Lead Additive to non-ethanol fuel

[lewis505]

Lads-

Still having the occasional startup problems with my 1944 MB; have only been running non-ethanol fuel in it since replacing the gas tank [corrosion] - should I be adding a lead Additive to the non-ethanol fuel as well?

Thanks!

[bmorgil]

Lewis this is another good discussion. It comes up from time to time I think I will stick it in the tech section also.

The discussion ventures into the valve seats and valve material. If you don't have lead or a lead additive, you consider the seats and the valves. Here is one explanation on why.

It has long been established that hardened seats are needed on the exhaust seat to prevent the seat from receding into the port. The hot exhaust and the pounding from the valve causes the seat to slowly sink. To prevent this manufacturers harden the exhaust seat. I bet yours is already hardened. It was common on all hard working engines even "back in the day". Not all older engines need it but it is there on all modern unleaded motors. Most re builders like to be sure and put in hardened seats on engines without them as a precaution, because unleaded fuel can accelerate this wear on the exhaust seat.There are a lot of people going either way on this. I am old school, I would not assemble a motor without hardened exhaust seats. It certainly will not hurt. Stainless valves are a nice high quality addition to the valve train. Modern stainless valves are lighter and stronger.

The Willys engine (Basically a Continental Industrial Engine) may have had harden seats from the start. The reason being the exhaust valve gets hot and pounds on the hot exhaust seat. Hardening and/or lubricating the valve and seat, and in some cases the use of valve rotaters, makes it last much longer. The lead in leaded fuels provided great lubrication. When unleaded appeared, many auto engines without hardened seats, had valve seat recession. The exhaust valve would pound its way right down into the seat. I would not put a motor together without hardened exhaust seats. There is no draw back only positive, contrary to popular belief they do not fall out when installed correctly. All aluminum heads have inserted seats.

There are many who don't do it, and may or may not use an additive. They are not wrong for three reasons. If you don't put the motor under loads for extended periods it probably makes no difference. If the motor is loaded hard for extended periods it will make a difference. There may not be enough material to install them. And it is quite possible the seat area has been "hardened" already. If you clean up the exhaust seat area, you may see an insert or a "Hardening Ring" where the metal looks a little different, where the seat may already have been induction hardened.

[LarrBeard]

Doc Dana gave a very good answer to the additive question, but we still can't make a good guess to why you have occasional start-up problems.

If I take the '48 out for a run and put it away, then let it sit for several days or a week, it takes a lot of cranking to get it to fire. I suspect that fuel in the line to the carburetor drains back to the fuel pump and whatever gas in is the bowl of the carburetor may evaporate because of the hot engine. In warm weather, I just crank it, but in winter I cheat with a little squirt of Mother's Helper (starting juice). Not too much and I let it crank through several timers before I hit the ignition...

Once it starts, it may splutter a few times as the bowl fills and the float closes things off - but otherwise, it just takes a few more turns to get things primed.

Does this sound familiar?

(A friend of mine who worked on M39A1's in Korea/Viet Nam told me that when the motor pool crew went down the line and started the motor pool vehicles weekly, they had a squirt can oiler filled with gas and every Jeep got a squirt to make them easier to start.)

[bmorgil]

Good catch Larry, I suspect you both may be suffering from bad or cruddy fuel pump check valves. In addition the manifold "stove" in the 134's is a carburetor cooker. It can boil the fuel in the carb bowl out on a hot day and lead to a hard start later.

In the 134 fuel pump there are two valves that prevent the back flow of fuel. If one or both of them is leaking for what ever reason, fuel will drain back when the motor shuts down. This will happen in a few minutes or a few days depending on how long it has been setting and how bad the leak down is. Realistically expect some. These are old designs. They weren't intended to set long duration's without starting. If you are running any ethanol in a pump with incompatible rubber, it would deteriorate the check valves. The fuel system in these old things is really touchy. The sight glass is the first entry point of the fuel. It is the crude fuel filter of old. The fuel flows through a strainer in the bowl and fills it. The valves set at the pump under the fuel. If they leak a little the fuel flows past and possibly back to the tank. So if the sight glass is empty you are probably going to have to crank it a bit if the fuel has boiled or evaporated out of the carb.

This is the argument for a filter between the pump and the tank in the suction line. In general this is a low pressure circuit. Any restriction in the suction line is very bad. It causes a few problems. This means if you want to clean the fuel here, you MUST use a low restriction filter designed for the suction side. Again I have seen people get away with a lot on the suction side. It doesn't make the installation correct. On the other hand you can buy filters for the suction side, and make it correct if you suspect heavily contaminated fuel in the tank supply. Here is some great info. https://aeromotiveinc.com/fuel-filtration/

On the hot pop (ether) Larry, I am a fan. Not a good idea on a diesel with glow plugs however! We have less than 7 to 1 compression. Ether can be a friend. I have seen the very best engine builders in the world spray a little (key word little) juice in 10K+ cost motors right before they light them. Excessive cranking isn't good for anything. A little on our engines is OK. We don't have dry sump high dollar oiling systems to pre-pressurize however. Starting with a little oil pressure is a good thing. On mine I am able to jump on the start lever and crank it till the oil pressure comes up, then I hit the start key. A few cranks and your off is what you are shooting for.

[lewis505]

Thanks fellas - I think I'm running into the same "operating issues" that LarrBeard has + I'm not operating the vehicle as often as I'd like to; thanks everyone for the intel!

Chris