Mercruiser 170

[Magnum P.I.]

Hey guys! Just registered and new here. My question is, what in the world is a Mercruiser 170? I've had the 3.0 before and never anything but mercury and mercruiser but haven't seen this thing before. Are they relibale? Aluminum block/head? What? it's in an 85 Sea Ray I'm considering purchasing. 23 ft cuddy. My Toyota T100 is gonna be mad at me! Any replys would be great. Thanx Mike.

 

[TwoBallScrewBall]

Re: Mercruiser 170

It's a ford 3.7L engine. I don't know much about them either, other than it was a very limited production engine that can be hard to get parts for, and more expensive than your typical marine engine which is already expensive. If it's running well it is a strong, economical powerplant. My dad had an 88 robalo 21 footer with one in it, ran good. Not as good as the twin 200's on the 26 footer he replaced it with, but I digress...<br /><br />If it's running with low hours it's a good engine. But purely from what I've gathered here from other posts, it can be a picky engine that can drain a bank account faster than others. <br /><br />Hope this helps.

 

[Topmason]

Re: Mercruiser 170

Cast iron sleeved aluminum block with Ford 460 pistons, rods and head.<br />The 470 denotes 4 cylinders, 170 H.P.<br />They're made to run 5 grand all day long, but have issues.<br />Do a search on this forum; "mercruiser 470" and you'll find alot of info about them.<br />Mine was the 3.7 LX with a 4 bbl carb rated @ 180 H.P. and I loved it. Had to replace the liquid cooled voltage regulator once, about 180 bucks.<br />Would have been better to do the alternator conversion.

 

[Magnum P.I.]

Re: Mercruiser 170

Yeah, this one hasn't had the conversion yet, have not heard it run yet. Fairly clean, dry stored one owner boat at a dealer and was a trade for new. Several other dealers that I have talked to say it is a tough power plant with the right maintenance. Winters here in Texas are two or three days and not brutal. It will be trailered and kept at home. Not scared to add the external alt and has a pulley on the crank. Guess I need to do more research. Don't really care for all the power in the world and the 4 cyl is ok for me and saves weight over a small or big block. I use my T100 as a one ton truck anyway. Boat's clean enuff to constitute any future repairs that may need to be done. I thought all Mercruisers used GM??? Guess not.

 

[beckerdg]

Re: Mercruiser 170

I have one in an 86 cuddy of similar size. You won't get there fast, but I like my boat and am usually not in a hurry. Seems lots of folks don't like the engine which is actually a merc block with some of the other parts coming from ford as the other posts mentioned. I am still running the stator and water cooled VR but had to swap the VR once with a used one I bought. Powerful engine for its day, but a bit short on legs for a cuddy that size.

 

[airman]

Re: Mercruiser 170

I've got an '82 with 1300hrs on the meter and it still pulls WOT with a 21" prop on a 21' cuddy. Just pulled it out of storage after sitting for 3 years and it ran great for a 60 mile weekend trip. I converted to an alternator a few years ago but all I did was bend up my own brackets and move the coolant tank to the port side of the engine.

 

[Topmason]

Re: Mercruiser 170

The 470 bridged the gap from GM 4 bangers to GM V-6's, in mercruiser's eye's anyway.<br />My 3.7LX replaced a 302 rated at the same H.P. but I lost 200lbs. and that lil 3.7LX was a perfect match for my 21' Glasply hardtop cuddy with custom built(heavier)Alaskan bulkhead.<br />Boat and trailer weighed in at 6000lbs. I can't imagine the trailer weighing more than 1500lbs.

 

[MrBill]

Re: Mercruiser 170

I have an 89 3.7L and think its a strong reliable engine, albeit some critical design flaws, most of which can be overcome.<br /><br />1. Charging system - stator with water cooled regulator, conversion kits are available.<br />2. Closed cooling system - some early 470's have undersized heat exchanger, and are prone to over heating. Should be equipped with 4" diameter (rather than 3") heat exchanger, regularly service lower unit impeller to ensure good raw water flow to exchanger, voltage reg and exhaust. I change my lower unit impeller every 50-65 hours or end of season. <br />3. Cam shaft direct drive coolant circulating pump - on some models replacing water pump requires engine removal.<br /><br />Search this forum for '470' or '3.7' and you'll find alot of info...and many opinions of both good and bad about that engine package.