Mercury 500 seized engine

[Howstar]

Hear is bit of update i bought engine on ebay last weekend i have poured ,all types of oil down the boars from the
spark plug holes ,heavey duty penertrate oil,brake fluid,petrol redex,and air line oil,
Yesterday took the side , covers off, the piston was still dry and rock solid in rust see photo
i have got some Wynns engine flush from halfords,and put that down theside holes
Things are starting look less rusty and tiny bit of movment i give it good going over at the weakend

[Rapier]

I guess it wasn't a case of leaving a plug out for a few days then. That looks like it'll need a strip down, but am no expert.

[se7en]

You really should take it apart, you haven't any idea what its like inside the crank case, if you want a realiable engine, there are no short cuts !!!

[Tremlett 15]

You really should take it apart, you haven't any idea what its like inside the crank case, if you want a realiable engine, there are no short cuts !!!

I would go with this one. Do you have a workshop manual ??

[SpiritOfSelkirk]

Like all Mercury 4 cylinder 30, 40 and 44 cubic inch (Merc 500 is a 44 cube engine) engines they are wonderfully built heavy duty engines of unparalleled durability. I use them as a stock recreation engine and as Modified racing engines for CBF, APBA, NOA & NBRA Modified Outboard hydro racing where they reach into the 90+ mile per hour ranges. To have a manual as reference is always good whether your a newbie or well experienced in mechanics. Also look to the aftermarket for parts that can and will cost much less in restoring your engine. For rust seized engines a total dunk sunk bath on CocaCola checking out the progress in 2 day blocks should render piston movement but from there take it apart slowly gently and then bath in engine cleaners and then examine for damage. That is the worst part, fixing it back up will be a pleasure as things progress.

[Howstar]

Been told few times about coco cola ,but sounds bit to risky to me,only spent a hour a night after work ,
putting oil on to pistons,so lets get finger crossed, hope the weakend works wonders.

[Rapier]

Been told few times about coco cola ,but sounds bit to risky to me,only spent a hour a night after work ,
putting oil on to pistons,so lets get finger crossed, hope the weakend works wonders.

Howard, based on the experts above, I personally wouldn't risk not stripping. It's an otherwise good looking period motor and could give you years of service once it's properly sorted.

[rnb]

Try soaking the seized pistons/bores in some Diesel , normally should do the trick. The crank is such an important item on a two stroke so i would look at the bottom end just to make sure the bearings and crank seals are okay . dirt is an engines enemy and a leaking crank seal may make an engine impossible to start.

[Howstar]

Thanks guys
I have got a manaual .and it does not look to hard to split the block from the rest of the engine,
also iI am doing car a mechanics course at night school ,so I could take it along and strip it down there,
i will post when i get any more info and picture,

[SpiritOfSelkirk]

I used CocaCola several times to do the job of loosening the engines successfully prior to tear down. Diesel fuel or kerosene (lamp oil) are also very good if there is existing movement but no rotation. The thing is to separate the crankcase front and crankshaft end caps from the engine block to lift and free the crankshaft assy from the crankcase torque holding it down. At that point the seize should let go to lift out the crankshaft, connecting rod and piston assembly slowly carefully and with penetrating oil helping to lube it along. Even engines with some moisture in them sitting for 30 years can come apart successfully for future restoration but there will for sure be a requirement for some replacement used or new parts to restore the engine. Always keep in mind the aftermarket suppliers for gaskets, bearing seals, bearings, piston rings, pistons etc. as there are great savings there you won't get anywhere else.