Oliver OC-3 crawler

My neighbor and I just bought an Oliver OC-3 crawler that has been sitting for a few years. It is equipped with backhoe and it runs from a Hercules four piston gas engine. We got it to start while cold, but when it warms up the engine dies and it refuses to restart until it completely cools down. During the time it does run, we were able to ascertain that the hydraulics work, that it moves forward and it turns right. It has'nt run long enough to try the left turn yet but we really need it to run long enough to get us to the place where we can load it onto a trailer. I am hoping to get some advice as to how to deal with this cold running, warm stalling engine. It has a Zenith carburetor and I took it apart to clean. It looked fairly clean to start with. We put new plugs and wires in it and I checked for spark which it has, so I am stumped. Any advise would be greatly appreciated.

vapor locking?

(quoted from post at 06:05:47 04/29/23) vapor locking?

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Hi, 2X4. No, I checked for that. The engine doesn't get very hot before shutting down.
Its 3:00AM in the morning here. I just woke up worrying about this problem - sticks to me like the smell of old gear oil! ... maybe the problem is electrical. This old gal's fired by a magneto, but the bottom line is that I get spark at the plugs so the problem must be in the fuel system. The carburetor is an old Zenith with the ID number missing ... going to be a problem getting a rebuild kit for it. I was looking at new carburetors, but they are bolted to the intake with 5/16" studs. This carburetor mates with the manifold via 1/4" studs .... maybe a hot cup of coco will help. Thanks for the reply, 2X4.

(quoted from post at 06:45:04 04/29/23)

(quoted from post at 06:05:47 04/29/23) vapor locking?

Click to expand...

Hi, 2X4. No, I checked for that. The engine doesn't get very hot before shutting down.
Its 3:00AM in the morning here. I just woke up worrying about this problem - sticks to me like the smell of old gear oil! ... maybe the problem is electrical. This old gal's fired by a magneto, but the bottom line is that I get spark at the plugs so the problem must be in the fuel system. The carburetor is an old Zenith with the ID number missing ... going to be a problem getting a rebuild kit for it. I was looking at new carburetors, but they are bolted to the intake with 5/16" studs. This carburetor mates with the manifold via 1/4" studs .... maybe a hot cup of coco will help. Thanks for the reply, 2X4.

Click to expand...

Did you check the fuel flow by pulling the drain plug out of the carb bowl and see how long it takes to fill a pint jar?

When you took the carb apart did you clean all the passages with a fine wire or torch tip cleaners?

Some pictures and dimensions may help people here identify your carb. Places like McDonald Carb and Ignition may be able to identify your carb if you call and talk with them (and maybe email a couple pictures and dimensions). Then they can supply a kit for it as well.

Change all the fluids ,I suggest

I put a spark tester on one of the plugs should jump about 3/4 inch for starting. Clean all terminals

Check for vacuum leaks in manifold ,it will lean it out, when warm

Just some thoughts .

Cant wait to hear you got it going !

I like the oc 3

Should be an IXB Hercules engine!. Send me an e-mail and phone number. See when it dies if it still has spark too. I can come up with a carburetor number. J.

My HG came with a Marvel Schebler fixed jet carburetor, I couldn't get it to run at all. I put a Tillotson carb on it and it ran
good for years.

Check your fuel flow from the tank. May be slow because of a screen in the tank and while setting the fuel builds up in the carb and will run until the carb bowl is empty. I know this may seem a little simple solution but it happens. Also try running without the fuel tank cap, sometimes the vent in the cap stops up.

(quoted from post at 12:14:01 04/29/23)

(quoted from post at 06:45:04 04/29/23)

(quoted from post at 06:05:47 04/29/23) vapor locking?

Click to expand...

Hi, 2X4. No, I checked for that. The engine doesn't get very hot before shutting down.
Its 3:00AM in the morning here. I just woke up worrying about this problem - sticks to me like the smell of old gear oil! ... maybe the problem is electrical. This old gal's fired by a magneto, but the bottom line is that I get spark at the plugs so the problem must be in the fuel system. The carburetor is an old Zenith with the ID number missing ... going to be a problem getting a rebuild kit for it. I was looking at new carburetors, but they are bolted to the intake with 5/16" studs. This carburetor mates with the manifold via 1/4" studs .... maybe a hot cup of coco will help. Thanks for the reply, 2X4.

Click to expand...

Did you check the fuel flow by pulling the drain plug out of the carb bowl and see how long it takes to fill a pint jar?

When you took the carb apart did you clean all the passages with a fine wire or torch tip cleaners?

Some pictures and dimensions may help people here identify your carb. Places like McDonald Carb and Ignition may be able to identify your carb if you call and talk with them (and maybe email a couple pictures and dimensions). Then they can supply a kit for it as well.

Click to expand...

Two good ideas, but to answer them: No. I was in the field and all I had was a can of carb cleaner. What I did was pull the carburetor and I brought it home with me where I have the tools to do a better job. I ordered a rebuild kit based on the gasket patterns. It will arrive this Monday - all I really need are the gaskets ... I hope,
As far as the gas line is concerned ... well, that is another issue I need to address. A metal gas line comes out of the bowl and then transitions into a rubber hose, and then it changes into another copper tube which inters the carb. It is kinked in a couple of places, so I will be visiting my favorite hydraulic store Monday to get a new gas line. With the aid of a tube bender, I should be able to improve that situation. My neighbor and I will be returning to resume our efforts this coming Wednesday. Thanks much for your suggestions.

Thanks for the reply, 560Dennis. A leak in the intake manifold is something I will defiantly check. I didn't think of that.
As far as the ignition system is concerned: This is another cringe factor. The generator is completely disconnected and a 12 volt battery is directly running the magneto and points. I've got spark at the plugs, and because I don't want to disconnect the mag in the field, I can only hope and pray it will be enough to get it on a tailor. Home is where I want to do a proper 12 volt conversion. :roll:

Aren't they 2 cycle carbs?
I was tempted to use an old 9N carb that I had laying around, but the studs that go into the manifold are 5/16" and the manifold will only take 1/4" studs.

Yaa ... vacuum in the gas tank is something I've seen before ... The gas line has a glass bowl that I keep an eye on. As long as it is full to the top, I figure I've got gas flowing. My issue is with the line itself - numerous kinks.

Yaa ... vacuum in the gas tank is something I've seen before ... The gas line has a glass bowl that I keep an eye on. As long as it is full to the top, I figure I've got gas flowing. My issue is with the line itself - numerous kinks.

running out of gas will usually give you a bit of a warning- as the mixture leans out, it will backfire and misfire. If it cuts out completely
like youve turned off a switch, but starts right up again after a cool down I'd suspect a bad condenser in the magneto.

Dont overlook the insulating washers on the grounding lead going into the magneto too.

Thanks Warbaby We will change the capacitor on our next visit. The way that the mag is situated, it is near impossible to work on the points without removing the mag from the governor and I really want to avoid doing that in the field - little to no experience with magnetos and a fear of messing the timing up in a place where we don't have all our tools. I can reach the capacitor though, so that, at least, will be another point to check off.

Those old magnetos seem mysterious nowadays, but they are pretty simple units- as long as they are working!

Take the cap off (if youre lucky, the last time that cap was off, they didnt put the 2 screws closest to the block back in tight!) and roll
the engine over by hand until the impulse coupling snaps.

Mark (or kinda remember) where the rotor points to on the body of the mag and remove the rest of the magneto. The magneto drive is a simple
slot on the back of the engine's intermediate gear so you can only put it on 2 ways- either dead on, or 180 degrees off.

If you just pull the mag without noting the rotor position beforehand, you still have a 50/50 chance of getting it right, and even if you
dont, just to move the sparkplug wires two spots forward on the cap and youre back in business!

I have an OC-3 and have had the exact issue several times in the last 20 years. It was the coil in the mag every time. I changed points, condenser, plugs, wires, and checked fuel system each time. Mine was always the coil.

I hope that isn't the problem with our OC-3. I really don't want to mess with that magneto out in the field. We ordered a new carburetor and intake/exhaust manifold from OliverCrawlers.com - hope to receive it soon. Yesterday, we drove out there to play with it - it starts easily and we let it warm up before putting any load on it. It runs very well until we put a load on it - that is when it starts to misfire and then it quits - not to start again. I checked the spark plugs and they are coated with black soot. Adjusting the fuel mixture on the carburetor didn't seem to help, so I'm hoping the new carb and manifold will solve this problem.
The thing is in a tight and steep location, so we will need to drive it out so that it can be loaded onto a trailer.





This post was edited by mudmuckgrease on 05/16/2023 at 04:53 pm.

(quoted from post at 16:53:14 05/16/23) coated with black soot.

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the implication is running rich. without knowing how hard the engine was running it might be idle or might be main mixture. the photo implies that it doesn't appear to be an intake restriction.

you could grab a set of next-hotter plugs and then try lean out the main a bit (e.g. 1/8 turn) at a time.

I ve tried adjusting both idle and running mixtures with no favorable result, so I figured the carb is toast. It doesn t have its brass ID tag, so I don t know what rebuild kit is right for it plus, it mates to the intake manifold via two 1/4" studs, but I can only order a carburetor with 5/16" studs. That means I would have to drill out the " mounting holes to 5/16". Both the intake and exaust manifold are one unit and looking at the picture of the carburetor, you can notice that the exaust manifold is broken with a makeshift patch to accomidate the muffler. At this point, I just threw up my hands and ordered a new carburetor and manifold. When I receive them, I ll remove the four manifold mounting bolts, slap on the new manifold with nice new gaskets, and mount the new carburetor. If that doesn t fix the problem, then our attention will have to be directed to the magito which is unknown territory for me and I really don t want to deal with it out in the field.
Then there is the charging system: there isn t any. We are going to have to get a 12 volt conversion kit.
Then there is the hydraulics: The fluid is more water than oil!
Look at it s bucket: Its lower lip is sagging very sad little crawler.
I can t wait to get this thing home going to have a lot of fun putting it back together.

This post was edited by mudmuckgrease on 05/17/2023 at 10:12 am.