V6 175HP 1987 rebuild

Boston Habba

Seaman
Joined
Jul 26, 2003
Messages
65
I'm rebuilding my 87 V6. Problems all started with a bad head gasket and things went down hill from there.I'm pulling it apart to find the source of some pretty bad noises. Sounded like metal banging on metal (loud knock). I've opened the top of the engine and it looks pretty good except for one cylinder (chrome bore) that has some minor scoring. Doesn't look bad but I need to do acid test to see if it is worn thru to the aluminum.<br /><br />Pulled the intake manifold (reed block housing) and the reeds etc look like new! When I look into the crankcase I can see the the crankshaft counter weights and the cap bolts have a light coating of rust. Doesn't seem right to me. Could this be caused by the leaking head gasket letting water into the engine? I'm going to open the crankcase. I need some advise on what to look for.<br /><br />Thanks
 

NEECAPRS

Petty Officer 2nd Class
Joined
Jul 25, 2003
Messages
126
Re: V6 175HP 1987 rebuild

Repirts: Look for real concentrations of rust. Is it on both counterweights(top and bottom)? Which cylinder is scoured? Has the engine been sleeved and, if so, is the rust in the same induction path? If the bottom and top 'weights are both rusted, look also for the bottom main bearing to be bad caused by failure of the bottom shaft seals (2). Hard metal on metal sounds like a bad piston failure(not showing up yet) or a bearing failure. The noisiest are rod bearing failures. If you find a bearing failure and crankshaft damage, let me know. We repair that sort of thing and bring happiness back to boating! NEECA, (860) 683-1317 ;)
 

Boston Habba

Seaman
Joined
Jul 26, 2003
Messages
65
Re: V6 175HP 1987 rebuild

Neecaprs,<br />Thanks for the reply. Engine has not been bored and sleeved. The rust appears as a light coating on all the cranks and the weights. I have never worked on a 2 cycle before and I expected the cranks etc to be coated with oil. As I understand it the oil is brought into the crankcase with the fuel, so I expected to see it allover everything. Am I wrong? I know that the engine has been getting oil because the cylinders are coated. Later this week I should have the time to open the crankcase and take a good look. I'll let you know what I find.
 

NEECAPRS

Petty Officer 2nd Class
Joined
Jul 25, 2003
Messages
126
Re: V6 175HP 1987 rebuild

Repirts: Should be light oil coating everything. The light rust may be from long ago. Is this motor an oiler(oil injection) and do you run it in or near the Bay or Harbor? If so, I'd suggest adding light amount-100:1- of oil to the fuel. Reason is that oil injection puts almost no oil into the engine while you're idling your way in through the "No-Wake" zones to the ramp or dock at the end of the day. Then the motor sits that way, rinsed somewhat free of oil until your next day out. If you add salt mist, you can see the potential. ;)
 

Boston Habba

Seaman
Joined
Jul 26, 2003
Messages
65
Re: V6 175HP 1987 rebuild

Well, found the problem. The bearings on both end of one crank were badly rusted. Luckily the crankshaft is ok. I'm replacing the bearings and a couple of other thinks while I'm at it. Also removing the oil pump and going to premix.<br /><br />I have never replaced rings before. How do I actually use the ring compressor. I think I can figure it out but some step by step direction would be abig help.<br /><br />Thanks
 

NEECAPRS

Petty Officer 2nd Class
Joined
Jul 25, 2003
Messages
126
Re: V6 175HP 1987 rebuild

Repirts, Sounds like good luck prevailed on crank bearings. I can't picture the top bearing being rusted without rust on the shaft journal. It is a roller bearing,isn't it?<br />What kind of ring compressor do you have? They're really only tricky while pulling the rings down into the grooves with it. Presumeably it has a definite bottom to catch and seat on the top face of the block. The edge of that side only needs to be two or three ring widths below the lowest ring. It's by far easiest if you lightly grip the rod,wrapped in a cloth, in a vice for this. Set the rings over their locating pins and very slowly and observantly tighten the compressor, keeping it straight on the piston. What you need to observe is that the pins fall into the end recesses in the rings-- not be healed over the pin on a full width portion of the ring. It will help you concentrate on this if you imagine putting the whole engine together with an unoticed cracked ring! As you start getting the ring compressor nearly all the way in, you can rock the compressor and rings back and forth to verify that the ring are free, over the pins. If you get a hangup before that point--STOP--you may have one ring on top of a pin. Before you put the piston into the bore, the compressor has to be so tight on the piston that it won't move back and forth anymore.<br />When you put the piston into the bore, tap it in--and out of the compressor-- with a plastic mallet or a wood hammer handle. Try to avoid metal. Use one hand to position the rod and keep a downward pull as you're tapping/ pushing the piston in. Watch the compressor closely and stop if one side of the bore 'swallows' it. Of course, don't turn the piston much lest you drop a ring end into a port.<br />By the way, it's really not a bad idea to have one or two extra sets of rings on hand when you start this!<br />Good Luck--and let us know your progress! :)
 

Outrage 19

Petty Officer 1st Class
Joined
Jul 24, 2002
Messages
317
Re: V6 175HP 1987 rebuild

Hi Repirts. I recently rebuilt my 87 150HP V6 so I thought you might like to here from someone who didn’t have much luck using the old ring compressor. I’m sure NEECAPRS knows what he is talking about but let me tell ya getting those rings to line up with there locating pins takes some patients. After I got them lined up getting the rings to go into the bore was another lesson in patients. After braking 3 rings and the top of one piston I found it easier and safer not to use the ring compressor and just work the rings in with my fingers. Start at ether end of the ring and work it around into the bore pushing lightly on the top of the piston. Don’t push too hard or when it goes in you will smack the next ring on the block face and crack it. I’m not saying mine is the best way, just something else to try if you run into problems with the ring compressor. Good luck
 

NEECAPRS

Petty Officer 2nd Class
Joined
Jul 25, 2003
Messages
126
Re: V6 175HP 1987 rebuild

Outrage, I like your way better--much better!! More sensitive+ gives a last chance to see the ring and be sure it's not broken. With no lead in, I didn't know it could be done that way. Thanks from both of us!! :)
 

Outrage 19

Petty Officer 1st Class
Joined
Jul 24, 2002
Messages
317
Re: V6 175HP 1987 rebuild

Your welcome NEECAPRS, glad to give back a little of what I get out of this forum. One other thing, watch your finger nails I broke two off back to where they bleed, but I didn’t brake any more rings or pistons.
 

NEECAPRS

Petty Officer 2nd Class
Joined
Jul 25, 2003
Messages
126
Re: V6 175HP 1987 rebuild

Outrage: I think I tried that once upon a time! Don't mind a little blood-- seems perfectly normal-- especially next to the machine shop. But, when it gets so I can't see what I'm doing, then I look for a change of method!! :D
 
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