Onan Stripped Oil Pan Repair

Van Living Forum

Help Support Van Living Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

B and C

Well-known member
Joined
Dec 8, 2014
Messages
5,283
Reaction score
14
Location
Atascocita, TX
I apologize in advance for a long post.  :s

I'll post here as there are knowledgeable folks to help me decide my game plan.  Here are the facts as I know them.

My Onan MicroLite 2800 generator has a ruined (?) aluminum oil pan where an RV tech overtorqued the drain bolt (12-1.25) and stripped the pan threads :-(  This was discovered upon my return from a three month trip out West when my normal shop/guy unscrewed the drain plug and the aluminum threads from the pan came out with it.

I do NOT want to return there (rv tech) and have them screw something else up.  He also broke a key off in a lock he did not need to open.  They did get the old key out and provided two newly cut keys for replacement though.  The tech is not the sharpest tool in the drawer.  I had to show him where the generator was and where the side panel comes off for oil fill.  I guess he never thought to follow the exhaust pipe to where it came from and may well have never seen a generator before.  IDK

Anyway, to remove the oil pan on the genny would require disconnecting and dropping a 110 LB Box.  After it is out, the whole assembly would have to come out of the box and turned over onto something that would support it and not screw something else up just to get to the pan for removal.  The upside of this is I would be able to replace the hardened motor mounts where it attaches to the box.  I am not experiencing any other troubles with the mounts other than they have hardened with age (from 2000) so this would be a minor repair while it is apart.  I took the box out when I first got the van and it was a pain.  The previous owner had not exercised it and the jets were clogged.  This was the only means I had to get to the jets for cleaning.  I forgot to mention a 100 LB battery would also have to be removed for access to a mounting bolt.  I do not want to remove the genny for these reasons.

I have come up with four ways to fix this without removing the generator.  


1. Rethread oversize with a tap
2. Put in a heli-coil.
3. Glue a nut to the pan and use it as a new oil drain.
4. Self tapping bolt 1 oversize.

1. The oil pan boss does not have enough meat left on the sides (with flat gasket space left over) to hold new threads and leave a flat space for the gasket washer by tapping it.  

2. I would also have tap it to put in a heli-coil.  I am not sure of the downsides of doing this other than they anr not made for frequent bolt removal and it would be a pain to get the tap square in a small hole as it is recessed in the box that encloses it.

3. Gluing a nut to the flat part of the oil drain hole (where the gasket goes) seems easy enough.  What I am thinking about is the original J-B Weld two part epoxy.

4. Use the oversize self-tapping bolt to cut new threads and then replace it with a 1 oversize regular oil pan bolt.  Amazon sells both!  Plenty of lubrication and back it out about a 1/2 turn for each turn in to break off the shaving and a thorough flush afterwards (with diesel fuel or gasoline?) to get rid of any chips that may have gotten into the pan.  The drain hole is in the very bottom and not the side.

I Guess the new 1 oversize self-tapper with a replacement bolt would be the way to go to start.  If this doesn't work, the epoxy is my next best option.

I have always changed my own oil up until a few years ago and have never stripped an oil pan bolt or hole.  Guess the genny will be my new thing to change oil on.  The vehicle will still get the oil change place to do it.

Anyone have experience using an oversize self-tapper that wants to give me some pointers or an opinion on the other ways?  

Thanks for making it through this long post but I was trying to give all the info I can.
 
It maybe possible to get a rubber pop in plug like Dodge used for a while. It has a lip on both sides and just presses in. I didn't like using them and replaced them often but never had a drip just moist around the edge. If the hole is big enough a small expansion plug could be used as well. Marine motors use suction to do oil changes on several applications and it is done through the oil fill so you could just plug the hole. If you are going to use JB Weld consider using pipe with a tee as you can hold the tee as you remove the plug and not put pressure on the glued joint and pipe threads being tapored tend to seal better in my opinion. Good clean roughed up surface and JB Weld works well. I think I would use a tapored pipe tap and a brass pipe plug with sealant or teflon tape if you have room to just tap the exsisting hole in the block.
 
bullfrog said:
...Good clean roughed up surface and JB Weld works well.  I think I would use a tapored pipe tap and a brass pipe plug with sealant or teflon tape if you have room to just tap the exsisting hole in the block.

I think J-B weld will be my next choice.  I like the idea of a tapered pipe plug.  Very well could be option 3.  Thanks for the input.
 
I have experience with the emergency repair self threading oil pan plugs. sometimes they work sometimes they don't. sometimes they seal when you first put them in but don't seal when you go to change the oil. if it was mine I would fix it right either put a new pan on or pull the pan and weld a bung in. highdesertranger
 
Thanks HDR,

I think my plan of removing the 1 oversize tapping bolt and replacing it with regular 1 oversize bolt will work (hopefully).  I'll remove the tapping bolt and tighten, remove, tighten, remove, tighten the replacement bolt that is not the tapping bolt a few times before I call it fixed.

Can'tcha tell, I REALLY don't want to pull the generator. :p   I'll be 70 next month and this old body ain't what it used to be.
 
From what I remember last time I changed oil in mine it looked like a 1/4 pipe tap might do the trick. I'd put a wired safety pin through the plug though since vibrations and heat expansion differential of aluminum/steel could help the plug to loosen.
 
You have a real interesting problem.
If it we're me, I'd bite the bullet. But instead of just a drain plug I would add a petcock.
Extending the the drain to a valve that you can open for draining the oil. And hopefully omitting anymore damages caused by sledgeomatic mechanic's. And I, even though it's not my favorite job. Do all my maintenance now. Like yourself I've had my share of loose lugs, yanked wires, broken items. And the worst, no oil or pan bolt!. So I adopted the same thinking as when I lived in my house. "It's your's take care of it". The benefits are, you save money and you will get to know every system on your vehicle. Even if something happens when you are away from a parts store you can in most cases "rig" something up and keep moving. The biggest advantage for me is I know what has been done and what is likely to be the next project. So I can buy items here and there and when it's time to do the repairs I'm ready. It's so much better than when it actually is, a problem and I have to cough up higher parts and labor prices. I haven't done the figures but I'm sure that I have replaced 90 percent of the consumable parts and the cost has been under half of paying shop prices. A good manual or two is really all you need to do most of the maintenance yourself. Even if it's just the basics your going to save money for the big job that comes up eventually. Hope this helps you and a few others who have had maintenance nightmares also.

Sent from my Z981 using Tapatalk
 
Beep and eats wrote: "...instead of just a drain plug I would add a petcock".

I agree a petcock of some kind would be best. My Onan is mounted under the van and the housing for the generator is flush with a lot of other stuff under there. The Onan has a steel case it is housed in from the factory that has a 1 1/8 inch hole in the bottom to access the drain plug. The drain plug is about a 1/2" above the opening. A petcock would stick out of it a ways. I would be forever worried I would damage it and lose my oil.

I thought I would try a Dorman fix https://www.dormanproducts.com/p-101359-090-179cd.aspx?origin=keyword rubber drain plug and replace it each time I changed the oil. Twas not to be. The big round rubber part is almost 1 1/2" in diameter. It would not fit through the 1 1/8" hole in the case. I briefly thought about trying to make the access hole larger but could not figure out a way without having jagged edges left to cut myself on when it was time to change the oil.

Back to the one oversize drain plug. I bought a Dorman https://www.dormanproducts.com/p-52668-65402.aspx and filled the end with grease to hold the shavings. It went in straight and the grease held the shavings. Removed and cleaned.

Inserted new drain plug, filled with oil and ran it for an hour. No leaks.

I just ordered two piggyback drain plugs for it as I couldn't tell them apart from the descriptions and one was not in stock at the parts store.

Dorman:
https://www.dormanproducts.com/p-102264-090-086cd.aspx
https://www.dormanproducts.com/p-5587-65228.aspx

The first one says single oversize in the description but says double oversize in the specifications. I'll wait for them to come in and install the correct one. This is about to be finished!
 
The bolts came in late yesterday. On the packaging they both say single oversize. :-( Not much money wasted and it was piece of mind.

Well, this morning after drinking my pot of coffee and procrastinating some more, I put one of the piggyback drain plugs in the pan. You ask, "what is a piggyback drain plug"? Well a picture is worth a thousand words and here is what I installed: https://www.dormanproducts.com/p-102264-090-086cd.aspx?origin=keyword

I started late and rain was threatening. I jack up the back of the van to get underneath for access to the generator. Put down a tarp to lay on and put a drain pan under the drain. Removed the plug I put in last week and drained a brand new quart of oil. :-( Let it stop dripping and ran a rag up in the hole to clean it. I may have made a mistake as I put RED loctite on the main bolt and tightened it in place. I then put in the little 7/16 piggyback bolt. I filled it with oil and fired it up to check for leaks. While it was warming up, I cleaned and put away the tools and the used oil. I shut the genny off and checked for leaks, none :)) Folded the tarp and put the jack back in the van. As I was walking back to the house to put the tarp away it started spitting rain. Finished just in the nick of time. I hope using the red loctite doesn't bite me in the a$$ down the road. Hopefully it will just keep the big plug from backing out when removing the small one. The piggyback main bolt had the added benefit of being the same length as the original drain bolt so I shouldn't be leaving any old oil in the pan. When I measured the depth of the drain pan hole, it was slightly longer than the bolts were long.

I sure hope this is the end of the stripped oil pan saga.
 
Thanks

I know it was he** of a lot easier than dropping the generator to remove it from the housing to properly tap new threads or replace the pan altogether.
 
I know that was "whew" w/ a smile. MacGyver'ing saves the day again.
 
Good job on the fix!  Just hold the piggyback with a wrench when you go to change oil in the future.  Red loctite shouldn't be a problem.  It will still come loose, it just tends to pull threads if use with bolts in aluminum castings.
 
Thanks,

The red loctite is going to have to be it. The big bolt is in a recess. The little 7/6 bolt is not overly tight. I won't have to change oil for another year anyway. I use it when camping for making coffee every morning at 15 minutes a pop and for the convection/microwave maybe once a week for the little while it takes. Manual says change oil every 50 hours of use or yearly, whichever comes first. On my last two three month outings (a year apart), I put less than 30 hours on it each time so yearly it has been for me. I put an hour run time with a load once a month for exercise. Manual says two hours though.
 
Those kits typically use a steel pig with a brass plug, so it should be alright.  The brass doesn't seize. 

Funny, I do the same thing, coffee and micro in the morning as needed.  If I need to use AC I'll usually pay to camp with a plug-in.  Sometimes when it's hot up at El Mirage I run the generator for AC during the day.  I exercise my generator about every other month to keep fresh gas in the carb, and so far that seems to keep it running good whenever I need it.
 
If I ever have a problem with the drain plug it will be down to using a tap on it as I am sure the threads will come out with the plug.

I think I would forget if it was the month to exercise it or not so I do it near the first of the month every month. It still takes 10-15 seconds to get it started. When I start it every day it fires right up.
 
You know, I forget too... Lol! It's kinda like I walk past the rig in the driveway and suddenly think, "maybe it's about time to run the generator again." I also put some Stabil in the take before I park it and that seems to help.
 
I have a 35 gallon gas tank. Takes a LOT of Stabil for that. I store my van with a full tank.
 
Because of all the problems with ethanol in gasoline used in boats around here stations have started selling non-ethanol gas at an increased price. also most small airports sell it also. You might want to consider using it if you store with a full tank.
 
Top