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This Brigg 407577, I'm wonder how to diagnose a bad head gasket, without a leak down tester. All I have is a compression tester. It runs pretty good, but with a little cough ever few seconds. Sometimes longer. When I pulled the dipstick, (after shutting it off) I noticed a little smoke come out.

The compression was about 165 to 170 on one side. The other side was about 100. It doesn't really smoke.

You have read what Bert always says. Smoke out the oil filler = head gasket.

BlazNT said:

You have read what Bert always says. Smoke out the oil filler = head gasket.

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Yes. That's why I'm posting this. But it's very little. Was hoping for more info and maybe something else to look for.

The side that has lower comp is the culprit. The gasket is just starting to fail.

Pull the head and change it. Clean well and put it on there. You answered your own question when you wrote this.

Those gaskets are notorious for going bad all the time. When you take it off you see a small bad spot on the block side of it where the skinny part of the block is ~!~!

Boudreaux In Eunice La. said:

The side that has lower comp is the culprit. The gasket is just starting to fail.

Pull the head and change it. Clean well and put it on there. You answered your own question when you wrote this.

Those gaskets are notorious for going bad all the time. When you take it off you see a small bad spot on the block side of it where the skinny part of the block is ~!~!

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Thanks. I thought I knew the answer. But a 2nd opinion never hurts.

hrdman2luv said:

Thanks. I thought I knew the answer. But a 2nd opinion never hurts.

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I too have asked questions for what I already knew the answer to but darn it is hard not to with all this talent just a keyboard away.

BlazNT said:

I too have asked questions for what I already knew the answer to but darn it is hard not to with all this talent just a keyboard away.

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You ain't lying. Especially about something like this. I could've gone ahead and took the head gasket off. But what if I'd did that, and it was fine. Then posted my problem and some of this talent said "did you check this?". Something simple that I didn't think about could've saved me two hours plus parts. That I would've had to eat.
Eating good parts doesn't make for a good meal.

I sure wished they'd add a thank you button to this forum. A lot of times they'd come in real handy.

Neither head gasket was bad.

Well thats a fine howdy do. What next?

IF the gasket was good then you might have a valve that is not seating properly. Those gaskets look good when you pull the head off. The bad side is behind the gasket and it is a small area that can be overlooked.

Boudreaux In Eunice La. said:

IF the gasket was good then you might have a valve that is not seating properly. Those gaskets look good when you pull the head off. The bad side is behind the gasket and it is a small area that can be overlooked.

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Yeah, both sides were good.

I wish I had that engine in front of me so I can see whats going on there.

Boudreaux In Eunice La. said:

I wish I had that engine in front of me so I can see whats going on there.

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It's all back together now. And running OK. Better than before. But still not great. I didn't see any light shining in around the valves after I cleaned them (still on the head). A little bit of carb cleaner seeped through one after about 2 hrs of sitting flat. But it wasn't even a drop. Just noticed a little wet spot on the edge. I'm thinking it was a little dust or some loose carbon, from when I was cleaning it.

She's a bit cold natured now. Take a couple of minutes for everything to smooth out.