Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

[Troutboy NZ]

Hello from New Zealand!

I was having problem with saltwater deposits getting into the lower cylinder and after replacing the head gasket (looked fine!) was still getting water in there - not much at all, but you could definatley see the lower plug was cleaner than the rest and once cooled, salt droplets would form on the ceramic.

I pulled the exhaust cover and the inner gasket looks like this! I think this is where the water was getting in??!!! It did not look like it had actually broken through the gasket, but was surely loosing the seal due to the burning of the gasket!?? This engine has only done about 50 hours.

What would cause this and do you think this would be the likely cause of water intrusion into the lower cylinder? I have reasembled with new gaskets and scraped off the old gasket residue as best I could with wet and dry sandpaper and a very careful blade. All cylinders look clean as a whistle with no corrosion at all.

 

[TOHATSU GURU]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Did the engine ever get hot?

 

[Troutboy NZ]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Hi Guru, No it has never been overheated to my knowledge, no alarms have ever gone off and the cylinder head gasket was near perfect? The cooling galleries with all pretty good too, just some minor salt deposits. Would this burning of the gaskets indicate an overheat?

 

[gary - k7gld]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Did the manifold gaskets seem to be reasonably well torqued? Could they have been loose enough to allow leakage and burning by exhaust gasses?

 

[Troutboy NZ]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Yes, they appeared to be fine, certainly weren't loose and the engine had NO running problems what so ever - ran beautifully and still does?

 

[TOHATSU GURU]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Almost certainly. But, if the factory didn't get the torque right to begin with, then steaming blow by could do it. The burn may not be a temp scorch so much as a steam degradation eating the gasket up. I would take it to a Tohatsu dealer as it's warranty barring overheat. Your distributor( who pays the warranty out of her own pocket to get a better price on the engines from Japan) may argue with the dealer, but I think you have a government run national consumer advocacy agency that has real teeth...Maybe that's your neighbors to the West though.

 

[Troutboy NZ]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Hi Elvin, unfortunatley it's out of warranty as it's just over a year old, and the old guy who had it before me never took it for its initial 10 hour service within the first year, so warranty is null and void Mercury tell me in NZ. He didn't even keep the service book or warranty info.

I will take it for a run this afternoon and see how it goes. If you look at the small burn mark not the big one, I'm sure I can see where some water has pushed through into the manifold causing the leak.

One other question is I can't see how the water droplets actually get into the cylinders? It's a long way from the gasket and baffle, in your opinion does it get sucked through the exhaust ports at high rpm as a vaccum?

 

[Troutboy NZ]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

Took her for a run yesterday at WOT for 2 hours and checked this morning and not a drop of saltwater evident ANYWHERE so it WAS definatley the problem. As the engine is getting no water anymore, I got a really good chance to examine the plug condition with new plugs installed - I pulled all the plugs and the middle plug is definatley running leaner than the others so this could explain why the middle pot is getting hot and burning the gasket in the middle area.

Still runs perfectly. My only concern now is that for the past 6 months I've been misting this tiny amount of saltwater into the engine, and even though I run it at least twice a week for a good hour each time that I may have done damage to the crank, bearing surfaces etc??? When I looked into the ports through the exhaust they were clean, no rusting or scouring. if it is a lean condition I may have just caught it in time! I'm hoping the small amout of salt water misting blowing into the bores hasn't managed to get past the cylinders!

 

[TOHATSU GURU]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

I doubt that there was any damage, but add a little oil to your fuel for the next few hours. Also, they are only giving you a 1 year warranty in NZ?

 

[Troutboy NZ]

Re: Look at this exhaust gasket from a 1 year old Tohatsu M40D2!!!

No, the warranty is a Mercury Warranty as the engine is actually a Mercury Lightning XR aka M40D2, (you know how it goes with Merchatsu's!). it's actually a 3 year warranty plus an additional 2 year warranty, so 5 years in total, which is great, however, they are extremely strict as to the servicing being followd by a qualified dealer in order for any warranty work to be honored.

To be honored, it needs to have it's 20 hour service within the first year, and this was missed and nothing documented, so Mercury want nothing to do with it. It's not a huge deal for me anyway as I prefer to do it all myself and do it properly - there is a large lack of skilled outboard mechanics in New Zealand unfortunatley.

Learn't the value of having bolts re-torqued that's for sure!!