Mariner 30 2S Head

HughN · 16 July 2014, 17:08

Grrrrrr.

1990's Mariner 30 Hp 2S (Yamaha based)

I thought some new gaskets had sorted a leak between the inlet manifold and the reed block / main block. Alas not - it gave out after about 10 miles and I ended up getting a tow in this afternoon (from about 200 m from the slipway).

Using 1200 grit wet-and-dry and a very flat surface (kitchen worktop!

) in different directions, the inlet manifold casting seems to be as flat as such a crude method can determined. In the absence of a surface table and with the block still on the engine is there any way I can determine if the block is warped? Mucking about with the edge of a steel rule didn't show anything.

I may not be able to read replies for a while - I am off to beat the outboard senseless with the branch of a tree, as Basil Fawlty did to his Maxi....

uncle al · 17 July 2014, 06:16

The problem may be gasket faces not flat, but it could also be excesive crankcase preasure, take the sparkplugs out and DO NOT wipe the electrodes are they the same colour? does the electrode sparckle? if it sparkles it could be a piston picking up.

HughN · 17 July 2014, 07:30

Thanks Uncle Al,

The spark plugs look fine.

There can't have been enough light yesterday and/or I was very tired, but I found a high spot on the crack-case cover this morning. The centre web is every so slightly higher, giving a 20 thou gap at the side that was blowing.

I hate taking power heads off and various bits like gaskets are a pain to find now.

Yep, time to give it a good beating.

HughN · 17 July 2014, 14:17

Taking the bull by the horns I am 99% of the way to getting the powerhead off. The remaining 1% is proving to be the difficult bit.

The manual says to remove the six bolts holding the powerhead to the drive casing then to pry the two apart.*

Should I have taken the lower tray off first (I'm not sure that is possible)? I can't see anywhere to get any tool in to pry the two apart

*They must have wet themselves laughing when they wrote that - a bit like the car manuals that start the replacement of a lightbulb with "First, remove the engine and gearbox as in Chapter 2"

uncle al · 17 July 2014, 15:53

Yes service manuals can be a great source of enjoyment, he said with tongue in side of my mouth

HughN · 17 July 2014, 19:30

And off it popped!

Off to the machine-shop tomorrow...