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Hot!Briggs and Stratton L Head - Low Compression

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gibbywmu
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2019/06/19 08:36:22 (permalink)
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Briggs and Stratton L Head - Low Compression

Hi All,

I was hoping that someone having experience in repairing B&S L Head Engines could provide some insight on my issue, before I decide to just scrap this engine for parts.

I have a Husky Pressure Washer with a B&G L Head Engine. The Engine Model is the 10L902-0010. Pretty much a standard B&L L Head Engine. The cylinder is low on compression, around 80psi. It runs very, very rough......not to the point that it stalls, but very poorly. Changed plugs and still did not resolve.

Background Info - Purchased for $25 at a local online swap sale. Ran ok for about 5 min, discovered it needed a new pump. Purchased for around $70. Purchased new carb (kit w/ diaphragm and all), new air filter, sparkplug, and fresh engine oil. Started running funny, realized sparkplug hole was stripped. I definitely did not do this, so purchased another head on Ebay for $10. Inspected cylinder and seemed ok. No knicks or pitting. Piston looked ok with normal carbon buildup. Intake manifold looks ok. Did not disassemble, but no signs of cracking.

The head gasket looked ok, but not sure how to tell if its 100% ok? Wondering if this is the main issue? I see they are very inexpensive, around $5 on Ebay. I'm definitely willing to take the risk for that amount.

I don't have any sort of leakdown testers, so I won't be able to tell where the air is coming in at? I'm thinking its got to be sucking air somewhere.

I don't mind taking the head off again if someone needs to see a picture of the head gasket.

Any suggestions on where else the problem is? Or am I right and thinking the head gasket is not ok?
 


24 Replies Related Threads

    AVB
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 10:18:57 (permalink)
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    First your spec (type) number is wrong as it doesn't per Briggs.
     
    As for the compression it is within specs as these engine has an ACR which limits startup compression. Considering the potential age of this engine check your check valve clearances as they do close up over time. Also the intake manifold as I have seen a few with holes rubbed into them.
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 10:27:24 (permalink)
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    AVB,
     
    Not sure what you mean by my spec (type) number is wrong.  This is the model # of the B&L Engine.  I have the parts diagram right here in front of me.  I can even show you a pic off the engine.
     
    I will tear off the head again and look at the valves. From what I remember, they seem ok.  Do you need pics if I post?  I'll also remove the intake manifold and inspect.  Looks ok from the top, of course you can't see the bottom side.
    AVB
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 10:41:21 (permalink)
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    All I finding on the Briggs site is a 10L902-0110 and not a 10L902-0010. Maybe type forgot to that IPL on their site.
     
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 10:59:16 (permalink)
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    AVB,
     
    You are correct, it was a mistype.  It is a 10L902-0110...........which doesn't make a huge amount of difference.  All these L Heads are basically the same.  Just trying to figure out where this air leak is coming from if that's what I have.
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 14:16:42 (permalink)
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    Hi All,

    Here are some more pics from today. I removed the intake manifold and inspected, it was fine. No cracks or fractures. It may be this head gasket, its not in the greatest shape and some oil was coming out of the bottom of the cylinder head. Piston, Cylinder, and valves look ok. Both valves seat properly after turning the flywheel to inspect.

    What are your thoughts on this head gasket?


     

    Roy
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/19 22:26:14 (permalink)
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    That gasket is a large part of your problem, replace it and properly torque the bolts but before you do remove the breather and check the valve clearances. 80 psi with a leaking gasket tells me they are excessive, the compression release is not working which will kill performance
    AVB
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 07:36:11 (permalink)
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    Nearly half of the graphite sealing area of the head gasket on the side should is missing.
     
    Now I would differ with Roy as this is a L-head setup. Unless someone has already grounded the valve stems the valve clearances has the tendency to close up and not open up. I do know if the clearance are too much that ACR (automatic compression release) would become ineffective. Now these camshaft ACRs do failed on these camshafts but not very often. This ACR bump should be felt on the exhaust valve of this engine just before the top of the compression stroke when both valve are closed. It basically just cracks open the exhaust valve to release some of the starting pressure. If no bump is felt then it is likely the camshaft's ACR has failed, requiring a camshaft replacement.
     
    Now if the valve clearance(s) are too much and no one else been in the engine then the camshaft lobes could be worn but I kinda doubt this is case even with these plastic lobes.
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 09:49:50 (permalink)
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    AVB,
     
    I agree with you.  I'll start by replacing this gasket tomorrow when it comes from Amazon.  Hopefully this will resolve all of the issues I'm having.  If not, I guess I'll look to the valves next, but as I mentioned, looks like they are seating properly.  There is no wiggle in them at all when they are fully seated.
     
    Not sure how this gasket failed....but I did buy it used so no telling how well/not well it was taken care of.  I've never had a pressure washer blow a head gasket before.
    AVB
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 10:54:05 (permalink)
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    The graphite coated gaskets should never be re-used. Even all metal ones really should be re-used.
     
    The graphite tend to tear upon removal and the metal ones are formed to the imprefection of the engine they are used on initially.
    kshansen
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 10:58:42 (permalink)
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    gibbywmu
     
    If not, I guess I'll look to the valves next, but as I mentioned, looks like they are seating properly.  There is no wiggle in them at all when they are fully seated.
     



    Why not remove and inspect the valves while the head is already off?
    How can you tell if they are seating good without removing and inspecting them?
     
    At the bare minimum have you checked with a feeler gauge and checked for the "compression relief bump" AVB mentioned?
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 11:17:56 (permalink)
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    To be honest, I don't have feeler gauges, valve spring tools, lapping compound, lapping tool, leak testers, etc.........so I'm not about to throw more money at this engine nor does it make sense.  If replacing the gasket doesn't work, so be it.  I paid $25 for the pressure washer and I'll sell it for parts if its still not running right.  Just thought I would get as far as I could with the tools that I have.
    Roy
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 11:40:55 (permalink)
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    AVB, I worded that poorly. I meant to say that excessive valve clearance would kill performance and render the compression release ineffective. Even a new engine would normally have 75 psi  cranking compression. 80 sounds odd especially with that leaking head gasket.
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/20 11:44:54 (permalink)
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    I'll definitely keep everyone posted after I replace the head gasket tomorrow.  Is there a possibility that it has bad piston rings also?  I noticed that I after I put fresh oil in it, and it started running poorly (whether from the blown head gasket or otherwise), there is definitely unburned fuel getting into the oil.  The oil is almost dirty again which makes no sense.
    Mikel1
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/22 16:06:51 (permalink)
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    80lbs doesn’t seem low to me.
    Head gasket help any?
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/23 21:03:46 (permalink)
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    Head gasket did not fix it :(.  NO idea what's wrong.  Its beyond me now.  I'll just scrap this engine for parts.  I'm not investing more money in feeler gauges, leak down testers, etc.  Was hoping this was the fix!
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/24 14:53:23 (permalink)
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    Guys,

    So we have some life.  My mistake.  It was a new carburetor, but somehow when I installed it, the diaphragm was not right.  I pulled it off and sure enough, it had a hole in it.  No worries as I had a spare diaphragm.   Installed, engine ran great right away!  (No pump on).  Now, here's where the trouble lies.   When I installed the pump (this is a brand new Annovi Reverberi pump, the same style that are on my other 3 pressure washers), it start to run for about 1-2 seconds, and shuts off immediately.  Its like with the load of the pump on, it can't handle it.  Shuts off right away.   I turned the water supply off, disconnect the hoses, and fired up again.  Runs perfect with no water supply.  Only let it run for a couple seconds so the pump coudn't get damaged.

    Now...........why with a new pump does the engine want to stall out immediately if it runs fine w/out the pump on?  What am I missing here?
    Roy
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/24 15:41:11 (permalink)
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    Sounds like the unloader is not opening with the gun closed.
    gibbywmu
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/24 16:01:55 (permalink)
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    Roy,
     
    Sounds like it by the symptoms right?  This is a brand new pump.  Now, I did install a new carb and had issues as I just discovered.........due to a diaphragm not being installed correctly.   I did remove the Unloader Valve on this AR pump, and its brand new.  Still has white grease on the spring.  Definitely not the unloader valve.
    Mikel1
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    Re: Briggs and Stratton L Head - Low Compression 2019/06/24 23:18:16 (permalink)
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    Yeah I was thinking like Roy.
    I seen this on my other forum you mentioned it was burning oil.
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