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Author Topic: Generac oil leak - repair/replace  (Read 4446 times)

dcg9381

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Generac oil leak - repair/replace
« on: September 22, 2008, 02:27:38 PM »
I've got an '02 Gulfstream class-A with a 4800 watt Generac generator.  I believe the model is 50G.
The motorhome is new to me - no history on it.
The generator hobbs time shows 850 hours.  The generator is leaking oil (when running) and giving some blue smoke (not out the exhaust) at start up, indicating I've got oil on parts of the exhaust.

I've worked on lots of motors, but not generators and mostly larger motors than this.  To service, it looks like it'll need to be completely removed and inspected.
Oil leaks only when running - indicating a seal in the area of a moving part (which is most of this thing). 

Any opinions on repair vs replace for a 850 hour generator?  I know Generac doesn't have the best reputation.  A new one will run me around $1750 - assuming I can get the exhuast and remote accessories bolted on from the old one.


Gary RV Roamer

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Re: Generac oil leak - repair/replace
« Reply #1 on: September 22, 2008, 04:56:16 PM »
I had a Generac 5500 for five years and it leaked oil for 3 of them. Never seemed to lose a lot but the pan underneath was always wet. Appeared to be seepage from the lower crankshaft seal. No way to even inspect closely without pulling it out (mucho work - need a forklift to do it right), so I just checked the oil every few months. Never had to add any between annual oil changes though.
Gary
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Gary Brinck
2004 American Tradition
2007 GMC Acadia
Homebase: Ocala National Forest, FL

dcg9381

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Re: Generac oil leak - repair/replace
« Reply #2 on: September 22, 2008, 09:08:21 PM »
I have access to a fork lift via work, although it would cost me a few bucks to drive the motorhome on the daily commute.
Make that model 55G, not 50G.
55G

A little oil on the pan I could handle.  I was working on trim this weekend and had it at a friends house, slightly unlevel - tilting toward the drivers side.
It left a significant puddle of oil on the ground, maybe 1/5 of a quart in about 3 hours.

Anyone know if replacing the crank seal can be done externally after pulling the genset - or are we talking tearing into it and displacing the crank enough to get to the seal....

Then there is the - with 800 hours on it, unknown maintenance history - is it worth it?

Gary RV Roamer

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Re: Generac oil leak - repair/replace
« Reply #3 on: September 23, 2008, 09:33:30 AM »
I think mine was a 55G as well. Don't know about the repair procedure, but my bet would be that it is a tear-down.
Gary
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Gary Brinck
2004 American Tradition
2007 GMC Acadia
Homebase: Ocala National Forest, FL

Karl

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Re: Generac oil leak - repair/replace
« Reply #4 on: September 23, 2008, 09:49:15 AM »
Here's something you can try: Remove the oil filler plug and place your thumb tightly over the opening while someone starts the generator. It may blow your thumb right off and get very messy (be prepared to stop it QUICKLY), but that would indicate excessive blow-by at the rings, possibly forcing the oil past the crank seal or valve seals and out past the valve cover gasket. If that's the case, I think you would be throwing good money after bad by rebuilding the engine. If you can get at the top of the cylinders, just try tightening the valve cover bolts slightly. You may luck out! :) 
Karl (Cheesehead) Kolbus   Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting "...holy cow ...what a ride!"

dcg9381

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Re: Generac oil leak - repair/replace
« Reply #5 on: September 23, 2008, 01:23:09 PM »
I have a leak down tester, which might be a little easier and more scientific than using the "thumb" method.  I just have no idea what leak down should be on a generator, I'm going to assume less than 15%.

The local service center for these things says that effective life should be 3000 hours or so.  It'll have to come off to be serviced / diagnosed... Unless I found the loose valve cover as indicated.. :-)

Karl

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Re: Generac oil leak - repair/replace
« Reply #6 on: September 23, 2008, 06:27:23 PM »
Quote
I have a leak down tester, which might be a little easier and more scientific than using the "thumb" method.
A leakdown tester requires outside air be piped into the cylinder at TDC and you have no good way to position the piston properly unless you can get a wrench on the crank bolt. Too much dis-assembly required, IMHO.
Karl (Cheesehead) Kolbus   Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting "...holy cow ...what a ride!"

Benzman

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Re: Generac oil leak - repair/replace
« Reply #7 on: December 03, 2008, 01:42:19 AM »
Greetings!

Karl; don't try run the generator with the oil cover off.  It will blow oil all over the place and it is not an indication of blow-by.  The crankcase is a sealed negative crankcase pressure ventilation system.  Also, I have never seen one have bad blow-by, ever.  Many other problems, but never blow-by.  I'll explain more in depth if you wish.

RV Roamer and dcg9381; Generac generators up until recently were leakers.  The 55G (probably model 9592-x) typically leaked at the aluminum oil filler tube.  This is two pieces and is bolted together under the sheet metal before is screws into the engine.  There's an o-ring in there and it flattens with heat over time and allows oil to seep out.  I would suggest replacing it with a gasket, home made or similar.  Also, if there's an air leak to the crankcase, the oil will seep out.  So, check the oil filler cap for an o-ring and check the valve cover gaskets for cracking.  The breather in the center is never a problem.  Rarely is the engine case gasket or seal a problem, but I have replaced one or two out of the many over the years.  So, check the oil filler tube o-ring, it's likely the culprit.

Hope I helped.

Benzman - RV Generator Trainer
What I hear, I forget. What I see, I remember. What I do, I understand. - Confucius

Generators are my specialty, humor is my pass-time, and God is my everything.

Gary RV Roamer

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Re: Generac oil leak - repair/replace
« Reply #8 on: December 03, 2008, 08:25:36 AM »
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Generac generators up until recently were leakers.

Mine certainly was! It made for a messy generator compartment but never interfered with operation, nor did it actually use much oil. For the 25-30 hours a year we typically ran the genset, it wasn't even necessary to add oil between changes. Ours started leaking when it was about 24 months old and we ran it another three years with no problem other than the need to spray the compartment down with degreaser once a year to get rid  of the oil film.

Thanks for the tip - it sure is nice to have somebody onboard who really knows the product.
Gary
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Gary Brinck
2004 American Tradition
2007 GMC Acadia
Homebase: Ocala National Forest, FL