What more can I do?? 70hp Mercury starting/running problems

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Hi Diver I see from your last post you have a manual so forgive me for shouting at you .You will probably have to replace the piston on #1 & rings on all 3 not forgetting to hone the bores etc.I hope there is no damage to the bore.But if there is you can just bore 1 cylinder as factory oversize pistons are the same weight as the other pistons so it wont affect the balance of your motor.

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I haven't had time to study the manual to closely yet.. But it appears I have to disassemble the entire powerhead in order to get out the pistons. Is this correct? Or can I get to the pistons by taking off the "lid" on the side? If I can get to them without a stripdown, I'm thinking of leaving the boat on the water while working on it.. Possible?

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Diver you will have to take the powerhead off the center section & dismantle it completely. The lid on the side as you call it is a water jacket cover.Read the manual thoroughly before you start & dont buy any parts until you knw exactly what you need.Have fun & take your time doing it right once is alot faster & cheaper than rushing it & redoing it when it goes wrong

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

Again, thanks a lot, Sharkcat! I will let you know how it's going. Hopefully I will be able to start working on it tomorrow.

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I've got the boat on land now.. I've read about how to remove the powerhead, and that seemed like an easy enough job... But it isn't.. It is stuck! Any tips on how to loosen it? I've tried gently tapping on it, pulling and tapping, pushing from the bottom and up.. But all I do is lifting the engine and boat as a unit.. I have removed all the nuts and bolts I can see, as the manual tells me.. Does anyone know how many nuts/bolts I have to remove? Also: this is not to clear in the manual: Where does the powerhead come off? I can see to gaskets and it looks like both could be the one.. Is it the top or bottom gasket I should concentrate on?

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Do a search for stuck powerheads youll find lots of info.The powerhead will separate at the top gasket.Take the gearbox off before you do anything else as it may be the driveshaft stuck in the crankshaft got my fingers crossed for you good luck

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I've got the powerhead off now, and disassembled it.. The rings on piston #1 are lodged into the piston, and there is a lot of small holes on the top of it. The cylinder is to messed up to hone.. Piston #2 is also scratched a bit, and so is the cylinder. #3 lookes fine.. <br /><br />I'm thinking it might be cheaper to by a new motor, or at least a new block.. My father tells me it is possible to buy "small blocks" for cars, and that is a factory overhauled block with pistons and every thing i need.. Does anyone know if there is something like this for outboard engines also?

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

And also: I don't have the ser.nr of my engine.. Is it possible to get a new piston for it? Can anyone help me with a part number? Again: my engine is a 1982 Mercury 70HP 3cyl (most likely manufactured in Europe)

 

[maillon]

Re: What more can I do?? 70hp Mercury starting/running problems

Diver,<br /><br />This engine is done. Have a funeral and say good bye.

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Hi diver doesnt sound too good but if the rest of the engine/ gearbox is ok it may be worthwhile getting new pistons & rings & reboring your block.How are the reed valves?The serial no. should be on a tag on the center section & may also be stamped on a welch plug on the block somewhere..look for a shiny circle of aluminium..<br />Rebuilt powerheads are available but you really need the serial no. to get the right one..Catch 22.Good luck

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I took the block to be rebored, I've replaced piston #1, and honed cylinder #2. I'm going to rebuild the cooling system, and redirect the water canals. This work plus parts cost me about 1.000,- US$. I don't think that is too bad. I've been helped out a bit by a guy who rebuilds marine engines, and he says this will give me another 8-10 years at least with this engine. Hopefully he's right! I will pick up the block today or tomorrow. Hopefully all the ordered parts have arrived. And even more hopefully, I will be able to go waterskiing next week!

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Diver before you put this thing back together check the reed valves.You really have to find the cause of the failure or you will be doing this again It might be worth putting in a set of boyesens.Lots of holes in the piston sounds like severe detonation..Lean mixture,too much advance,bad gas all can cause it.Check the reeds.

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I will check the reed valves, just to be sure everything is in perfect condition! The guy who bored it for me said he could clearly see signs of no cooling to the upper cylinder. This was supposed to be a recurring problem on these engines? And this is why he told me to rebuild the cooling system on it. Thanks for all the help, Sharkcat. I will let you know how it's going.

 

[SpinnerBait_Nut]

Re: What more can I do?? 70hp Mercury starting/running problems

Diver, I just wanted to add one more little bit of info here.<br /><br />Starting fluid is bad for 2 stroke motors.<br /><br />There is no lubricant in it and it ignites hot and can, stress can, cause you problems.<br /><br />Just a thought so you don't have a messed up engine once you get it back together.<br /><br />Good luck.

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

Thanks for the tip, SBN. I will use WD40 instead, if needed. By the way: I was supposed to be on the water now, but the shop didn't have all the parts after all... They are missing a transfer cover, and won't get it untill end of this month... But THEN I will get back to you guys and tell you how it's working!

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

I've got all the parts I need now, but when I look in my manual, it doesn't tell me how to assemble the powerhead! Am I looking at the wrong place? It covers all other models, except '82, 70HP.. But the torque spec. are listed in the back.. (I have the Clymer manual '69-'89) Can anyone help me with a step-by-step on how to assemble the powerhead? (Pistons are already in the block)

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Hi diver will go to the library tomorrow & see if they have a manual for your motor if so I will let you know & if you post you email Ill scan the relevant pages & email them to you

 

[The Marine Doctor]

Re: What more can I do?? 70hp Mercury starting/running problems

Similiar steps should be taken from the 3cyl 2 carb 65hp's.<br /><br />TMD

 

[Diver503562]

Re: What more can I do?? 70hp Mercury starting/running problems

Sharkcat: Hope you havn't gone to the library just for me, because I have put it back together with a little phone support from an old mechanic.. <br />I think I might be able to put the powerhead back on tomorrow. <br />But now that I have a new piston and stuff, I need to run it on low throttle for a while, right? How long apx. do I have to take it slow?

 

[sharkcat]

Re: What more can I do?? 70hp Mercury starting/running problems

Hi diver I did go to the library just for you but the manual was out so it was a wasted trip Great that youve got it together.hope you are back on the water soon Have been really busy at work hence the longtime between posts