Issue with Briggs 8hp

[creia]

[quote="ronspol"]OK. I think I may not have understood your question. I bought this short block over a year ago, just now getting to the project.

Would have been good to know in your ORIGINAL post!?
Michael

[Deere2me]

Well, I tried the leakdown test. Even at low pressure (30 psi), I have air in the crankcase. If I'm not mistaken, I should never have leakage into the crankcase. The story on the block is, I emailed Briggs & Stratton looking for one. They had one in stock, and it was $300. They did give me the P/N, so I ended finding one on ebay for $50 from a dealer. It did have the masking tape on across the cylinder top. Not sure what to do now, it seems to leak past the rings?

Edit: I don't think I had TDC, I believe if one valve is even slightly open it can leak down into the crankcase (valve in block). Will try again....

The valves won't let air into the crankcase!
You need to get a manual, and go over the compression section.
Alum. bore or cast iron bore?

[KE4AVB]

If he got the right short block it should be the same the original engine which was a sleeve bore.

[ronspol]

It is a cast iron liner, it looks clean with no signs of corrosion. What would be a typical compression reading on this type engine? I notice Briggs only recommends a leak down check. Also, has anyone had experience with Sea Foam additive to loosen the corrosion? I thought I would try it as a possible solution, pour a little into the cylinder with the piston maybe 1/4" below tdc and let it sit and retry the compression/leakdown tests. If it doesn't pan out, then pull it apart.

[bobodu]

I'm lost....what corrosion? Briggs gas never published compression members but you should see 100 pounds although I have seen them run at 55. Maybe I missed it but I don't see where you blew air into the cylinder to find the leak....

[StarTech]

If it was me I would go ahead and simply tear the engine the rest of the way down. That I way I could inspect everything and know for sure if there is problem. Sometimes it is the only way to know what is going on. Sometimes it is just a waste of time not to.

Some engines are just picky about everything being right and others refuse not to run even when they are falling apart. I got a 5 hp in the shop right now that runs and uses a quart of oil a day. Ran leak down test on it and it leaks everywhere. Pulled the head. It has a bent exhaust valve, an worn out intake valve that not even closing all the way, worn out rings and a leaky head gasket. How it is starting and running I have no idea; by all rights it shouldn't even start.

[Mek-a-nik]

OP says he has air in the crankcase. He never said if it's a normal amount or excessive damage past the rings. This has become a bad motor before we know more about the air.

[KE4AVB]

OP says he has air in the crankcase. He never said if it's a normal amount or excessive damage past the rings. This has become a bad motor before we know more about the air.

I think most us are thinking along the lines as I am that new short block for $50 just sounds to good to be true and that there is probably something wrong here.

Just thought of an idea ronspol. If you have a local technical trade school in your area why not give them a try. The instructors at my technical school were really good at fixing things and the students need the practical experience too. They are supervised while they are doing the work. Book learning can only go so far.

I know I greatly appreciated the parents that allow us to work on their equipment when I was training.