2000' Onan 4000 Microquite generator replacement

[Lakeplay]

Has anyone replaced their old generator with something newer? Mine bit the dust and while researching, I've been seeing a lot of issues with this model. I don't want to spend the money fixing this one if its problematic. Besides, its 18 years old. Ideally I would like to remove the one I have and install something newer in the same place.

[maillemaker]

One thing I noticed right away was a lot of oil under the generator.

I struggled with my Onan 4BGE for the better part of a year before I simply bit the bullet and replaced the entire ignition system. Turns out, when you identify aftermarket, non-Onan parts for the starter motor, and the ignition coil, you can replace every electronic bit on the generator except the voltage regulator and the control module for less than $200. You can replace those last two components for $300.

So you can replace every electronic part of the generator - everything but the mechanical motor and the generator head - for $500.

The number one killer of generators is lack of use. Monthly exercise under load is required. There are 2 main reasons:

1) The carburetor will gum up if gas sits in it. Replacement carbs are around $300. They can be tricky to rebuild without having leak problems afterwards. Some generations of Onan they list the carb as unserviceable for that reason. It is important to have fresh gas, heat, and vibrations agitating the internals of the carb once a month.

2) The copper slip rings tarnish with lack of use. This causes an increase in resistance between the brushes and the slip rings. High brush resistance can smoke the voltage regulator. Flight Systems sells a "slip stick" that you can use to polish the slip rings.

But - if your generator has an oil leak, you may have a serious mechanical problem with the engine. The engines on these things are generally bullet proof.

[fourthclassC]

Had to chime in here. I agree with all. 220 hrs is not much. These are plauged with carb and fuel pump issues, but all solvable with much less cost then a new generator (at least one that fits and is made to work within the rv setting) It really is easy to drop the unit and take it out for service. By the way, the fuel pump is replacable without dropping the unit.

[Chum_lee]

Lakeplay wrote:

A Good Cigar wrote:
How did the old generator bite the dust? How many hours are on it?

Tech told me it has internal issues. Backfires, white smoke. Only 220 hours.

Oh please! I have the same genny (1999 model) with over 1800 hours on it. Chances are yours is just broken in, it's not biting the dust unless someone did something really dumb which would be hard to do since it has basically sat around all its life. If it has compression, chances are the carb is dirty or it has some other, simple, easily repairable problem.

Get another techs opinion or apply yourself and fix it yourself.

https://cdn.ltvdns.com/leisurevans.com/owners/3rdparty/Cummins-Onan-RV-Generator-Handbook.pdf

Chum lee

[Lakeplay]

DSteiner51 wrote:
I had a Honda engine carberated that unless the gas was turned off the carb would allow gas to flow into the engine while going down bumpy roads. New engine with <10 hours, missed so bad it would hardly run while smoking horribly. I drained the crankcase and put new oil in, replaced the spark plug and the problem was solved.

Could this be a problem on an Onan too? Have you checked the oil level to see if it has risen?

Oil level hasn't changed. I have only owned it for 6 months. One thing I noticed right away was a lot of oil under the generator. Might be a crank case gasket leaking.

[DSteiner51]

I had a Honda engine carberated that unless the gas was turned off the carb would allow gas to flow into the engine while going down bumpy roads. New engine with <10 hours, missed so bad it would hardly run while smoking horribly. I drained the crankcase and put new oil in, replaced the spark plug and the problem was solved.

Could this be a problem on an Onan too? Have you checked the oil level to see if it has risen?

[Lakeplay]

camperdave wrote:
Well, I do not think the newer models are significantly more advanced than what you have, it's going to be significantly cheaper to repair your unit than replace (unless you go with a portable).

White smoke to me means oil. But backfiring means carb. Could be a gummed carb? Stuck choke? sticky valve or valve seat? I dunno, but I would not be surprised if a new carb and filters solved the problem. I'd start there. Actually, I'd probably start by running a can of Seafoam through it lol.

If that doesn't do it, I'd remove the whole unit myself and save at least some labor hours. Mine is just bolted up under the motorhome, unhook all the attachments and lower it with a jack. Then bring it to a small engine repair shop instead of an RV or Cummins shop. These are low tech engines.

I'm not very mechanical so taking it out myself and having a small engine repair shop is probably what I will do.

Thanks everyone for all the helpful reply's.

[Lakeplay]

STBRetired wrote:
Have access to a pickup? Have a friend help you take it out of the RV (not difficult, just heavy) and save the $1K that Onan wants to do the removal. If you are fairly mechanically inclined, they are pretty easy to fix. Parts are available from aftermarket (cheaper) and Onan (expensive, but only source for some) and the repair manuals are available online. Replaced a failed stator in one and rebuilt the engine in another (after something like 8000 hours of runtime) with no problems. Both run great again. Much cheaper than new ones and feel much better about having the generator match what the enclosure was designed for.

I think that's what I'm going to do.

[Lakeplay]

DrewE wrote:

Lakeplay wrote:

A Good Cigar wrote:
I say get a better tech! Did he specify what the problem was? I'm guessing that he didn't
It is almost impossible to destroy an Onan after only 220 hours!! Onans have a built in low oil pressure switch to protect the engine, and oil pressure is just about the ONLY thing that could cause "internal issues" in a engine with so few hours! I am no expert by any means, but it is certainly worth your peace of mind and usefulness of your RV to have that generator looked at by a competent tech! More than likely, it'll be the usual problem of a gummed up carb, or a bad control board, both ~$500 repairs!
Good luck:)

Its actually been looked at by 2 tech's. One was a ONAN tech who told me it had to come out and would cost a minimum of 1k.

I don't think the current 4KY generators, which this is, have an oil level switch, though at times they have included one. They certainly don't have an oil pressure switch because the lubrication system is a splash, rather than a pressure, system.

Any significant work would require removing it, yes. That's a good bit of labor, but it's not really complicated and doesn't require special tools or skills. It's a matter of disconnecting the things that are connected (AC and DC wiring, fuel line) and then unbolting the unit from its mount and safely lowering it down or sliding it out through the side opening. In some cases, it may be necessary to have the side or end of the RV up on ramps or something to get clearance underneath.

Many of the Onan problems I've heard of--though not all--stem as much from lack of use as anything. Making sure gas doesn't have time to get old in the carburetor goes a long way to keeping it running well. Other common problems are pretty easily solved; the fuel pumps sometimes wear out, for instance. I suppose that's not much consolation when you're one of the others, unfortunately.

(Even if it fit and had adequate cooling, I'd give a lot of thought to how to route the exhaust gasses from a Champion or other portable generator safely out from under the RV if installing it.)

I did some more reading on the champion. It is not supposed to be in an enclosed space so that's out unless I just use it as a portable.

[camperdave]

Well, I do not think the newer models are significantly more advanced than what you have, it's going to be significantly cheaper to repair your unit than replace (unless you go with a portable).

White smoke to me means oil. But backfiring means carb. Could be a gummed carb? Stuck choke? sticky valve or valve seat? I dunno, but I would not be surprised if a new carb and filters solved the problem. I'd start there. Actually, I'd probably start by running a can of Seafoam through it lol.

If that doesn't do it, I'd remove the whole unit myself and save at least some labor hours. Mine is just bolted up under the motorhome, unhook all the attachments and lower it with a jack. Then bring it to a small engine repair shop instead of an RV or Cummins shop. These are low tech engines.

[STBRetired]

Have access to a pickup? Have a friend help you take it out of the RV (not difficult, just heavy) and save the $1K that Onan wants to do the removal. If you are fairly mechanically inclined, they are pretty easy to fix. Parts are available from aftermarket (cheaper) and Onan (expensive, but only source for some) and the repair manuals are available online. Replaced a failed stator in one and rebuilt the engine in another (after something like 8000 hours of runtime) with no problems. Both run great again. Much cheaper than new ones and feel much better about having the generator match what the enclosure was designed for.

[DrewE]

Lakeplay wrote:

A Good Cigar wrote:
I say get a better tech! Did he specify what the problem was? I'm guessing that he didn't
It is almost impossible to destroy an Onan after only 220 hours!! Onans have a built in low oil pressure switch to protect the engine, and oil pressure is just about the ONLY thing that could cause "internal issues" in a engine with so few hours! I am no expert by any means, but it is certainly worth your peace of mind and usefulness of your RV to have that generator looked at by a competent tech! More than likely, it'll be the usual problem of a gummed up carb, or a bad control board, both ~$500 repairs!
Good luck:)

Its actually been looked at by 2 tech's. One was a ONAN tech who told me it had to come out and would cost a minimum of 1k.

I don't think the current 4KY generators, which this is, have an oil level switch, though at times they have included one. They certainly don't have an oil pressure switch because the lubrication system is a splash, rather than a pressure, system.

Any significant work would require removing it, yes. That's a good bit of labor, but it's not really complicated and doesn't require special tools or skills. It's a matter of disconnecting the things that are connected (AC and DC wiring, fuel line) and then unbolting the unit from its mount and safely lowering it down or sliding it out through the side opening. In some cases, it may be necessary to have the side or end of the RV up on ramps or something to get clearance underneath.

Many of the Onan problems I've heard of--though not all--stem as much from lack of use as anything. Making sure gas doesn't have time to get old in the carburetor goes a long way to keeping it running well. Other common problems are pretty easily solved; the fuel pumps sometimes wear out, for instance. I suppose that's not much consolation when you're one of the others, unfortunately.

(Even if it fit and had adequate cooling, I'd give a lot of thought to how to route the exhaust gasses from a Champion or other portable generator safely out from under the RV if installing it.)

[Lakeplay]

A Good Cigar wrote:
I say get a better tech! Did he specify what the problem was? I'm guessing that he didn't
It is almost impossible to destroy an Onan after only 220 hours!! Onans have a built in low oil pressure switch to protect the engine, and oil pressure is just about the ONLY thing that could cause "internal issues" in a engine with so few hours! I am no expert by any means, but it is certainly worth your peace of mind and usefulness of your RV to have that generator looked at by a competent tech! More than likely, it'll be the usual problem of a gummed up carb, or a bad control board, both ~$500 repairs!
Good luck:)

Its actually been looked at by 2 tech's. One was a ONAN tech who told me it had to come out and would cost a minimum of 1k.

[A_Good_Cigar]

I say get a better tech! Did he specify what the problem was? I'm guessing that he didn't
It is almost impossible to destroy an Onan after only 220 hours!! Onans have a built in low oil pressure switch to protect the engine, and oil pressure is just about the ONLY thing that could cause "internal issues" in a engine with so few hours! I am no expert by any means, but it is certainly worth your peace of mind and usefulness of your RV to have that generator looked at by a competent tech! More than likely, it'll be the usual problem of a gummed up carb, or a bad control board, both ~$500 repairs!
Good luck:)

[pianotuna]

Use part of the output to power a cooling fan. The fan needs to be 12 volt similar to the thermostatically controlled ones for radiators.