MEP-802/803 fuel return improvements

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smokem joe

Member
466
16
18
Location
Green OH
I'll try to remember to pull one next time I am at my shop. The latest roll was a little bit snugger, but not as tight as what I've gotten locally. I could still seat it all the way on the T fittings and injectors no problem
 

lonesouth

Member
306
0
16
Location
Tallahassee, FL
I tackled this last night. Soup to nuts, took about 3 hours. My 803 is a 2000 non-reset unit, so most of the nuts are not caged. I went ahead and installed rivnuts, which led to a little extra work that is not necessary to complete the fuel line repair. Here is some of what I did:

1. remove all of the bolts from the rear panel to get access to the fuel tank to remove/connect the old/new fuel return line
- the bolts along the bottom have nuts on the back side, all other nuts are caged
2. remove all of the bolts from the top cover
- all bolts going into the radiator area are caged
- most others came off using an light weight impact driver and holding the nut with my fingers
3. remove front top cover to get access to the support that the front and rear top cover mount to
- there are only about 10 bolts to get this off, one of them is caged, the rest are bolt and nut
- the panel cover has to come off and most of the screws broke off while attempting to remove them

With all of these covers off, locating and removing the fuel return line is easy. My old fuel line pulled apart and came out easily. Getting the old hose off of the Tees required a little more effort, though. I simply took the section of Tees out as a whole line, and rebuilt it on my workbench using the 3.2mm gates hose. The hose was rather tight and I used some WD-40 to lubricate the ends while reassembling. I also had to use a towel and a air of pliers to hold and twist each piece to a secure connection. No hose clamps are required. Once pieced together, I strung the new Tee section back on top of the engine and, using WD-40 again, was able to put the hose onto the return barbs. After getting all the hose connected, I fired up the generator and watched for 5 minutes to verify that there were no leaks.

With all of the panels off, I was easily able to install the rivnuts. I used Astro Pneumatics 1442 rivnut setter, with a 10-32A mandrel to install the aluminum rivnuts. You will want to use aluminum rivnuts to avoid galvanic corrosion(dissimilar metals). For bolts, I reinstalled the original bolts as they are, I believe, plated to prevent galvanic corrosion. I stripped a few, and broke many of the screws that attach the control panel cover and will be replacing those with zinc plated 10-32 bolts/cap head screws. From what I've gathered, zinc has a lower instance of galvanic corrosion with aluminum, and the plating prevents the steel from contacting the rivnut.

When installing the rivnuts, I found that installing the rivnut on the tool fully would make it easy to over-pull the rivnut, essentially stripping out the treads. The easy fix is to thread the rivnut onto the mandrel until only a few threads are still uncovered. This limits the full pull of the tool and still creates a strong bond on the rivnut. It did take some trial and error, but I had the process down after the third one. There were a handful of places where I could not install a rivnut due to the mounting hole interfacing with multiple panels, most notably on the front top cover, in which laces I simply reinstalled the bolt and nut.

All said and done, from disassembly to fully reassembled, I finished this project in roughly three hours. I had put it off for fear of the hundreds of nuts and bolts that would be impossible to reach. After going through it, it is perhaps 40 total nuts and bolts to attack, many of the nuts are caged and therefore not a real problem. I suspect going back with nuts and bolts would have taken much longer than using rivnuts, though. The 1442 tool is overkill for aluminum 10-32 rivnuts, and you can easily strip them out, but it is easy to learn how to do it properly. I have other uses for the tool with larger rivnuts, so that is why I went with it. If you are just wanting to install rivnuts on your MEP, you should be able to get by with either a cheaper, lighter-duty, setter, or just use the bolt/nut/lockwasher method which is well documented in numerous youtube videos.
 

Farmitall

Active member
Steel Soldiers Supporter
460
27
28
Location
Eubank, KY
I tackled this last night. Soup to nuts, took about 3 hours. My 803 is a 2000 non-reset unit, so most of the nuts are not caged. I went ahead and installed rivnuts, which led to a little extra work that is not necessary to complete the fuel line repair. Here is some of what I did:

1. remove all of the bolts from the rear panel to get access to the fuel tank to remove/connect the old/new fuel return line
- the bolts along the bottom have nuts on the back side, all other nuts are caged
2. remove all of the bolts from the top cover
- all bolts going into the radiator area are caged
- most others came off using an light weight impact driver and holding the nut with my fingers
3. remove front top cover to get access to the support that the front and rear top cover mount to
- there are only about 10 bolts to get this off, one of them is caged, the rest are bolt and nut
- the panel cover has to come off and most of the screws broke off while attempting to remove them

With all of these covers off, locating and removing the fuel return line is easy. My old fuel line pulled apart and came out easily. Getting the old hose off of the Tees required a little more effort, though. I simply took the section of Tees out as a whole line, and rebuilt it on my workbench using the 3.2mm gates hose. The hose was rather tight and I used some WD-40 to lubricate the ends while reassembling. I also had to use a towel and a air of pliers to hold and twist each piece to a secure connection. No hose clamps are required. Once pieced together, I strung the new Tee section back on top of the engine and, using WD-40 again, was able to put the hose onto the return barbs. After getting all the hose connected, I fired up the generator and watched for 5 minutes to verify that there were no leaks.

With all of the panels off, I was easily able to install the rivnuts. I used Astro Pneumatics 1442 rivnut setter, with a 10-32A mandrel to install the aluminum rivnuts. You will want to use aluminum rivnuts to avoid galvanic corrosion(dissimilar metals). For bolts, I reinstalled the original bolts as they are, I believe, plated to prevent galvanic corrosion. I stripped a few, and broke many of the screws that attach the control panel cover and will be replacing those with zinc plated 10-32 bolts/cap head screws. From what I've gathered, zinc has a lower instance of galvanic corrosion with aluminum, and the plating prevents the steel from contacting the rivnut.

When installing the rivnuts, I found that installing the rivnut on the tool fully would make it easy to over-pull the rivnut, essentially stripping out the treads. The easy fix is to thread the rivnut onto the mandrel until only a few threads are still uncovered. This limits the full pull of the tool and still creates a strong bond on the rivnut. It did take some trial and error, but I had the process down after the third one. There were a handful of places where I could not install a rivnut due to the mounting hole interfacing with multiple panels, most notably on the front top cover, in which laces I simply reinstalled the bolt and nut.

All said and done, from disassembly to fully reassembled, I finished this project in roughly three hours. I had put it off for fear of the hundreds of nuts and bolts that would be impossible to reach. After going through it, it is perhaps 40 total nuts and bolts to attack, many of the nuts are caged and therefore not a real problem. I suspect going back with nuts and bolts would have taken much longer than using rivnuts, though. The 1442 tool is overkill for aluminum 10-32 rivnuts, and you can easily strip them out, but it is easy to learn how to do it properly. I have other uses for the tool with larger rivnuts, so that is why I went with it. If you are just wanting to install rivnuts on your MEP, you should be able to get by with either a cheaper, lighter-duty, setter, or just use the bolt/nut/lockwasher method which is well documented in numerous youtube videos.
I think you made a mistake putting back the original bolts into aluminum rivnuts. For all the work you did, you should have used all stainless replacement hardware. They are available from a couple of different sources and not expensive.

You will get galvanic corrosion between plated steel bolts and aluminum rivnuts. Also use anti seize lubricant on everything during reassembly or you'll be breaking screws/bolts left and right in the future when they weld themselves together via corrosion.

This subject has been covered in threads here on the board.
 
Last edited:

lonesouth

Member
306
0
16
Location
Tallahassee, FL
I did read up on the subject and zinc plated bolts are recommended compared to stainless. Though I'm planning to go back with the anti-seize.

https://www.albanycountyfasteners.com/blog/2017/09/15/stainless-steel-and-aluminum/

From Anode To Cathode

To mitigate the effects of galvanic corrosion even further, it is recommended to use materials that are less likely to cause electron transfer when exposed to each other and an electrolyte. The following list is a list of materials. *Note: the closer the two metals on this list, the less likely they will be to suffer from the negative effects of galvanic corrosion.


  • Magnesium
  • Magnesium Alloys
  • Zinc
  • Beryllium
  • Aluminum Alloys
  • Cadmium
  • Mild and Carbon Steel, Cast Iron
  • Chromium Steel (With Less Than Or Equal To 6% Chromium)
  • Active Stainless Steels (302, 310, 316, 410, 430)
  • Aluminum Bronze
  • Lead-Tin Solder
  • Tin
  • Active Nickel
  • Active Inconel
  • Brass
  • Bronze
  • Copper
  • Manganese Bronze
  • Silicon Bronze
  • Copper-Nickel Alloys
  • Lead
  • Monel
  • Silver Solder
  • Passive Nickel
  • Passive Inconel
  • Passive Stainless Steel (302, 310, 316, 410, 430)
  • Silver
  • Titanium
  • Zirconium
  • Gold
  • Platinum
 

hyderind

New member
19
1
1
Location
manitowoc, wi
When you take everything apart, buy some good 10-32 aluminum rivnuts (30 to 40 cents each) and a installation gun and put them everywhere you do not have a captive nut. Also buy you a small qty of captive nuts and replace the ones that are rusty. I throw all the bolts away that are rusty and replace. I use zinc coated locking flange bolts. Be careful when you mix metals as you will get galvanic corrosion (SS and Aluminum). Aluminum adjoins zinc in the galvanic series. Be very careful not to drop nuts and washers into the main generator when you take them out of the top behind the air filter. While you everything apart clean up all the lost nuts and washers in the control panel area too. I spend the day taking a unit apart and putting in rivnuts. Now fix everything and clean everything. Replace your well nuts too! It takes no time to put everything back together again. You will be glad you did!
Hey, newbie question....why not SS rivnets instead of AL?

https://www.amazon.com/Stainless-St...=10-32+threaded+insert&qid=1569786120&sr=8-10


Thanks

Chris
 

Coug

Well-known member
669
276
63
Location
Olympia/WA
Hey, newbie question....why not SS rivnets instead of AL?

https://www.amazon.com/Stainless-St...=10-32+threaded+insert&qid=1569786120&sr=8-10


Thanks

Chris
Stainless steel and aluminum do NOT play nicely together.
Causes a galvanic reaction, where one metal causes the other to corrode at a fast rate.
Antiseize forms a barrier between the two parts to help slow/minimize the corrosion, and allow the parts to be separated again, but it's still not a good idea to mix metals.

Galvanic-Corrosion_2 (1).jpg
Chart taken from this site, which also explains it a little better than I did:https://www.monarchmetal.com/blog/galvanic-corrosion-common-questions-answered/


edit: We like people asking newbie questions or ones they think might be stupid because asking the question ahead of time usually saves a huge amount of time/investment/involvement later on compared to NOT asking the question. Plus, for every person that asks a newbie/stupid question, there are probably a dozen people who were too afraid to ask but would like to know also.
There are no stupid questions when it comes to trying to learn and understand the how and why of things, but there ARE plenty of stupid mistakes from not asking.
 
Last edited:

hyderind

New member
19
1
1
Location
manitowoc, wi
Stainless steel and aluminum do NOT play nicely together.
Causes a galvanic reaction, where one metal causes the other to corrode at a fast rate.
Antiseize forms a barrier between the two parts to help slow/minimize the corrosion, and allow the parts to be separated again, but it's still not a good idea to mix metals.

View attachment 777886
Chart taken from this site, which also explains it a little better than I did:https://www.monarchmetal.com/blog/galvanic-corrosion-common-questions-answered/


edit: We like people asking newbie questions or ones they think might be stupid because asking the question ahead of time usually saves a huge amount of time/investment/involvement later on compared to NOT asking the question. Plus, for every person that asks a newbie/stupid question, there are probably a dozen people who were too afraid to ask but would like to know also.
There are no stupid questions when it comes to trying to learn and understand the how and why of things, but there ARE plenty of stupid mistakes from not asking.
Hey Coug,

Thanks for your patience! I had read earlier that it was a good idea to also replace the existing bolts .... so I was going to replace the existing bolts with zinc plated bolts something like these.

https://www.amazon.com/gp/product/B018UGR7Z6/ref=ox_sc_act_title_2?smid=ASSHDL8LKX3H3&psc=1

So...my thinking was....it would be zinc bolt on SS rivnut....which should be OK with no evil AL touching. My 803A has not arrived yet....so I'm assuming the frame is steel.

But wait....... :)

According to your chart....it reads that SS touching carbon steel is bad? Am I reading that right? Since when? :)

In that case, AL rivnets and Zinc bolts make sense.

BTW, thank you for your newbie comment. With currently knowing very little about generators...except that Kohler Standby Generators are expensive as heck and a 803A is a better choice....SteelSoldiers is making the learning journey fun and exciting!

Best,

Chris
 
Last edited:

Coug

Well-known member
669
276
63
Location
Olympia/WA
Actually, what I was talking about is the sheet metal of the 802/803 is mostly aluminum, so putting rivnuts into the aluminum sheet metal will cause you issues later on, not the difference between the bolts and the rivnuts. You can get away with stainless bolts and aluminum rivnuts because of antiseize and stuff like that, but there's nothing protecting the aluminum from the rivnut, otherwise the rivnut wouldn't install properly.
 

Guyfang

Well-known member
7,267
993
113
Location
Burgkunstadt, Germany
Some folks have used riv-nuts, and are happy with them. I have taken many, many of these sets apart, and when reassembling them, always had to get most of the screw/nuts, "kinda" tight. Then maybe push here, pull there to get everything to line up. With Riv-nut, that might not work. What I did was to use about 8-10 punches. Put things together, then shove the punches into some of the holes, to line things up. Then insert the screws and tighten up nuts. Remove the punches, and fill those holes with screws and nuts. Worked for me.
 

Hard Head

Member
Steel Soldiers Supporter
542
3
18
Location
Greenville SC
Never had an issue with aluminum alloy rivnuts. Aluminum is best to prevent galvanic corrosion. Use aluminum alloy bolts or high quality zinc plated steel to reduce galvanic corrosion. I get mine from a NASCAR supplier in Charlotte NC. I have installed over a thousand in MEP-80X generators. Don't rivnut slots! Like at the front edge of the control panel. You would have to get them perfectly aligned in order to prevent cross threading. I just use all new serrated Hex Flange Screws Flange Bolts with serrated nuts or Nord Lock washers to prevent vibration loosening where nuts are still required. All the old bolts, washers, and nuts go in file 13. You might want to keep a few cage nuts since they often need to be replaced where damaged in the unit.
 
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