Valve/Piston Interference or am I having senility problems at 60?????

Hello OMC folks - I just brought home an old boat with a 2.5 litre (I think) 4 cyl GM engine and stringer drive - about 1972 I think - looked like it hadn't run in a couple of years at least. Are these old Chev Nova engines??
The upper thermostat housing was freeze cracked across the top and some water was still in the exh manifold when I drained that but I was suprised to find that the engine would rotate at the crank pulley and there is no water in the oil. When the crank pulley rotated to a certain point it jammed but when I rotated it backwards it went past that point the first time around and then stopped at the same point the second time thru - so now I'm thinking stuck valve and that this is an interference engine and feeling really smart and that this thing might run again after all.
But when I took the valve cover off it looked like all the valves were moving back to closed or at least close - certainly none were open very far if at all when the crank pulley would hit - so quickly lost the smart feeling fast! I'm a pretty good mechanic but not on marine engines - What am I missing guys?????
Thanks
Ron

If you're a pretty good mechanic then you aught to be able to check the valve lash settings on a Chevy. If they are within the correct adjustment then the valves probably aren't the issue, but that every second rotation thing is bothersome.
With the engine in the boat it is turning the drive as well as the crank. It could be the tight spot isn't in the engine at all.
The freeze crack scares me. It is very likely that the engine has freeze damage elsewhere and you won't know until you have spent time money and effort getting it going. It would suck to find out the engine is toast after all that. Good luck.

Nothing free (or cheap) ever proves to be so.

the water is in the bottom.. the dispstick will show clean oil in an engine that has freeze cracked. hang upside down and take that fitting out of the bottom of the pan. If water starts trickling out of the loosened fitting, you'll know not to waste time on the valves etc.

Thanks O2batsea and Hystat - It hadn't occurred to me that if the engine hasn't been run the oil won't be milky! I'll check it tomorrow.
It also occurred to me that the jam may be in the drive not the motor - the drive leg is in the up position - would that make a difference? I guess if there was reduction in the drive and the jam was downstream from the reduction that might account for the jam to be about 2 turns backwards before you feel it again?
But first I'll pull the pan plug

welcome aboard !

no it's not a nova but a chevy 2 . But not exactly ether, it was put in postal trucks and forklifts. The pan and other stuff fits.

I got my 86' and was not run for 8 years . 2.5 l.

so here we go.

You may have 2 tubes, one for the dipstick and one that runs to the drain plug on the pan.

If so you can't easily pull the plug on the pan.

I had that setup but discovered the tube to the plug was half rotten off.

So i just broke it off pulled the plug and let it drain. I caught the first half in a cut off bottom bleach bottle.

The rest i let go into the bilge.

I found water in the pan, but i believe it entered from the tube at the plug.

Anyway, while the pan drained, I removed the leg. before trying to turn the motor.

Heres how but in the following post i have a shift cable you may have a wire. You will move the drive towards the side of the wire or cable 6 inchs enough to clear the ball gears.

You may have issues raising and lowering the drive. If so remove the half moon gear, i jam the drive up with a piece of wood. 3 - 9 / 16ths flat.

Now the drive can lower and raise manually.

Lower the drive all the way. Now place a flat piece of wood under the skeg on the floor. Raise the bow of the boat till the skeg just touchs the wood.

Looking at the drive from behind, you will see 2 rubber bumpers. Gently pry them off and mark them before so they go on exactly as you removed them. Exactly understand?

Now you see the pivots. Remove the 4 screws on the pivot caps. Mark the caps, again they must go on exactly as removed.

See how the buching sits on both sides the split facing you. It goes back on exactly the same.

Ok now with someone else raising the bow another 2 inch's or you lifting and draggin or sliding to the side of the wire or cable tie the drive to the swim platform.

You need only clear the ball gears. My son raises the bow and i swivel the drive, on the flat wood.

Ok now your ready to start the motor after you get it ready.

Say you need a plug for the pan cause you had the tube you can get a new one or do what i did.

I filled the hole with solder. However it is a one inch plug, so you will need a one inch wrench, i have a round one in my box.

Install the plug, fill with 30 weight straight oil. 4 quarts with ph30 filter. Actually right now advance auto has a sale 14.99 5 quarts and a filter.

Make sure the old o-ring comes off when you pull off the old filter.

Ok open the dist cap. At this point if i were you i would pull the dist. i didn't but you may want to and spin the oil pump, with a drill. To prime it. You could try bumping the starter with the cap center wire off. Ether way when you ready you have to inspect the points.

Me i just sanded them and checked the spacing and dabbed a little grease on the shaft sanded under the cap and the rotor and closed it up.

Ok the fitting that enters the carb has a filter clean it. The fuel pump is a bell shape ? Open it there is a filter, clean it. The rubber good?

Pull the spark plugs. New set or clean up the ones there. MR 43t ac's i use nothing but those on mine. Napa or wherever.

Now the carb linkage moving good ? Run straight from the fuel pump to a portable fuel tank with fresh gas and not from the onboard tank.

Dribble some gas in the carb, and with a good battery crank it.

Let us know what happens we will go from there.

Oh don't buy anything i have a basement full of stuff for the 2.5 that i don't need.

How to fix stringer tilt problems!

Wow! Thanks Chiefalen -
No tubes around the pan plug - pulled it and - no water! let out about 1/2 cup of old oil then closed it back up. Felt the freeze plugs on the port side - looked or felt ok - no draining signs but also no water in block when I pulled the block drain on that side. So odd that only the thermostat housing would split??? Or maybe I'm deluding myself!
Let out small cheer then tried to tilt the drive - tried 12 v positive to first one then the othjer of the motor wires direct from a test line - (the ignition switch is missing and I figured that might controll to tilt juice) - it buzzed but no go - am I right that the twin solenoids put 12v positive to alternate wires to raise and lower? Then pulled plug on tilt worm casing - maybe a 1/2 cup water so pulled the small gear at the rack and the cover, pulled the clutch out - not too much gunk but motor still just buzzes - how do I get the worm shaft out - that may be gunked up too.So I need a seal kit at least. and probably need to pull and clean up the motor.
Then the drive would go down - but hits something I couldn't see with maybe 1 1/2 in of rack travel left so doesn't go completely. Couldn't see the bumpers you were talking about - saw 2 pin holes in the intermediate casing that mated up (if they closed) with 2 pins on the drive. Mine is elec shift.
Then pulled the lower unit drain and much more water but all the case bolts loosened - haven't pulled it yet - still worried about the engine. but if that lives will need to redo the lower unit - a first for me - this is the first I/O I ever worked on. I was suprised that all the bolts loosened - they all had some kind of grey gunk on the threads - wonder what?
So with drive as far down as I could get it - ball gears meshed up - and with the valve rockers off the 2 center cylinders - they were the ones coming to TDC when the engine would jam - I tried again to turn it from the crank pulley - and again it went thru almost 2 clear turns to stop at the same point as # 2 and 3 were coming to tdc the second time thru. yet the valves all seem to be closing and the thunk - I do it lightly - definitely sounds like its in the engine not the drive - but maybe move the drive out of engagement as you suggest to rule that out. This has me stumped - there seemed to be an awful lot of rust down in the head from the thermo casing but I don't want to pull the head if something else is bad. Maybe the timing chain - it does have a chain right?
Its interesting that you're from NJ - I got the boat from Cape may - its an old seacraft - and took it here to near Annapolis.
Thanks for the parts offer as well - so far a thermo housing if the rest checks out. - I could weld it but the thermostat facing is really shot with rust - its a wonder the cyl walla arn't thru as well -
Was (is ) the 2.5 a decent engine? I had forgotten the chev 2 cars. Also anything I can spray the pan with to keep it from becoming flakes?
Thanks also for the post on pulling the tilt apart - I'm sure not going to take the clutch apart!

The clutch is actually the simplest thing.

You got a manual ? You will have a pm in a minutes after i post this.

Look at the back of the boat see where the worm gear goes nearest you ther maybe a triangle piece with 3 screws you remove that.

There maybe a c clamp that comes out, and what i do is raise the drive by hand and let it down fast not so fast as to break anything the worm gear should pop out.

There is a hammer blow coupler between the motor and the worm gear. that might be bad.

no chain 2 gears for the timing.

You have a pm

What a great manual - its really complete - thanks so much - that was next on my list after figuring out the obstruction problem - I'll read the tilt and drive parts and give you a call. From the looks of the cooling circuit diagram I have a 140 hp engine rather than 120 as the water from the drive pump comes in a hose beside the valve cover up to the thermo housing - did the 2.5 engines come in both designations or is it a 3.0? I need to look at the engine # I guess.
Today or tomorrow I'm going to try to figure out the every other turn jamming problem since thats the tail that wags the dog!

They are same " almost " Look at the crank if you have a plain pulley it's a 2.5 if it has a harmonic balancer it's a 3.0.

or pull the valve cover it will be marked on the head. year also.

your welcome.

Re: Valve/Piston Interference or am I having senility problems at 60????? Stringer Stringer Stringer

OK guys thanks to you I think I've narrowed down the interference problem - loosened all the rockers , pulled the push rods and the crank still hits something every 2 turns forward or back at the same about 40 degree rotation point - so must be a stuck lifter?? I plan on squirting it with PB Blaster and trying a long maybe 1/2 " piece of shafting down the pushrod hole and giving it a little tap - I'm afraid to hit it hard because the lifter may be sitting on the cam base circle - probably is since it only obstructs a small angle of turn??

Anyone have a 2.5 thermostat housing and maybe a front crank pulley??

Thanks again for the manual Chiefallan - I've got the 76 stringer elec drive off, upper gearcase oil is clean so I'm not messing with it, lower had a little water at the bottom so will reseal the prop shaft and swivel housing seals, solenoids read the right ohmage and the elec cable looks good.

Big problem with the water pump though - I got the 4 big SS bolts out the bottom of the upper gear case (what a fight!) and tapped the pump plate and housing loose on the upper gear case but the pump shaft won't release from the upper (hidden) connection in the upper gearcase. I even put a plastic sleeve around the lower end of the shaft, grabbed it with vise grips and gave it a wack but no go so the pump housing plate, impeller and shaft are still attached loosely to the upper housing. Manual only shows a spline connection, what am I missing ???????
It is so nice to be able to ash a question before not after I break something expensive!
Thanks!
Ron

The pump housing if done right would have alot of sillycone around it might even be blue.

What i do is spin the housing with a screwdriver and hammer.

You might even break up the plastic housing.

Thats ok see you will need a whole new kit anyway.

When you get it out, the 2 shafts impeller and gear, and bearing carrier will all come out in one unit.

Don't buy anything yet. Like i posted before i got a ton of stuff in the basement. The pump kit could come with all the shafts or just a pump wait till we know for sure.

About the motor i would pickle it. Kero or diesel. Remove the battery from the boat and put it in the garage. Want the way i do it in detail ?

I make sure the boat is way, away from the house and no trees overhead. Let it sit for a few days or a week.

We need to know if the shaft splines went or what.

What does it say on the head under the valve cover.

Should say year and 120 or 140 or 2.5 , 3.0. See we don't know if someone dropped a different motor in.

But for sure if a 2.5 or 120 there will be a plain crank pulley. If a 140 / 3.0 a harmonic pulley.

Well, you were right - it was hard to see but there was 120 then a space and 9 stamped under the valve cover and it definitely has a normal (not harmonic) pulley - so its a 120 engine.
On the water pump I have the big ss swivel housing off and tapped the pump plate and housing loose (seems like its an aluminum not plastic housing) but the shaft itself is solid in whatever its mounted to above, I can move the pumphousing down a little and can see the impeller but the shaft seems stuck in the spline above, maybe side to side wacks with a brass hammer??

Any hammer with a piece of wood sitting on the shaft so your hitting wood and the wood is hitting the shaft

The shaft you see is connected to another shaft with splines and the second shaft goes thru a bearing carrier on the end of the second shaft is a gear.

you have a pm

Got the PM and thanks. out of stock
Did get the pump shaft out of the spline above though so that's all apart and I can order the pump parts - lot of work with a lot of side to side tapping and pulling with the vise grips - didn't seem to be any damage to the splines - more like a lot of salt but I can clean that out. The round housing the pump housing fits to (I think it is a low profile housing - bolts are ~ 6") seems to have an old salted up crack in the lower part of it at one of the thru bolt bosses, maybe freezing, but its solid enough and the upper gear case wasn't leaking oil out - do the 4 - 6" SS bolts I took out hold that retainer to the upper gear case or would I have to take the gearcase apart from the top of it?? I really don't want to mess with the upper gearcase shims etc unless I have to!
Will also start on the stuck lifter and crank pulley.