Does every outboard have a head gasket?

[swick]

I'm considering buying a 15' bass boat with a 1986 Mercury classic fifty on it. The seller says its a 4 cylinder and he is replacing the water pump because it was overheating. I asked about the possibility of a blown head gasket and he said that there is no head gasket on that model. I don't know much about outboards but sounds strange to me. Is it possible that he is right or maybe just doesn't know what he is talking about? Thanks for your input.

 

[BR]

Re: Does every outboard have a head gasket?

Previous owner is correct. There is no head gasket. The part commonly mistaken for the head is a water jacket cover over the combustion chamber. The cylinders are blind bored in the block. Overheating is most commonly associated with a bad water pump in the lower unit or an obstruction in the cooling passages.

Good luck!

 

[swick]

Re: Does every outboard have a head gasket?

Thanks BR! Thats what I was hoping to hear, just sounded strange being that I am used to working on cars not outboards. If all goes well he will change the water pump monday and hopefully will solve the overheat prob and I'll be buying it. 1 follow up question that I forgot to ask the seller, would do you know if this is a 2 stroke or 4? From my limited research I have found that the 86 classic fifty is actually a 45 hp, my neighbor believed it was a 4 stroke but I'm not certain as of yet. Thanks again.

 

[rolmops]

Re: Does every outboard have a head gasket?

In 1986 there were no 4 stroke outboards.Yours is a 2 stroke.You will have to use a 1:50 mix of gasoline and TC-W3 (2 stroke)oil.
If the seller used straight gas to show you how it runs,you should not buy it.

 

[swick]

Re: Does every outboard have a head gasket?

Thanks rolmops. What kind of damage can be done using regular gas and how quick would it happen if someone did run it with regular gas? Are there symptoms I can look for? Thanks again.

 

[Silvertip]

Re: Does every outboard have a head gasket?

You are being given irrelevant information. The previous posters reference to "4-stroke" was unnecessary. You have a 4 "cylinder" two stroke engine. His reference to "straight gas" meant that if the owner ran the engine without the proper fuel/oil mix the engine can be damaged. If the engine has oil injection this is not an issue. If the engine originally had oil injection and it has been removed, then pre-mix is required. The reference to straight gas was not a reference to "regular" grade gas. That's what you are supposed to run.

 

[swick]

Re: Does every outboard have a head gasket?

Thank you Silvertip. I should have said "straight" in place of "regular" but we are on the same page. I will be going to see this boat in person this coming week and I will find out whats what. The seller seems very honest thus far, but I feel more comfortable gaining some knowledge from you guys before I make the purchase. So far everything seems good, I do not know if it is oil injected or not, I guess that will be another thing for me to find out. Seller said that it ran fine until it overheated last week. Hopefully it is just the water pump, which he said he will fix before we make a deal. He also agreed to take it out on the water with me before we make a cash exchange. Is there anything else I should look for?

 

[BR]

Re: Does every outboard have a head gasket?

A compression test is always a good indication of the health of an outboard motor. Numbers should be within 10-15% of one another for all cylinders. You also may want to check the lower unit gear oil for water intrusion by draining some out, that is if he didn't change it out when doing the water pump job.

Just my 2 cents.

Good luck!

 

[swick]

Re: Does every outboard have a head gasket?

Thanks again BR. What would water intrusion indicate, a bad seal or something worse?

 

[BR]

Re: Does every outboard have a head gasket?

Yes, water in the lower unit indicates a bad seal somewhere. Either prop, water pump housing, shift shaft, or drain and vent plugs. Condition of lower unit oil may also be a good indicator of previous owner's maintenance or lack thereof.

BTW if you do water test this boat, pay attention to how easily it starts, idles, and the 'hole shot' - how it performs from a dead stop to wide open throttle. If it performs well in all of those areas it likely has no serious issues.

Good luck!

 

[swick]

Re: Does every outboard have a head gasket?

Thanks again BR. Yes def, water testing it. I will pay attention to all of the areas you suggested. I will let you guys know how it works after.