1994 Mercury 2.5 260 Rebuild

[Rock Steady]

Greetings Scream and Fly,

I recently purchased a HST w/ 1994 Merc 2.5 260. It fried the No. 6 piston and cracked the Block towards the outside. there is a slight amount of metal on the Reeds. The motor is being disassembled at Sanderson Marine in Chester, VA.

I visited yesterday and discussed with Mechanic Charles Probst, and Lee Sanderson in depth. Crank looks good and all pistons look good except for No. 6 that is a molten pile of chit.
Step 1:We are sending the block to be repaired to someone up North to the tune of about $1,000. I will give that persons name as soon as I can.
Step 2: This motor has O-ring style heads that compression is higher but we have not measured the CC's yet. Lee recommended I go with Stock Heads so that I could more safely use 93 octane. Agree or would I be loosing some HP by not using the same heads? He also mentioned that the cut on the heads is rather trip and only a few can do that work. There is some metal stuck on the No 6 cylinder ports.
Step 3: Choose Pistons, Lee recommended I go with newer top pin pistons. He cautioned that if I use the same pistons the pins may fall out at anytime and destroy my motor. But reality is that they looked ok. Also leeds me to believe that the 93 fuel w/ 32:1 oil was ok. After I CC the heads I will no for sure.
Step 4: Reassemble with all new bearings and re-use the crank. Should I have the Crank balanced? I don't plan to turn above 8000rpm.

All this is costing to much and I won't get motor back until I pay of course. Estimate was about 6k for all new parts, bearings, pistons, rods, wrist pins etc. What parts should I demand they reuse besides the block and crank? Rods should be ok. Would pistons be ok if I re-ringed them? Would that fix the Pin issue?

So I have had some thoughts of buying a used power head instead of fixing this one for now. I have about 3k to spend right now. Thoughts? Most have said I should go ahead and bite the bullet and rebuild this one and take my time. So depressing though! I would be ready in style next spring though....

I am recreational boater by nature and have boated my entire life 1st boat when I was 14 which was a chaparel 16ft w/ 90hp, that I had running 60mph when I sold. This my 2nd HST w/ 2.5. I have owned several bigger performance boats, a 22ft Scrab with 454mpi and a 38 with twin 502efi's. I can't afford to feed the big blocks anymore is why I am not in that game anymore. So I like the river racer type boats, what a thrill! The whole reason for buying this boat was to satisfy my need for speed and not break the bank, neither is being satisfied now! uggggg..... I should of known...

[K-Dawg]

Well, Lee is a very respectable guy in my opinion and he has always been fair and honest in anything I have bought from him. I bought a set of sporty propshaft seals from him and didnt realize they were the wrong ones until I opened them. Called him and all he wanted was for me to pay the difference for the correct ones and said to keep the others he sent first. I personelly would not have any second thoughts about any advice he gave me. Good luck in whatever you chose to do.

[Rock Steady]

After this fiasco is somewhat finished I do have some plans to work on other parts of the boat. I have a GPS Speedo w/ Recall but its missing the Receiver. Question I have is can I just purchase a Garmin Receiver and this will work? There are some listed at West Marine online for about $70. Anyone know?

The center sponon for this HST has had a repair done and about half of the boat is just primered. So I plan to pain this, roller and tip method along with a few other places like the transom. I am thinking either black or Yellow as to not clash with Red (could be difficult to match)

I also have a really nice sterring wheel from my last big boat but its the 6 screw type, the one on this boat has the one nut fasten type. Is there a conversion?

I am going to have the rear seats recovered/redone. Does anyone know where I can find how the rear seats looked or how they are supposed to go together? I see a hinge on one but not sure how it attaches.

On my last HST I had a twin temperature gauge since the 2.5's have 2 temp sending units. This one has a single, can someone explain this? Perhaps one is to make it go into Limp mode and one is to send to gauge? IDK for sure.

This is also equiped with a Volt meter and an amp meter, Should I get both of these working? Comments?

It is equiped with Water pressure gauge but not sure if its working properly. How would I test?

Fuel Gauge is not working, and I think the tank is original, chances are the sender is not hooked up or is not working. Where can I purchase another? I want this working as because this all may have been caused by low fuel.

What other gauges are of importance? Why?

As all you know this motor does not charge the battery, at best it maintains itself. I have heard that there is a upgrade available, alternator. Is it belt driven? What modifications are necessary. Would I need the bigger cowl? Alin style? I plan to install a GPS speedo, Bilge pump on a manual switch only, running lights, and a basic stereo w/ 2-4 speakers.

Lastly, the interior gunnel is really ruff, all the grab handles are missing (know where I can find the originals?). I may roll and tip this area or may purchase/make some gunnel pads or possibly some vinyl coverings.

[laglass69]

You will save yourself alot of heartache if you go with top pinned pistons now while your motors being rebuilt. Mercury quit using side pins for a reason. THEY COME OUT and trash your engine. If your dead set on re-using your old pistons at least send them to John Marles (Us1 on S&F) and have them top pinned. Give Jay Smith a call, He can answer any of your engine questions and probably save you money on the rebuild. Do a search on him and you will find nothing but praises. (281)-576-5088.

Here's my opinion on your other questions:
You should be able to buy a hub adapter so you can reuse your old steering wheel.
One sending unit is for the warning horn, the other is for head temp gauge
If you already have a volt meter installed I would get it working, 260's dont like low batteries
You can test the water pressure gauge itself with a little air to it
Fuel sending unit can be purchased from any marine store, Academy even has them, just match the ohm rating on it to your gauge
Simon motorsports makes a alternator upgrade for 2.5's, it is belt driven but wont fit under stock cowl, have to use alien cowl

[transomstand]

I visited yesterday and discussed with Mechanic Charles Probst, and Lee Sanderson in depth. Crank looks good and all pistons look good except for No. 6 that is a molten pile of chit.
Step 1:We are sending the block to be repaired to someone up North to the tune of about $1,000. I will give that persons name as soon as I can.
Step 2: This motor has O-ring style heads that compression is higher but we have not measured the CC's yet. Lee recommended I go with Stock Heads so that I could more safely use 93 octane. Agree or would I be loosing some HP by not using the same heads? He also mentioned that the cut on the heads is rather trip and only a few can do that work. There is some metal stuck on the No 6 cylinder ports.
Step 3: Choose Pistons, Lee recommended I go with newer top pin pistons. He cautioned that if I use the same pistons the pins may fall out at anytime and destroy my motor. But reality is that they looked ok. Also leeds me to believe that the 93 fuel w/ 32:1 oil was ok. After I CC the heads I will no for sure.
Step 4: Reassemble with all new bearings and re-use the crank. Should I have the Crank balanced? I don't plan to turn above 8000rpm.

All this is costing to much and I won't get motor back until I pay of course. Estimate was about 6k for all new parts, bearings, pistons, rods, wrist pins etc. What parts should I demand they reuse besides the block and crank? Rods should be ok. Would pistons be ok if I re-ringed them? Would that fix the Pin issue?...

The block is going to Ruck, he's the best in the business. I like the idea of reduced compression heads, the gas sucks today, and considering the cost of burning down the motor, it's cheap insurance. Side pin pistons are almost guaranteed to spit one out sooner or later, top pins are a MUST. I would leave the crank balance question to Lee, and accept his advice, the other advice he's giving you is excellent.

[Rock Steady]

That explains why this motor only had 1 sending unit installed, what I don't know is if that went to warning horn or to gauge, but its at my electical guy now and getting all that sorted out and wiring cleaned up. I guess rather than blowing the bank on new gauges I should just fix what I have if possible. Later on down the road maybe a new set would be in order for the bling factor...

Does anyone know approximate distance range of a 2.5 w/ a 20 gallon tank? That is running under 4-5k rpm.

[Rock Steady]

Lee said I don't need the crank balanced unless I plan to race or turn up the motor to higher RPMs, so I have my answer. I just always had the idea that perfectly balanced is a NICE thing to have regardless of RPM.

[laglass69]

The sending unit with the spring and one tan w/blue stripe wire and a ground goes to the horn. The one that goes to the temp gauge looks like a rubber plug and has 3 wires if im not mistaken.

[rock]

The guy up north is most likely Jim Ruck and that is exactly where you want the block to go. I would also agree with the stock heads. You can always cut them to increase compression. Top pin is the best way to go. I like the Wizards but they are fairly expensive. I have no clue what the Merc top pins cost. Might be more than the Wizards, don't know. Maybe you could replace the melted piston and send them out to all be top pinned. That would be depndent on the other 5 pistons being useably. Get out the micrometer. If you have questions about the crank, send it to David Eden. He's the best. It is all expensive but what about this sport isn't. I would look for a used 2.5 drop on till I could afford to do it right. Use the boat without quite as much power then sell the drop on when the new bullet is done.
You can buy a different reciever. There should be pics of many HSTs on here. Use the search function or just look thru the photo albums. Never heard of twin temp guages but who knows. I would think you could have one on each head so as to monitor temps more accurately. I want all my guages working or I would not have put them in the boat. Temp, water pressure, tach, and maybe pyrometer. I have a friend that installed solar panels on a couple flat surfaces on his 260 to help charge the motor while it was sitting on the beach. Good luck.
Rock

[rock]

I need to learn to type faster. I started my reply at post #3 asnd by the time I posted I was post #9 and all the questions had already been answered.
Rock

[Rock Steady]

Ok that was really nice of all of you to comment, thank you! Very useful information to me. I guess I will let Sanderson do their thing and get the motor back into shape the best way they know how with budget in mind. But they will own my rebuilt motor until I come up with the coin! Not cool... So if I got a used motor that is cutting into what I can give them, and I am already scrapeing penny's to afford that@!

[Rock Steady]

Any 20 year old boat is going to need alot of work, this one is no different. I will get there, need to have patience and I will have myself a damn nice boat in a year or so. Better than nothing!!! Least I have something to do ALL the time... Work and watch the other yahoo's riding around... Story of my life... I have no silver spoons in my mouth but I am have always done pretty good for myself. Had some amazing toys in my day.

[hst714]

jesus man, i really didnt expect this purchase turn into a rebuild for you, i was actually praying you didnt take the boat away that day.

the sender in the head that is hooked up is for the over heat horn. it sounds if it gets hot, to test the horn you could ground the sensor i think.

there is no sender for the temp gauge.

and so you know, i think you would be fine using the heads that came on the motor ive used the motor just the way it was with no problems. i hope you get to enjoy it soon i feel bad , if i could help in any way i will. and for the furture do not ever run that thing out of gas it could lean the motor out.

[hst714]

and you can use top pinned pistons i would go wizard all the way you have 5250 rod your gonna have to have them machine the end down a bit to accept the new pistons. ruck is the man in the block biz... use the stock crank and rods replace the pistons,rings,wirstpins bearings,and main bearings this is my advice and again i cant believe this happened

[hst714]

and while your at it call brucato and get those injectors flowed!!!!! thts weird you fried a no.6 piston either ran low oon fuel or maybe a injector failed???? idk