# mcculloch Mcc18 fuel tank leak



## wa5ngp (Aug 14, 2010)

My Mcculloch mcc18403b has a fuel leak, I think in the tank itself. When I fill it with gas it just runs out the bottom,

I have got portions of it disassembled but it looks like I'm going to have to take the whole thing apart in order to get to that tank. Any suggestions?

I do have the exploded parts diagram but it doesn't really help me see what all I need to remove.

Any suggestions are welcome. 

tks
Don


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## wa5ngp (Aug 14, 2010)

I'll answer most of my question. I think that you have to remove all of the black external plastic housing including the metal handle.

You do not have to remove the flywheel.

some good luck. It wasn't a tank leak, a hose broke. Gasohol damage I assume.

Now, if I can remember how to put this thing back together.:jest:
I did take photos. The tricky part will be the trigger throttle, springs etc.

I now have several boxes full of miscelaneous pieces. I need to act fast while there is some short term memory.


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## paulr44 (Oct 14, 2008)

I can't find that model on mcculloch's part site (ordertree.com), and googling it with or without the "mcc" doesn't return anything...one of us will need an IPL which you have in order to tell you anything about it. If you post the cosmetic model, that may help. OR post some of the pics you took.


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## wa5ngp (Aug 14, 2010)

my bad,
I goofed it should be mcc1840B, somehow I got a 3 in there.
http://weborder.husqvarna.com/order...08/MIUS2008-MCC1840B-9096311221-966001301.pdf

I thought Poulan bought Mcculuch, is it now a cheap husqvarna?


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## paulr44 (Oct 14, 2008)

Some good luck in finding it was a hose, sometimes that style rear handle-tank wears through the seam underneath and the tank itself then leaks. I can't really help unless you get stuck and post a picture or two of where you are. I have worked on most mass-merchant type saws like this, and most all older McCullochs like the 10-10. Husqvarna has bought numerous companies and or their names, the product sold through the box-stores is through the EHP division, aka Electrolux Home Products. I'm not sure if McCulloch was absorbed, but am fairly certain Poulan/Weed-Eater was. Their is a difference in quality and durability between Husky dealer products and EHP --- after all, you get what you pay for. Good luck!


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## wa5ngp (Aug 14, 2010)

I did not realize that there was that much consolidation. I will say that this Mcculuch mass market thing has been extremely good up until now. Much better than a Poulan I had before. 

Its all apart and I bought some clear fuel line. I hope its ok, got it at Ace Hardware, it did say fuel line not aquarium tubing. The OEM stuff was a black rubbery hose. 

for the future I'm gonna buy some avgas and use that for my small engines to see if I get less rubber and plastic deterioration.

don


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## paulr44 (Oct 14, 2008)

There's a poulan fuel line kit that has both a primer and a supply hose in it, I'll try to remember getting the number from my work files. Poulan and Mc are nothing like they used to be, especially Mac being a pioneer in the saw biz. Can't recommend aqua. hose probably not suitable for fuel. Avgas may not have alcohol in it and is often very high octane probably won't work in an OPE product. We had trouble with SEF fuel (94 octane) trying to be run in Stihl equipment that FD's were trying to use. SEF is AKA tool fuel. If you want non-alky fuel there are numerous brands of canned fuel out there incl. Stihl moto-mix and others that aren't excessively high oct.


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## wa5ngp (Aug 14, 2010)

finally got it back together. I had the most trouble with the throttle cable and the little springs on the levers. The hose I got is fuel line so no need for the p/ns, tks anyhow.

So you are saying that the high octane avgas might cause problems? Why is that? The lead in it?

Interestingly, the hose for the oiler looked just fine. It was the fuel hose that had deteriorated as you might expect from the gasohol.

don


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## paulr44 (Oct 14, 2008)

I have no research data regarding avgas vs. pump gas concerning operating in OPE or auto engines. I can tell you based upon the principle of a diesel, enough compression (with high enough latent combustion chamber temps) will auto-ignite fuel. On THAT basis, given that OPE and auto engines can "diesel" or detonate (aka spark-knock) with low octane, and that the higher the compression the higher octane requirement, THEN the inverse could be true in that fuel that requires the higher compression temps such as avgas or racing fuel may not be able to be ignited in a lower compression engine. Octane after all, is a measurement of a fuel's ability to resist auto-ignition.
I stated knowledge from experience with the SEF fuel, not laboratory or test cell data. You can do research and after having done some myself at that time it will make your head spin unless you're good with chemistry, engineering and science.

Lead is of no consequence as it was added as a lubricant for the valve train and upper cylinders of 4-stroke engines, and other than possibly promoting combustion chamber and exhaust port deposits won't affect a 2-stroke negatively. Legal concerns aside of course, as that's a whole 'nother issue I won't get into.

I will skip the P/N for the hose, glad you got it back together, but if the aquarium line rots out make a new post and I'll get you the OEM P/N for the hose kit.


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## 30yearTech (Sep 14, 2006)

paulr44 said:


> Lead is of no consequence as it was added as a lubricant for the valve train and upper cylinders of 4-stroke engines, and other than possibly promoting combustion chamber and exhaust port deposits won't affect a 2-stroke negatively. Legal concerns aside of course, as that's a whole 'nother issue I won't get into.


While it may have added some lubrication properties ( I don't know), lead was added to gasoline as an anti knock agent. The octane ratings of gasoline can be increased by the addition of small amounts of antiknock agents. The first commercially successful antiknock agent, tetraethyllead and was developed in the 1920s. Tetraethyllead was used to promote the development of higher efficiency, higher compression engines. However, tetraethyllead is highly toxic and poisons *catalytic* converters.

Pre igntion (knock) can be a common problem in 2 cycle engines, this is one reason manufacturers recommend at least mid grade or minimum 89
octane fuel. In a 2 cycle engine pre-ignition will destroy the wrist pin and crank pin bearings.


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## paulr44 (Oct 14, 2008)

We're both right Ken, see http://en.wikipedia.org/wiki/Tetraethyllead
However, you trump me on the initial reason for it being added.
And yes, we've seen a host of piston crown collapses, wrist pin and main bearing damage as you indicate.


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