Compression issue after rebuild
- Thread starter Emsguy
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The Road Warrior
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- Aug 12, 2021
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Every time I ask this question regarding the Briggs model you’re having compression issues with, I get called out and disfellowshipped,
The question is, why are you putting that much effort into a Briggs engine that is known as one of the cruelest jokes every perpetrated on the American consumer?
Briggs has been aware of the compression issues for many years. I scrap a truckload of these Briggs lemons annually.
Do yourself a BIG favor and scrap the headache and find a B&S 18-18.5 HP horizontally opposed, flathead engines. Lots of them out there if you know where to look. Usual cost is from free to 50 bucks.
If properly cared for, it’ll last a lifetime.
Ok everyone, give me your best shots!
bertsmobile1
Lawn Royalty
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- Nov 29, 2014
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no arguement from me
I have 22 motorcycles of which 15 SV and get ridden a lot because they always go and require minimum maintenance ,
Most of the mowers I use regularly have flat head engines in them .
Sounds like a camshaft problem to me, you said you replaced them, did you do it by part number, or with used parts? Model 31 B&S singles had a lot of cam problems! Tappets were not right in a lot of the new engines when they were built. Also, the ACR arms were not hardened right at the factory. You did not post the code number, so i do not know the year it was produced. If your starter is damaged it may not crank it over, {never beat on a B&S starter it has a ceramic magnet in it for the field, if it gets a crack in the magnet the start will self-destruct and will draw the battery and have no power to turn the engine over. The ACR on the cam is very important, as the starter is not capable of turning the engine over if the compression is over 90 lbs. is the spring broken on the ACR flyweight? just some of the things that might be wrong with it, yes, i have been a B&S dealer over 50 years now, i know these engines well, my E-mail for my business is stanbms@msn.com
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It is a brand new cam shaft. The spring is working and the cam shaft is lined up correctly with the dot. I’ve went through every suggestion on here to set the valve lash and still get the same results. Here is a video of what it is doing…..
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Key has been replaced and is still intact
Ok,
Just want to update. I purchased a leak down tester last night and ran 100 PSI at TDC (compression stroke) The results were about a 15-18% leak. Hissing could be heard coming from the breather tube which was connected to the intake tube as well as hissing could be heard coming from the dipstick tube when I removed the dipstick. I took measurements of the bore from the top, middle and bottom with a telescoping gauge and measured with a dial caliper with a result of 3.563in which matches appropriately with the service manual. So at this point I’m thinking that this has to be an issue with the piston rings and causing blow by. I did purchase a new piston during this rebuild (p/n 594539) and I am fairly certain that I followed the instructions correctly with making sure the paint lines were to the right of the gap and making sure to use the correct ring for the center ring. I also made sure that no ring gaps were lined up with each other upon placing the piston back in. Did I miss something? Are the gaps suppose to be at a certain position on the piston (center ring at 2 o’clock position 8 o’clock position, etc) ?
Just want to update. I purchased a leak down tester last night and ran 100 PSI at TDC (compression stroke) The results were about a 15-18% leak. Hissing could be heard coming from the breather tube which was connected to the intake tube as well as hissing could be heard coming from the dipstick tube when I removed the dipstick. I took measurements of the bore from the top, middle and bottom with a telescoping gauge and measured with a dial caliper with a result of 3.563in which matches appropriately with the service manual. So at this point I’m thinking that this has to be an issue with the piston rings and causing blow by. I did purchase a new piston during this rebuild (p/n 594539) and I am fairly certain that I followed the instructions correctly with making sure the paint lines were to the right of the gap and making sure to use the correct ring for the center ring. I also made sure that no ring gaps were lined up with each other upon placing the piston back in. Did I miss something? Are the gaps suppose to be at a certain position on the piston (center ring at 2 o’clock position 8 o’clock position, etc) ?
Did you check the exhaust seat in the head? It may be loose.
Alright,
Here is a super exciting update. I think I have the problem figured out. When I ordered a new crank shaft, I went part number for part number. But here is the problem. The flywheel key inserts are in different locations. The crank shaft on the right is the bad one. Gotta be the wrong crank shaft that I ordered! Now for the Briggs and Stratton experts, why did the change the design of the part number?
Here is a super exciting update. I think I have the problem figured out. When I ordered a new crank shaft, I went part number for part number. But here is the problem. The flywheel key inserts are in different locations. The crank shaft on the right is the bad one. Gotta be the wrong crank shaft that I ordered! Now for the Briggs and Stratton experts, why did the change the design of the part number?