1994 120 HP Rebuild.

[brian66r1]

Hi there.


After all the problems I had with this (please see previous posts), I decided enough is enough. I pulled the transfer port covers off and looked into the cylinders above the pistons with a torch. In the number 1 cylinder, I could see scratches in the bore. Pulled the head off and it looked pretty evident that a ring was broken.

I removed the block, separated the crank cases, pulled the number one piston out and found the top ring broken in 3 pieces. Pulled the rest of the pistons out and found the top ring on the number 4 piston broken also.

There were marks in the number 1 cylinder from where it looks like it had once seized and there was scratches there too from where the broken ring was rubbing on the bore.

Need a piston, a set of rings, probably replace the big end bearings, a gasket set, I'll put a new thermostat in there too while I'm at it. I also need a new stator. The pistons all have "B3" stamped on the crown, is that a 3rd oversize?

I'm in Melbourne Australia and the price for parts here is almost twice as much as in the US. Anyone able to point me in the direction of a good priced supplier there who can help?

I've missed the best part of the summer and it would be great to get a day or 3 in before it starts getting too cold.


Brian

 

[pnwboat]

Re: 1994 120 HP Rebuild.

I take my blocks to a local machine shop that specializes in outboards and let them check out and measure the cylinders and make the determination on what size piston to use. Not sure what the "B3" means on the pistons. I would not assume anything. There are two different standard size pistons available. 3.312 inch and 3.375 inch. I believe your motor used the 3.375 std size pistons but you need to double check. The pistons are also available in oversizes ( .010, .020, .030, and .040) but the cylinder must be bored.

Here's a couple of sites.

http://outboardparts.com/

http://www.maxrules.com

http://www.boatpartstore.com/

Be aware that there are cast pistons and forged pistons. Cast pistons are a little cheaper. I've had good luck using the Wiseco forged pistons. I like the way they're made and they use "floating" wrist pins that are held in place with clips and can be installed/removed without any special tools. The original pistons are cast and have "pressed" wrist pins. This requires a hydraulic press and a special tool to remove and install them.

After you get the motor re-assembled, be sure to use double the amount of oil, 25:1 fuel oil mixture during the break in period.

Good luck!

 

[jerryjerry05]

Re: 1994 120 HP Rebuild.

After the measure,contact Wiseco piston.

 

[Justinde]

Re: 1994 120 HP Rebuild.

Hi

I'm in Sydney and have found ebay to be a very good source of some spares, I got a waterpump kit complete for $55.00, rather than $300.00.... I have seen complete gasket kits available as well as other parts. I stumbled onto this site http://www.mobymarine.com.au/ and they seem to have a lot of parts available I have never used Moby,but I have used http://www.mandwmarine.com.au/. Before I bought my boat, these guys rebuilt it. They have HEAPS of spares and are VERY knowledgable with Force Engines. Get them fast but, they are closing down in April.

Hope this info helps

 

[Justinde]

Re: 1994 120 HP Rebuild.

Actually just found this

http://www.ebay.com.au/itm/Chrysler...at_Parts_Accessories_Gear&hash=item53e8256d8c

Check its the right one!!

 

[spool]

Re: 1994 120 HP Rebuild.

Hey,

I'm in melbourne aswell (eastern suburbs) If you need some help let me know!

Are they wiseco pistons or STD chrysler/force pistons?, Easy way to tell is the wiseco have circlips holding the wrist pin in where as the standard pistons have pressed in pins.

I've got a spare set of brand new conrod bolts if you need some?

I used that gasket set and it was good.

As for the pistons, I used these guys, they ship out of brisbane and all stock is local (no long waits!)
I contacted them and got the needle roller wrist pin bearings from them aswell (not listed on ebay)

The kit includes, rings, wrist pins and a piston ($280 for 4 new piston kits) they DO not include the needle rollers which MUST be replaced if you use a wiseco piston.

http://www.ebay.com.au/itm/WISECO-M...AU_Boat_Parts_Accessories&hash=item27baeb4470

How bad is the damage? You might be in for a shock when you take it to the machine shop, I had a crack in my block and had to sleeve a cylinder.

The trouble you'll have getting parts is no one will ship to AUS, www.crowleymarine.com is good, they do ship to AUS (but take 5 weeks to get here) the price is worth it.

Anyway Good luck with it!

 

[brian66r1]

Re: 1994 120 HP Rebuild.

Thanks everyone.


Great price for the gasket set. I saw those pistons last night and wondered if they were the latest from wiseco? With what they call an "Armor Glide" coating on the skirt. They are listed on the Wiseco site for $111 each kit. I think for $69 each and if the kit includes rings, pins and clips. It would be foolish not to put a set of them in when I re-assemble it. The raised part on top of the crown looks a little odd compared to the original ones though. It looks like it hasn't been machined properly or not finished yet.

Anyway. This is what I found after I pulled the head off:

This is when I pulled the piston out:

I don't know if I did this or it was like it from before I bought the boat. Never the less, it has been seized before:

When I took the bottom ring off the number 1 piston and slid it back in the cylinder. It measures 0.95mm gap. I'm not an expert but I would think that is past it's allowable tolerance:

I'll keep posting as this project (unplanned) progresses.

Thanks for your replies. BTW I'm in Sunbury north of Melbourne. Anyone with any knowledge of a good machine shop close to me, feel welcome to let me know

Brian

 

[spool]

Re: 1994 120 HP Rebuild.

That's not too bad but its hard to tell from photo's how deep the scoring is, Mine was WAY worse, i required 30thou oversized but i couldnt get P3 pistons so i went P4, 40thou

They're old clearance stock so thats why its cheap. They're not coated on the skirts from what i can tell, Still nice pistons. My rebuild was fairly cheap and its running well

 

[brian66r1]

Re: 1994 120 HP Rebuild.

Thanks Spool.

I can just catch my nail on the scratches on top of the bore. The scoring from where it looks like seized previously is OK. It will hone out. I'll have to try the scratches first before I decide if I'm going to re-bore.

Did you do the rebuild yourself or have it done? Is yours the same motor? I haven't seen too many of them around here. What is it mounted on and how well does it perform?

Brian

 

[jerryjerry05]

Re: 1994 120 HP Rebuild.

Try to only go .010 if possible.The .040 and you will need to re-jet the carbs.
That scratch doesn't look that bad for a .040 bore.

 

[spool]

Re: 1994 120 HP Rebuild.

Thanks Spool.

I can just catch my nail on the scratches on top of the bore. The scoring from where it looks like seized previously is OK. It will hone out. I'll have to try the scratches first before I decide if I'm going to re-bore.

Did you do the rebuild yourself or have it done? Is yours the same motor? I haven't seen too many of them around here. What is it mounted on and how well does it perform?

Brian

I've got a 105hp on a 3.9M Haines hunter v133, I got the machine work done at a local shop and i assembled and built the engine myself.

I've got hydro foils and it gets on a plane quickly and goes pretty good! (when it goes) Mine is the same engine.

Jerry 40thou oversized is not that big (less than 100cc increase), are you sure a rejet is warranted? mine runs fine with 40thou oversized and the original carbs, I agree that taking less material off is better.

Have a read of this, i had far more damage than you do.
http://forums.iboats.com/showthread.php?t=519860&page=2

 

[jerryjerry05]

Re: 1994 120 HP Rebuild.

At .040 you'll be running leaner than you should.
New plugs.Run the boat at FULL throttle for about 3-4 min.Turn the key off at full throttle and check the condition of the plugs.
See how they're burning.That will help to determine if you need to re-jet.
At .040 They don't seem to last as long.
I've built a couple of motors for customers and the block they had was scored past .030.I told them there was NO guarantee if I continued.I did and the motors didn't last the summer.

 

[spool]

Re: 1994 120 HP Rebuild.

At .040 you'll be running leaner than you should.
New plugs.Run the boat at FULL throttle for about 3-4 min.Turn the key off at full throttle and check the condition of the plugs.
See how they're burning.That will help to determine if you need to re-jet.
At .040 They don't seem to last as long.
I've built a couple of motors for customers and the block they had was scored past .030.I told them there was NO guarantee if I continued.I did and the motors didn't last the summer.

Hrmm, I might try that jerry, have you had any luck rejetting carbs for chryslers?

 

[Frank Acampora]

Re: 1994 120 HP Rebuild.

Although pistons are offered at .040 oversize, Chrysler (and probably Force) recommended no greater than a .030 overbore due to cylinder wall thinness.

That cylinder doesn't look like it needs anywhere near .030. I would not be surprised if .010 cleaned it.

Original specs I read were (I think) end gap on rings should be .006 to .016. That translates to less than 1/2 mm max. However, I don't remember ever having a ring in tolerance and it is better to have too much end gap than too little.

Those pistons tend to break rings; if money is not an object, replacing all four with Wiseco would be better.

I just read the ebay ad: That piston is the standard Wiseco without armor glide. The P2 suffix indicates that it is .020 oversized.

 

[spool]

Re: 1994 120 HP Rebuild.

Hrmm, I might try that jerry, have you had any luck rejetting carbs for chryslers?

I began to look into this, after many visits to carb specialists and marine parts dealers I ended up with a part number for the jet im after, however mercury Australia lists it as obsolete and out of stock....

I currently have a .084 main jet in both carbs, the next step up is .090, i found the part on crowley marine and ordered a few of them (at $2 each), the part number was F10189 which is apparently the 115hp carb jet, two sizes up was .094 with the part number F10190 but i could not find stock of these.

As i had no choice but to go 40thou, what kind of short comings are to be expected from the reduced cylinder wall thickness? prone to cracking or cooling system issues?

 

[Frank Acampora]

Re: 1994 120 HP Rebuild.

If you really get desperate for jets, order any size you can get. Buy a Decimal drill of the proper size and drill it out.

I am surprised that you needed to go to .040 oversized. It did not look that bad.

Most engines will not experience any problems at that size. Remember: That is only .005 on each side over .030 BUT if you do crack a cylinder, start flipping rings because of exhaust port warping, start destroying head gaskets, then you could probably attribute those problems to the bore. I personally have never done an .040 overbore so I have no firsthand experience. Don't beat yourself up, worry about the engine, or baby it. If anything is going to happen, it will happen and there is nothing you can do to prevent it

 

[Justinde]

Re: 1994 120 HP Rebuild.

NOt wanting to hijack a thread, but my 1988 125 was rebuilt before I bought it. One Cylinder- the lowest (4) is 40thou oversize, the rest were honed and standard.

I read with interest rejetting etc when going up 40thou- would I need to look at the same for just 1 cylinder?

 

[Frank Acampora]

Re: 1994 120 HP Rebuild.

Justin: That's not hijacking. You have an engine with an .040 overbore. You may have some valuable info to add. For example: How long have you had the engine? Has the overbore given any problems? Or, has it been trouble free for the time you have run it.

And, If you have run it for a significant time at full throttle (hours) without problems, then don't worry about re-jetting it. lean running due to undersized jets only expresses itself at or near full throttle. As more air flows through a venturi, it delivers more fuel per unit of airflow. Thus: 1. The high speed jet only limits fuel flow at or near full throttle. 2. Overbores by increasing cubic inch displacement should result in more air being pumped and if anything at all, a richer fuel mixture. BTW: An .040 overbore on all four cylinders results in less than 1 cubic inch increase--less than 1%. The engine will not notice it.

Do the numbers yourself: Engine cubic inches = cylinder square inches times stroke times 4. Cylinder square inches are bore diameter divided by two times itself times pi. In this case 3.375 divided in half (1.6875) times itself times 3,14.

 

[Justinde]

Re: 1994 120 HP Rebuild.

Thanks Frank

I have still problems at WOT with overheating. New waterpump/exhaust plate etc, but overheats at WOT.

I am, however, yet to successfully complete a link and sync, so I'll report back when thats done, and the boat has been run...

Thank you again Frank, you are a wealth of information!

 

[spool]

Re: 1994 120 HP Rebuild.

Thanks Frank

I have still problems at WOT with overheating. New waterpump/exhaust plate etc, but overheats at WOT.

I am, however, yet to successfully complete a link and sync, so I'll report back when thats done, and the boat has been run...

Thank you again Frank, you are a wealth of information!

I have noticed since going 40 thou over my low speed jet is now happy at aprox 1/4 turn further than normal, I will rejet my carbs soon and report, time will tell if any issue surface

Lean afr mixture = higher EGT, which means more heat, have you checked the thermostat? Did you replace the impeller or the entire housing? What's the tell tail like?