Briggs 20 HP OHV Slow Cranking

[darrinster]

Model: 331777-1372-B1

*EDIT*

Got it running and it's blowing white smoke. Guess head gasket is blown.



Adjusted the valves to specification. Owner installed a new solenoid. Engine will crank normal if I hold my hand over intake tube connected to the carburetor.

If I don't hold my hand over the intake tube you can hear hissing coming from valves when cranking the engine.

I had another engine that did this, but for some reason after I removed the carburetor and reinstalled it the issue went away. Tried it on this one but of course it didn't fix it.

 

[mechanic mark]

https://www.briggsandstratton.com/n...nginemanuals.html?searchrequested=331777-1372

operators manual & parts list

http://faculty.missouri.edu/~schumacherl/276781SingleCylinderOHV.pdf engine repair manual

http://www4.briggsandstratton.com/m...on_Troubleshooting_Detail_Reference_Guide.pdf

http://www.briggsandstratton.com/eu/en/support/faqs/engine-emits-white-blue-smoke-while-running

 

[darrinster]

Still wont crank right. Battery and starter is good. Adjusted the valves so many times with different clearances. Only thing helps is if I put my hand over the intake coming from the carburetor. Then it spins with no issue.

Would this mean the cam needs replaced?

 

[mechanic mark]

You must not have looked at manuals that I posted. Page 10 in operators manual: intake valve .003-.005, exhaust valve .005-.007, spark plug gap .030, adjust valves with engine cold. Check oil level on dipstick, if it is high & smells like gas carburetor problem. Fresh gas, air & fuel filters & spark tester to check for spark at plug. The answer to your camshaft replacement is no. How are you adjusting valves, procedure?

 

[darrinster]

You must not have looked at manuals that I posted. Page 10 in operators manual: intake valve .003-.005, exhaust valve .005-.007, spark plug gap .030, adjust valves with engine cold. Check oil level on dipstick, if it is high & smells like gas carburetor problem. Fresh gas, air & fuel filters & spark tester to check for spark at plug. The answer to your camshaft replacement is no. How are you adjusting valves, procedure?

1/4 past TDC. Also tried one valve fully closed and one open to adjust I've adjusted quite a few briggs OHV engines and never had an issue.

I don't think the compression release is working. I adjusted both valves to .002 and it still has a hard time getting over the compression stroke.

Any idea why holding my hand over the intake would allow the engine to crank normally? Cam lobe worn off?

 

[Tinkerer200]

I can send you Valve Adjusting Instructions which include a test for the compression release working, And YES, it could be the camshaft. By holding your hand over the intake you are limiting the amount of air entering thus reducing the amount of air to be compressed.

Walt Conner
wconner5 at frontier dot com

 

[darrinster]

Cracked open the engine and here is the problem. New one is on the way.

I opened up my parts engine and it had the same issue. Judging by how many are sold on ebay they must fail quite often.

 

[darrinster]

Replaced the camshaft, starts so easy now. Runs better also. Removing the old gasket was the hardest part.