Mercrcruiser 1986 3.7L 170 possible seized?

[tsport]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

On April 1 I gave an update - what I viewed as a positive development (motor unseized, it doesn't turn all that well but at least it's free). Not sure what the next approach should be..any ideas? I'm hearing mainly negative comments and believe me I've read all about this engine's faults. But surely there are owners of this engine out there who have constructive/helpful advice? I've never completely rebuilt an engine before and hope this one will not require that.

This engine was in a 1986 Four Winns 170 Horizon - a very nice boat. It has a great hull - looks nearly new - and the previous owner had gutted the interior and started the restoration of the floor. He had been told the engine ran so I went on that (with healthy skepticism of course) but for a mere $500 I bougt a dismantled but complete engine/outdrive, complete but dismantled hull, 70 yards of fiberglass with equivalent amounts of resin, mixing buckets, etc., a 2000 lb hydraulic hoist, a marine upholstery sewing machine with extra needles, attachments, etc., and a great trailer with new tires. So, the hull restoration will be nearly all labor on my part - I'm retired so I have the time. So I'm way ahead money-wise but know that, even fully restored with running engine, this boat will still only be worth maybe $5000, I don't want to sink several thousand dollars on an engine - this one or a replacement. I would LIKE to get this engine running, and even add the improvements I mentioned (upgraded alternator, enhanced heat exchanger) and stay under $1000.

So if there are forum members supportive of my goals I would like to hear from you. I'll pose again the question. I have the engine turning over (with plugs removed) with fully charged battery but it's still very sluggish in its rotation, even after penetrating fluid - which broke it loose - then 10W-40 in cylinders, more penetrating fluid (Pete 104 I saw your advice on the diesel/ATF but since the enging freed up on just penetrating fluid I held off on that..still useful at this juncture?).

Any suggestions that might further loosen internals to get it free cranking so I can then fuel it, attach water, and see if she'll run?

ok here's a option from what I have read it doesn't sound like you have gotten the motor to spin over enough to build up any oil pressure. that means every things dry in there ( bearings rod and crank shaft, lifters, valves and all the seals) so the first thing you should do is pull the distributer and turn the oil pump with a drill to get the oil pumped through the motor (make sure you mark the distributer so you can put back just how it came out same position) then put some diesel fuel in all the cylinders and get it to spin freely, you have to get it to spin with the starter with the spark plugs out like a top. it may take some time , if you can't get it to loosen up then you will have to tear it down,and to be honest I would tear it down anyway just to check the condition of everything if you pull it apart and all the hard parts are in spec as in bearings look good no excessive wear no scoring of the cylinder walls or pistons, rings are good end gap measures out cam looks ok lobes aren't worn same on the lifters. Then theoretically you could put it all back together using the same parts and new gaskets and seals (after you cleaned it all and made it as new looking as possible) and it will give you a decent service life, OR you can get her loose don't check anything get her to run and idle real nice put her in the boat and the first time out underload she throws a rod out the side and and you wish you did everything I just suggested.Because the bottom line is you really don't know what you got with that motor without checking it out. Right NOW you have a half seized motor that's nearly 30 years old And I'm only trying to help ya because I've been there and done that. Oh yea w-d 40 is not a lubricant technically it didn't hurt using it theres just better stuff out there

 

[a1nowell]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

Dancer, check your private messages.
Larry

 

[tsport]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

On April 1 I gave an update - what I viewed as a positive development (motor unseized, it doesn't turn all that well but at least it's free). Not sure what the next approach should be..any ideas? I'm hearing mainly negative comments and believe me I've read all about this engine's faults. But surely there are owners of this engine out there who have constructive/helpful advice? I've never completely rebuilt an engine before and hope this one will not require that.

This engine was in a 1986 Four Winns 170 Horizon - a very nice boat. It has a great hull - looks nearly new - and the previous owner had gutted the interior and started the restoration of the floor. He had been told the engine ran so I went on that (with healthy skepticism of course) but for a mere $500 I bougt a dismantled but complete engine/outdrive, complete but dismantled hull, 70 yards of fiberglass with equivalent amounts of resin, mixing buckets, etc., a 2000 lb hydraulic hoist, a marine upholstery sewing machine with extra needles, attachments, etc., and a great trailer with new tires. So, the hull restoration will be nearly all labor on my part - I'm retired so I have the time. So I'm way ahead money-wise but know that, even fully restored with running engine, this boat will still only be worth maybe $5000, I don't want to sink several thousand dollars on an engine - this one or a replacement. I would LIKE to get this engine running, and even add the improvements I mentioned (upgraded alternator, enhanced heat exchanger) and stay under $1000.

So if there are forum members supportive of my goals I would like to hear from you. I'll pose again the question. I have the engine turning over (with plugs removed) with fully charged battery but it's still very sluggish in its rotation, even after penetrating fluid - which broke it loose - then 10W-40 in cylinders, more penetrating fluid (Pete 104 I saw your advice on the diesel/ATF but since the enging freed up on just penetrating fluid I held off on that..still useful at this juncture?).

Any suggestions that might further loosen internals to get it free cranking so I can then fuel it, attach water, and see if she'll run?

ok here's a option from what I have read it doesn't sound like you have gotten the motor to spin over enough to build up any oil pressure. that means every things dry in there ( bearings rod and crank shaft, lifters, valves and all the seals) so the first thing you should do is pull the distributer and turn the oil pump with a drill to get the oil pumped through the motor (make sure you mark the distributer so you can put back just how it came out same position) then put some diesel fuel in all the cylinders and get it to spin freely, you have to get it to spin with the starter with the spark plugs out like a top. it may take some time , if you can't get it to loosen up then you will have to tear it down,and to be honest I would tear it down anyway just to check the condition of everything if you pull it apart and all the hard parts are in spec as in bearings look good no excessive wear no scoring of the cylinder walls or pistons, rings are good end gap measures out cam looks ok lobes aren't worn same on the lifters. Then theoretically you could put it all back together using the same parts and new gaskets and seals (after you cleaned it all and made it as new looking as possible) and it will give you a decent service life, OR you can get her loose don't check anything get her to run and idle real nice put her in the boat and the first time out underload she throws a rod out the side and and you wish you did everything I just suggested.Because the bottom line is you really don't know what you got with that motor without checking it out. Right NOW you have a half seized motor that's nearly 30 years old And I'm only trying to help ya because I've been there and done that

 

[dancewithme951]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

Thanks for all the latest feedback. I'm in the process of disassembling - slow going with 30 y/0 exhaust manifold/intake manifold bolts holding on for dear life - and will know soon if this old gal can be resuscitated. Further reports from the ICU will be forthcoming.

 

[dancewithme951]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

OK, bad news. As it turns out - amazing how much better you can visualize everything once engine is disassembled and on a stand - I have 2 damaged cylinders, #3 and #4. Each has a circumferential gouge which I'm guessing could be where one of the rings on each cylinder was resting while this engine sat for who knows how many months/years. Possible rust set up between the ring and cylinder wall and this "ring" of erosion was created and possibly that's what was the cause of the seize. The worst is #4 and I'm guessing at its deepest the gouge is maybe one mm deep. #3 is barely noticeable but still there. Given it clearly looks like water encroachment the head gasket was intact so I'm not sure what the water source would be...phase separation from ethanol laced gasoline?

So, what are my options and which would make the most economic sense?

 

[Volphin]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

Could you retrofit the boat to a 4.3L?

 

[dancewithme951]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

Sure, Volphin, repowering is an option since I have an empty hull right now and I love that engine. I've shopped for use 4.3s but haven't found one I can afford. But I do believe that the Alpha 1 Gen 1 outdrive I have would fit. And I know I could part out my 3.7 but that's a lot of time spent as a seller on eBay, time I'd rather spend working on/playing on boats. As far as my current dilema, I'm about to call my local machine shop and see what it would cost to resleeve cylinder #4, clean up #3 and then bore all to match #3...we'll see.

 

[harleyman1975]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

I'm on board with ya now. If your going to run that engine your at least gonna have a fighting chance with a fresh short block! May as well have them go through the head too. Check it for straightness and cracks as well. Since it is apart might as well do all the upgrades while it is out of the boat. Waterpump, timing chain, ect, ect, ect...

 

[dancewithme951]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

UPDATE: talked to the machine shop and he didn't want to deal with resleeving #4 and said, even IF there's enough metal in the existing #4 sleeve to bore it smooth it would likely render the sleeve dangerously thin. And IF that wasn't the case, and he could rebore #4 and the other 3 to match #4, the cost just for all that - not even including anything the head might need - could easily be $300 or more.

So-o-o-o...PlanB: found a good and never machined used 470 block on eBay for $125. The owner had lots of great pictures and the cylinders look pristine, the rest of the block very clean. So think I'll use that block as the platform for my rebuild. And I'm looking at a possibly very cool 12V water pump upgrade that will eliminate the troubesome recurrent seal issue with the current camshaft driven rcirculating pump. And I've already ordered upgraded CID ignition, new belt driven alternator (think I'll have a go at fabricating my own mounting bracket!). It's funny, I spent close to an hour last night pouring over dozens of posts on this hot rodder forum touting the virtues of this woebegotten engine, e.g., weight-to-power ratio. It encourages me to do as those gearheads do - seek new and innovative ways to ameliorate the flaws and maximize the virtues.

I'll post pictures as all these things come together. Thanks again everyone for your feedback and support!!

 

[SDSeville]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

And I'm looking at a possibly very cool 12V water pump upgrade that will eliminate the troubesome recurrent seal issue with the current camshaft driven rcirculating pump.

Tell me more about the water pump upgrade. I am in the middle of replacing the seals on mine.

 

[dancewithme951]

Re: Mercrcruiser 1986 3.7L 170 possible seized?

SDSeville I'm still gathering information. Need to ensure I find a durable continuous duty 12V pump that produces comparable flow/pressure to existing pump.