Mercury/Tohatsu 3.3 spares?

[john_morris_uk]

Our 2 stroke died when we were away cruising N Brittany and the CI's. It just stopped and refused to start again. I checked fuel, spark etc etc and couldn't get it to go. Then I spent 46 Euros on a French OB motor mechanic telling me that it was dead. He said that the piston had scraped the bore and it wasn't worth repairing.

Assuming that I can get it apart, are pistons etc available for these little two strokes? I have heard that its often impossible to remove the bolts holding the things together and that they are scrap once they break down.

What's the suggestion before I waste time trying to strip it?

 

[cliff]

Assuming that I can get it apart, are pistons etc available for these little two strokes? I have heard that its often impossible to remove the bolts holding the things together and that they are scrap once they break down.

What's the suggestion before I waste time trying to strip it?

Pistons etc ARE available however the cost is frightening,and will make your eyes water, although less than the cost of a new OB.

Unless the bore is completely feck'd I would not think it is that that is causing the problem - more likely the little fuel pump or blocked jets in the carb. Remember the 2t's are low compression engines at the best of times.

Getting them apart is usually fairly easy with a little patience and a good supply of "Plus Gas" or the like. I have never had a problem with stripping the power head but the lower end can be, and usually is, a bit of a bugger.

 

[DannyB]

Don't look at stripping it down as a waste of time, look at it as an interesting diversion. Buy an impact screwdriver to help get the screws out, they are usually stainless steel into alloy and glued in by corrosion. Boiling water over the screws can help as can loads of penetrating oil, not WD40. Best of luck, it is probably something minor. Some mechanics won't look at repairing small motors because its difficult to justify the labour charges when it can take hours just to get inside one. But if its your own time, then it can be quite therapeutic. Best done in a shed, some SWIMBOS don't like engine blocks on the dining room table.

 

[john_morris_uk]

Cliff's comments interest me as I am still not sure why it has died.

The symptoms were that we were motoring along the river at Treguier and the thing just suddenly stopped. It was quite hot but I am pretty sure that the tell tale of water was still running ok.

My initial reaction was the normal "spark or fuel".

The spark is there - not the biggest and fattest - but more or less what I remember from previous times I have checked it.

I then thought 'fuel'. There is no fuel pump on these OB's - fuel is gravity fed from the tank. Removing the fuel pipe from the carb shows readily available free flow of fuel. Removing the float chamber shows that it flows through the float valve ok, and the float valve works correctly.

I then removed the carb' and checked the main jet - clean as a whistle and the needle jet is clear as well.

There is compression felt when you put your thumb over the spark plug hole and the spark plug eventually gets wet with fuel when you attempt to start it but there is NO sign of life. Not even a cough and splutter.

The whole thing leaves me stumped. These are simple motors and they don't normally go wrong.

In answer to the other poster - yes I do have an impact driver.

 

[VicS]

Yes have a go at it.

Start by checking/cleaning/resetting/replacing the plug. Check that you have a good spark from the lead.
If you can beg borrow or steal a compression tester test the compression. Anything over 60psi and it might run but prefer to see nearer 100 (or more).

Try spraying some fuel mixture into the carb intake. If it fires and runs briefly probably all you need to do is clean the carb.

Low compression ... probably more economical to break it for spares or flog for parts on eBay.

Try tearing it apart to see whats wrong.

Parts diagrams for Mercury HERE or for Tohatsu HERE

 

[VicS]

In view of what you said while I was typing

Try repacing the plug if you have not done so.

Try the fuel in the carb intake trick

Test the compression properly.

 

[john_morris_uk]

Yes have a go at it.

Start by checking/cleaning/resetting/replacing the plug. Check that you have a good spark from the lead.
If you can beg borrow or steal a compression tester test the compression. Anything over 60psi and it might run but prefer to see nearer 100 (or more).

Try spraying some fuel mixture into the carb intake. If it fires and runs briefly probably all you need to do is clean the carb.

Low compression ... probably more economical to break it for spares or flog for parts on eBay.

Try tearing it apart to see whats wrong.

Parts diagrams for Mercury HERE or for Tohatsu HERE

I think that our posts crossed.

The french mechanic removed the head and so I may need a new cylinder head gasket just to check the compression. No problem with borrowing a compression tester (I only have a diesel one in my workshop), but I think I can borrow a rubber ended 'car type'.

The thing had died the previous evening - but then went again after a few pulls, so that does make me wonder about the french mechanics assertion that the bore is gone. There is a line down the bore, but I think a compression test is the way ahead before I strip anything more down.

Thanks for the encouragement.

In the meantime, our son is bleeding in my ear that a new 15 hp OB is 'an essential safety item' for the boat - just so he can plane everywhere....

 

[firstascent2002]

If you can't revive it, can I make you a sporting offer for the parts? The leg and gear box on mine are in a bad way but the head is fine! I'm in exeter so not far. Obviously I do wish you every luck fixing it but if you can't....well I could stop my ebay trawling!

 

[mickywillis]

Might I suggest that you remove the flywheel first and check that the mild steel key in the tapered end of the crankshaft is intact?
If for any reason the key has broken, the flywheel can rotate on the crankshaft, causing the timing of the ignition spark. you will get a spark (not necessarily at the correct time on the cycle!), you will get compression and you may (or may not!!) be getting fuel into the crankcase and porting into the head!!
If its an older engine without CDI, you will have points/condensor. Check or replace these as a matter of principle.
Good luck