TOPIC: 800FGS now what?

Hey guys, got the motor freed up. Nothing like a little Marvel oil in the old cylinders for a couple of days. Of course when I turned it over the fly wheel with the wrench a few times the belt broke, gee go figure. Have to add that to the parts list. No to the lower unit problem. Here's a few pics to show what I mean.

Bent Skeg


Sorry this one is a little fuzzy


Cracks with stop holes

Ok so am I looking at a new lower unit housing or the just replace the whole thing? Couldn't see this when I was picking it up since it was buried in the mud some.

Also, I assume these wholes on the side are the water intake? Is that gray piece actually a trim tab/anode?


Sorry lots of questions, not real familiar with the Merc's.

Thanks,
Bob

the money and effort needed to repair that lower wont be worth it, you will find a complete lower unit faster than you will a housing
and you will find another motor faster than just a lower unit

its advised to get yourself a parts motor, it will be likely the same price as trying to buy just a gearfoot

yes they are the water intake holes and as to the trim tab maybe an annode as well...depends on the metal

a few thoughts on what you have found so far.
First is that depite you can now spin the motor the rings could still be very stuck in the ring grooves. The best and easiest way to check is to pull the transfer covers off on the intake side and look in the ports and push on the rings and see if they spring. I would also suspect rust on the walls as that is what happened, the rings stuck to the walls due to corrosion. BUT BEFORE YOU DO THAT:
There is another possibility. The rings may not have been the problem at all. It could be just your distributor shaft is stuck. That is why the belt broke so your distributor is definitely stuck and this may have prevented the motor from turning the first time you tried, you just laid into it more the second time and broke the belt allowing the motor to rotate.
If you are really going ot keep it and run it then all the gaskets and seals should be done in the powerhead. No need to pull the crack assembly to do this if the rings are springy.
I would disassemble the distributor and replace the ball bearings they are a standard size so readily available and NON Merc prices. Measure I.D. O.D. and thickness. a bearing supply house cna match them up based on that. Mcmaster Carr is a good supplier for this, they have a great web catalog for such things, get sealed pre lubed style bearings. You are going to have to take the dist some what apart to do the points anyways.
Second, as far as the lower unit goes they are plentiful so just surf for a better one. The drill holes in the cracks are there to stop the cracks so someone did this long ago. Beware that the later ones had different cams for the shift lock, You can tell the difference by the length of the gear housing protruding in front of the long front stud. The ones that proture slightly, like yours are correct. The ones that protrude a bit more are wrong or at least require more things to work OK. Also, on the lowers if you are LUCKY you can find the correct fit with a stainless drive shaft portion at the water pump, you can tell these as the shaft is steel at the top so it is dark and possibly rusted and the lower portion will be shiny when soot is rubbed off. Preety much look for a 69 and older lower, but that is not an absolute year cut off but a safe one.
Randy

I agree with Randy in that the distributor drive belt rarely breaks unless there is something amiss in the distributor and the bearings are usually the culprit.
That would be totally awesome if that is the case, but as Randy suggests,..You STILL need to take a good look at the rings and ideally take the time to replace the upper and lower end cap seals and bearings.
We'll coach you through it when you're ready.

The mid-'70s lower units with full stainless shafts are a very good retro fit to these old girls.
True - they do protrude a smidge forward at the front of the mating area with the drive shaft housing (DSH), but the quality gained with spiral-cut gears, and less seal failures is worth the 1/2" +/- that is only apparent to a keen eye.
The shift shaft will need to be shortened and care taken to shim and down-size the O.D. of the reverse lock cams to function properly with the old-school lift system for the reverse lock hooks, but a worthy effort IMHO.
You also gain the ability to easily use late model better designed propellers with the later lower units.
The original unit is 12" long at the gear bullet and the later ones are 13.25" long at the same measurement points, but check out the attached pictures of a 700FGS with the mid-'70s lower unit and see if the visual difference bothers you.
The DSH used for the 700FGS is identical to the DSH used in your 800FGS.
Personally - I'm okay with the slight extrusion,...But I am,...Dr. Frankenmerc,...The guy that in the spirit of Dr Frankenstein takes parts of many dead Mercs and puts them together to bring another one of my creations,..BACK To LIFE!!!! n-yuk n-yuk n-yuk.

and,..Yes,...I have a LOT of complete lower units or parts thereof if you end up needing one or a part, etc.
Thom

Madprops/Rany/Thom, thanks for the info. I have more questions and will try to get at the distributer and see if that's indeed the culprit, tomorrow. AS you can see it's late. Working 1600-2400 this week. I'll post more tomorrow.

Bob

Randy, sorry forgot the d in your name on the last post, very late night.

Ok good news I think. The distributer turns freely so not sure what made the belt break other than the motor has been out in the elements for quite a few years, supposedly with the cover off for a "few" months. Maybe just the torque from trying to turn it over broke it.

Unfortunately slept late and have to head in for a long day. More to follow.

Bob

Well, I was able to get the lower end off today and it looks like it's frozen. I'm going to have too try and take it apart and see what's up. I don't have a manual yet or a parts breakdown. I think I can get it apart and back together if I can find the parts breakdown diagrams. Worked on my Rude Fat Fifty that way no problem. Rebuilt a Citroen motor in my carport, when I lived in Rota Spain, without any manual. Of course that was just an overgrown VW motor with overhead cams and I was only 25 then. Wow, a quarter century ago. Sucks getting old.....

I'll try and take the power head off next I guess and see if I can clean it up. Anything I should worry about taking it off, beside the coils and throttle linkeage?

I'm thinking I'll spray it down with Purple Power and maybe hose it off at the $.25 carwash. A little too cold to just use the garden hose. Or should I just use the Ceaner and wipe it down with a bunch of old rags?

That's enough for now, getting late.

Bob

OK, I've started taking the lower unit apart but I'm stuck.

How do I remove this bearing housing? Also notice what was left of the impellor!


Does this unscrew counter clockwise?


Do I need any special tools for this?

Bob

Make up adapters for a puller to go to the bearing housing.----Push on the end of the propshaft.

---

Or an adapter for a slide hammer on the end of the propshaft and see if you can pull the propshaft and bearing housing out together.

Professor,
Thanks I'll try that. I may just see if Harbor Freight has a long puller for cheap. I'm on travel in San Diego right now and there's a Hargor Freight by BWI when I get back Thursday.

Anyone,

Do I just make an adapter to get the shifter shaft out? Thread counter clockwise?

Also, quick dumb question; Can I get a descent compression check by just spinning the crank using a socket and breaker bar? I know the distributor belt is broken but that shouldn't affect turning it over by hand will it?

Thanks,
Bob

Yes I just make the tools I dont have. Yes I believe the shift cover is standard counter clockwise loose.

If the starter works, jump the starter with jumper cables to get compression. Take all the plugs out to free up the starter so its only working on the cyl your taking PSI from. Using small gauge jumper cables can strain a starter with all cyls working against the starter.

Conrad

Conrad, thanks I'll give it shot when I get home from travel. Not sure how I'm going to get the #6 cylinder though. The hose on the checker I have doesn bend to well to get down there.

Bob

if the motor will crank over evenly with the starter and you can check the other 5
cylinders with a with a pressure meter the compression should be in the ballpart as the other cylinders.

Yeah #6 is hard to get at, but I have gotten good about twisting my hose psi meter just right to get them to start. By no means force it and strip your threads.


If the top 5 check out the bottom one usually is the same. It is the least likely of all of them to have a problem unless there is obvious water intrusion from the bottom seals.


Reasonabe PSI numbers should be in the 115-135psi and as even across the board as possible. Within 10 percent.

I believe my 700 merc cranked 130psi across the board when I got it.

To jump the starter put your negative on the black wire that is grounded to the block, then press the positive jumper lead to the post on the side of the starter motor. Dont dilly with it. Press it on firm and quick or you will get arking and make it into a welder


I let it turn 4-6 times then check.



Conrad

I have attached pictures with instructions on how to dis-assemble the gear case.
HTH,
Thom

Jim/Conrad/Thom,
Thank you very much for all the info. It is greatly appreciated.

Thom, Thank you for the pics, look easy enough to fabricate. Also Looks like I may as well look for another lower unit then since even if I remove everything I won't be putting it back in since the current case is cracked.

Bob

Well, got back at the engine today and did compression check. Here's the result:
1. 96 2. 70 3. 75 4. 105 5. 95 6. 120

That was with just the Marvel oil from a week ago in the cylinders. I removed the upper and middle inspection covers and the pistons look ok and the rings seem springy. The tops of the pistons are very carboned up of course.

I guess the question is do I tear it all down or just remove the head and look down the cylinders?

My Rude was in the 85-90 range and All I did was rebuild the carb and fuel pump, new spark plugs and she fired right up. Of course she was in a garage all her life and not left to the elements like this tower was.

I may still take the lower unit apart but if it's a lot of work putting the guts into another unit and no guarantee it will be good maybe I should just get another one.

Any thoughts on all the above?

Bob

Bob,
The 'head' on these Mercs is just a water jacket cover and removing it won't give you a better look at the cylinders or pistons.
All the readings are quite low, but other than the 120, the others aren't too far apart in numbers.
I would be tempted to fire the beast off and let her run for 10-20 minutes at a fast idle, periodically squirting some fogging oil in the carbs as she is running.
Once the powerhead is warm to the touch, shut her down and then run new compression tests.
If the beast hasn't run for several years +, it is very likely they will all come up 15-20 psi, and it would be interesting to see what numbers you come up with.
I have attached a couple pictures to show you what is under the 'head'.
It is best left alone if it isn't leaking too much water out around the spark plugs when running.
Thom

Yes, those are low. My 1965 900 Inline 6 had most of the rings stuck on the exhaust side of the piston. On the intake side they were all springy. So sometimes the intake side can be fooling you.

Mine had great PSI numbers to which is weird for stuck rings! It pumped 125+ on each hole with nearly all the rings somewhat stuck .

I did kinda a no no and free'd all the rings up, cleaned the lands, did a quick hone and put it back together with the same rings. It has 130 on each hole now. The used rings were in very good shape just stuck from sitting for hundreds of years.

If I were you Id take the time and pull the block, then split it to see inside. Its good practice and then you will know for sure whats going on

Thom,
Thanks for the pics. Interesting you should mention leaking around the spark plugs. #4&5 spark plugs had rust around the base of them. Not sure if that was from exposure or water leaking. I would assume it was water leaking since the other plugs didn't look like that.

As far as running the beast, I guess I can get a water pump rebuild kit and put the lower unit back together then try and fire it up. Or should I just take the power head off and remove the crankcase cover and break it all down to really check all the rings and clean up the pistons? I need to check the bearings and replace the seals on the crank anyway right?

Bob

Conrad,
Thanks was still typing when you posted. I was just wondering that when I was replying to Thom's post. I'm guessing that makes the most sense since I should check the bearings and seals on the ends of the crank as suggested by Randy. Then I can clean up the whole block etc to paint and make it look good.
I guess I should probably get a manual at some point to make sure I get it all right.

Thanks for all the inputs guys I really appreciate it!!!!

Bob

Thom's suggestion of running it is a good one. It may loosen up and the compression will rebound considerably.

No need to get a water pump. Leave the lower unit off. Hook your garden hose right up to the brass water tube that leads up to the block. My garden hoses usaully slide right over the tube. Once pushed up over the tube a ways wrap a bungee cord aroudnt he hose and hook it to the leg to hold the hose up. Now turn the water on full force. This should be enough water to keep it cool. Definatly put your hand on the bock several times while running to make sure its remaining cool. Your using your garden hose to supply the pressure to cool it.

If your hose does not fit well, you can make adaptors out of rubber hose until it fits tite.

This way you can try to run it and run it for a few hours if you like trying to break those rings free again.



There is a product that mercury made that you spray into the motor while its running to remove carbon build up. Im sure Thom knows the name.

Otherwis you could tear it down, whatever you feel like doing. If you got spark ya might as well see if it will fire up for awhile.
Conrad

A note: Just dont over rev the thing on the stand without a lower unit on. And the motor is pretty noisy with the lower unit off. Something I personally like but my neighbors dont.

Conrad.
Wow great idea! Why didn't I think of that. That would be why you guys are the experts and I am but the lowly apprentice, hence my moniker Waterwings (trainee marine diy restorer and retired naval flight officer on the water i.e. Water Wings.

I'll have to try and find the spray. I will probably use sea foam in the gas mix as I did on the old Rude. It's great for eating carbon. It did wonders on the three old metal Evinrude Day Cruise tanks. Sparkled like brand new inside once I was done. I still have to do a compression check on her to see how much it came up after running four tanks of gas through he on the water.

I like the idea of the hotrod sounding engine without the lower unit on also!!!!! Nothing like the sound of power no matter what your running!

I'll have to wait until it warms up here though and I can use the hose. Been n the 20's and 30's. Should be near 40 later this week. That will give me time to mess with the lower unit also. I'll also have to find a cheap tank with a Merc fitting. Also need a new hose the one with the motor is basically toast but took it for the motor fitting. Looked at Wally World yesterday an no Merc hoses.

Thanks,
Bob

I just want to edit my full force comment on the garden hose. The garden hose will produce more PSI than is needed so you dont have to run it full force if you have a good connection.

Conrad

When you say the plugs had rust on them, do you mean on the outside of them or on the inside (cylinder) side? If its on the inside then pull it apart, not a bad idea anyway on an unknown motor of this age. The crank seals should be changed anyway, as Thom mentioned water can get through the bottom ones & you can wreck a motor big time very easily if it gets in there, I have seen motors where the no 6 big end has failed & taken the crank, rod & block with it - all because a tuppence ha'penny seal failed.

Geoff UK

Conrad,
Thanks, since I'm on well water I can probably get away with cos to full open spigot but I'll keep it at about 1/2 open then.

Geoff,
Sorry should have been more clear. Rust was on the outside of the plugs. I'll probably change the crank seals after I try and run it. Don't want to tear it apart too far if I don't have too. I do want to pull the power head off anyway to clean it up and clean up the mid section before repainting it.

Bob

When using a garden hose on the bottom end of the copper water tube it is critical on your model Merc that you have a tight fitting hose with a hose clamp snugged (not enough to collapse the copper tube) but snug enough to keep the water supply IN the hose & tube.
Any water that is allowed to escape and squirt upward from the garden hose and outside the copper tube can ricochet around up in the exhaust area and end up going into a cylinder.
This would be a bad thing to allow to happen.

I can't recall off the top of my head what the Quicksilver decarbonizing agent is and have been using the Sea Foam products last few years with great success.

Looks like yer back to bein a busy guy eh Doc? Is that a Carlson, or what?

Frank

Thom,
Thanks will keep that in mind. Nice collection and work area. I'm jealous, wish I had that much room to work. Is that a skeg weld job for yourself or customer engine?

Bob

Frank,
Man-o-man do I wish I was back in full swing, but I'm not, and the surgery was a real foul-up on the surgeons' part. I might have to re-visit the operating table.

The pictures are several years old, and I am just sharing some 'shop history' through them.

Bob,
Yes - I am very fortunate to have a nice lil shop to work my Mercury Magic in.
It has real decent lights that I snagged out of a large office downtown that was remodelling and gave them to me free-bee.
There are (3) sets of 4 foot florescent bulbs - I think there are (6) or (8) bulbs per fixture.
I am very fortunate to have good heat, plenty of room, and I really like the way I set up the work benchs.
I can spread a project out on one bench as is shown, and keep the other one clear (dreaming) for use with other repairs as needed.
It doesn't really show very well in the pictures, but there are actually (2) work benches that are about 8 ft long running parallel with each other. There is about 3 ft between them and my tools are mostly located at one end, making a 'U' shape pattern.
I have the floor padded between the benches where I stand most of the time.
I have a nice chair to sit on and take a break when my back and legs get really painful, which happens way too much these days.
I've attached some more pictures - at least I can do that.

Thom

Thom,
Very sorry to hear your back still isn't right. I guy I workes with had bad back problems and he had a "squirrel cage" put around his lower spine. After it was done it still really didn't help. Still had pain all the time. Hopefully that is not the case for you!

Wow very nice set up. Some of those lower units look familiar! LOL I know if I even tried to get half thatset up in parts the wife would go crazy. I think I need to get this 800 done and on a G3 so she can feel why I wanted it!

Bob

Well tinkered around with the lower unit today. Made a tool out of an old spark plug socket as Thom suggested and got the shift rod out. Like Neil's lower unit mine is sry as a bone inside from what I can tell in the shift well. I still have to make a shaft and bearing puller to get the prop shaft and bearing housing out. Hopefully I'll be ablr to grt to that in the next day or so.

Bob

P.S. Thom I hope your back is starting to feel better, we'll keep you in our prayers.

Waterwings wrote:

OK, I've started taking the lower unit apart but I'm stuck.

How do I remove this bearing housing? Also notice what was left of the impellor!

Bob

Just a thought here. Looking at that impeller you need to find ALL the missing bits or you can/will have serious cooling issues. The broken off impeller pieces can find their way into the cooling passages in the powerhead blocking of ports & causing overheating issues. You need to do this before you run it at all IMO.

Geoff UK

Geoff,
Good point. I was wondering that myself when I took it apart and saw that. I'm going to check the lower unit some more. I probably need to take the "cooling cover" (nomenclature?) off the head and see how it looks inside before I attempt to run it. This is starting to look more and more like a complete tear down the rate I'm going.

Bob

Waterwings wrote:

This is starting to look more and more like a complete tear down the rate I'm going.

Bob

Thats what I would do with it, then you will know what you have hanging on the back of the boat!

I would tear down ANY motor that has been stuck. Far too often I have seen someone free up a stuck motor, run it, then a few hours down the pond the motor sounds like a coffee can full of BBs. If you've got moisture enough to stick rings, you've got moisture enough to rust bearings. A rusty bearing has a short lifespan, so even if you free it up, it'll come back to bite you. Worse yet, it might take a crank, crankcase and rods with it... Tear it down, inspect, reuse what's good, replace what's not...

- Scott

Scott,
Thanks, I'm leaning very heavily that way. It gives me the chance to learn the engine better and really give it a good cleaning so I can paint it.

Bob

Well, tried messing around with the lower unit again. After turning upside down and bouncing it off a board so to speak some of the impellor parts came out, along with water out of the shifter housing, gee go figure.

questions: How do I get the drive shaft out?
Shouldn't that come out before I try and pull the prop shaft and bearing carrier assembly?
If I use a puller can I just pull the bearing carrier assembly off the prop shaft as it comes out of the lower housing or do I have ti use the dent puller attached to the prop shaft method?

Bob

pull the propshaft out and take the nut off the driveshaft then pull it out with the upper bearing and waterpump base.pinion will fall off.

Bob
How was your Christmas?
Did you get a chance to "visit" with the Merc?
Neil