Do not use lead free gasoline

[sschefer]

Re: Do not use lead free gasoline

I purchased a 1973 Grew 17 foot I/o with Kiekhaefer Mercury 165 hp engine. The manual says "do not use no-lead or lead free gasoline. Use any good grade automotive regular gasoline that has a minimum octane rating of 93 (research method)" To my knowledge most auto gasoline now is lead free.
I have asked several sources and the only suggestion is to use a premium gasoline such as Esso Supreme at 91 octane. I read that I should use Marine gasoline but I could not find any information on properties. Any advice would be appreciated. Soddy

Ideally, you should pull the head and have hardened valve seats installed and replace the valves. It's not a big job, mostly shop time and will save you headaches down the road.

 

[jkust]

Re: Do not use lead free gasoline

So since you've never run it without the "additive" you have no idea what would would happen?

It never really crosses my mind until a leaded gas thread comes up.

 

[HT32BSX115]

Re: Do not use lead free gasoline

It never really crosses my mind until a leaded gas thread comes up.

Back in the 60's and 70's my dad worked in the oil fields. We had access to "drip" (condensate) gas and ran it in everything. It was unleaded. (It was unrefined!) It pinged like a "sonofagun" if you stepped too hard on the pedal but it was free so we ran a lot of it. Some people ran it more than a 100,000 miles. We never worried about valve seat wear. The 66 MarkTwain with the 150 Mercruiser ran most of it's 39 year life on either drip gas or unleaded later. Since the hour meter failed in the mid 80's at 1500 hours, I don't know how many hours it had on it when I sold it in 2005.

I also don't know what the valves looked like, we never had the head off. (in 39 years!)

Ideally, you should pull the head and have hardened valve seats installed and replace the valves. It's not a big job, mostly shop time and will save you headaches down the road.

Ideally, just put gas in the boat and go boating and don't worry about it....Use the money you'd spend on the valve job to buy gas and beer!

If you ever wear out the engine, have it rebuilt. They'll take care of the valves and seats.....

 

[glenn property of pam]

Re: Do not use lead free gasoline

when unleaded first hit the market there was problems with hi compression motors burning the exaust valve's (turbos especially). proberly wasnt a big deal in the usa as they tend not to run the high compression of the small euro 4 bangers. it seemed the high combustion temp and carbon build up was a problem on some cars so most people changed the valves to hardened or stainless. fuels today have addatives that help so its not that much of a problem. i would not worry about putting modern unleaded in a motor designed for leaded other than the fuel lines.
on a good note if you ever burn a valve it doesnt kill the motor and a quick head rebuild will fix it so i would just pull the sticker off the gas cap and go boating.

 

[Silvertip]

Re: Do not use lead free gasoline

The problem with no lead will be valve wear. After maybe 1000 hrs of no lead your valve seals will be worn and you'll need a compete valve job. Performance will eventually suffer, but not much you can do other than the valve job now

Valve SEALS do not go bad from no lead fuel because the fuel doesn't even get to them.. Valve SEATS are not hardened on older engines and thus the need for lead or a lead substitute. However, as has been pointed out, that was basically a problem in trucks where the engine was being lugged. It isn't a problem in a boat.

 

[Tail_Gunner]

Re: Do not use lead free gasoline

Valve SEALS do not go bad from no lead fuel because the fuel doesn't even get to them.. Valve SEATS are not hardened on older engines and thus the need for lead or a lead substitute. However, as has been pointed out, that was basically a problem in trucks where the engine was being lugged. It isn't a problem in a boat.

Is that due to heat being built up in the heads....

 

[Silvertip]

Re: Do not use lead free gasoline

Is that due to heat being built up in the heads....

Truck engines back in the day had the gas pedals on the floor most of the time just to maintain road speed. Very low engine vacuum results, engine rpm was relatively high, and borderline detonation was constant. Back the timing off a bit to compensate and there was a significant power loss. It was not uncommon to need a valve job on the six cylinder engines of the day at 45,000 miles or so. Chevy had used sodium filled exhaust valves in their truck engines back then. A valve job could done in a half a day on those engines. I did my first valve job on a 1936 Chevy at the ripe old age of 12. A mechanic looked over my shoulder and did the final adjustments but the car ran.

 

[Jlawsen]

Re: Do not use lead free gasoline

Valve SEALS do not go bad from no lead fuel because the fuel doesn't even get to them.. Valve SEATS are not hardened on older engines and thus the need for lead or a lead substitute. However, as has been pointed out, that was basically a problem in trucks where the engine was being lugged. It isn't a problem in a boat.

Slivertip, I respectfully agree to disagree, (not about the valve seals, they're for oil and have nothing to do with fuel). The 165 is a truck engine as are all GM Marine engines. They are used because of the extra torque required by a boat engine.

Norhbeach can tell you what happens to a 165 without hardened seats. I'm pretty sure its documented in the Liquid Limo restoration thread.

I don't understand why folks on here would not recommend such a simple and basic mod that has such a great potential for helping to ensure a pleasurable boating experience.

 

[1stgenbird]

Re: Do not use lead free gasoline

Ideally, you should pull the head and have hardened valve seats installed and replace the valves. It's not a big job, mostly shop time and will save you headaches down the road.

Really? Spend money on a valve job to prevent something that may or may not occur many years down the road? Do most people keep their boats for 10, 20, or 30 years?

Forget the additives, put unleaded gas in, and don't worry about it.

 

[HT32BSX115]

Re: Do not use lead free gasoline

Forget the additives, put unleaded gas in, and don't worry about it.

YES, I guess no one read my message in this thread about running the in-line 6 for 39 years and on unleaded gas for most of those years.

If we could have worn the darn thing out and did a valve job, we might have noticed the valve seat wear. But it kept running!


MOST of these boats end up with a cracked block LONG before they ever get enough valve seat wear to make a difference....


Just pump the gas in and go boating!