B&S 18.5HP Fuel Pump problems

jacorcesApril 9, 2014

I posted an earlier message regarding my engine problem and received a replies from Tomplum and Woodsrunner55 that were right on. Thoughts were that I had a blown head gasket and after taking off the head they were correct. Many thanks!!!

What I am trying to find now is the bolt torque pattern, torque setting for the head and valve clearances. I have not found the specs online (short of purchasing a repair manual) and was hoping someone would know or have a repair manual they could forward. The engine is a Briggs & Stratton 18.5HP model 31P777-0296-E1. The engine in a Craftsman riding mower.
Again many thanks in advance!!! jacorces

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Your head bolt pattern is:


Torque it to 220 in/lbs. Do the sequence with 70 in/lbs, then again at 140 in/lbs, and then lastly at 220 in/lbs.

See page 98 in the manual

Your valve specs and torque specs are on page 172. Your intake valve lash needs to be 0.003" to 0.005" and your exhaust valve lash needs to be 0.005" to 0.007".

Your manual is here:

http://dl.dropboxusercontent.com/u/12502267/B%26S Service Manuals/10_276781SingleCylinderOHV.pdf

Good luck.

This post was edited by optsyeagle on Wed, Apr 9, 14 at 20:14

    Bookmark   April 9, 2014 at 8:12PM
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Optsyeagle, Thanks for the input and link!!!

    Bookmark   April 9, 2014 at 9:46PM
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There is actually newer info on this. If it is done already- no problem as only thousands have been done this way. Torque in thirds to 250 Inch pounds. Glad it worked out.
6 ....2... 4
3 ..7..1..5

    Bookmark   April 9, 2014 at 10:28PM
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Did B&S update the torque specs?

    Bookmark   April 10, 2014 at 8:18AM
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Yes. APSI #87 Nov 2012 It will be updated in the manual according to the sheet. They basically did a head change w/ new fasteners. Then they decided it would be less confusing to do the old heads that way as well.

    Bookmark   April 10, 2014 at 10:44PM
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When you say new fasteners are you talking about the head bolts or some other redesign.

    Bookmark   April 11, 2014 at 8:47AM
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Well, the head shape did change. You might recall that the head bolts socket size got smaller on later models as well.

This post was edited by tomplum on Sat, Apr 12, 14 at 7:00

    Bookmark   April 11, 2014 at 10:59PM
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I guess my question is, if one was changing the head gasket on a 31C707 model Briggs motor would they use the old head bolts and torque to 220 or buy new head bolts as well, and torque to 250 or just use the old head bolts but torque it a little higher at 250 in/lbs.

I may be changing one soon on a motor that was built in 2004.

    Bookmark   April 12, 2014 at 8:36AM
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An excerpt from the bulletin
"APSI #: 87
MODELS: 210000 280000 310000 330000 OHV VERTICAL SHAFT ENGINES"

"Briggs and Stratton recently changed to a new design cylinder head bolt for model 210000, 310000, and 330000 OHV engines. The new bolts require a higher torque during installation. At the same time, we have modified the bolt tightening sequence to reduce the chances of head warpage at higher torque settings.

To prevent confusion, use only the new tightening sequence and new torque value when servicing both older and newer designs, including the model 280000 OHV. The following procedure will replace what is currently shown in repair manual 276781 Single Cylinder OHV Air-Cooled Engines."

    Bookmark   April 12, 2014 at 10:31AM
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Thanks Tom

I guess this new torque is only applicable if I get new head bolts. In my owners manual the part number for new head bolts is 690360. Is that the part number for this new design or would there be another part number?

The new torque sequence. Is that the sequence you had above. My current head looks a little different then your sequence above. Mine looks like this:





What would be the new sequence with the new head bolts?

Lastly, my manual says to "remove and discard plastic push rod guide". Do I need to buy a new one of these for when I put it all back together?

    Bookmark   April 14, 2014 at 1:39PM
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I guess the real answer is what gets printed in the new manual. I personally wouldn't get new head bolts nor the plastic guides unless they are suspect. You only on rare occasions find issue with the guides. The below sequence is if you will be using the new torque settings. If you are more comfortable with the 220 Inch torque, I would use the old sequence.
6 ...2... 4
3 ..

    Bookmark   April 15, 2014 at 12:24AM
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Thanks Tom. That is very helpful and timely. I will use the old bolts and use the new sequence and 250 in/lbs of torque.

    Bookmark   April 15, 2014 at 9:27AM
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Just an update. I removed my cylinder head on my 31C707 B&S 16.5Hp lawn tractor and yes, just between the cylinder and the push rod gallery was a nice little blown path through the gasket. Not huge, but not sealed either.

Anyway, I put a new gasket back on without any significant problems. I used Tomplum's new torqueing sequence (in 4 stages) and 250 in/lbs of torque and she fired up and purred nicely. I do hope that this new torque spec and sequence will give me more then 4 or 5 years out of this new head gasket.

Thanks again Tom for that procedure update. I didn't know about it but I am glad B&S are doing something to address this issue. Sorry for quasi hijacking this thread.

    Bookmark   April 27, 2014 at 5:53PM
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