Cleaning fuel pump and carb castings for rebuild

53a1 · Post by **53a1** » Thu Apr 02, 2009 7:48 pm

I scored three M38 fuel pumps and a carb at a jeep yard sale. What's the proper way to get the castings pretty for rebuild?

Thanks.
Dave

Post by **wesk** » Thu Apr 02, 2009 9:42 pm

Pretty or functional or both?

1-Function-All access plugs and caps removed and all interior parts removed. Soak for at least 24 hours in carb cleaner. The submerged can system. Using the system diagrams in the TM 9-1828A (Fuel Pumps) & TM 9-1826A (Carter Carbs) clear every passageway.

2-Pretty-Electroplate housings.

GPA · Post by **GPA** » Fri Apr 03, 2009 3:29 am

You can expect good results if you put the carb body into an ultrasound cleaning machine.

Post by **wesk** » Fri Apr 03, 2009 9:18 am

With the same fluid. The ultrasound will accelerate the cleaning. In one day you will have completed three days of soaking. But you will need access to a machine. Hot caustic commercial cleaning system do very good but again you must have access to the equipment.

GPA · Post by **GPA** » Fri Apr 03, 2009 9:59 am

Hi,
I see it, access to a machine is the problem. Small ultrasound machines are available for a reasonable price here. Check out the situation price wise Wes. Usually everything is cheaper in the U.S. but this machine could be the exception. If you do carbs and similar things often and need one, I can look around for a good deal and send you one. But there is the 220/110V difference.
Zoli

Post by **wesk** » Fri Apr 03, 2009 10:38 am

Thanks for the offer Zoli, but I have access to all the machinery I need. I do this for a living. It's the original poster who would need the equipment.

53a1 · Post by **53a1** » Fri Apr 03, 2009 11:47 pm

Thanks for the info. What about silica blast? I took my pump appart this evening. It was pretty easy.

53a1 · Post by **53a1** » Fri Apr 03, 2009 11:50 pm

Do I need to seal the casting with paint or something if I were to silica blast it?

Thanks.

Post by **wesk** » Sat Apr 04, 2009 9:43 am

NO-NO-NO! Fine dirt and dust is the most notorious enemy of passageways in the carb. I would never deliberately introduce any fine powder or dust to any carb. Use liquid solvents and dry compressed air or notrogen only.

53a1 · Post by **53a1** » Sat Apr 04, 2009 10:52 am

Good advice. I will remove the linkage parts and do those only. The cast iron bottom part is rusted like most are and I wish I could do that part.

How about the fuel pump castings Wesk?

I have it appart and there are no small holes. Looking at the condition of the casting after cleaning I think a fine silica blast is the only thing that would work. I will only do the external surfaces so I don't bother the surfaces the check valves sit in.

Thanks.
David

Post by **wesk** » Sat Apr 04, 2009 11:36 am

The size of the hole is not the issue. The fine silt deposits end op coating the entire unit externally and internally. Compressed air will not remove them and liguid cleansers will cause a lot of it to migrate and collect at restrictions in those passageways. If you soak the body long enough in the correct solution it will emerge spotless. The gallon cans of Carb cleaner are available for about $14 and have a dip basket with them. Although this process is new to you many of us have been cleaning and rebuilding carbs since the 50's. It works when you do it right.

For the lower cast iron body simply use a strong rust remover like Naval Jelly.

As Zole mentions the Ultrasonic cleaner tanks finish the process in hours that normally takes several days worth of soaking.

53a1 · Post by **53a1** » Sat Apr 04, 2009 2:44 pm

Thanks Wesk.

I'll try the carb cleaner but the guy at NAPA said the stuff they sell now is so weak you may as well use kerosene or gasolene and it costs 29.00 bucks for a gallon

Post by **wesk** » Sat Apr 04, 2009 6:43 pm

29.00 bucks

That's because you are buying it from Napa. Try the economy stores, farmer stores and such. I get it at Farm & Fleet here in northern Wisconsin. And yes it is weaker than the original stuff. If you want a serious quick cleanup and don't want to invest in an Ultrasonic cleaner then go to your auto-machinist and have him hot caustic tank it for you.

Keith · Post by **Keith** » Sat Apr 04, 2009 6:44 pm

I just rebuilt my M38 carb and fuel/vacuum pump and used Gunk carb cleaner (w/basket) from local parts store (~$20). Was happily surprised at how well it removed rust from bolts, linkages, hardware, etc - almost to original - after soaking for ~3-4 days. It also removed all other deposits with minimal scrubbing which I performed about once each day. Good luck.

GPA · Post by **GPA** » Sun Apr 05, 2009 3:59 am

I have used American made Gunk about 15 years ago and before and it was a good product, it did remove most of the deposits overnight from carbs to be overhauled. Then came the "new formula". We were told the old stuff was too strong, dangerous and not friendly to the enviro. Only problem was it did not work anymore. This is the reason for 3-4 days of soaking time. I am using a product here called Super-Kromofag. It is made for paint removal. We are not talking about days of soaking, not even hours, but minutes. Producer recommends 5 minutes, but 2-4 is enough (when liquid is fresh). It does remove everything, without damageing the surfaces. Its smells same as the old Gunk from memory, but my nose is not a german shephards'. Cleaned parts look like new. For copper or brass parts I am using another product made by a company specialized for making kitchen/bathroom cleaning products. Soaking time is about 2 minutes and gold/copper/brass becomes bright original color, if you leave it longer it turns a little darker. You guys should check some industrial or domestic cleaners not just those made for automotive use.