Tohatsu / mercury 3 cyl water on plugs.

[ice_spy]

I have a tohatsu md50, 2003 3 cyclinder. Motor was running fine for approx 3 hrs then blew a head gasket. Possible cause was a blocked thermostat with a bit of plastic lodged in there.
Gutted thermostat, skimmed head approx 6thou and skimmed deck / black approx 10 thou. Only enough to flatten the surface areas.
Motor has little to no corrosion. No pitted edges on flat surfaces.
Replaced two head gaskets now, torqued properly to spec stamped on head. 18 ft pound.
New bolts installed.

Again tested today with new gasket and still plugs coming out milky. Dropped in the water for quick run and no power due to water in cyclinders. Definitely leaking, not just moisture in the block.

The only thing I can think of now is that the gaskets used are non genuine and maybe not sealing as good as original gaskets?
Base gasket has been replaced but power head pulled on off 3 times, gasket still looks ok nice and thick with no tears but maybe this is not sealing and somehow ingress water through the base plate gasket?
I don't know what else to do, my boat is out of action until I can get this water leak fixed. The head looked good with no signs of cracks, although I have not pressure tested the head. Could the exhaust ports cooling plate be leaking somehow?
I was under the impression that only a head gasket would allow water in the cyclinders not a base gasket or side cover exhaust plate gasket.

Any help or suggestions would be most appreciated, I can not afford to keep buying head gaskets and now I don't even know for sure what it is. The only option I thought was to replace the head gasket with genuine and try again.

[Fast Fred]

look at the bace gasket, and exhaust cover gaskets. i'd pull exhaust covers have a look in there. right after i checked the fuel tank to see if any water in fuel.

[ice_spy]

No water in fuel, so it's possible if the side cover exhaust plate gasket has failed this could allow water in the cyclinders ? Also if the base gasket failed this could also allow water in the cyclinders? I will check the exhaust plate cover side plate gasket 1st and see what I find.
Thanks Fred.

[Fast Fred]

yes, ether of those could leak and wet it out, exhaust is easiest so go there first, should be a tell tale spot were it's leakin in.

[ice_spy]

I really appreciate your advice to help me. So far no one else can/ has. Even marine workshops.
Could I do a compression test to attain if the head gasket has failed again or if not the water then must be coming in from somewhere else ? Like the exhaust post cover.

[Fast Fred]

yes, you could comp' test it. that will let you know the head gasket is sealed up, and the leak is one of the other two. then pull the exhaust covers see what you can see.

[ice_spy]

Ok so as I have another spare head gasket I pulled it to be sure of good seal. These are the pics. It seems there was very good seal and gasket glued / stuck to both surfaces. Comp test showed cyclinders to be at approx 103 psi average. I did hit a spike on first test showing 130 psi in one cyclinder but on 4 more tests could not get that figure again. I guess I have no other choice than to pull the side plate and inspect / replace gaskets. The lower cyclinder seems to be the wettest so that could indicate a leak from the side cover maybe ? Due to gravity ?
http://i159.photobucket.com/albums/t156/ice_spy/20150829_104057.jpg (http://s159.photobucket.com/user/ice_spy/media/20150829_104057.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/20150829_104130.jpg (http://s159.photobucket.com/user/ice_spy/media/20150829_104130.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/20150829_104156.jpg (http://s159.photobucket.com/user/ice_spy/media/20150829_104156.jpg.html)
In order block, head with gasket on, head with gasket removed surface gasket to head side up.

[ice_spy]

Ok so I only snapped 7 out of 14 bolts... that's a good start. Lol. Applied heat and inox spray but they were definitely not coming out easy. Didn't want to apply too much heat to the plate. At least they are a stud to remove and didn't snap flush with the block.
So as you said Fred, it appears the gasket was leaking. Looked like it failed around the top of the plate which would allow water to fall to the bottom cylinder? as it did seem bottom was wettest then middle then top the dryer.
I will replace the head gasket I think i do not need genuine this gasket seemed to seal good, but i will purchase genuine for the side plate cover. Now to try and remove the broken bolts without me doing any more damage. Wish me luck.
http://i159.photobucket.com/albums/t156/ice_spy/20150829_114817.jpg (http://s159.photobucket.com/user/ice_spy/media/20150829_114817.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/20150829_114915.jpg (http://s159.photobucket.com/user/ice_spy/media/20150829_114915.jpg.html)
Thanks Fred, really didn't want to remove this side cover exhaust because I knew bolts would snap but what option did I have really. Had to be done.

[ice_spy]

So after some Google reads, is the best method to remove broken studs that are not flush with the surface to weld a nut on the end of the broken stud and shock them off slowly with some spray, any particular rust penetrate spray in a can recommended?

[zul8tr]

I would not weld a nut. Those studs look long enough to grip tight with lock pliers. I have had luck doing that + penetrating spray like PB Blaster or better yet Kroil spray (see below) + some heat on the aluminum casting not the stud. Apply the spray let sit awhile, some heat on casting then lock pliers rocking CCW and CW a bit (careful here patience) to break the bond and not the stud add more penetrating spray and work in intervals of heat and rocking with the pliers. Before you close it up I would clean that scale off the cooling area with some pool acid (muriatic). Dab with a brush and flush with water carefully keeping out of pistons and cylinders.

If studs break off next step is drill and easy out tool or drill and retap, hard to get center here but doable.

Kroil

http://www.kanolabs.com/penLub.html#anchor173855

[Fast Fred]

heat them with a map gas torch. hot enuff but not hot enuff to melt alu. yellow can.

[ice_spy]

Is approx 105 psi on all 3 cyclinders too low compression? Could the water in the cyclinders have caused damage that lowered the compression?

[Fast Fred]

could be the gauge, they are all about even, thats what to look for, how do the piston skirts look through the exhaust port?

[ice_spy]

Bore and pistons look ok, no scores or grooves that I can see, only pollished but no cross hatch left. I will post some pics up tomorrow morning. :)

[Fast Fred]

how much time is on the power head? how fast are you turnin it in rpms?

[hydroplay]

Your studs/bolts should be fairly easy to remove since there is so much of the body above the block. My wife likes PB Blaster so use it after heating the bolt and boss. Let sit for a day and try one with heat and a vicegrip. If that doesn't do it try all that again and let sit for another day. Worse case- cut and file, mill if you can, bolt flush with casting surface so you can center punch it, drill and use an easy out. If you screw that up, drill it out and use a threaded insert like a HeliCoil

[ice_spy]

Cool, thanks for the good advice from all. Slow and steady should win the race. I buggered a head bolt, drilled and tapped a new thread that was off center and basically butchered it. Beyond a helicoil, when I had the block deck skimmed I also go them to center a screw in insert. This saved the my horrible effort to fix in a hurry. So inserts is also another good option if helicoil fails.

After looking at the pics and my head again, I noticed large amounts of carbon soot that had deposited in the head after last test. Assembled clean both piston tops and head chamber I thought it was strange to have so much deposits. Thinking it was just from the minutes of running. Now I look, I know for sure it is all the carbon and sludge build up inside the exhaust ports that was being sucked clean with water into the combustion chambers. This tells me 100% the water was indeed coming from the exhaust plate side cover gasket failure.
Hers is some pics of the bore and piston skirts, including the ring and crown area where most overheat often binds around the rings and above. All wear seems normal, no scratches I can feel with my fingernail, no deep grooves or areas that looked excessively worn. Rings feel free and not stuck.
You can see in one of the pics the very bad misalignment in the intake ports block castings to cyclinder sleeve. Perhaps I should be doing a tear down, new rings and hone and a clean up and port match of the block and sleeve. I know from experience not much is needed to bugger up bottom end performance when messing with ports and grinding. So I would only be doing a clean up really. Small shamfers on the edges is all that is needed from experience with jetski 2 stokes.
http://i159.photobucket.com/albums/t156/ice_spy/CM150830-08572701.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-08572701.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/CM150830-08585202.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-08585202.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/CM150830-08594003.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-08594003.jpg.html)
123 top to bottom in order above pics.
http://i159.photobucket.com/albums/t156/ice_spy/CM150830-09003904.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-09003904.jpg.html)
http://i159.photobucket.com/albums/t156/ice_spy/CM150830-09011805.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-09011805.jpg.html)
You can see in this last post the amount of 'flushed' out carbon and sludge from inside the exhaust chamber that was the deposits in the head once I removed it.

[ice_spy]

http://i159.photobucket.com/albums/t156/ice_spy/CM150830-09033306.jpg (http://s159.photobucket.com/user/ice_spy/media/CM150830-09033306.jpg.html)
Port misalignment pic

[DRAGRACR]

Looks like #3 is leaking to me. Look at the gasket ring it has soot on it. Prob pulling water in. Block may not be true.

[zul8tr]

What brand and type oil and mix are you using?

[Fastjeff57]

On removing broken studs/ bolts with Vise Grips, don't try to just unscrew the stud: take your time and wiggle it back and forth, getting it looser and looser before trying to unscrew it. That method has worked for me where I couldn't use the old "hot wrench" on the block (such as in the bilge of an inboard).

Jeff

[Tiller guy]

Vise grips and lots of heat around the bolt area, but not the bolt. When they move go back and forth and a little at a time. That seems to work the best for me. I hate easy outs because when they break off your screwed. Hardened steel is impossible to drill out by hand when surrounded by soft aluminum. 103 PSI seems to be on the low side?

[ice_spy]

Well got them all out bar one. Took to the machinist to remove the last bolt as it snapped off flush. Heat and vise grips worked a treat.

Assembled the motor today.
Bad news. Water still on plugs, bottom cyclinder the worst.
So far I have skimmed the head , the block.
Replaced the exhaust plate gasket and the powerhead base gasket. All surfaces clean and flat. No scratches or pitting. Head looks perfect, no cracks although not pressure tested.
All bolts were torqued to spec and re torqued after 10 mins running.

I GIVE UP ! Spent $400 and still nowhere. Can't understand where it could be leaking in still. The only thing I can think of is I'm using non genuine gaskets and perhaps the head gasket has failed.
Well that's it for me. Can't afford a new engine.
Feeling dissapointed is an understatement. :(

[Steves Jem]

Well got them all out bar one. Took to the machinist to remove the last bolt as it snapped off flush. Heat and vise grips worked a treat.

Assembled the motor today.
Bad news. Water still on plugs, bottom cyclinder the worst.
So far I have skimmed the head , the block.
Replaced the exhaust plate gasket and the powerhead base gasket. All surfaces clean and flat. No scratches or pitting. Head looks perfect, no cracks although not pressure tested.
All bolts were torqued to spec and re torqued after 10 mins running.

I GIVE UP ! Spent $400 and still nowhere. Can't understand where it could be leaking in still. The only thing I can think of is I'm using non genuine gaskets and perhaps the head gasket has failed.
Well that's it for me. Can't afford a new engine.
Feeling dissapointed is an understatement. :(

Try replacing the bottom Crankshaft seal and check the adaptor plate and base gasket. If the adapter plate and base gasket are bad, then water can enter and be stored under the crankshaft end cap and if you have a bad crankcase bottom seal be sucked up affect the bottom cylinder.

Stephen

[ice_spy]

Thanks Stephen. It so hard to give advice when you can't see it or know much about what's going on. Appreciate the help.
The base gasket is brand new. The adapter plate every time I pulled it off (the powerhead) had no water sitting. The crank case bottom seal is around the drive shaft that is separate to any water ports. It is free to air so to speak. I'm beginning to think it is cheap head gaskets that I'm using. The bottom worst due to gravity maybe. I've pulled the head off so many times now, I have to eliminate the chance of it being due to cheap inferior gaskets. At least all bolts free and easy to remove now, it's no big problem to remove the head.
I asked a marine workshop and they said they would recommend original head gasket before anything else.
With compression down which seemed strange, and another test showing bottom cylinder is the lowest psi reading, perhaps it's simply blowing the head gasket now I've had the deck milled , the piston height / squish might be too much for the cheap gaskets. If I take it to a shop the 1st thing they will do is put a genuine head gasket on anyways I suppose. I can save money trying this at least.
I do have new seals but I think this will require to bust the crank halves? And another new base gasket.

Well so much for " I give up". I'm more like " He who endures, conquers ". Lol.

[DRAGRACR]

Zoom in on #3 on the head gasket you posted a pic of.... The gasket is leaking whether you had the block and head skimmed or not... (dark spot on the gasket ring at edge of cylinder) You need to have the surfaces re-checked and if possible not by the shop that did it.... This is also why compression is low. I would also go up on torque to 25-30lb. If it is like my yamaha you cant get a torque wrench to the 2 bottom bolts so you have to do them by hand. Are you sure you are clamping down tight enough on the bolts?

[ice_spy]

Thanks Dragracer, yes I remove the powerhead to reach the bottom two bolts. Perhaps your right and I need to torque them up to at least 20-23 lb. I think 25 to 30 could be too much.I lightly sanded the head and the engine deck with some 1000grit and flat surface before last rebuild to make sure the slight machine marks were not affecting a blow out on the head gasket.
I'm leaning towards the head gasket the reason for failure so I have one more spare aftermarket head gasket to test with higher lb. before I go buy a genuine one. Is there an up and down surface for the gasket? Like car engine head gaskets? There is no marks on the gasket.

[ice_spy]

Sorry missed the replys on last page. Zul8tr , TCW3 oil Castrol brand and premium 95 octain. 50:1 with a slight drop more for a little more lube.
Dragracer checking my photos again to look for the leak. Thank you guys. Will let u know how I go.

[ice_spy]

Looking at the pics again, notice how bad the misalignment of the gasket is on the bottom piston. This could be causing the failure too as it seems to be most misaligned on cyclinder #3. Lower edge. Could be these cheapo gaskets. They do look rather thin to me on the sealing ring and very wide. Ok here goes attempt # 4.

[comprecbrkr]

You should also check the reed valves, a broke one could also cause same problem , cheers lee

[ice_spy]

Checked the reeds, they are ok, not broken and sealing pretty good.
Called a boat mechanic and booked it in. I have to bite the bullet and leave it to the experts. Some things although seem simple enough to do myself, really need the expertise of mechs that have experienced the same problems with this model of engine. He said it is a common problem with this motor apparently. So if a new set of original factory gaskets fail ($$$) they will have to replace them at their cost not mine I would imagine.
Can't say I didn't try. And at least all the bolts are free and easy to remove, no bolts to snap on them.
Will post back with another compression test in about a week or two when they ring me and tell me it's ready to go. I don't trust the readings I'm getting at the moment. With a Skimmed head and block it should be around 130 psi I rekon.
Thanks to all for your help and advice.

[zul8tr]

Why not put some high temp sealant on that head gasket. Have you checked the flatness of the head and the block with a machinists rule and a backlight, could reveal low spot(s). Ex. I always check the split crankcase halves (I deal with Merc split crankcase engines) with that process and have found the lows and the highs especially around the bolts. Then fix them. Also came across this issue on the head and block of my Yamato, I wound up sealing the alum. gasket to solve it.

[zul8tr]

Sorry missed the replys on last page. Zul8tr , TCW3 oil Castrol brand and premium 95 octain. 50:1 with a slight drop more for a little more lube.
Dragracer checking my photos again to look for the leak. Thank you guys. Will let u know how I go.

More oil wouldn't hurt for high rpm operation. I am sure you have seen the sticky thread in this section about 2 stroke oil see page 3.

[ice_spy]

I'll have a read on that thanks Zul8tr, no I haven't seen that thread. Plea see e post a link if u can.
So it was mentioned that I should check and or replace the bottom crank seal. When I dropped the motor off to the boat repair shop, we talked about the motor and he also informed me of the crank seal. I was not aware of water entry due to crank suction and water running g up the drive shaft. I thought being not near water ports and free to air it would not be a place of entry. There is an O-ring, and two seals. So highly possible this is the place of water entry, would make sense due to the bottom cyclinder being the wettest every time.
Hopefully this is the problem. Will post back when I know for sure.

[Roflhat]

hi mate, here's a link to the thread on oil and mixtures.
I've been recommended to run 32:1 in my 70ces, it revs to around 7500
Cheers
http://www.boatracingfacts.com/forums/showthread.php?13077-What-2-stroke-oil-yall-runnin/page3

[Steves Jem]

I'll have a read on that thanks Zul8tr, no I haven't seen that thread. Plea see e post a link if u can.
So it was mentioned that I should check and or replace the bottom crank seal. When I dropped the motor off to the boat repair shop, we talked about the motor and he also informed me of the crank seal. I was not aware of water entry due to crank suction and water running g up the drive shaft. I thought being not near water ports and free to air it would not be a place of entry. There is an O-ring, and two seals. So highly possible this is the place of water entry, would make sense due to the bottom cyclinder being the wettest every time.
Hopefully this is the problem. Will post back when I know for sure.

Yes what the mechanic has discussed is correct. The bottom seals on Crankshafts are either a double seal or two separate seals. One to stop any water entering and one to stop crankcase pressure escaping. When these are being replaced you have to ensure the each seal is inserted the right way. You will sometime come across the bottom of the crankshaft below the seal being a little bit rusty. With any motors being used for racing it is a common practice to replace seals and O-Rings within reason each time the motor is being rebuilt. The replacement of seals and O-Rings are as a precaution to prevent any possible issues.

Stephen

[ice_spy]

Update.. bottom seals replaced, the motor has had all new original gaskets replaced also. Tested on the tap, the bottom cyc was still getting heaps of water. The point of entry was not the bottom seals as hoped. Compression seems to be correct at approx 105psi in each cyc. tested cold. We attained the idea that water entry is from the lower section of the leg as it could not be coming from any other point. removed sandwich plate, under bed pan and exhaust tube tuner. The top of the exhaust tube had rock hard gaskets, and upon removal the flat surface was not dead flat. Being pressurised with water at the top of the exhaust tuner tube, water could be drawing in to lower cyc if this is leaking. God willing, this will finally be the solution to the problem.

[ice_spy]

Gaskets in lower leg top of exhaust tuner replaced and on the tap, a little bit of water. Too for a test run and plugs came back dry no water. Flushed on the tap with fresh water and bottom plug was wet again.
Read a few posts about not running a thermostat. Bad news. 100% should always run a thermostat in 2 stroke motors. Replaced thermostat and no more water on plugs both on the water and flushing on the tap. Problem solved. Run a thermostat !! .
Power is down significantly , only pushing 3 to 40000rpm
I was hoping the lack of power was also due to not running the thermostat. I did however bend out the reed cage stoppers approx 4 mm thinking I would attain higher rpm. I'm confident that this has had an effect on performance and why the motor is now lacking power. The reeds were fibreglass but not the correct ones, they were 3 peddle off something else that were cut down to 2. Going to change them and bend back the stoppers to original postion. Oh the joys of a motor not running correctly. Missing driving my boat. Taking so long to get the thing running good again. At least the water in the cyclinders has been finally fixed. The only thing this motor hasn't had done will be a hone and a new set of rings.

[zul8tr]

Do the reeds and test, then consider the rings if a compression and leak down test confirm they need fixing.

[fs5]

Mate, give Scotty's mobile marine a call up here at brissy. He can line you up with a nice set of carbon ones.

[fs5]

A lot of guys don't run the stops either.

[ice_spy]

Thanks mate, I'll give him a call and order a set of new reeds. Much appreciated.

Zul8tr, wow thanks for the direct link, what a great read. Very interesting thread on oils. Reminds me of the old valvoline commercial that the moto was "oils ain't olis" . Lol.

[ice_spy]

Well I tested the boat again with the reed stoppers bent back to original postion. Slight improvement of power down low. I'm thinking these reeds are useless as some are only just sealing on the edge when closed. They barely have 1mm and some have 3mm. I have to order new reeds as these are hopeless. Even though before the water induction it ran fine, I can't presume these reeds should still be any good.
I also beleive 100psi is too low ? I know it will run ok but it should be up around 120 to 130 I imagine with the shaved head and block. Possibly the water running in the bores has done damage to the rings and bore and not sealing properly. No scores were present but if it was on on 140psi per cyl then that's almost 50% increase in compression. Maybe the 18p surface prop doesn't like running on 100psi. I can't remember what it was initially when I bought the motor I think 115 to 120psi. Not sure.
If I have to throw a set of rings and hone it then so be it.
First I will try new reeds and remove the reed stoppers? And give the carbies a clean and inspection possibly the high speed jets are blocked? 100% no more water getting in , at least that's fixed.

[ice_spy]

I've ordered a new set of race reeds from CCM, looking forward to them arriving and hopefully will solve the new problem of very noticeable power loss. If not it has to be lack of power from 100 psi compression. Nothing else has been touched, timing, jets etc...

[RWN50]

i have a tohatsu 50 here in brisbane and done a bit of testing with heads etc. stock should be about 130psi, either your loosing compression somewhere or your gauge is off. i had 40thou taken off my head and nothing off the block and was approx 155psi. i now have a center firing billet head thats ~170psi. 105 is way too low.

you should have gone original gasket from the start, the only other thing i could imagine it being is a hairline crack in the head or the domes??

Id give you my head and an oem gasket to try if you where closer.

as far as reeds go. i use carbon fiber with retainers removed