FT9.9 AE X Cylinder head removal

[cleddau1]

1999 model owned from new; water in oil and misfiring so assuming blown HG or worse. The workshop manual states to remove camshafts prior to removing cylinder head is this necessary?

[boscoe99]

In a number of motors the cam shafts have to be removed to gain access to some of the head bolts. Not sure about the F/ZT9.9.

What is the reluctance in removing the cam shafts? Just follow the service manual so there will be no big troubles.

[cleddau1]

Thanks Boscoe, I can get at all the head bolts easily just did not want to remove camshafts if not really necessary. On further study of the manual it looks as though the camshaft drives the oil pump so maybe this is why they need to be removed first.

[cleddau1]

Oops! Misread manual; removal of camshaft(s) only required on the bigger engines according to Clymer. I have removed all the cylinder head bolts but the head is reluctant to move, any suggestions for encouraging it to break free.....

[cleddau1]

Still stuck, just wondering if I have removed all the bolts; 6 under rocker cover and 2 on the exhaust side. Are there any others?

[panasonic]

Still stuck, just wondering if I have removed all the bolts; 6 under rocker cover and 2 on the exhaust side. Are there any others?

What is the S/N of the engine?

If this is it...I suspect it may be stuck on the two dowel pins...items 31.

Please provide all info on engine data plate so we can be sure if this is the correct parts break down and go from there.

[panasonic]

I may have a proper service manual.

[cleddau1]

Thanks Panasonic,
6G8 FT9.9AE
X 762948 U
Any advice on freeing the dowel pins?

[panasonic]

Thanks Panasonic,
6G8 FT9.9AE
X 762948 U
Any advice on freeing the dowel pins?

Send me a private message and I will send you what I have.

I count 8 bolts to come out. Use a plastic mallet and tap around the cylinder head just above the split line. Don't go wailing on it...especially up high where the valve cover is....good way to Crack the head.

There should be a couple of "prying" points at crank case, head joint. They are little notches that a flat blade screwdriver will fit in. Try them. Head gasket might be sticking a bit too.

You may have to resort to wedging it off. use something with a very shallow angle on it to start. Hardwood or plastic wedge so you don't be damaging the mating surfaces.

Those dowel pins are a close fit and the head needs to come straight up.

Good luck

[cleddau1]

Success!

used a short length of 2 by 1 and and a hammer and tapped around the head as suggested and off it came. Although not mentioned in Clymer I had to remove the oil filter housing to clear a bolt on the base.
The HG was intact but it looks as though water was tracking between HG and block.
Thick gunge in all the water passages and extensive carbonisation of pistons and combustion chambers.
As part of investigation of misfire I had alreadydiscovered the electric choke was defunct so motor had probably been running rich for some time.
Question is whether to dismantle head, lap valves, refurbish oil pump etc or just clean it all up and replace the HG.
Any suggestions?

[panasonic]

Might be not be as bad as it looks...scrape all the crap off the mating surfaces and see what it is like then. Small wire brush on a drill to clean off carbon from head and tops of pistons. With head upside down fill the domes with varasol or mineral spirits, leave overnight and see if any leaks by the valve seats..

Was the engine burning oil before this? Might be a good time to replace valve stem seals seeing you got the head off.

Try this link to your engine manual... It is the "Yamaha" service manual. Do yourself a favour and park the Clymer book right in the wood stove...lol

https://www.vansoutboardparts.com/se...&limitstart=20

It will be 1999 YAMAHA F9.9W / T9.9W your particular model and S/N range is at the beginning... page 1-1

Once you get it cleaned up a bit, send on a few more picture's.

[cleddau1]

Thanks Panasonic, engine has never used any oil at all and before deciding to remove head I checked compression and also pressurised cylinders to 50+psi and no air detected through inlet or exhaust ports or dipstick hole.
Thanks for link to manual and for US engine code. Yamaha parts are much more expensive here.

[cleddau1]

Cleaned the head and block today, not sure how much more I need to do....

[TownsendsFJR1300]

Looks NOW like a completely different engine... Great job!

I would set the head upside down, spark plugs in and fill the chambers
with Seafoam and let sit overnight. It should not leak out. If so, re-seating, etc, is due.
Never mind, Panasonic already addressed this.

Depending on the hours, might be a good idea to change out the valve seals/ check valve slop/guides while your this deep...

If there's NO excessive carbon build up on the valve stem (inside the ports), your seals are very likely good.


Chase block threads if you haven't already...

[panasonic]

Looks good to me. If chasing the threads use good quality taps..

Let us know how you get on with it.