mick
Well-Known Member
When I took off my Tohatsu OB carb bowl it contained a little greyish paste-like stuff. What might this be? The engine hasn't been used for nearly two months.
Outboard carb deposits
- Thread starter mick
- Start date
Fire99
Well-Known Member
Is it two stroke?
If so it's probably emulsified fuel/2-stroke oil. The good part of the fuel evaporates and leaves goo behind.
I've had it in a onboard fuel tank before
If so it's probably emulsified fuel/2-stroke oil. The good part of the fuel evaporates and leaves goo behind.
I've had it in a onboard fuel tank before
Cliveshep
Well-Known Member
Greyish paste is aluminium oxides from corrosion due to moisture in the fuel or air and is regrettably all too common in little used engines.
You need to strip and clean the carb properly and blow out all jets with an air line, but, be warned, this pernicious problem most often causes trouble by forming in the jetways. These are the borings in the carburettor casting identified by little ball bearing-like plugs at the end of a jet way where another intersects it. No matter how well you clean the jets there is always loads more of the stuff lurking in the jetways which are much larger than the jets. Their purpose is to form a route for fuel and idling air supply from one part of the carb, i.e. float chamber, to another, i.e. the choke tube on the engine side of the butterfly.
In the end you are left with an unreliable engine with only two solutions offering themselves. One is to buy a new carburettor, the other is to strip the carb, remove butterfly and all jets, and prise out every single plug and drill out the jetways to remove the corrosion salts, and re-plug with small pieces of lead hammered in to re-seal them.
You need to strip and clean the carb properly and blow out all jets with an air line, but, be warned, this pernicious problem most often causes trouble by forming in the jetways. These are the borings in the carburettor casting identified by little ball bearing-like plugs at the end of a jet way where another intersects it. No matter how well you clean the jets there is always loads more of the stuff lurking in the jetways which are much larger than the jets. Their purpose is to form a route for fuel and idling air supply from one part of the carb, i.e. float chamber, to another, i.e. the choke tube on the engine side of the butterfly.
In the end you are left with an unreliable engine with only two solutions offering themselves. One is to buy a new carburettor, the other is to strip the carb, remove butterfly and all jets, and prise out every single plug and drill out the jetways to remove the corrosion salts, and re-plug with small pieces of lead hammered in to re-seal them.
Fire99
Well-Known Member
That's interesting about the aluminium oxide.
Regarding Jets, surely alot depends on the motor. My mariner 2.5 2-stroke had been standing for a few years and I got a few horror stories about how it was probably gonna be a right mess etc and possibly uneconomic to recommission. (since naughtily I didn't do any laying up procedures when I stopped using it)
I stripped my carb, which has One Jet and a needle and thats it. I gave it a general clean and reassembled. After checking oil/impellar and a genearl grease-up, motor is running absolutely fine and not given a days trouble since.
Cliveshep
Well-Known Member
Smaller engines with very basic carbs have incredibly tiny jets, it doesn't take much to block them, most especially the idle jets which are often no more than minute piercings in the choke barrel and barely visible to the naked eye.
I did a Yammie 20 earlier this year where the thing had been standing around for ever and the jet ways had completely blocked with corrosion salts. You could have cleaned the jets forever but never solved the problem. I got hold of it because it had one speed, flat out, and would never throttle down without stopping and idling never happened no matter how warm it got screaming about on full throttle. Moisture corrosion not only affects carbs, even mag coils are susceptible to damp after a few years and performance degrades, sometimes permanently.
I did a Yammie 20 earlier this year where the thing had been standing around for ever and the jet ways had completely blocked with corrosion salts. You could have cleaned the jets forever but never solved the problem. I got hold of it because it had one speed, flat out, and would never throttle down without stopping and idling never happened no matter how warm it got screaming about on full throttle. Moisture corrosion not only affects carbs, even mag coils are susceptible to damp after a few years and performance degrades, sometimes permanently.
Fire99
Well-Known Member
Yeah i'm sure it does happen.
I'm still of the persuasion that, especially on tiny outboards where you can easily test them in a bin/tank, i'd give the carb a good strip and clean-up and then re-assemble and give a good test. If it runs ok then great. New carbs are no doubt alot of money.
Refueler
Well-Known Member
Remove jets, bits and bobs till you have a basic body ... no need to drill out ... drop into a bowl of solvent .... many salts will dissolve with Kettle Cleaner in fact .....
If the carb has no plastic parts stuck in that cannot be removed - you can even set it on a upturned pot in a saucepan and gently simmer it in water ... that will not only remove salts but also any gumms that have dropped out of the fuel ... due to oxidation.
mick
Well-Known Member
Remove jets, bits and bobs till you have a basic body ... no need to drill out ... drop into a bowl of solvent .... many salts will dissolve with Kettle Cleaner in fact .....
If the carb has no plastic parts stuck in that cannot be removed - you can even set it on a upturned pot in a saucepan and gently simmer it in water ... that will not only remove salts but also any gumms that have dropped out of the fuel ... due to oxidation.
Thanks for tips. Also thanks to others who posted.
Fire99
Well-Known Member
Remove jets, bits and bobs till you have a basic body ... no need to drill out ... drop into a bowl of solvent .... many salts will dissolve with Kettle Cleaner in fact .....
If the carb has no plastic parts stuck in that cannot be removed - you can even set it on a upturned pot in a saucepan and gently simmer it in water ... that will not only remove salts but also any gumms that have dropped out of the fuel ... due to oxidation.
So were talking for this recipe:
Take One Carb body with associated bits and marinade in a bowl of solvents or organic kettle cleaner to taste.
Gently Simmer in pan until done.
Can we have it with chips or a Jacket?
And no doubt Rocket Salad will come with it. It always does. electrosys
Well-Known Member
I've not come across the white paste stuff yet (touch wood), but to remove the varnish deposits left by modern petrol, there are a couple of kosher Carb Cleaner products on the market.
Faced with a such a blocked carb on a lawn mower last year, I didn't have any Carb Cleaner handy, so I resorted to removing the carb, stripping down as far as possible, then swilling the body in a jar of acetone. Worked like a charm, but don't leave the carb to soak for more than a few minutes, as I've heard that rubber seals inside have been known to swell and rupture. Cellulose thinners would also probably work, but I haven't tested this.
Faced with a such a blocked carb on a lawn mower last year, I didn't have any Carb Cleaner handy, so I resorted to removing the carb, stripping down as far as possible, then swilling the body in a jar of acetone. Worked like a charm, but don't leave the carb to soak for more than a few minutes, as I've heard that rubber seals inside have been known to swell and rupture. Cellulose thinners would also probably work, but I haven't tested this.
Refueler
Well-Known Member
So were talking for this recipe:
Take One Carb body with associated bits and marinade in a bowl of solvents or organic kettle cleaner to taste.
Gently Simmer in pan until done.
Can we have it with chips or a Jacket?
You can laugh ... but having done this many times when I raced Go-Karts, ran Scooters etc. - as long as the carb body can be taken down to metal only - works a treat ... not only does it get loads of cr$% out of the carb - the heat in the metal bodywhen it comes out of the water causes it to dry quick as well ...
Only thing to remember is DON'T screw jets / parts back in until the carb body has returned to normal ambient temp ... otherwise you may never get them out again later !!
Fire99
Well-Known Member
Ahh good point about the jets. That is the sort of thing that could easily happen. Get all excited that your carb is nice and clean then hastilly put all the bits back together only for them to become a permanent fixture the next time you try and take it apart again.