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Briggs and stratton 15.5HP IC- Valves not opening

60K views 86 replies 9 participants last post by  dbuck 
#1 ·
Picked up a Yardman mower with a 15.5 Briggs on it today at a estate sale for $100. The guy said it would not start. I took it home and sure enough it will not start after adding fresh gas and making sure it was getting fire. I then took the OHV valve cover off and turned the engine over a few times. I discover the valves are not moving at all. Any idea on what might be broken or something come loose inside the crank case?









 
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#2 · (Edited)
I would take the head off, and see if the rod is bent. They could just need lubrication if the mower was sitting. Are they stuck open, or closed?

Could be a lot of carbon build up. Sometimes you can tap them free, by applying lubrication after each tap.I would still take the head off, and give it a good cleaning, and see whats going on.

What's the model/type/code?... Look on valve cover near the flange, vertical shaft it will be facing up on valve cover. Example would be 31C707-0230E1 040521ZF Keep us posted.
 
#3 ·
Are the push rods still attached? If so and the valves are not stuck then likely you have a broken cam or gear. Does the piston even move up and down?


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#5 ·
i agree with red. pull head off and go from there. i seen push rods snap. i seen cam shafts snap in 2. and i also seen rods take out the cam. also start looking at the block to see if you see any cracks.
 
#6 · (Edited)
I just took out the plug and put my finger there..seems to be blowing out quite a bit of pressure. Wish I didn't lose my compression tester, :crybaby: The valves moves freely as I pull and push valve rockers and opens and closes fine. Plenty of oil coated also on those areas so not dry or stuck....also no carbon to speak of . If it was a rod the piston not be getting pressure out the plug hole..right? With this engine is it possible to take it off the deck frame and just take off bottom sump to get to camshaft with out taking all other components off like flywheel etc?


By the way is this camshaft having a nylon gear like some or is it steel? Push rods all there but they kinda seem loose and not tight putting pressure up on the rockers...is this not normal?
 
#7 ·
it could have burnt the lobes off the cam. did you check the push rods?
 
#15 ·
Sounds like a camshaft issue to me as well after seeing the rods. I agree something with the lobes, shaft, or gear. Shoot us some pics inside.
 
#17 ·
#9 ·
pull the rockers off take out the pushrods and take pictures. i want to see the pushrods.
 
#11 ·
k they are fine hmmm its got to be something with the cam.
 
#12 ·
pull the engine pull the cam out and inspect it. theres 2 styles cames they put in these. one a solid gear cam and 2 a spoke kind. i am betting either cam broke or it burnt the lobes. both styles have steel gears.
 
#13 ·
correction 3 kinds 3rd one has a peice at the bottom of stem for operating the oil pump
 
#14 ·
Finally got the engine off the mower frame and set it up on a table. Draining the oil now and looking into the oil drain hole I see pieces of metal...too big to pull out the hole. I am now going to wait until all the oil drains dry and remove sump cover. Wish me luck nothing major that will cost $500 or a new engine. :thSick:
 
#16 ·
If it's just the camshaft. Then they are like $40.00 bucks. I will shoot you a like to your manual, and engine parts schematic so you can pull part numbers and get prices. As longs as you don't have any cracks, or major scoring on the crankshaft hopefully you will be ok.
 
#18 ·
hopefully it didnt damage anything
 
#19 ·
I have a bunch of photos to share now and need advice if this engine can be salvaged at a reasonable price. I think what happened was some kind of rod came loose on some counterweight if that was is called and also the crankshaft gear was broke in half. The crank does not seem bent as it turns easy and moves piston up and down. The piston connecting rod seems fine. What would have caused such a catastrophe? I also notice soke small piece chipped off the bottom of the oil sump and a small hairline crack on the top of the block. Not sure if it is completely through though. Could that be patched up with some JB weld? Need all input on this and if need more photos or question ......ask away. Also what is a replacement Model number engine like this I could use if this one is not worth it? :thanku:

































 
#21 ·
Worth fixing? For an intek single I'd say no. But it's up to you if you would like to spend the money. You can find a good motor for what it will cost to fix unless you can find a scrap engine and then who know what you get?


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#22 ·
get more of inside the engine so far i see u need balancer oil pan and a couple balancer parts and timing gear. seen one blow like this last year
 
#23 ·
heres what i would do its cheapest way. id go to the scrapyard find a ohv engine within the same hp range buy the engine and bring it home either use for parts or if you find one in really good shape slap it on and use your carb and other things
 
#24 ·
From what I can see, you need the following so far.

Oil Sump (#4 Confirm Part# 697106) Ebay Price: $70.00

Crankshaft Timing Gear (#741 Confirm Part# 697128) Ebay Price: $9.00

Both Counterweight Links (#757 Confirm Part# 793242) Ebay Price: $20.00

Part numbers are listed before "Confirm Part Number" in your parts list sheet I linked you earlier, Your around $100.00 bucks right now. JB weld is not that good under stress.

I would take it to a shop, and have them weld it and smooth it out. It's not that expensive considering what you are going to be fixing. $30 max for something like that to have welded, and smoothed over. If that's all the damage, and the crankshaft, piston, sleeve etc... is good I would fix it, but that's just me. The other guys on here are way more experienced with that.

Also check your Timing Gear Key. it looks like it is hanging out. Inspect it and possibly replace that as well if your going to fix the engine.
 
#25 ·
if my local yard had mowers in (people havent done spring clean up yet) i could get a block with all insides and have compression for 10 - 20 dollars. so give your local scrapyards a visit u may never know they may have a section for stripping mowers
 
#26 ·
Where I live there is no local scrapyards like in the big cities..it is hard to fine used parts unless you drive 200 miles. Someone mentioned it needs a new oil sump. What is wrong with this one? Is it the small chipped off piece? Anyone here can sell some used parts for this engine? How much does a new replacement engine cost that would bolt on? Does not have to be so big HP also?
 
#27 ·
shipping would be the killer. check craigslist for a ohv briggs
 
#28 ·
and by the way i live out in middle of no where 45 minutes to travel to closest walmart. theres hmmm 3 scrapyards withing 20 minutes from my house lol
 
#29 ·
that engine is toasted but good....no fixin it.. u can find some other B & S engine to repower it with....in fact u could even put on a Kolher too..less than
 
#30 ·
find a good Kolher or a Briggs that has pressurised oil & filter.....they will last a long time... u can find them for 50 - 100..from other people..

there is ppl out there (specially on craigs that have engines..)b sure u hear them run before u buy one...
 
#31 ·
Scrap metal...block is cracked, sump is bad..ugh..

Id salvage the head, crank, rod and piston, cam, lifters, etc...clean em, put em in a box with the carb, starter, shrouds, etc...never know when you might need em in the future..and find another engine.
 
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