Mercury Viking will not run

[Lucky]

Hi all you knowledgable forum members,

I need advise on a strange behaviour of my Merc OB. It is aViking 10HP upgraded to 15HP. I had a problem last fall when me and the missus was out on a trip to town. We where going great and entered into the town and I pulled back the trottle when entering the habour. Then suddenly white smoke or steam came out of the exhaust!

Started it up again and it went on for just a few seconds and the same thing happened again! Got the motor off the dink and started looking at what could be wrong, no appearant issues to be seen. I spoke to a OB mechanic who knows Mercs and got the advise that it's either the thermostat or the impeller that has failed.
I mentioned that I believed the head gasket had blown, silly me, 2 strokes don't have them! I did the fix as advised and tried to start the engine just a few days ago. And what happened, the same thing again! The motor would run using start gas but not on petrol!

Could there be a cooling water ingress into the power head? This is a bit of a mystery to me.

I have now taken the engine off the rig and repalced all gaskets, still the same problem! I replaced the fuel pump diafragm a couple of years ago, and also rebuild the carb.

Anyone with an opinion as to what this might be is welcome with their advis. It would be very much appreciated.

Looking forward to hear from all you clever people on the CF.

Thanks from Lucky

Happy lead free sailing

[a64pilot]

I know nothing about a Mercury Viking, but I have never seen a two stroke without a head gasket
You sure it doesn't have a head gasket?


Sent from my iPad Pro using Cruisers Sailing Forum

[Pete7]

Originally Posted by a64pilot

I know nothing about a Mercury Viking, but I have never seen a two stroke without a head gasket
You sure it doesn't have a head gasket? Sent from my iPad Pro using Cruisers Sailing Forum

They made a series of engines using lost foam casting technique so the block and head are all one piece, hence some don't have a head gasket. Yamaha came up with the idea and then built the 50 and 60hp 2 stroke engines for Mercury from 1990 onwards. The advantage is less machining and fewer mechanical fastenings required so greater profits. Although Yamaha are arch rivals they are in cahoots with each other, probably to get around import tariffs for the US market.

I would try a compression test to see if it has seized, and that is now the reason for it overheating straight away.

Pete

[Lucky]

Hi all,

Got it started today! Changed the described 1,5mm sparkplug gap to 1,0mm and it started, but only run on one cylinder. Will ha to check what this might be tomorrow. Both spark plugs are new so it's a bit odd!

And it is a single cast for the cylinders and head.q
Qthanks for your replies.

Happy lead free sailing from Lucky

[Scaramanga F25]

Perhaps, the electronic module.

Happened to me on 2 different Merc 15s. 2 strokes.

[Cadence]

Originally Posted by a64pilot

I know nothing about a Mercury Viking, but I have never seen a two stroke without a head gasket
You sure it doesn't have a head gasket?


Sent from my iPad Pro using Cruisers Sailing Forum

My thoughts exactly. I haven't seen one without?