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Discussion Starter · #1 ·
Well everyone thank you so much so far for all of your suggestions with the no-crank issues. It was the forward pto switch that was faulty and I had to re-install the original solenoid.

This tractor has been sitting for quite some time. This is my first time looking at an Onan engine. (B48M) I have never touched a MS carb before. Can I unscrew the top to attempt to clean? I dont have any intake gaskets yet, so I would like to at least try to get the old girl running before I have to order a ton of parts. Can I use RTV silicone for intake gaskets? It looks like it has to be removed to get the carb off...any carb tune-up/cleaning advice/tips would be very appreciated.
 

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Red Tractor Nut & Diesel Addict
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You can do the cleaning with it mounted, but as you know, much better if removed. No, you cannot use any form-a-gasket in place of the gasket. It would squeeze into the jet areas & clog them right off. Unscrew the topit the float will come with the top section. Just use a thin blade when you go to remove the top to release the gasket from the bottom of the carb. Once you get that off, then take & post some pics so we can see what you are up against.
 

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Take it off to clean it. I have had a great learning experience with my DD carb. I thought I had it clean but I was wrong, then I thought I had missed a passage but i was wrong again. The first time i missed the idle "port", not the jet but the actual port that feeds the idle circuit. The link to that is at the bottom of this post. I put it back together but still had problems with getting it adjusted. I still had to use about half choke to get it to run. Finally had time to take it back apart to find out what was wrong. Everything was open and clean, gaskets looked good. On a SWAG I placed a piece of 400 grit sandpaper on a flat piece of steel plate, I took the upper half of the carb and lightly sanded the mating surface of it to see if it was warped. It was, severely. It took a awhile but I got both the upper half and lower half mating surfaces flat again, the made a gasket out of thicker material. The carb works great now.

So definately take it off and clean it and check the mating surfaces. If it has the composite float, look at changing that out too. Another area of head ache for the onans is the intake manifold. Its a two piece design that is sealed with RTV like stuff. That seal can sometime break away and let air into the manifold.

Here is the link to my ordeal with the idle port.
http://gardentractortalk.com/f41-mechanical-forum/dd13-carb-issues-pics-7614/

Hope it helps
 

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Discussion Starter · #4 ·
Here are some pics as requested. It has the composite float, now is the time to ask about ordering a carb kit. There is a place called Gary's parts I think, do you recommend a certain kit?
 

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Red Tractor Nut & Diesel Addict
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Any of Gary's DD kits are fine. You will have to order the brass float separate, as it never comes in a rebuild kit. Gary has those also. Just a good cleaning should do you fine. Be sure to take the fuel inlet plate off the carb side. Usually fines will collet in there, then later break loose in chunks, hanging up the needle or blocking fuel. Do check for flatness as Coldone said.
 

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You may not like Garys intake gaskets. They seem to be single use. I had to take my intake off multiple times and could not reuse the gaskets. I got some thick gasket material from NAPA and started to make my own. Other than that one down side I have used his other gaskets and and kits and been happy with them.
 

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Discussion Starter · #7 ·
Thanks Guys,

I ordered a carb kit and brass float from Gary's today, and also picked up some gasket material. So it'll be a week or so before I get the parts.
Then I will be asking for more help on this carb. Back to the 1650 now.
 

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Red Tractor Nut & Diesel Addict
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coldone said:
You may not like Garys intake gaskets. They seem to be single use. I had to take my intake off multiple times and could not reuse the gaskets. I got some thick gasket material from NAPA and started to make my own. Other than that one down side I have used his other gaskets and and kits and been happy with them.
Even the intake gaskets from Cummins are the gray graphite covered gaskets which come apart when disassembled. The original gaskets from a few years back were perforated metal with fiber inside that could be used over & over. I assume they are NLA.
 

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Tractorholic
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Years ago I helped with a fellow's stockcar and he would coat both sides of his gaskets ( old style fiber type ) with wheel bearing grease because so he could reuse them a few times before having to replace them , I still do that with my carb gaskets , Al
 
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Alc said:
Years ago I helped with a fellow's stockcar and he would coat both sides of his gaskets ( old style fiber type ) with wheel bearing grease because so he could reuse them a few times before having to replace them , I still do that with my carb gaskets , Al
Good idea Al.
 

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Discussion Starter · #12 ·
Hello everyone,
well I have cleaned the carb and installed the carb kit, I have also taken apart and cleaned the fuel pump(it is seperate) from the carb. The pump has fuel up to it, but do I have to prime the system somehow to get it flowing?
 

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Red Tractor Nut & Diesel Addict
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slingblade said:
Hello everyone,
well I have cleaned the carb and installed the carb kit, I have also taken apart and cleaned the fuel pump(it is seperate) from the carb. The pump has fuel up to it, but do I have to prime the system somehow to get it flowing?
It should start pumping as soon as the engine is cranked over. If it doesn't, you must still have a problem with the pump if the vacuum hose is good and good fuel flow to the pump.
 

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Discussion Starter · #14 ·
the vacuum line was ok, I changed it anyway. Still no fuel, the pump appeared to be ok inside..installed a different pump(mikuni) also looked ok inside..still nothing. So I must have 2 bad fuel pumps. I popped the top off of the carb and filled the float bowl with gas. My carb rebuild was successful it ran for almost 5 minutes..does anyone recommend a certain fuel pump? Or should I get an end cover for my carb and add the integral pump? So I am excited that this beast runs, and the rear hitch worked, I haven't tried movingit yet.
 

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Never messed too much with those vacuum fuel pumps but maybe there is a problem with the vacuum "pulse " . Do you have a vacuum gauge you could put on the line to get some readings ? Al
 

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slingblade said:
does anyone recommend a certain fuel pump?
I highly recommend going electric. Mr Gasket makes one that works great with these carbs, low pressure so not to over power the float/needle. It's part # is 42S. If your fuel pump on the carb is assembled correctly, you don't have to do anything to it, just leave as is, except block off the vacuum port.
 

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Alc said:
Never messed too much with those vacuum fuel pumps but maybe there is a problem with the vacuum "pulse " . Do you have a vacuum gauge you could put on the line to get some readings ? Al
Yes, if the dipstick plug isn't sealing, or the crankcase reed isn't functioning, the pulse will be very weak.
 

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Discussion Starter · #18 ·
ok I hooked up a vacuum guage and it read about 8hg when cranking. Pretty low, the dipstick is sealing pretty well.
Where is the crankcase reed valve located, and is it easy to clean/repair?
 

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Red Tractor Nut & Diesel Addict
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slingblade said:
ok I hooked up a vacuum guage and it read about 8hg when cranking. Pretty low, the dipstick is sealing pretty well.
Where is the crankcase reed valve located, and is it easy to clean/repair?
It is in one of the valve covers, where your rubber breather tube connects from air filter to block. Kinda hard to get at, but easy to repair the reed.
 

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Did you get the float and needle valve set right? If the needle isn't droping out of the seat it won't pump gas either. Make sure you can blow through the hose going to the carb from the pump.
 
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