot even find this motor in the manual, much less which heat exchanger it is. There is a leak around the back end cap of the exchanger, and the cap looks damaged. I'm wondering if someone tried unsuccessfully to remove the exchanger, got frustrated, and just pulled the cover while the exchanger was still in place. I used a water clamshell to pump water into the lower unit which seems to circulate ok. However, when I started the engine liquid of some sort poured out the back of the exchanger. Also, I discovered there was no liquid in the closed loop reservoir or overflow bottle.
I am about to abandon the exchanger in favor of fresh water cooling as I am on fresh water, not on the ocean, and for the life of me I cannot remove the 3rd, center bolt holding the exchanger to the block. Ubolts removed fine. Thinking the exchanger was attached to the block before it was installed in the boat.

So, my question is: can I abandon the exchanger system and just run fresh water through the motor? I believe my '83 Bayliner didn't have a heat exchanger, or most boats I've known.

Thanks.

Chuck in Texas
 
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stonyloam

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No you can not! You have a 470 engine which is cooled by antifreeze circulating through the exchanger. What came out of the exchanger, antifreeze or raw water? If water you probably need a new gasket for the end cap. You need to fill the reservoir/exchanger with 50/50 automotive antifreeze. It could be that someone drained the raw water from the exchanger by removing the cap rather than by using the drain underneath, or it may have been left full of water and froze, which can damage the cap. Your engine should be listed as the Mercruiser 4 cylinder in the book, under the engine section. You will want to do a compression check on the engine, if OK you should be so the way to figuring it out.
 
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Bondo

Bondo

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So, my question is: can I abandon the exchanger system and just run fresh water through the motor?
Click to expand...

Nope,.... You've got a copy of Mercruiser's bastard red-headed step-child they've tried to forget, 'n have abandoned,.....

The infamous 470,....

It's an aluminum block, with a cast iron head, it needs the stable temps from the heat exchanger,....
I believe the heat exchanger is also part of the manifold system, so again it can't be removed, 'n run otherwise,....

Click the link in my signature titled Don'S Adults Only Section,....
In there you'll find links to the Merc factory manuals,....
You've got a very steep learnin' curve ahead of ya,....

That's the motor everyone loves to hate,.....
 
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stonyloam

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Under the exchanger there are two drain plugs, the aftmost drains the raw water from the exchanger, the forward one drains the antifreeze. Also the innermost hoses on the exchanger will have antifreeze in them, so be careful you don't want to spill it all over. I would suggest removing the rear cap and checking for damage. DO NOT RUN IT without the block full of antifreeze, it will overheat and you will damage the head gasket. If it has a new engine you should be able to get a lot of years out of it.

Yeah Bondo, can't argue too much, but some of us love a challenge, and to suffer a bit LOL!
 
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Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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first - throw the clymer manuals away. they make great knee pads, and they work great leveling the one end of a couch with the broken leg sitting in the garage.

you can find your manual on-line here http://boatinfo.no/lib/library.html

as others covered, you have the infamous 170/470/475 peyote-induced-design motor. a Mercruiser only block casting with a modified ford head on it and a GM bolt pattern for the flywheel housing. Think of it as the platypus of engines

you need the heat exchanger.

the heat exchanger has removable end caps for maintenance and repair reasons.
 
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stonyloam

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Nah, we have to hang around here and feel smug reading all the "cracked block" threads in the spring and all the "how do I winterize" threads in the fall, there are actually a couple of good things about the ol 470 ;)
 
Rick Stephens

Rick Stephens

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stonyloam said:
Nah, we have to hang around here and feel smug reading all the "cracked block" threads in the spring and all the "how do I winterize" threads in the fall, there are actually a couple of good things about the ol 470 ;)
Click to expand...

Yeah.... but how many other engine owners talk about not plugging the leaking water pump weep hole? All ya'all are different.
 
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stonyloam

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Well sometimes ya just gotta play the hand you are dealt. Mine turns 30 this year and is running just fine (now). One head gasket, one set of cam seals, 1 regulator and one alternator conversion, 3 starters, 3 sets of plugs, 1 set of wires, Bunch of points, and a Petronix conversion, 1 carb rebuild (running original fuel pump) and who knows how many impellers (original thermostat). Never left me stranded. 5 minutes a year to winterize :). Yeah PITA at times, but what boat engine isn't ;).
 
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chuckm51

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Jun 24, 2010
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That you all for the encouraging comments!
And for the useful information. I really need an owner manual.
I am so reminded of the "other" boating adage: The definition of a boat is a hole in the water into which you pour money.
I bought 2 different socket handles looking for one to access the 3rd nut under the exchanger, and finally got it off without trapping my arm under the loose exchanger.
The rear metal end cap is warped, and the gasket looks like an original fabric material. Someone tried to stop the gasket leaking by cranking down harder on the center bolt and warped the cover. The front gasket and cover look new. The new cover looks to be of thicker metal with a rubber gasket.
New gaskets and cover ordered..
Question: The water I observed leaking out through the damaged rear gasket/cover came from the body of the exchanger, not the interior copper tubing. Is that leaking water lake water? I am thinking that is so.
Although we owned a new Bayliner 16 back in the 80s, my experience is mostly with old outboards. Old, finicky tedious outboards. So my patience is pretty good.
Thanks again. With any luck I can attempt to start it next week. Oil and filter change too.

Chuck in Texas
 
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chuckm51

Seaman
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Jun 24, 2010
Messages
58
Sorry, I'm not seeing a service type manual for my motor anywhere. Can someone post a link for the 1985 Mercruiser 170.

Thanks.
Chuck
 
achris

achris

More fish than mountain goat
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May 19, 2004
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27,468
First off, got a serial number for that engine? The boat may be 1985, that doesn't mean the engine is....
Once you post the serial number, I can link you to the right manual.

Chris......
 
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chuckm51

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Jun 24, 2010
Messages
58
Hi gentlemen,
Thanks once again. The engine serial number is #6921208.

I have a completely new issue to address now and I wonder if I should start a new thread to discuss it? I put the exchanger back together with a temporary gasket for the rear cap and reattached all the hoses. I filled the reservoir for coolant with radiator flush and topped off with water. Got the clamshell turned on and fired up the boat. I immediately noticed smoke at the engine and observed smoke emitting from 2 of the electrical terminals on the water-cooled voltage regulator.
I notice an old thread discussing this exact topic, from 5-6 years ago. Should I make this a new thread? The fix looks expensive regardless.
Thanks again.
 
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achris

achris

More fish than mountain goat
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May 19, 2004
Messages
27,468
Manual number 8 is the correct manual. HERE is your link to it.
With the smoked regulator you have 2 options. Find a second hand regulator and replace it (that part is no longer available from Mercury), or fit an external alternator kit, I believe is available from Breezeworks.net. HERE is an old thread regarding alternator brackets.

Chris.........
 
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chuckm51

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Jun 24, 2010
Messages
58
Hi all,

Well, I got the new end cap for the heat exchanger, and new gaskets. Installed same and observed no more leaks. So I filled it and added radiator flush to the fresh water system. Boat started right up with its new spark plugs. Within moments I noticed the waste water being expelled from the lower unit was foamy - I think the radiator flush mixed with the sweater side. When I removed the radiator cap I saw the freshwater water level was way down.
I assume there is a breach somewhere in the fresh water lines in the exchanger.
Does anyone have a suggestion for proceeding? I can't see it being repairable. Find one out of a boat junkyard?
I disconnected the 2 wires from the stator to the voltage regulator, and can run the boat off the battery, at least for testing purposes.
Any advice would be appreciated.

Chuck in Texas
 
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