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10.5 HP Briggs and Stratton OHV Model 215807-0324-E1
On a Murray rear engine 30" cut riding mower.
This is an older mower (2005 I think, that I purchased second hand)

I am hoping someone can give me a few pointers as to what I should look at next. Thank you in advance.

Details:
The first time I mowed the lawn this season the mower ran OK but after that it would pop/rough idle and want to stall out when engaging blades.
At least until it got warm. Even then I could tell it had less power.

Since I then I have done the following, Some of it because it looked like it needed and others trying to fix the issue.
- Replaced carb
- Cleaned fuel tank (though the inside looked good. It has mostly had non-ethanol gas)
- Replaced all of the fuel lines and fuel filter, along with new gas cap and fresh gasoline
- New air filter. Though it does the same thing with filter removed.
- New spark plug and magneto
- Pulled Flywheel to check timing key.
- Compression test (145ish PSI), I haven't been able to find a spec for this. I have a leak-down tester on the way though.
- Oil Change
- Valve adjustment (0.005 on both intake and exhaust) based on a chart I found for Briggs engines.
- Cleaned debris from around governor.

The engine starts right away now and seems a bit stronger but it is still popping. The popping occurs at all engine speeds. choke and no choke.

I have a short YouTube clip of the problem but I do not have enough posts yet to allow me to post links.

Regards,
Zach

Water in the fuel would give you a pop, but you said that taken out all the old and replaced it with new, I would remove the valves and take a good look at them, you may need to lap them, you didn't say if the popping was from the intake or exhaust, so I would go by exhaust...!

You could try and send me the link to video in a PM.

Yes what is your you tube channel name ???? I'll check it out also ........ I agree withe the valves being out of whack...

Did you check for push rod travel on both ??

Run it for 10 minutes then pull the oil dip stick..... If it's smoking are steaming it's a head gasket . but you have real good compression soooooooo.....

Let us know Mon Ami....

Thanks for the replies.

Sorry from the video you can see its popping from the intake and I removed it at the end when forum would not let me post.

I replaced the fuel twice from different sources. Just in case.

My Youtube is Zach Morris
I attempted to add the link again with a dash in front below.

-https://youtu.be/-T94PXk_EIQ

Sorry I just saw the push rod comment reading the post again.
I watched the push rods and valves while moving the flywheel by hand several cycles and I spun the push rods in place to feel for anything out of place.
I did not pull the push rods out yet as I didn't remove the rockers.

-Zach

If you pull the rods check for bent rods also ~!~!

A longer video would be nice and then showing it with the blades engaged also ~!~!

Thanks. When I get a chance to work on it again I will grab a longer video.

Going by the video you have a problem with the inlet valve.

Thanks for the comments:

I was thinking intake valve issues as well but I am no expert so I wanted some other opinions.
Once my leak-down tester arrives I will get a baseline and then pull the head to check/lap the valves and inspect rods and all again.

Looks like I will be getting some exercise with the push mower for a bit. haha

Thanks
-Zach

Update:

The leak-down test was in the green. It took some effort to get the thing to sit still in order do the check.

I pulled the head earlier today. My untrained eye doesn't see anything obvious other than carbon buildup.
-The head gasket appears to be in good shape to me. (I will be replacing it anyway)
-The rods appear to be straight.
-I double checked to make sure none of the supports for the rocker arms had backed out but they look firmly seated.
-I pressed on the valves by hand. The intake valve seemed to take a bit more pressure to move but not much.

My plan now is to get the tools I need to get the valves removed, lapped and a new gasket set for putting everything back together.

Pictures
https://drive.google.com/drive/folders/14B4A2Y11pDJ5GUmQ33Ao08QwZnygWmCI?usp=sharing

Slightly longer video than before. I forgot to get a clip with blades engaged.
https://youtu.be/XouGjm1CsFU

Thanks,
-Zach

Looking at your pic number 121311 the head gasket engine block side looks that if its been blowing. it may well be the way the photo was taken, you will know when you replace it with a new one, make sure you clean both faces well before fitting, and do the bolts in order.

Thank you for taking a look. I see what you mean in the photo.

When I get a chance I will take some photos of the push-rod ends.
The steel one has perfectly spherical ends and the aluminum one has a small area where it is flat on both ends. I couldn't really tell if this the way they are made or if it indicates wear.

I have on the way:
- A valve lapping tool and compound.
- A gasket kit (head gasket, exhaust, valve cover ect)
- A valve spring tool.

Any suggestions on cleaning method for the head gasket and the carbon build-up?
I was thinking about some of those green scrubbing pads, carb cleaning or WD-40, and maybe a blade.

Appreciate the comments!
-Zach

A brass wire wheel/cup will work perfect and not damage anything......... One that goes in a drill of course....

That will clean off all your areas... Be sure to scrape off the major parts of the gaskets first.........

"green scrubbing pads, carb cleaning or WD-40" they will all do the job, many videos on youtube that will show you how to clean it and how to do the valves/head bolts.

Thank You. The parts/tools I need arrived yesterday and now I am just waiting for some decent weather.

I will take some pictures along the way and update when I am done.

Appreciate all the help.
-Zach

Did yo get it running?

Hydestone said:

Did yo get it running?

Click to expand...

Still waiting for some decent weather at a time when I am actually home in order to work on it. Hopefully this weekend. I will definitely post the results one way or another once I have worked on it.

Regards,
-Zach

The wife went out with friends tonight so I had a little time to work on the head in my workshop... err closet with a workbench.

I cleaned the head, pulled the valves and lapped them.

The intake valve did feel like it was wanting to stick a bit when I removed the spring and worked it back and forth. After lapping, and using some lube in the channel and working it back and forth the sticking went away but there was still noticeably more resistance to the way it felt sliding the intake valve back and forth than there was for the exhaust valve. Anyone know if this is normal?

I also tried to take some pictures of the end of the aluminum push rod to show what I was talking about previously about it being flat and not being sure if that was wear or how it is designed.
When I put the valves back in I sprayed some cleaner into the intake and exhaust ports and checked that the valves did not leak until opened.

Side Note: Getting those little spring keepers back in place was more of a pain than I was expected. Eventually got it.

I took several pictures during the process and I have posted them to the link below.
https://drive.google.com/drive/folders/1JDacJyeVPT1CTI97IfSXmOCa3LGA0hBX?usp=sharing

Regards,
-Zach

Pic 215856 there is some rust on the stem (is that the inlet valve) which you need to remove with some wet and dry paper, by the looks of the valves they needed doing so you haven't wasted your time there...! if the inlet valve is not bent it should be fine with a clean up, didn't see a photo of the push rods so can't give you an answer to that one.

EngineMan said:

Pic 215856 there is some rust on the stem (is that the inlet valve) which you need to remove with some wet and dry paper, by the looks of the valves they needed doing so you haven't wasted your time there...! if the inlet valve is not bent it should be fine with a clean up, didn't see a photo of the push rods so can't give you an answer to that one.

Click to expand...

Thank You. Good to know.
I have the sandpaper on the way and I will do that.

The push rods are in photos 212918 and 212852

I will try to get some decent photos of the completed valves when I am done.

Thanks again.
-Zach

Just an update on this since I haven't posted in some time. I finally got a chance to get it all put back together and today was the first time I have used it to mow the yard since.

Before that I took the valves back out and cleaned them until they were smooth. When I have a chance to upload them I will share the pictures here. Both valves were lapped after and sealed well. The rust spot on the stem was gone and both valves moved well after reassembly.

I had to get new head bolts in order to reinstall the head as the old ones would not torque to the 18ish ft lbs required. They stretched.

After putting everything back together with new gaskets, oil check, valve adjustment, ect it started up on the first try but was still backfiring through the intake but sounded a little better. Being suspicious of the replacement carb I reinstalled the original carb and after some struggles getting it started the mower runs smoothly. Aside from a sticking choke on occasion when trying to get it started cold. I am no longer getting the power drop and the struggling to run that originally caused me to start working on it. I suspect the valve work fixed my original issue and it was masked by the cheap replacement carb.

Thank You to everyone for all of the help and the comments. I will try to post some more pictures when I get a chance.

Regards,
-Zach

Thanks for letting us know your outcome Mon Ami ~!~!