Rebuilding 88 merc xr4

[fishingguy76]

I have my merc 88 xr4 broken down for rebuilding. There is a rod and a gear that
is mounted to the crankshaft for the oil pump system. I have eliminated the oil injection years ago. Can I remove these and rebuild without them or do they need to be in there for some reason? 409313

[FORBESAUTO]

Remove the shaft/small gear and install the block off plug in its place so the bushing in block cant come out. Leave the plastic gear on crank to take up space, if removed it would increase the volume of crankcase on that cylinder, lowering crankcase pressure,

[fishingguy76]

Thanks Forbes. Can I get rid of the oil pump or should I put it back on?

[FORBESAUTO]

Get rid of all of it. The block off plug will go in it’s place.

[FORBESAUTO]

409330409331409332

If ya want to take the time, you can drive out the bushing in floor of cylinder, fill in bushing hole, void where gear is, and hole for pump shaft in front half with epoxy. This will get this cylinders crankcase volume even closer to the same as the rest. Also clean looking.

[fishingguy76]

Thanks, I just got all the pistons and bearings out. I'll be taking the block to the machine shop tomorrow morning for honing and boring. I made it this far with only the one question. I imagine there will be more.

[FORBESAUTO]

http://parts.promarineusa.com/productdetail/M50/1/1/43453

Here’s the plug you need to remove and block off pump and shaft.
Good luck on your build, ask any questions you may have and someone on here will be glad to help and have the answers.

[fishingguy76]

Thank you, thank you, thank you. I will be getting me one of those. Tackling this is a bit intimidating, I'm feeling a bit more comfortable now knowing I can yell for help when needed. Do I need the piston pin tool, or is there some other way to get the needle bearings in the new piston.

[FORBESAUTO]

The tool makes things much easier. I know some will probably have some negativity over this, but you can use white lithium grease in rod to help hold needles in place so you can stack them all in. It will also help hold washers in place also. Take your time and you can slip the wrist pin in without knocking the needles out, without using the tool.

[rock]

I usually use as 13mm socket. While I may be wrong on the size just find the deep well just a shade smaller than the wrist pin, stack your bearings and slip socket thru piston and rod then displace socket with wrist pin. Socket will help hold every thing in place while you insert pin. The fun part is getting those freakin little clips in place. They suck but it is doable. Good luck and welcome to the site.

Rock

[mach351]

Once you use the Mercury circlip installation tool, you’ll be ruined and will refuse to put a circlip in without it lol

[FORBESAUTO]

409405

This is is the circlip tool Mach is speaking of. You’ll find the wrist pin and needles not that bad to deal with, but those dang circlips will make you wanna throw and punch something putting them in :eek:

[fishingguy76]

I should probably get the tools. They should re-sell on ebay after I'm done. Dropped the block off today at the machine shop. Guy said it didn't look too bad. His guess was a head gasket failed and let cooling water in the cylinder. Oh well, stuff happens. Now I wait for him to tell me what size pistons I need. Where do I go to purchase pistons and bearings? BOAT> Break Out Another Thousand, or more.

[FORBESAUTO]

The pro marine pro and pro-v pistons are very good replacement pistons for the money. The difference between the two are the pro-v has the coating on the skirts where the pro’s do not. I have used both with no issues. I normally use the pro-v in more performance situations where the motors will be turning a few more rpms. Pro marine is a very good source for all your parts and a wide variety of tools. Their website is promarineusa.com click on the outboard parts section of page and it will open to the outboard parts section.

[FORBESAUTO]

When you get it all back together, I personally recommend to prevent from scuffing a new piston:
Start out with 25:1 oil fuel mixture, let it idle at fast idle (1300-1500)on hose for 30 minutes. Kill it, let it completely cool down, repeat this step six times. Run it easy in water for three more hours, varying rpm staying under 4500 rpm (high load is the most important thing you are trying to avoid, try to keep the motor free running). After this you change mixture to 32-1. Run it four more hours easy with occasional brief 5k rpm again varying load/ rpm. Go to 40-1 for next 5-10 hours without any long wot runs (once motor begins laboring and no longer acceleration freely, let out). To me the longer you wait, the better. After this mix 50-1 and run it however you want.(assuming you are leaving it stock)

[fishingguy76]

Is a powerhead stand needed? Which one?

[FORBESAUTO]

It’s nice, so you ain’t walloring it around on a table. I just use a regular Automotive engine stand and made me a fixture to allow me to adapt to power heads and lower units.

[fishingguy76]

Is there a specific stand for every motor, or is it a one size fits all kind of thing?

[FORBESAUTO]

The Automotive engine stands are universal, but they wont adjust down to as small as the bolt pattern of the power head. I just made an adapter plate to bolt the power head to and then bolt it to the stand. This will be the least expensive way to do it. Something like this.

https://www.ebay.com/p/Jegs-80040-Red-Engine-Stand-1000-Lbs-Capacity-360-Degree-Head-Motor-Stand/1328616707

[FORBESAUTO]

I just took some angle iron and formed a square then welded it up. Drilled some holes in it to add cross bars, extensions or whatever to it so I could mount whatever to it from power heads to lower units or whatever.

[bullet123]

I use same thing. Picked it up at Harbor Freight. I hang complete 2.5 motors to mine for powerhead removals. Holding up so far.

[fishingguy76]

I got some bad news on the block. One cylinder is damaged to the extent it has to be re-sleeved. Cost 800.00 bucks. But, my 135 parts motor has a good block, just a honing on all the cylinders. So I want to rebuild the motor as a 2.0 135. A substantial price saving of 5 to 6 hundred bucks. I am a bit unsure of the differences between the xr4 and the 135. I would assume cylinder bore and carburetors would be different. The block should bolt right up with the mid section, right? Same ignition parts?

[nitro_rat]

I’ve never had a bore sleeved but from what I’ve heard $200 per hole is approximately the cost to do one hole. A few questions:

Who is quoting you $800?

Where are you located?

What year is your 135?

[99fxst99]

I’ve never had a bore sleeved but from what I’ve heard $200 per hole is approximately the cost to do one hole. A few questions:

Who is quoting you $800?

Where are you located?

What year is your 135?.
Yeah, what he said. $200-250 should sleeve that block, one cylinder

[fishingguy76]

Cleveland Ohio area. A company called cometic gasket. He quoted me between 55.00 and 65.00 dollars a hole if damage wasn't bad. With the one bad needing a sleeve he gave me the 800.00 quote. The two motors are the same year 1988.

[nitro_rat]

I sent you a pm. Cometic makes some nice stuff but I don’t guess I’d let them do any machine work on an outboard for me! That’s probably what they charge to bore and sleeve a small-block Chevy! This ain’t no car mota!!!

[bullet123]

That’s crazy!! Send it to James Perry. Best there is since ruck retired. Fair priced too.

[nitro_rat]

I sent you a pm.



Send it to James Perry.

I pm’ed him James’s #

[fishingguy76]

I talked to Mr. Perry, he patiently listened to my story. Many thanks to him for his patience and understanding. I broke down the the 135 and you can see the original cross markings, what ever they are called, on the cylinders. One not so bad cylinder that had the burnt piston. It goes back to the shop tomorrow, we will see what they have to say about this one. The only differences are the carburetors, which I have, and the exhaust ports, which I also have. So I'm leaning towards the 135 rebuild, which is the original max horsepower rating of the boat I have anyway. I know I'm giving up a lot of power, but I boat and fish on Lake Erie, rarely does that lake let you open it up.

[David]

135s were 2L, the XR4s were 2.4s. Would you be losing a lot of low end?

[Merc 2.5]

Not sure of yr of 135 but it's probably crank rated at 135 and xr4 is prop shaft rated , my guess is about 30 or 40 hp difference. , xr4 better motor mho

[fishingguy76]

I'm sure I'll lose some. The boat came with the 135, I hung the Xr4 on it. That was over kill. If the 135 block comes back renewed at a reasonable cost??? The 135 rebuild kits are much cheaper than the Xr4 for some reason, I'll go that route. It looks like the Xr4 already had the larger gear case on when I bought it, so that should hook right up. I might have to switch the mid sections.

[fishingguy76]

I agree, that Xr4 is a SCREAMER!! That is the tough decision, I'm retired, cost is a big concern, sometimes what you want and what's best is a bit cloudy.

[Merc 2.5]

I agree

[nitro_rat]

Put the 135 powerhead on the xr4 mid. The 135 tuner is very restrictive.

[fishingguy76]

Dropped off the 135 block at the cometic gasket today. He agreed on the 1,2,3,and 4 cylinders being in excellent shape, as well as the pistons, they look brand new other than the carbon build up on the tops. He will clean those up with a hone, and bore the other two one size over. I broke a bolt taking it apart, he said no big deal, he can get it out easily. Total cost on the work will be 230 bucks. If I could still do a back flip, I would be! So this will be a hybrid mota, I'll have to come up with a catchy name for it.

[nitro_rat]

Get a set of reeds and reed block spacers from Chris Carson. Send your heads to James Perry and let him cut them to probably 28cc’s. He can tell you for sure. I think the ports are pretty low in that motor, probably not worth changing carbs unless you raise the porting. Ditch the timing modules and time it to 24*. It should run good.

[rock]

James was looking for xr4 blocks a while back. If you want to sell it you may want to bring it up to him.

Rock

[Merc 2.5]

James was looking for xr4 blocks a while back. If you want to sell it you may want to bring it up to him.

Rock

I believe you are correct, he's building sum crazy motors with those blocks

[fishingguy76]

I talked to James a few days ago. He said he has at least 4 projects to complete. He is also going on vacation in two weeks so he is loaded up on things to do. I might just keep the Xr4 block for a winter project. Depends on how this one goes.

[Merc 2.5]

Yep 1 them is mine:D

[bullet123]

Nope. I sent you. 2.5 crank. Just sent you extra top cap Incase something went wrong with bearing replacement. Btw. Still have coils/plate sitting on my desk

[Merc 2.5]

OK what Is shipping on that and I'll get it sent over ,pm me (nope I sent you 2.5 crank) that for me? I remember y u sent 2 caps in case I screwed 1 up lol

[bullet123]

Sent you a text. Don’t want to hijack

[bullet123]

I think posts are all wonky!! I didn’t post here

[fishingguy76]

I'm starting to put together a parts list. Does everything on the crank get replaced or can I reuse anything?

[Merc 2.5]

Usually everything replaced, depends on situation of motor but pressed on crank breaking (bottom I believe )? Some mite leave it , they say they don't usually fail that often ,then again depends on motor, hours,what happen originally, better safe than sorry tho, a lot of guy probably have a press n their shop,but I don't so I would weigh my options

[nitro_rat]

The bottom bearing is pressed on the crank. It is commonly reused. A lot of guys reuse the other crank bearings too if they look good. Not recommended in the manual to do so. Just depends on what you’re trying to do.

[fishingguy76]

I see there are plastic rod bearings? Are those ok? I'm thinking sticking with new metal.

[nitro_rat]

It’s a good upgrade!

[fishingguy76]

Here is a pic of the top of the crank where the flywheel and the upper bearing and seals would be. Are these marks a concern? 410535

[fishingguy76]

Still don't have my block back. Looking ahead, If I leave the heads off and install the flywheel, can I just turn the flywheel until #1 is at tdc, and then adjust the pointer on the flywheel for the timing procedure?

[bullet123]

I've never heard of doing it that way. I guess it would work, but I recommend a dial indicator through plug hole. If you are going to time it higher than 23 degrees, index every hole and set timing with highest one.

[FORBESAUTO]

I actually prefer doing it with the heads off. I made me a piston stop by using a metal bar that goes diagonally across the cylinder and bolts down on deck using the head bolt holes. Drill you a hole in plate so that it is dead over the center of the piston. Weld a nut on top side over the hole you drilled, now you can insert a bolt in nut and adjust it to stop piston anywhere you want. Turn the motor clockwise until piston hits the stop you made and note reading on pointer (let’s say it’s 5 degrees btdc) now turn motor counterclockwise until piston hits stop( let’s say it’s 6 degrees atdc). You would need to move the pointer 1/2 degree towards btdc so that it would be at 5.5 degrees atdc. Repeat the process until the pointer falls in exact same point in both directions (atdc and btdc). This process will give you dead nuts perfect TDC.

[FORBESAUTO]

411083

Forgot I had a pic of it in my engine building album

[FORBESAUTO]

This procedure is just used to make sure your pointer is perfectly adjusted to TDC. Now you can use a dial indicator either set up to center of piston (or through plug hole later) in each cylinder to mark flywheel at 25 degrees btdc which will be 0.150 in hole btdc. Do this so you can check your wot timing on all cylinders (25 is the most you safely want to run)

[Euroski]

Still don't have my block back. Looking ahead, If I leave the heads off and install the flywheel, can I just turn the flywheel until #1 is at tdc, and then adjust the pointer on the flywheel for the timing procedure?

Sounds OK but I would use a dial indicator for accurate results

[FORBESAUTO]

Let me clarify my statement of marking 25 degrees on flywheel. It’s 0.150 from the highest point of piston travel not necessarily in the hole

[FORBESAUTO]

Using the piston stop method to find true TDC is the most accurate way to find TDC. It eliminates bearing clearances and the small amount of rotation of no piston movement while the rod rocks from one side to the other. This is the method we use when setting up a degree wheel when porting a motor or degreeing a camshaft.

[bullet123]

I agree with you (Forbes) on you method and what you use it for, but I assumed he was just gonna take head off and watch for tdc.

[FORBESAUTO]

I’m jus trying to help a fellow S&F member out, and maybe help a few others while at it. I’ll add you can do same thing with dial indicator just go same amount of thousands below top of travel each way (Just the solid stop elimates any error in my opinion). If you just watch indicator until it stops moving, you can be off 1/2 degree or more, and before ya going to marking on your flywheel need to have pointer perfect. You can also make a piston stop that goes in through the plug hole to do same method with head one.:cheers:

[fishingguy76]

I appreciate all your tips! Forbes, your metal plate technique is brilliant. Got me to thinking, I am a carpenter/electrician kind a guy. Machinist, not so much. I have some planed flat 1x4 stock I could cut and drill to fit the holes. If I were to run a drywall screw, head towards the piston, a specific distance from the stock and cover it with some duct tape or some other protective material, would that do the trick? Don't laugh at me if I'm an idiot (I already know that). lol I could do that quite easily in maybe 10 minutes.

[FORBESAUTO]

It needs to be solid and rigid, your gonna be turning the engine until it stops against the piston stop in each direction. Go to Home Depot or Lowe’s and get ya a piece angle iron for rigidity, drill ya two holes for the head bolt holes and a hole in middle. If ya don’t have access to welder use a 5/16 bolt and a nut on each side of plate to lock it down ( may have to grind down nut and bolt on piston side so it’ll be thin enoug to stop somewhere on your degree increments on flywheel, anything over .150 thick will be more than 25 degrees and most flywheels don’t go that far)

[fishingguy76]

Got the block back, looks good! Ordered parts, mail man showed up yesterday carrying a rather large bundle. He asked what I had won. lol I told him that its just the start, expect more. Fuel pump rebuilt, along with two carbs, third one is taking a bath right now. It's so much better to be actually working on putting it back together than to be waiting and waiting. I guess patience is needed at times. I bought a new head that matches my one good one, I feel better about that. What's another hundred at this point. Still trying to figure out how this motor fried. Oil injection was working, carbs all looked ok when they came apart, I've seen much worse. Reeds? Could a failing water pump caused the two lower cylinders to fail before the top 4? It would be nice if I could figure out why this motor failed. Or maybe a bad trigger?

[Merc 2.5]

How did motor go down originally? Was you at wot?

[fishingguy76]

It was on the boat when I got it. I hung the Xr4 on it and used it as a parts motor. The original owner died and it sat in his garage for years. Finally the family had to get rid of it. No one had a clue as to what happened.

[fishingguy76]

I received the two new pistons. One ring is thicker than the other, but the grooves on the piston are also. So that's self evident where they go. One side of the rings has #'s and letters, do they face the top of the piston? Does it matter? There is no dot like the manual says to look for.

[FORBESAUTO]

More than likely the ring is not square, usually one side has taper, the tapered side will go up. Also normally writing will go up. The piston usually has instructions on ring orientation also.

[fishingguy76]

No instructions, all it says is "pistons are not the same 1 keystone 1 rectangular. The righting on one side of the ring says .015, which is the size of the piston and RN. Both are marked at either side of the ring gap.

[FORBESAUTO]

Also look at the locating pin on piston, they are normally positioned on upper part of groove. Then look at half moon on ring it will also be cut offset, not in center of ring. Place the long side on the bottom

[fishingguy76]

I'm looking at them with a bright light and a magnifying glass. Can't tell if there is a difference. Writing up sounds like a good bet.

[FORBESAUTO]

Are your locating pins not off centered in ring groove?

[fishingguy76]

I used needle bearing grease on the piston pins. Can I use it on the upper main bearings? (Them damn circlips)!

[fishingguy76]

I got the crank, and bearings installed in the block Saturday. Yesterday my son helped, we got the pistons in and the crank cover on. No hangups, or rough spots. Rotates smoothly. I'm contemplating on how to proceed, I'm thinking putting the flywheel on, setting top dead center, and buttoning the backside up. I guess I'll have another cup of coffee and think some more.

[fishingguy76]

All I have left are the switch boxes, a few clamps and cable ties, and putting this motor back on the boat. I got the tdc on #1, arrow on flywheel pointing at 0. What is the number I'm looking for on the primary pickup? Set the max. spark advance to 24?

[fishingguy76]

Motor is back on. I set the timing to 24 btdc and the throttle pickup to 11 atdc. The modules are gone, I'm not sure what the throttle pickup should be. The book says 11, but not sure if this would be correct with the modules gone? Put the plugs back in, hooked a tank of gas with 25-1 mix and turned the key. Boom, before I could count to two it was running. Let it run to temp and shut it down. Everything looks and sounds good. The idle in neutral is 700rpm in the driveway with muffs. Seems low to me. Any thoughts on any of this?

[Merc 2.5]

Imo, I would start with 21ish on wot timing and let the motor break in, better safe than sry, with the idle, I'd just try bumping the idle timing up 1 more deg?

[Merc 2.5]

Glad to hear it's up and running, good job!

[fishingguy76]

Thanks Merclover, So I should back the wot timing down a bit, and raise the idle up a bit. Sounds like a plan. Should I raise it back up after break in? I was a bit nervous when I turned the key for the first time. I never expected the motor to crank and start so quickly. I was pretty excited to say the least. I've put it through 3 cold-hot cycles now and all seems well. Hopefully a couple more today, rain moving in though.

[93Intimidator193]

New to the forum. I feel the need to share my $.02 on circlips for the 2 cents it's worth.
I've never built an outboard but I have rebuilt and reringed many 2 cycle motorcycle engines. IF YOU BEND A CIRCLIP WHILE INSTALLING IT, THROW IT AWAY AND BUY A NEW ONE! Don't even try to use what appears to a good old one. It will break and the outcome is catastrophic. I don't care if you have to wait a week for a new one, you won't know it but you'll be glad you waited.
I realize you got it running and that's awesome. I'll be working on a 200 Merc soon and really appreciate the experience and wisdom so freely shared here. I'm sure I'll be asking questions.

[Merc 2.5]

I would think 24 is little high for a 150, most. 150s I've seen 21 22ish* but yet set idle timing where u and motor are happy. # doesn't matter much on idle, it will vary

[bullet123]

There is no perfect number for idle timing. Put in water and adjust

[fishingguy76]

Well Merc, it's not a 150 anymore. It's now a 135. The book says 18btdc at cranking speed, but that's with the advance module that has been trashed. I just came in from another cycle. After warm up at about 1200 rpm, I moved the throttle back to the neutral position and the idle speed was holding at just under 1100 rpm. I'm thinking that's good for now. I doubt it will be that high when in the water.

[fishingguy76]

Thanks Bullet, that's the plan. I guess the question is, how much do you add to the timing without the advance module?

[Merc 2.5]

I wanna say it in the 3* range. Box will raise it to 21 or 22*

[bullet123]

I set my idle 750-800 in neutral.

[fishingguy76]

After much research I have no good answer for Max advance timing at cranking speed without the box. I'm going to set it to 18, which is the manual spec. I'll go out and try it. It's probably the safest thing to do. After break in, maybe I'll go a bit higher, we'll see. I don't see how setting it to 18 now will hurt me.

[fishingguy76]

After 8 cold hot cycles in the driveway, finally made it to the lake. I had dropped the lower to put a new water pump in and failed to hook up the linkage. So after putting the boat in, and letting it warm up, I put it in reverse and there was nothing. I can be such an idiot sometimes. Since we had the tools, we pulled it out and parked in the parking lot and dropped the lower a bit and hooked up the linkage. Back in the water. Lake Erie was starting to show her teeth with 3' waves and building. Only had it out there for about 40 minutes before my courage started to turn wimpy. It performed well, idles so smoothly. Hopefully in the next week we can get back out a few more times in calmer weather.

[bullet123]

Good Deal

[Glastron1987]

Seems my out of water idles at somewhere between 1000-1200 give me an idle in water of about 750. Nice its running. Also I set my max advance to about 23-24 btdc without the box. So far it has not blown up.

[fishingguy76]

Glastron, I would be comfortable with the 23-24 setting if it was still a XR4, but it is now a 135. I'm thinking playing it safe during the break in. I can up the max advance after, I don't think it would be much more than 20 though. I am still open to that discussion however. I changed the ignition to CDI a couple of years ago. The new rectifier-regulator part bolted down where that box was. There was no mention of any timing changes with the CDI instructions. It idles great in or out of the water! Never owned an outboard that even came close. My tack might be off a bit, shows around 600 in gear.

[Merc 2.5]

Sounds like you got it running good, good job on the build , I had got a 2.0 150 non finger port motor and had the black boxes from factory, i replaced reeds and removed boxes and set timing to 21*, I had done research but the air box had timing instructions on it and that's how I came up with the 21* box bumped timing up 3 or 4 * after I had done all that ,that motor ran perfect from idle to wot , I turned it up to 23 one day and maybe I was just paranoid but I swore I heard a little rattle especially on hole shots, I dropped it back down and tried to replicate it and it wasnt doing it anymore. Maybe it was just that motor , if it were mine I'd do 21, just my 02. Ur call tho and I'm no expert , mine was also early 80s,

[fishingguy76]

Thanks Merc, the 135 is 2.0, same as the 2.0 150. The timing specs are the same for both motors. 11* throttle pickup and 18* max advance cranking with the box. It can get a bit confusing, the 150 XR4 is a 2.4, which is different, 7* and 22*. I have mine set at 18* right now. After a few more hours of break in, I'll make the decision on where to go with that. Thanks for the input.

[Merc 2.5]

Well do you have us some updates? Always like ending a thread with successful rebuild, have you got the break in hours on it yet? How ole girl doin?:cheers:

[fishingguy76]

So far so good. Between the time I have to go, and the lake co-operating not getting out so much. Been out 4 times, started fishing. Doing real well catching walleyes. Only on maybe hour 5 of the rebuild, under load, not counting driveway time. Haven't took it over 3500 rpm yet. With each time out I build more confidence in it. Knock on wood!

[fishingguy76]

Have been out a little more. Yesterday I opened her up and trimmed her out for the first time. Topped out at 5600 rpms, and showed no sign of trouble. The book says top end should be between 5000 and 5500. I'm not gonna worry about it being a little high. My tach might be off that much. Kept it between 4000 and 4800 after. It wants to run. Had to resist the temptation of just letting it go. So, all good so far. The timing is still at 18, and I see no reason to change it. Still have about 2 hours left of break in time under load. Starts like a dream, idles nicely, and has a decent hole shot with just my son and I. Last week I had my son my daughter and her boyfriend with me, along with a full cooler of ice and fish, and it was slow out of the hole. I'm just gonna have to deal with it.