2.5L 200 HP rebuild/repair

[CardsFan84]

I am rebuilding/repairing (not really sure of the difference at this point since the motor torn apart) my 2.5L 200HP and I know that I will need a lot of guidance from the good people here on the forum. I am still hopeful that this motor can be salvaged but I am needing to get it completely removed and torn apart. My first issue with that is that I cannot remove a bolt from the lower cowl. Please forgive me if my terminology is incorrect, as I have only been a boat owner for 6 months and this is the first time that I have worked on an outboard. I will attach pictures and follow whatever advice I can to get this motor back in working condition. Here is a picture of the bolt that I can't seem to get a socket on. I've tried everything I have and I've been to Home Depot looking for a thin wall socket set with no luck. Any and all suggestions are welcomed.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

I did some grinding to a socket and finally got the lower cowling off. Now I'm stuck on my next problem. I have removed the 10 nuts and washers to remove the powerhead but when I try lifting it seems like it's still attached somewhere. It lifts part of the steering arm that connects from the throttle cables to the front of the motor. I am assuming this isn't normal? Any help here would be greatly appreciated as I would hate to ruin this motor or damage the boat or garage. I will take some pictures of my lifting rig, so if you see anything that looks wrong let me know.

 

[carholme]

Re: 2.5L 200 HP rebuild/repair

84;

Looked at your previous posts to find your s/n. 0D246123 is a model:

1200412ND MERCURY 1993 200

Parts listing:

http://www.crowleymarine.com/mercury-outboard/556.cfm

Service Manual P/N: 90-824053R3

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/824052r3/cover.pdf

You must have Adobe Acrobat reader installed to use this manual. If you scroll down to the lower part of the opening page, you will see the various engine components in red. Click on the one you want and when the first page opens, click on the "Save As" icon at the top LH corner of the page and you can save it to your computer.

Hope that s/n is the one we are talking about.

Gerry

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

I just wanted to post some pictures to help illustrate where the powerhead wants to separate. It seems like it would come off easily if I could lift it with the steering arm detached from the cables. Here is where it is lifting:


I've read previous suggestions about using an air hammer but I don't have one and wouldn't know where to use it at on the motor. Please help with any suggestions on where to pry or how to get this separated.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

I finally got the powerhead separated from the mid section. I had taken the adapter plate bolts out preventing me from getting the force needed to separate the powerhead from the adapter plate. I will split the powerhead this week to inspect the crank and rod assemblies. The damaged cylinder's rod appears to be discolored on the end so I have my fingers crossed there isn't too much damage.

Carholme: Thanks for the link to the manuals. I downloaded a manual but it was slightly different than the one you posted. The one I had was for a 2.5L 200 that matched my motor as best that I could tell.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

Unfortunately I have finished disassembling the motor. When I took the #4 piston and rod out there was no trace of the rod bearing. It appears that the crankcase, crankshaft, and the block may all be trashed. Here are some pictures (they didn't turn out very good, but I can take more if anyone is interested in parts). I guess my first attempt at rebuilding an outboard won't be taking place with this motor. PM me if anyone is interested in any parts.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

The project continues. I purchased a used crank and block off of ebay. They appear to be in good shape, and am waiting on bore gauges and a caliper to check bore and roundness. Any advice on reusing the existing pistons? The five pistons appear to be ok but I am concerned about reusing them. I am also having a difficult time determining the manufacturer of the pistons. The only thing I could find was Persen on one underside and 646,647, or 648 on the other. Also 4 pistons, including the damaged one, have a "U" on them and 2 have an "S" on them. Could this be correct? The damaged piston was #4. Any other advice on what to replace/reuse is greatly appreciated. I would really like to keep the cost down, but I understand the importance of new parts when needed. Thanks for the help.

The new serial number for the block is 0G000907. The old was 0D246123. Hopefully I didn't just make an expensive mistake.

The rods are 644-818141. I am planning to purchase one rod to replace the damaged set. I'm assuming I will have to get the rod balanced to match the other ones. Is this correct or will it make that much of a difference? I can see where the other rods have been ground to be balanced.

 

[chum1]

Re: 2.5L 200 HP rebuild/repair

That is quite an undertaking for not working on an outboard before but you have to start somewhere :facepalm: Thanks for sharing. First thing I would do is keep track of cost vs finding a good powerhead somewhere those parts will add up quick! but when its all said and done you should have a very good newer engine and the experience of what makes it tick good luck

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

I am planning to purchase one rod to replace the damaged set. I'm assuming I will have to get the rod balanced to match the other ones.

Just weigh it ,it should be close enough not to require any mod's. Measure the exhaust port height on the new block as serial # says it could be a Xr6 150,175 or 200 block.

 

[carholme]

Re: 2.5L 200 HP rebuild/repair

New s/n comes up as a model:

1200413ND MERCURY 1993 200XRI

Parts listing:

http://www.crowleymarine.com/mercury-outboard/573.cfm

Gerry

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

If its a Xri make sure that the recirc nipples/fittings are in place as I have seen a few blocks without them.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

"If its a Xri make sure that the recirc nipples/fittings are in place as I have seen a few blocks without them."

I am assuming you are talking about all of the brass check valves? If so I have confirmed that everything that was on the old block is on the new one. I did notice that one of the brass nipples is broken off flush. What is the best way to get these out?

Another issue as a result of the initial damage was the challenge of reusing the damaged cylinder head. I have lightly sanded using 320 grit paper and glass to try to get it smooth again. Will this cylinder head work, or did I screw up not buying a set off of ebay for $75?


I purchase a connection rod today as well. As soon as my bore gauges arrive I will know if I'm going to have to spend a good chunk of money to get larger pistons. Hopefully this block is a standard bore. On the pistons, I'm assuming the way to tell port from starboard is by the "S" or the "U" on the underside of the piston. If this is the case, it looks as though the damaged piston has a "U" on it. That would give me four port pistons and two starboard. Could this cause this kind of bearing failure?

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

That would give me four port pistons and two starboard. Could this cause this kind of bearing failure?

No ...it would just be low on power/performance. The pistons are stamped P for port and S for starboard and the U means up. You will need to mike the old pistons to see if they are worn and able to reuse them. The heads can be resurfaced to true them up and any dings will fill in with carbon over time, just make sure these is no ring/bearing material embedded that will come loose or cause a hot spot.If you have the plastic caged rod bearings replace them all with the caged metal ones. The recirc nipple/elbows are on the block ,this is where the recirc line attach to block from front intake. The Xri block usually has a cap on them or I have seen them with out them(Xri recirc's back into VST tank). A 2.5L is a 3.501 std bore size and .004 is wear limit in my opinon but manual say .006.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

I will check the recirc lines tomorrow after work. I got the bore gauges and caliper today and measured the bores on the new block the best I could. I measured each bore a minimum of four times to ensure I was getting as accurate readings as possible. Here is what I found:

Cylinder #1: 3.512"
Cylinder #2: 3.5125"
Cylinder #3: 3.5275"
Cylinder #4: 3.5125"
Cylinder #5: 3.528"
Cylinder #6: 3.5125"

I was expecting the measurements to be larger than the piston diameters for the different oversized pistons. Do you think this is measuring error or can these be accurate? Also, I know the manual says that one oversized piston wouldn't make a difference since the weight is practically the same as a standard bore. Is it ok to have two that are different bores?

One other thing that I am considering would be trying to have the bad cylinder resleeved on the old block and reusing the old pistons if they mic fine. My concern would be with using a mismatched crank case and block set. I will have to research the costs of my two options. If cost is relatively close, which direction would you go?

Thanks for the replys Faztbullet. As you can tell I am learning more about this stuff everyday. I have all winter to get this project finished, and although money is a concern, I do not have a problem doing what it takes to do it right. I would rather spend $2500 and learn the intricacies of how my outboard works than spend that money on a rebuilt powerhead and still be clueless about outboard motors.

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

If your measurements are correct, cylinders #1,2,4 & 6 are worn very bad or has been bored .010 oversize and the same on #3 and 5 or bored .020 with wear. i would take this to a machine shop and have doubled checked as you can get .010 thru.040 pistons for this engine. Did the block you purchased not have the front crankcase section???

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

I will call around to find a machine shop in my area. The block I purchased did come with the front crank case section. I was just throwing the idea of seeing if the old block was salvagable and having the one bad cylinder resleeved and reusing the existing 5 pistons only having to purchase 1 standard bore port piston. After re-examining the old block, there appears to be minimal damage from the rod and was just trying to weigh cost options. It looks like i can get the 6 piston kits I need for the new block (assuming .015 and .030 bores) off of ebay for around $480 total.

My old front crank case has extensive damage from the rod hitting it, and my concern with using the old block and new fron crank case would be how they fit together. I wouldn't want to waste time and money resleeving the block and buying a piston if the two halves wouldn't bolt up flush or caused a bind/issue with the new crank. The new block, crankcase and crankshaft all came from the same motor, so I would figure they will go back together with no problems.

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

You can mismatch halves but its a pain to prep to make work. Just have the Xri block checked and it if it has been bored your in luck as you will only need to buy pistons. If you need parts you can pm me as I do sell them.

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

Inspection/Remeasuring:

After inspecting the pistons a little closer I was able to remove enough unburned carbon to gather some valuable info. Piston's 1,2,3, and 5 are all .030" oversized. Piston 6 is .015" over. After borrowing a 3-4" mic from work I measured them at:
Piston #1: A - 3.521", B - 3.520"
Piston #2: A - 3.522", B - 3.519"
Piston #3: A - 3.523", B - 3.519"
Piston #5: A - 3.523", B - 3.519"
Piston #6: A - 3.509", B - 3.507"

The manual I have doesn't show the allowable tolerances for a .030 oversized piston, but it states a standard piston should be 3.494+/- .001" and a .015 oversized piston should be 3.509+/-.001". I am assuming a .030 oversized piston should be 3.524+/- .001". According to the manual I should be able to reuse pistons 3,5, and 6.

After measuring the pistons using the mic I decided to recheck my cylinder bores using the mic instead of the caliper. I measured each bore 5 times in various places and recorded the measurements.

Cylinder #1: 3.5135, 3.5135, 3.514, 3.510, 3.515
Cylinder #2: 3.513, 3.515, 3.511, 3.5135, 3.5185
Cylinder #3: 3.530, 3.530, 3.521, 3.530, 3.5265
Cylinder #4: 3.511, 3.519, 3.515, 3.516, 3.5125
Cylinder #5: 3.531, 3.5315, 3.535, 3.525, 3.531
Cylinder #6: 3.5145, 3.512, 3.515, 3.517, 3.513

I called a local machine shop on Friday to ask about pricing for boring, miking, and resleeving. I was quoted $38 to mic, $110 to bore one cylinder plus $50 for each additional cylinder on that side totalling around $420 for all 6. I didn't ask about honing pricing. Does this sound right? I am wondering if I could just hone each cylinder to achieve the desired overbore size, assuming that my measurements are correct and verified by the machine shop.

I also checked on the recirc line on the new block, and it appears to have the fitting on the top just like the other block. Both blocks have the exact same set up with a fitting on the side plugged/capped off. I will take a picture next time to confirm this as I am still confused as to just which fitting you are talking about.

 

[Faztbullet]

Re: 2.5L 200 HP rebuild/repair

That price is pretty close as a 2.5 is a PIA to bore due to sleeve extending to bottom of deck. Do the pistons have a number etched into top of them or cast into bottom as you will need to find out which brand of ring to order if you reuse pistons. Ask the machine shop if they camfer the ports after machining and honing should run not more than $70 for all 6.....

 

[CardsFan84]

Re: 2.5L 200 HP rebuild/repair

The pistons are Persan with 647 stamped in them. The little I could find on them stated they were OEM spec or better and that all parts should be interchangeable with Mercury parts. It looks like I should be able to use Pro Marine or Sierra Pistons and rings for the rebuild. Any advice on where to get them?