Help and General Outboard Advice 4 hp Aero Marine

[Opus]

Hi all,

Long time lurker, reaping free advice, first time poster. Glad you guys are here!!!!

I have an old Aero Marine 4hp 2 stroke - integrated fuel tank and air cooled. Great little motor I picked up last September for my 9.5 ft Bass Hound.

Anyway, after picking it up I wanted to try it out before the winter season. I took it to a small 260 acre lake and it fired right up on the third pull and some choke, ran well with no backfires or stalls, although it did sputter somewhat at low idle. However, when I shut it down to fish a little (Hey, I ain't hitting a lake without fishing) it refused to fire back up 15 minutes later. So I fished some more, pushed myself around with the Minn Kota and tried it again about an hour later when it was cool and she started after the third pull and some choke.

When I got it home, I realized I had quite a bit of work to do - Nasty white film in the fuel tank and carb bowl. Even though I filled it with fresh fuel/oil per the specs before the fun run, I had simply added to the existing fuel and who knows how old that was. I was hasty and wanted to give it a spin. So afterwards I set about flushing the tank and fuel lines, spraying the carb with carb cleaner and put in a new spark plug. The old one looked fine when I took it out, although I knew it was old from the rust on the outside, but no pitting or discoloration - a nice gray with no buildup.

I took it back out on the lake several times before it got too cold to fish and it ran a great deal stronger, but I still had some hard starting problems when the motor was hot. I just learned to live with it, you know? I would launch, motor to my first fishing spot and realize I was in the area for at least an hour, using the trolling motor until the old girl could fire up and take me to another area.

Winter came and the boat and motor were put away. Springtime approaches and I decide to do a make-over on the motor. In addition to repairing all the dents and dings in the upper unit and stripping and repainting the entire kicker, I flushed the tank, replaced all fuel lines and removed and cleaned the carb. By the way, the carb is an old Walbro 129/131 (Only thing stamped on the carb body). It leaked from the main jet and from the bowl drain spring, and I simply got some automotive gasket material and replaced the original worn out washer/gaskets, which were basically of the same material. I soaked the carb overnight and inspected the float and needle valve above the float, which allows gas to enter the bowl, and it looked to be in good shape. I put everything back together and set the main jet and idle jet to the specs given on the motor cover.

Aero Marine, as many of you know, is an obscure motor originally made by McCulloch, who decided to drop out of the marine outboard business and sold their remaining stock to Aeroceanic Corporation of San Diego in the mid 60's - all of which means parts are rare and a carb rebuild kit almost as rare. The old Walbro is a simple gravity flow fuel system, so when a thorough inspection of the carb looked good, I figured that was enough. The rubber on the inlet valve above the float looked good and the float itself comes back to 90 degrees and has no leaks or cracks. As for the hard to find carb rebuild kit, the remaining items that would have come with it would have been the bowl ring and assorted gaskets, which I made myself from gas resistant automotive gasket material.

So after the spring make-over I have had the boat/motor out 5 times or so for a full day each time. The motor sounds and runs great, but still has the "hard start when warm complex". I can now get it to re-fire when warm but with multiple pulls, a slew of different choke positions and set at full throttle. To regress for a second, when I said it fires up cold after three pulls, it has to be on full throttle to do so. I can dial it down immediately and let's face it, a full throttle start on a little 4 hp is not a big deal - it's not like I am doing a hole-shot or anything Regardless, I launch the boat and pull away from the ramp area with the trolling motor first then face myself out towards the middle of the lake and go back to start the kicker.

This post is getting long...sorry...

I am thinking the the hard start when warm has to be fuel related and as I type this, I wonder if the bowl is getting to much fuel when hot? While I may be typing things you already know, the gravity fuel system works with the tank over the motor. A fuel petcock sits just to the right and slightly above the carb and must be opened for fuel to run to the bowl. In addition, the gas cap has a vent screw which must be opened to allow the gas to flow freely (excuse the back and forth between fuel and gas). I have noticed that when the vent screw is closed, a great deal of pressure can build up in the fuel system when hot. Is it possible that the fuel is getting heated, creating pressure and forcing the needle valve above the float to allow gas to seep in even when the float tries to hold it closed???? I would think that the vent cap would prevent pressure build up.

Again, the spark plug is new and gapped at Aero Marine specs - .025 or .035, I forget which. The tank is clean, the small fuel filter on the tank's fuel line nipple is clean/debris free and the fuel line is new. The Main jet and Idle jet are clean opened to the specs written right on the motor cover, as is the fuel/oil ratio - 100/1, or 1.5 ounces to a gallon of gas.

I also wanted to ask advice on a few things - I am not new to motors, growing up in a family owned gas station/garage, but new to 2 strokes and outboards. I have been lurking around the boards here for awhile and I do not remember seeing a fuel/oil ration as high as 100/1. I have noticed some threads about oil mixture resulted in recommendations of higher oil than factory specs (Only in some situations - not all). My motor sounds and runs strong, but frankly, I am surprised there is very little smoke from the motor. My biggest memories of going out boating with friends and their 2 strokes was lots and lots of smoke. Because the Aero Marine is air cooled, I can fire it up without worrying about trash cans of water (Prop and sheer pin pulled, of course). Little to no smoke even when running out of the water. I seem to get more smoke from my 4 stroke lawn mower than this 2 stroke. I know running lean on oil can do a great deal of damage to an engine and I wonder if there are any recommendations on the 100/1 mixture. I understand the only downside to more oil is smoke????

I also wanted to ask about lower end maintenance. Of course, I have no idea what is down there or when it has been serviced last, but I understand from these boards that these lower units are normally filled with 90 weight marine gear oil. There are two screws opposite of the propeller. Is this where service should be done? I hate to be so naive, but if I open this, what am I looking for if it is ok...nice dark, water free oil? If so, should it be left alone or replaced regardless as long as I am at this point? What horrors could I find?

I have gone on too much - thanks for reading and if you have any insights into the above, please let me know...

Best

Ron/Opus

 

[CATransplant]

Re: Help and General Outboard Advice 4 hp Aero Marine

First time I've ever encountered the Aero Marine brand. As you say, they were made by McCulloch, but I'm not sure just when.

I think the key here is going to be to research some of the other small air-cooled outboards from the same maker. Sears, Firestone, and other sold them. Check Discount Marine Parts at www.discount-marine-parts.com, under McCulloch. They claim to have a large stock of McCulloch parts, and may be of assistance.

As for the lower unit, it's a direct drive, if I'm not mistaken. Many of those used grease, rather than oil. If you take the plug out (assuming it has one) you will probably get a clue as to what was in there.

If you have a model number somewhere on your engine, that would also help when you contact Discount Marine. A photo here might well be of help in dating the outboard, too, since there are folks here who might recognize it as similar to another unit.

Finally, visit www.aomci.org and use the Ask A Member option to inquire about your outboard. The collectors of antique outboards over there are a wealth of information.

 

[steelespike]

Re: Help and General Outboard Advice 4 hp Aero Marine

First thing is go to a 50:1 mix.100:1 doesn't leave enough lube for infrequent use.TCW3 rated oil.Walbro LMG carb. initial carb settings are high speed 1 1/4 turns out from gently bottomed idle 1/2 to 3/4 turns out.Final adjustment warm under load.Lower unit grease is something like 105 assembly grease.
remove screws and case cover remove grease with a wooden paddle refill with 3 to 4 ozs of grease.I suspect a little flooding when stopped.To help warm start try shutting off gas when stopped leave vent open.Try warm start before opening shut off.You may want to
You may want to check the points clean and adjust .020.Champion J18Y plug set at .035.

 

[Opus]

Re: Help and General Outboard Advice 4 hp Aero Marine

First time I've ever encountered the Aero Marine brand. As you say, they were made by McCulloch, but I'm not sure just when.

I think the key here is going to be to research some of the other small air-cooled outboards from the same maker. Sears, Firestone, and other sold them. Check Discount Marine Parts at www.discount-marine-parts.com, under McCulloch. They claim to have a large stock of McCulloch parts, and may be of assistance.

As for the lower unit, it's a direct drive, if I'm not mistaken. Many of those used grease, rather than oil. If you take the plug out (assuming it has one) you will probably get a clue as to what was in there.

If you have a model number somewhere on your engine, that would also help when you contact Discount Marine. A photo here might well be of help in dating the outboard, too, since there are folks here who might recognize it as similar to another unit.

Finally, visit www.aomci.org and use the Ask A Member option to inquire about your outboard. The collectors of antique outboards over there are a wealth of information.

CAT,

Thanks much. You are not alone - many folks have no idea of the Aero Marine, but as difficult as it is to get info, I like the motor. I had stopped by several local boat repair shops and even a small engine repair shop and talked about cross referencing for a rebuild kit, but got nowhere. I read somewhere that Walbro created carbs for numerous brands back then, so it's just a matter of finding the info. I will check Discount Marine and I appreciate the advice!!! I also registered and posted on aomci.com over the winter and gained a great deal of knowledge on 2 strokes generally but little knowledge of specifics.

By the way, the model number of the Aero Marine 4 hp is "4000" and the serial number is "012466"...a date hidden in there???? I have attached a photo of the motor as you suggested and thanks so much for your time!!!

Ron

 

[CATransplant]

Re: Help and General Outboard Advice 4 hp Aero Marine

Looks a lot like the mid-sixties Sears engines made by Clinton. The 50:1 oil ration also sounds like the mid to late 60s. From what I understand, when Clinton went out of the outboard business, they renamed the rest of their stock, some with the Aero Marine brand. I'm betting that that web site I mentioned will have a carb kit for your Walbro carb, and probably a lot of other parts, too. They may even know what Clinton model matches yours.

One other thing to have in hand when you call them is the numbers on the carb itself. Generally, you'll find some numbers molded into the carb body, if you look closely. That'll help.

Frankly, it sounds to me like the little tiddler is flooding when warm and you shut it down. A new needle and seat will probably take care of that. I have a 5hp Tecumseh based air cooled motor that would refuse to start when warm. That was the problem. I rebuilt the carb and all was well, or at least as well as it could be with that shaky, noisy little outboard. Now that I have a nice-running Johnson 6hp, I'll be selling that other one.

 

[Opus]

Re: Help and General Outboard Advice 4 hp Aero Marine

First thing is go to a 50:1 mix.100:1 doesn't leave enough lube for infrequent use.TCW3 rated oil.Walbro LMG carb. initial carb settings are high speed 1 1/4 turns out from gently bottomed idle 1/2 to 3/4 turns out.Final adjustment warm under load.Lower unit grease is something like 105 assembly grease.
remove screws and case cover remove grease with a wooden paddle refill with 3 to 4 ozs of grease.I suspect a little flooding when stopped.To help warm start try shutting off gas when stopped leave vent open.Try warm start before opening shut off.You may want to
You may want to check the points clean and adjust .020.Champion J18Y plug set at .035.

Steelespike,

Thanks for the specs. I am the consummate rookie here but I gotta ask - is going from a mixture of 100:1 to 50:1 a rather large jump?

You also opened my eyes when you talked about carb settings being done while warm and under load. When I worked on the motor and made adjustments, since it is air cooled I just set the motor up on my hand cart, remove the prop and sheer pin, and ran the motor. IDIOT - NO LOAD. I knew better to not rev the motor without a load but I can't believe it never hit me to make adjustments under load...I should have known better!

Thanks again for the input and specs!!!!

Ron

 

[steelespike]

Re: Help and General Outboard Advice 4 hp Aero Marine

fuel mix change is indeed to twice as much oil.at 50:1 and it will smoke more.
A number of builders went to 100:1 some years back,most went back to 50:1
almost imeadiately.There are some present day motors that run 100:1 I don't know if they have special instructions for infrequent use or heavy duty operation.

 

[Opus]

Re: Help and General Outboard Advice 4 hp Aero Marine

Looks a lot like the mid-sixties Sears engines made by Clinton. The 50:1 oil ration also sounds like the mid to late 60s. From what I understand, when Clinton went out of the outboard business, they renamed the rest of their stock, some with the Aero Marine brand. I'm betting that that web site I mentioned will have a carb kit for your Walbro carb, and probably a lot of other parts, too. They may even know what Clinton model matches yours.

One other thing to have in hand when you call them is the numbers on the carb itself. Generally, you'll find some numbers molded into the carb body, if you look closely. That'll help.

Frankly, it sounds to me like the little tiddler is flooding when warm and you shut it down. A new needle and seat will probably take care of that. I have a 5hp Tecumseh based air cooled motor that would refuse to start when warm. That was the problem. I rebuilt the carb and all was well, or at least as well as it could be with that shaky, noisy little outboard. Now that I have a nice-running Johnson 6hp, I'll be selling that other one.

Cat,

Thanks - sorry for the delay...out on the water for the past few days. Just FYI, the carb is a Walbro with LMB stamped on the body and two numbers - 129 on one side of the choke and 131 on the other - nothing else appears on the carb.

And I agree with you on the flooding when warm. Although the needle valve looked good on inspection, I never looked at the seat. I am just going to have to rebuild. I got lazy last week and emailed the contact name on discount marine parts and never heard back. I just need to call.

 

[Opus]

Re: Help and General Outboard Advice 4 hp Aero Marine

fuel mix change is indeed to twice as much oil.at 50:1 and it will smoke more.
A number of builders went to 100:1 some years back,most went back to 50:1
almost imeadiately.There are some present day motors that run 100:1 I don't know if they have special instructions for infrequent use or heavy duty operation.

Thanks Steelepike - I am going 50:1, smoke or not!!!!!

 

[mfalcone]

Re: Help and General Outboard Advice 4 hp Aero Marine

I also have a 4Hp McCulloch outboard with a carb problem and it won't start.
Well, it will start if I squirt gas into the carb barrel, so I know it will run.

I've been reading the treads and I have adjusted the Idle and High speed screws as mention in one thread, and it's still not starting.

I'm thinking it's getting too much gas, so I'm going to check the float and needle valve next.

Anyone know if there's any spec's for adjusting the float on a Walbro LMB. I tested that it floated in water before I installed it.

Thanks,

Mark

 

[CATransplant]

Re: Help and General Outboard Advice 4 hp Aero Marine

For the last poster: You need to start your own thread with your question. Identify the outboard and problem in the title. It's considered bad practise to insert your question in someone else's thread, and you're unlikely to get the answers you want.

 

[Capt Ron]

Re: Help and General Outboard Advice 4 hp Aero Marine

I know, I know that this thread is over a year old but I came across it while searching to info on a Walbro LMB carb. The numbers are 131, 27.

The picture post of the AeroMarine motor is a dead ringer (other than color) of a Sears model 574-59660 motor that I just bougt this morning at a flea market for $10.
The seller told me the he had bought it at the same market but it had no fire. He took it to a small engine mechanic who also failed to fix it and had told him that parts were not available.
It didn't appear that the "mechanic" (I use that term lightly) even pulled the flywheel or otherwise attempted to toubleshoot the no fire condition. (Makes me wonder if the seller paid this jackleg).

To make a long story short, I found that the condenser wire was rubbing the flywheel and that the point were glazed (aren't they always). The coil checked good and produced a nice blue spark when reassembled.

The fuel line is missing so I mixed a little gas/oil to dribble in the carb throat, pulled the cord twice and it fired and ran for a second....$10 well spent.

Then I injected fuel in the carb inlet to fill the bowl but the motor failed to start. When I pressed the drain valve a stream of rust particles came out so I pulled the bowl to find evidence of a small amount of water that had turned to rust.

Removed the carb, disassembled it and cleaned. As an ex-O/B mechanic I've done hundreds of carbs... this one has a spring on the float pin, makes me wonder if it is original. I've never seen one before and would imagine that most people would just throw it away. I first just thought that it was the normal valve to float spring.

I thing however that this spring is there to conteract some of the float weight to assist the valve seal. I'd like to find a parts break down for this carb.

Also, I know not to highjack a thread but when I saw that picture I just had to post.

Capt Ron

 

[Robot Guy]

Re: Help and General Outboard Advice 4 hp Aero Marine

This also looks like a 4 HP McCulloch. Send me some more pictures and I'll compare further. Abode_repair@yahoo.com

 

[Capt Ron]

Re: Help and General Outboard Advice 4 hp Aero Marine

This also looks like a 4 HP McCulloch. Send me some more pictures and I'll compare further. Abode_repair@yahoo.com

Did you intend to post a picture? The link is an e-mail address.

I pulled the lower unit on mine to check the pump, there's a pump but not like the normal bladed impeller pump but a rubber disk that is moved around in the housing by a cam on the driveshaft. The top if the housing is open so the oil from the exhaust lubricates the disc and running without water is not a problem. However the exhaust housing will overheat without the water even though the motor is air cooled.

I made a movie of this thing apart but it is too large to upload...maybe I can pull some stills to post here.

The next problem that I encountered is finding the 105 grease. Lubriplate has it on their website: http://www.lubriplate.com/webstore/detail.aspx?ID=17
The cost is $17.60 plus shipping for an 8oz. tube. I did find a supplier that ordered me a 14oz. can for $12.44 total shipped to the house.

I had reassembled the carburetor while waiting for the grease (3 days) and installed a new gas line/filter. On monday the motor went in the bucket and started on the second pull and after tweaking the idle jet it settled into a sewing machine idle. I was glad to see the water mist from the exhaust holes and let it run for about 20 minutes. It will have to wait till I get a chance to put it on my 9' Avon to adjust the high speed jet, maybe this week end, I put the prop back on it this afternoon.

One thing that I did notice is that this motor is a lot quieter and smoother than other Sears motors that I have been involved with over the 34 years. Maybe because most of the others were higher hp, 7.5 comes to mind.

Here's some pics:
1) The top of the gear case showing the rubber disc seated in the water pump cavity. Note that the disc does not rotate but wobbles around in a circular motion as the cam on the driveshaft turns. The disc has a tab that fits in a cut out in the cavity. The water enters the screen just below the plate and is pulled into the left side of the disc. As the disc moves it creates a space towards the front of the cavity. This space moves around to the rear carrying the water along until it reaches the rear where the cavity is open and the water is expelled. This pressurized water is then forced from the cavity up the tube which passes through the plate grommet.

2)The plate has a bearing riveted to the topside. The hole in the plate is larger than the bearing and this allows oil from the exhaust to lubricate the rubber disc.

3)The plate in place showing the bearing and water tube grommet.

4-5)Motor without the lower cowling, need the trim strip between the upper and lower cowlings.

A long post but I hope that this might help someone in the future.
Capt Ron

 

[aeromarine4horse]

Re: Help and General Outboard Advice 4 hp Aero Marine

Hello, I am new to this forum, but I came across it looking for information on my own personal aero marine 4 horse engine. I am currently attempting to re-build one in my small-engines class (Yes I am in high school). I think that all I need to finish my project is a carburetor for my little aero marine but it is near impossible to find anything for it. If anyone has any information that could help me find my parts PLEASE contact me!!! my e-mail address is brandon_bergmeier@hotmail.com thank you in advance for your time, I greatly appriciate any and all information anyone might have.

 

[JIMMIKRON]

Re: Help and General Outboard Advice 4 hp Aero Marine

save your motor! add oil. start with 32:1 mix. ...questions at rootboy79@gmail.com

 

[JIMMIKRON]

Re: Help and General Outboard Advice 4 hp Aero Marine

Hi; I am a 1st timer. Paid $4 for Aeromarine 4 aircooled 4000 from scrap comp. Set points and it ran. Need lower cowl and choke knob. Any info appreciated. email me at rootboy79@gmail.com thanks

 

[JIMMIKRON]

Re: Help and General Outboard Advice 4 hp Aero Marine

delete

 

[ca2528]

Re: Help and General Outboard Advice 4 hp Aero Marine

I am in possesion of an Aeromarine 4000(purported to have been owned by John Wayne, may just have been the sales BS and not the reason I purchased it and the boat). It is missing the pad/washer on the screw unit that tightens up and holds the engine to the boat transom. Any thoughts on how to replace the pad/washer?

 

[TN-25]

I know this is a stale thread but I want to amend it to include an actual advertisement from Popular Science, February 1970. Note that it said within the ad that the brand was so new they wouldn't appear in the phone book. They were actually soliciting for dealers to carry them! I believe that 1970 was the end of the road for those outboards. I doubt the larger outboard models they alluded to in the ad ever materialized.

Looking at the models shown it appears that the 4 is an air cooled Clinton, while the larger outboards all appear to be the low profile McCullogh models. Who would need electric start on a 5 or 7½ horse outboard?