Generac 15KW generator engine tear down

[tcartwri]

Thanks Tim! I read the link you sent me and it sure sounds like that is why it happened, especially being that temps were around 100 degrees and the generator was running at close to 100% load for days.

Funny, we have had the opposite environment destroy gensets because of the cold. We actually have to insulate them in an enclosure, or the moisture in the crankcase will turn the oil into a milkshake in very short order and push all the seals out of the motor. This is at -40~50C.....

 

[pclausen]

When they do the guides, the original is oversized slightly and then a new sleeve is pressed in and honed to size. The guides do 90% of the oil control. You would be far ahead of the game to go to a proper machine shop.

I dropped the heads of at a machine shop. The exhaust guides and valves are shot. They would prefer to replace the guides, but as I think I mentioned before, Generac doesn't offer them separately from what I can tell. They are going to check to see if they can get bronze sleeves in the right size and oversize the original guides and press them in sleeves as you suggest. You wouldn't happen to have a source for suitable sleeves, would you?

 

[murphy1244]

Try B&S parts.

 

[tcartwri]

I dropped the heads of at a machine shop. The exhaust guides and valves are shot. They would prefer to replace the guides, but as I think I mentioned before, Generac doesn't offer them separately from what I can tell. They are going to check to see if they can get bronze sleeves in the right size and oversize the original guides and press them in sleeves as you suggest. You wouldn't happen to have a source for suitable sleeves, would you?

Ummm... they should know where to source them.

Here's an online source,

K-Line Valve Guide-Liners

 

[pclausen]

I think part of the challenge is that the machine shop doesn't know the specs of the valve, like stem thickness or length. They are primarily an automotive machine shop.

 

[displacedPA]

I think part of the challenge is that the machine shop doesn't know the specs of the valve, like stem thickness or length. They are primarily an automotive machine shop.

I would sugest going on the Kohler or B&S whatever the engine manufature is and plug in the serial number. You can buy everything you need part by part. and it will tell you the spec on the vavle guides ect.

I have done this with many engines and has worked every time for me

 

[pclausen]

Hmm, I poked around the generac web site and it doesn't appear to have a section for entering an engine serial number to look for parts. It seems more end user oriented.

 

[murphy1244]

Peter, That is a briggs vanguard engine.

 

[pclausen]

I wonder how I would go about crossing this Generac GT990 Engine ID D8547, to the Vanguard equivalent. I'll poke around on Briggs site to see what I can figure out.

I also called Generac who put me in touch with a local service center. I'll contact them tomorrow to see what they can tell me about guide replacement.

 

[tcartwri]

Well, I can't for the life of me find the specs for these guides. I can find the finish reamer that Briggs sells for the job, but no dimensions anywhere. would really hesitate to recomend a number to you as well. Briggs does sell these heads as an assembly for about $140 ea, and that's the route I went with my V-twin but the guides in that motor were not serviceable. Hopefully someone else has a number in a manual somewhere.

http://www.industriasfita.es/Data/herramtrabajo.pdf

 

[pclausen]

Tim, I found the entire head assemblies. Part numbers and pricing as follows:

0D8675ASRV Head assembly kit #1 $140.25
0D8675BSRV Head assembly kit #2 $145.25

This seems to be the easiest way to get this engine back up and running again, and the cost is not seem that much higher compared the rebuilding the existing heads once you include parts and labor. The machine shop quoted me $110 the rebuilt the existing heads, plus parts.

 

[Pete Judd]

Might want to try these folks. http://www.tulsaenginewarehouse. Briggs & Stratton Vertical Shaft Engines - On sale with free shipping from Tulsa Engine Warehouse

 

[hr3]

Found this hope it might help..

 

[pclausen]

Thanks. That will help a lot of I end up rebuilding the heads. Still on the fence. Trying to get a hold of an old friend that rebuilt this very engine model for tractor pulling. They make about 90hp and turns around 9000 rpm! He should be able to tell me about where to get guides or inserts.

 

[hr3]

Valve guides.. Part # 67813 Generac Generator Parts-67813-GUIDE, VALVE

 

[pclausen]

Thanks again!

Once thing that caught my eye was that in the pages you posted above, the heads use 4 head bolts, where mine have 6. Also, there don't appear to be any push rod guide plates on those heads.

When I Google the valve guides part # 67813, I get a lot of links to 8kw Generac RV generators, but none to the GT990 engine I have. Do you feel pretty good about those guides being the same ones used in my 6 bolt heads?

 

[Retired Iron Peddler]

Thanks again!

Once thing that caught my eye was that in the pages you posted above, the heads use 4 head bolts, where mine have 6. Also, there don't appear to be any push rod guide plates on those heads.

When I Google the valve guides part # 67813, I get a lot of links to 8kw Generac RV generators, but none to the GT990 engine I have. Do you feel pretty good about those guides being the same ones used in my 6 bolt heads?

I entered your valve guide part number into this web site Generac Parts and came up with $17.80 each. I don't know if they have them in stock or not. I've used this company for Generac parts in the past and received prompt service.

Bill

 

[pclausen]

I was finally able to catch up and talk to my friend that races these Generac engines. He posses a wealth of knowledge about these engines.

First of all, Generac designed and built this engine from the ground up in-house. They then sold the design to Briggs, who then marketed them under the Vanguard brand. Generac continues to manufacture the engines used in their own generators. This is the only V-Twin big block still being made in the US. They use 6 bolt heads. The 4 bolt head V-Twin engines are small block designs, manufactured by Briggs. All other similar size engines (Kohler, etc) are being manufactured overseas. Back in the day, Generac used to sell engines directly, but their sole focus these days is generators.

Generac has a policy of replacing engines under warranty instead of repairing them. My friend was able to pick up a GT-990 engine with 12 hours on in that had been replaced under warranty. The only issue with it was a minute leak from the crank case gasket. It wasn't even enough of a leak to cause oil to run down the block.

My friend and his dad get these engines, and then discard everything but the block, crank and bare heads. Then they bore them out and put in larger pistons, valves, valve train, etc and set them up to run 15:1 compression on methanol. They also discard the OEM ignition coils and run dual Bosch blue coils with dial Mopar racing ignition boxes with individual crank triggers for each cylinder. Spin around 9500 rpm.

At any rate, he's willing to swap out my entire engine for the 12 hour one mentioned above (was pulled from a 15kw generator just like mine) with some "boot", but probably less than what I would have had to pay for a new set of head assemblies. The only thing missing is the oil pump and pickup tube, which I can steal off my engine. Even has a new crankcase gasket I believe. Woohoo!

 

[tcartwri]

Boy that's a deal. Now, what are you going to do with two gensets....

 

[Dirtball]

Boy that's a deal. Now, what are you going to do with two gensets....

BACKUP !!!!!! Mount it on a trailer, get some of that yellow flexible gas piping and make up an " extension pipe" should you have to take it to a friends house who has LP. You need a special crimper for that line- don't do yourself if you haven't worked with it before. I think they won't even sell it without a license. Add a 50 amp basic receptacle for a quicky output connection. Make up a cord - 8/4 wire and provisions on the house side for an easy backfeed. or sell it and get a diesel unit as backup. Have fun.