Headgasket for mercury 9.8 -74

[Lasse Lehtonen]

My friend burned his motors (mercury 9.8) headgasket doe to the faulty impeller (we changed it last year)and now Im asking where to get a new headgasket for his motor. I have just similar 9.8 and it is a great little motor, so my friend would want to get it to work again. Thanks for replies.

 

[Chinewalker]

Re: Headgasket for mercury 9.8 -74

Hi Eki,<br /> Your motors do not have a head gasket, as the cylinder head is part of the motor block. What you do have is a water jacket gasket, which is easy enough to make with a piece of gasket material, scissors and a hole punch.... Might need some gasket sealant, too, if there is any corrosion on the mating surfaces of the cover and block...<br /><br />- Scott

 

[Lasse Lehtonen]

Re: Headgasket for mercury 9.8 -74

Thanks alot, chinewalker I expected there would be a head gasket (the exhaust gases are getting into the cooling system after overheat)but Ill open it today if possible and look for a gasket damage.

 

[joblo33]

Re: Headgasket for mercury 9.8 -74

There are two exhaust cover gaskets under a cover on the port side. One on either side of a plate. The gaskets are $5 canadian each at my local merc dealer. They're a common thing to go wrong on these old mercs. Be careful removing the cover as the bolts break really easily.<br />Eric

 

[Lasse Lehtonen]

Re: Headgasket for mercury 9.8 -74

Thanks for that info Eric B. I opened the "head" and cleaned the cooling system and there was very much corroded aluminium sand etc. Now Its clean and im going to put a new "head" seal there and then Ill look for those exhaust gaskets.

 

[Lasse Lehtonen]

Re: Headgasket for mercury 9.8 -74

Exhaust gaskets were blown all. Ill replace them tomorrow if I am able to get the parts tomorrow.I also cleaned every coolingwater flow hole with compressed air. I took some pictures from there and if somebody needs those pics I can mail them.I got all the 8 bolts out without problems exept one that broke , but I was able to get the end of that bolt out of there. Thanks alot for all who helped me with this.

 

[joblo33]

Re: Headgasket for mercury 9.8 -74

Sounds good! Make sure that bolt gets replaced with stainless. And check that the metal plate is straight, the heat might have warped it. I'm not sure what you should do if it's warped but it won't make a good seal. I had that happen once and I went to the marine recycler and got a plate off one with a blown powerhead. The owner just gave it to me for free.<br />Eric

 

[dajohnson53]

Re: Headgasket for mercury 9.8 -74

Originally posted by ^Eki_Virtanen^:<br /> Exhaust gaskets were blown all. Ill replace them tomorrow if I am able to get the parts tomorrow.I also cleaned every coolingwater flow hole with compressed air. I took some pictures from there and if somebody needs those pics I can mail them.I got all the 8 bolts out without problems exept one that broke , but I was able to get the end of that bolt out of there. Thanks alot for all who helped me with this.

Eki - can you describe the water passage to the flush inlet? My flush inlet is packed with sand. The cooling system works fine - good telltale flow, good cooling, impeller changed last year. But the flush inlet was totally packed solid. I've cleaned it quite a bit with a wire, but I'm wondering if the passage to the flush inlet takes a turn somewhere - I seem to have reached a dead end probing straight in with the wire. Thanks.

 

[dajohnson53]

Re: Headgasket for mercury 9.8 -74

PS - my engine is also a 1974 Merc 110 (9.8 hp). so I'm thinking the water passages will be identical to yours.

 

[joblo33]

Re: Headgasket for mercury 9.8 -74

I have the same problem with a 1974 7.5hp. I wonder if we should start a new topic.<br />Eric

 

[Saskatoon2005]

Re: Headgasket for mercury 9.8 -74

I have a 1973 7.5hp Mercury. I am just having problems starting mine. I am interested in pictures of the blown exhaust gaskets. Please email them to psinnider@hotmail.com. Thank-you and good luck so I will ne able to fix this problem when it comes.

 

[Lasse Lehtonen]

Re: Headgasket for mercury 9.8 -74

Ill email pictures to you Saskatoon2005 tomorrow, when Im able to get to my own pc where the pics are. My and my friend have the same problem with the flush inlet, the bolt is totally jammed and I really have tried everything to get it out on my own engine , I have heated, lubed and tried to open it, but it seems to be totally jammed on its place, so I have flushed mine putting it in a drum filled with fresh water and running it. I think the flush inlet is connecting straight to the hose coming up from the waterpump and there is a T connection between the flush inlet and the waterpump hose. (Ill try to watch it tomorrow when I have the lowerunit off.)If it is connecting straight to the waterpump hose you wont be able to push the wire much more than 5-7 cm before it makes a 90 degree turn. Be careful when cleaning the flush inlet, if the sand gets up to your coolingsystem it may block many of those tiny waterflow holes, the smallest are only 1 mm in diam. I would try backflushing it from the "pee hole" hose with a garden hose attached.(Be careful with pressure and dont run the engine when doing this.) Then the water is pushing that sand just out from the flush hole when cleaning it with a wire.

 

[dajohnson53]

Re: Headgasket for mercury 9.8 -74

Thanks for the information. If you find out anything new, post it - I'd be interested. Like I said, I don't have any cooling issues so I believe the packed sand is limited to the flush inlet itself. I always run the motor in a barrel anyway, but I just like everything to be in proper repair, if you know what I mean.

 

[Saskatoon2005]

Re: Headgasket for mercury 9.8 -74

I still have not received any pictures yet and am interested still...psinnider@hotmail.com. Thanks in advance...

 

[Lasse Lehtonen]

Re: Headgasket for mercury 9.8 -74

Sorry that those pictures have not arrived in time. My hotmail Dont let me paste any pics to my messages and I really dont know what is wrong with it. Ill keep trying to post them,but if it fails Im going to make my own internet side and put those pics there. I checked the flush port and its connecting straight to the hose coming up from the waterpump, and there is a 90 degree turn on that hose.I´ll keep you posted