1985 Mercury 200

[unclejunbug]

I recently purchased a 200 Mercury that had some work done after it was purchased new and has been sitting on a stand for over 15yrs. When I ran the serial number all I could find was that it said a 1985 200 3.4L. The serial number only watched numbers between 85 and 86. Is this correct or was I reading it wrong? Is that a good or bad engine? Only paid peanuts for it and it looks like it just came from the factory.

[Eagle One]

You mean a 2.4 liter 200 HP I believe. Motors made good power and were fairly reliable but just as with anything the more you do to gain power the less reliability you'll have.

[unclejunbug]

Thanks. It just has a little work. I put it on my ski boat. Just wanted to know what I have. Will the alien cowl U guys have fit my 85 engine?

[bobthebuilder]

I have one on my bass boat that I have ran for 3 years now with no issues at all. In fact I also have a 2.5 150 on another bass boat that uses more gas and wont run anything like my 2.4 200... I am now starting to run my newest creation which is a 2.4 200 modified.. the mods in my opinion should make it an even better motor. But what shortrns their life is turning them 7500 to 800 room's...... At 6,000 they run and run...

[unclejunbug]

Thanks. I just found out today from the guy that built the motor that its a new 88 powerhead and foot with the 85 center. When I bought the boat I paid the mans son so I didnt talk to him direct. He told me today the motor has never been in the water since powerhead and foot where installed. I got such a good price I bought it as if it didnt even run at all.

[bobthebuilder]

Sounds like you stole it !! But listen closely to this. You will have to break it in before you can run it WOT.... Idle it for 45 minutes to an hour then run it under 3,000 rpm for a good 2 hours and keep it under 4,000 for a while til you have about 40 gallons of gas through it if you want some nice slick pistons and cylinders... Go fast too quickly and it will stick a piston for sure... Chrome bore is not as bad as stel bore motors but they still stick sometimes. If you want to sell it at a nice reasonable price make me an offer... Seriously I can resale them from my shop. I am always on the lookout for good ones ready to go like that...

[unclejunbug]

Thanks alot for the info I usually have to pay for it around here. I was told the idle was performed after build but wasnt told about the rest. I wasnt planning on selling it. I just spent $900 on a bobs nose cone and an alien cowl. Stock cowl is good but I didnt want an older looking motor on my 99 boat. What woukld this motor be worth. I dont know about heads and any port work. But it does have reeds, and exhaust with I guess u call it a header. I was told the carbs where jetted different individually to keep down heat in certain cylinders. Have u heard of that? Motor was built by a racing team out of brunswick georgia. Dont know if u know Larry Mumford but hes a friend and he said the motor is jam up.

[bobthebuilder]

Usually when hey bore a chrome cyl out and install a steel sleeve they jet it .002 bigger to help it stay cooler in that cyl. Therefore it is most likely not an all chrome bore motor. thats OK but break it in right and always warm it up good before going WOT on it. Chrome cyls are best for real high rpm's like over 7,000 and it will make a little more HP with all 6 chrome but now days most have a couple steel sleeves in them. I have 2 with all good chrome and it took me a while to find 2 good blocks. But break it in right and it will make you a very good motor. Personally I like them better than the 2.5 200's and definitely better than the newer junk out there now. But I dont even care about EFI motors. I like carbs and simple stuff on an OB motor... Flokes will argue with me about gas mileages but I have both a 2.5 and a 2.4 and running on the same boat with same set up and props my 2.4 is better on gas mileage than my 2.5 motor. I also have a 2.0 liter and it is better than all of them on gas!! Not as fast but it is a super solid motor. I am selling it this weekend to a fella going form a 125 to the 150 XR2 and he will be impressed with this XR2.. I ran it o my 18ft Ranger bass boat and it ran about 58 on GPS all day with no issues and gave me right at 4 mpg on gas which is good for a 18ft Ranger loaded with 2 fishermen and gear and full of gas and water in live wells.. It had to work to keep us going but it did great! But the 2.4 200 really has power.... you will see!

[bobthebuilder]

Forgot to tell you to run 25 to 1 oil mix first 6 gals or so then I got o 32 to 1 for maybe 24 gals the to 40 to 1 until brake in is done. I have never blown a motor done that way but I have blown a couple trying to rush the break in especially on steel bores...

[rdkvector]

I've got an 87 2.4 200 with all chrome that I'm ready to sell, pm me if interested.

[unclejunbug]

Is it possible to rechrome a cylinder after boring. Could be to much trouble but just asking? Can u buy a chromed sleeve? Can I pull the plugs and look into the cylinder to see if its chrome. Thats the only thing I dont like about buying something that has had work, takes a while to find out what u have. Im one that if its not a good piece or needs to be better i fix it. I have a bit of OCD when it comes to anything that requires fuel to go. When I was a kid I had a header on my stick horse. Thanks guys for the info.

[bobthebuilder]

No one does re chrome anymore. There is no such thing as a chromed sleeve because a sleeve becomes egg shaped or out of round as one might say after it is installed. A chromed block is no sleeve just chromed on the aluminum about .004 thick... It is very hard, tough and slick. Very little friction. Now days they Nicasil a steel sleeve or might say sleeves as when they do it they nicasil all of them at the same time. It is a nickel ceramic alloy plating. Similar characteristically to chrome. The motors most likely to use it is modified 280's intended to turn very high rpm's.... A steel sleeve in your 2.4 200 is OK no problem. It could have a couple in it but it wont matter as long as you warm it up before you run at full throttle and brake it in real good before you run it full throttle. But my modified 2.4 is all 6 chrome and if I want to I can turn it 8000 or maybe more rpm's... But it is also precision balanced way above the factory balancing. That will also make it hold together at high rpm and make it last a lot longer too. I dont run it hard much just once in a while but the power is there whenever I want it... Actually I havent turned it past 7500 so far but it will with no problems.. But it also has a lot of other mods done inside it. I think it is about 240 hp or maybe more. I call it an almost a Bridgeport.... BP's have similar mods but have a little bigger exhaust port with a bridge in the center of the exhaust port to retain the rings from hanging on the port. I ported my 2.4 big time as much as I could without cutting on the chrome as it might chip it. Exhaust chest has serious work in it too. Front 1/2 of block cut .050 stuffed the block where oiler came out and ported the pistons. Also cleaned up the rod slots nice and smooth. I am using 2.0 liter heads on it and has 145 psi compression.... WH 20 carbs CCM square 4 peddle reeds. And so on..... Modified a little bit.. I still dont know how fast it will push my Skeeter bass boat but @ 75 mph it has a lot left to go... I want to put some more time on it before I let it rip WOT..

[unclejunbug]

Ok. I mess with new mustangs and the new gt500 blocks have Nicasil in the cylinders. Can I put a water temp guage somewhere on the engine? I noticed there is some sort of sensor if standing at the back on the right bank under the first cylinder. There is also a whole on the left just like it. Can I put a temp sensor in that empty whole or does it need to be in the out stream of water?

[bobthebuilder]

Those holes are for sensors that are from Mercury and they are dry sensors. Some of the older 2 piece heads had wet senders for temp gauges.. The dry ones are just either on or off to set off the over heated alarm that is part of the mercury control box.. Some folks drill and tap one piece heads for a sender like was on the older 2 piece heads. I had a mercury 200 that had 2 senders and 2 gauges on a ranger boat.. I think that is over done but they worked... They ran around 145 to 160.. Hitting the 160 at WOT running.
Now the newer designed ProXS motors have the sensors and sen info to the computer and it also has OBD on it and one a while back would not idle right and the OBD hooked to a lap top comp. said it was the port thermostat was running too cold. Put in a new thermostat and it idles perfectly.. They got them so sensitive now and very complicated that only a high tech well equipped shop can work on them and fix em right. Especially the power heads. Trim units and lower units OK but the EFI and Air Systems and electronic units and even the internal fuel pumps are technical to diagnose. I have a very good buddy near here who runs a modern well equipped shop and I take em there to diagnose and most times just let him fix em if it isnt much to be done. He cuts me slack and I make a little for my trouble and time and everyone ends up happy.... I even sent him a Yamaha 250 HPDI to rebuild a while back. I didnt want to mess with it in my shop.. I like the older Pre 2000 motors and preffer carb ones not even EFI although the early EFI ones are not really all that bad to deal with but carbs are a better motor in my opinion. I got one now I converted from EFI to carbs on my boat. The EFI needed about 800 bucks in parts to fix it back to like new condition and I had just took a carbed one in trade with a busted block and bad crank.. It threw a rod and busted cylinder and sleeve and everything. Block is toast! So I too that stuff off and put it on same year model and same exact motor except for the EFI and it runs great now and seems to use less fuel !!!!!!!!! GO figure that one out... Less fuel??

[unclejunbug]

So can I hope the overheat alarm works or do I need to use a temp sensor? Can I run it in line with the exiting water? At the top of the heads the water crosses over from right head to left and then out. Can I disconnect those lines and run two exiting water lines or do they need to stay connected? Will that even help anything? I assume it runs best at a certain operating temp.

[bobthebuilder]

Use 143 degree therms. Th heat alarm sensors are a simple thing. They fit right into the hole already in the head. Tan color wire hooks to the Tan wire from wiring harness. Small screw near top of block on starboard side where 2 halves come together. Plastic connection block should be there to join th wires together. The sensor just grounds out at higher temps like 185 to 190 and it sets off the alarm.. But a gague is sometimes added for folks who are super careful about overheating. I always hook up a water pressuer gague to thee top of block. Especially when runnig em high on a jack plate. But you never know when something like a plastic bag suspended in the water could get over the pick up area and fry your motor. Water gague is a must have.. usually it along with sensor to the alarm is standard and considered enough.. The heads dont have to be connected together but from factory they are. I usually keep factory setup on mine. Some just dump each hose from top of heads and hook up top of block to the popet valve on starboard side of block under switch boxes... But factory hooks head dumps together with it all into the popet... Usually factory set up works best on fairly stock motos.. Other set ups are sometimes used for drag racing and extremely high performance aplications.

[unclejunbug]

Finally got to take it out and. No good. But I think I found the problem. What is the box if facing back of boat on the left side of engine at the top next to the flywheel laying flat that has 3 wires? Is that a rectifier or something to do with timing? The red wire was so brittle it fell apart right as it entered the module. Where can I find one and how much should they cost?

[bobthebuilder]

Just completely remove it. The motor does not need it. It is an idle stabilizer unit. They are not available from Mercury anymore..

[bobthebuilder]

If that motor sit on a stand for 15 years it needs to have the following done to it. Carbs cleaned with NAPA carb cleaner not cheap make believe junk form Auto Zone or Advance auto but has to be professional grade chemical. Fuel pump rebuilt and every rubber hose replaced with fuel grade hoses. New water pump kit and 2 new thermostats. Otherwise it could totally destroy the motor first time you run it.... If it runs too hot one one side or the other because of bad therms it can burn it up in 1/2 mile or so... Also if one carburator is not right it can run one hole dry and destroy it. No gas getting to one cyl means no oil is getting in there either... CAREFUL dont destroy it... If you are not comfortable doing the work yourself you need to find an inexpensive outboard mechanic close by you... Maybe a retired guy who knows how t do it right. These things are nothing at all like a car motor or other motors. Nothing like them. Actually each cylinder is like a separate motor by itself except they are all on one crank shaft. 5 or 4 can be pulling the dry hole or holes along and destroying them because of a stopped carb. I saw one a while back blow up because of a rubber line broke on the fuel enrichment valve... totally destroyed the #2 cylinder.

[unclejunbug]

I rerplaced all hoses, plugs, and cleaned everything. After talking to u about water temp I changed thermostats. I dissasembled each carb 1 at a time soaked it for 30 min in carb soak and then cleaned them with napa carb cleaner and reassembled them. Removed 1 at a time because the last owner told me that the builder set the carbs as u said. The carbs are jetted different to help each cylinder stay cool. Top and bottom looked pretty much the same but the center one was different. Only thing I didnt do was rebuild the fuel pump. Got it off now though. The motor runs perfect when out of gear but when u put it in gear and get a load on it, it want turn up. Any ideas? I did find a dry rotted hose that I didnt see on pump when I removed it.

[bobthebuilder]

Does the timing trigger advance? Under the fly wheel hooked to throttle linkage. If ignition is working and timing advances it will be fuel system problems... Too bad you are far away. Hard to fix it online.. But make sure timing and ignition is dong OK and then it will be left up to the fuel system.. The carb jets normally are .082 on cyls 2 an 5 and the rest are .080.... That is main jets in bottom of carbs. Also there is a transfer from main jets to carb bowl where debris hides sometimes. Idle bleeds are probably .056 or could be small as .046 depending on where it was sold to run at. Smaller ones at very high altitudes. But problem is sounding to me like a fuel system not clean enough.

[unclejunbug]

Ok hopefully fuel pump thats my last resort. Only thing I havent spit shined.

[bobthebuilder]

There's a lot of things it can be... You just touched on the surface of potential problems.. But simple things first and things that it needed anyway after being sitting that long. The stator can cause it to not run at higher speeds. It has a low rpm circuit and a high rpm circuit. If I remember well the blue circuit is low speed and red is high speed.... But stators die from sitting up. It is a time expiration thing on them.. sometimes one 12 years old will run right on and again one only 6 or 7 years old will start going out. Anyway my next thing would be to test the stator with an OHM meter. I forget the readings and procedure but it is in the shop manual..

[Capt.Insane-o]

Ohm readings are poo poo on a stator. Running output voltages after the stator is hot is the only way to go. You need a DVA meter or adapter for a regular multi meter however. If any of the stator or trigger leads are rotten and cracked like the idle stabilizer wires, throw them both in the trash and get new ones.

Anybody who owns an outboard should learn to do basic ignition output tests, it will save you a ton of time and dollars down the road.

[unclejunbug]

I tried all that. Stator seems to be fine. Alright think I found the problem. No fire on 2,4, and 6. Forgot to mention I swapped engine from 1 boat to another. Other engine was a 4 cylinder, new one is a 200 mercury. Motor run excellent on other boat but once swapped over runs like crap. I think I have missed something somewhere. Old motor was a 99 force 120 so all controls worked the same. Plug even plugged right in. After connecting trim wires that are coming out the side of plug there is I believe 1 blue wire left. Does it need to be hooked to something. Am I correct when I say power goes to stator then to elec. box and then coils? Just woundering if there is something im missing from 4cyl to 6cyl. I would say it was something else but started when motor was swapped. Any ideas?