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post #16 of 38 Old 07-12-2019, 12:17 PM
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Re: Briggs Intek pushrods

I don't think he was gouging ou for the extra push rod as most of the time they are both bent.
The aluminum one is so weak that when the exhaust valve cannot open to let the exhaust out and after the combustion has occurred the Piston is trying to come up against compression that's not supposed to be there and the intake valve is trying to open but the piston and pressure is trying to force it shut so it bends that valve even though that guide is perfect. I see both pushrods bent all the time or I see an intake push rod bent on a Briggs single where the exhaust valve rocker arm stud simply loosened up. The exhaust push rod is just fine since its steel but the intake valve pushrod which had no valve train problems whatsoever is bent because the pressure of the engine trying to run forced or kept the valve shut when it was trying to be opened so the pushrod bends.

What I do think is he's not that well schooled or knowledgeable in knowing why he found bent pushrods. Very, very rarely when you find a bent pushrod can you simply replace it and not end up quickly with another bent pushrod. They don't bend on their own. I have seen a few we're completely through and bend and actually break right where they rub against the plastic guide underneath the rocker arm studs. It amazes me that a black plastic guide can wear through an aluminum push rod. But I've seen it three times.
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post #17 of 38 Old 07-13-2019, 02:59 PM Thread Starter
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Re: Briggs Intek pushrods

For the 2-Cylinder Briggs engines, the cylinder heads are one each, Right and Left. Mirror opposites. The parts lists do not help me to know which part number is the Right or the Left.
From Internet searches, the head numbers for my engine appear to be #796231 and #796232. Possibly the #796232 is the one on the Left when seated on the mower in the driving position-- the side with the fuel pump mounted near the head. Can anyone confirm?
With the rocker arm cover removed, numbers are visible inside the rocker chamber. These probably just identify the number of the mold used to make the casting-- the molds would have multiple cavities to make several parts in just one operation-- thus those numbers would have no meaning outside the manufacturing plant.

This video illustrates the technique that I believe others on this forum prefer.
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post #18 of 38 Old 07-13-2019, 04:31 PM
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Re: Briggs Intek pushrods

The numbers inside don't matter. The numbers from the engine are all that matter. The number are stamped on one of the rocker arm covers. It doesn't really matter because all 44 series heads will interchange.
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post #19 of 38 Old 07-13-2019, 04:34 PM
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Re: Briggs Intek pushrods

And never, never ever ever, buy a new head. You're ending up with the same junk that failed you in the first place.
You really never need to replace a head unless you find one with an extensive crack. If you have one that has to be replaced and simply get a used one off of another engine from eBay or swing by a local small engine shop and buy one out of their junk parts. Popped out valve c or slipped valve guide is an easy fix that cost zero money. A new head is like $150 plus. You would be better off to take your head to a machine shop and let them fix things which would result in a better quality head than a brand new one.
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post #20 of 38 Old 07-13-2019, 07:48 PM
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Re: Briggs Intek pushrods

The heads are offset on the block. #1 is p/n 796231 and closest to the flywheel.
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post #21 of 38 Old 07-13-2019, 10:08 PM
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Re: Briggs Intek pushrods

Quote:
Originally Posted by TobyU View Post
And never, never ever ever, buy a new head. You're ending up with the same junk that failed you in the first place.
You really never need to replace a head unless you find one with an extensive crack. If you have one that has to be replaced and simply get a used one off of another engine from eBay or swing by a local small engine shop and buy one out of their junk parts. Popped out valve c or slipped valve guide is an easy fix that cost zero money. A new head is like $150 plus. You would be better off to take your head to a machine shop and let them fix things which would result in a better quality head than a brand new one.
Edit: Looks like heads are coming down in price like carbs and pressure washer pumps....GOOD!!

Still, they are not new and improved. Briggs hardly ever does that. Kohler on the other hand had a head gasket blowing issue on the twin command they put out a kit albeit overpriced that FIXED the problem. GREATLY improved head gasket and new bolts/studs.
Briggs still give us the same old lousy single ohv blowing out head gasket that failed the first time...or 2nd.

I will put my cleaned, grooved, and loctited repaired head up against any new one in a overheat challenge to see which guide will slip first.
We could heat them in an oven and have a press with scale on the guide and see at what temp and pressure one moves then the other.
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post #22 of 38 Old 07-14-2019, 09:54 AM Thread Starter
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Re: Briggs Intek pushrods

Been thinking about the normal operating forces that might cause the valve guide to move where pressed into the cylinder head. Just two come to mind.
One would be the movement of the valve stem as it opens and closes. That movement is equal distance in both directions and the number of movements in each direction is equal.
The other is pressure of the exhaust gases through the port each time the valve opens. If full throttle engine speed is 3600 RPM, the number of pressure pulses is 108,000 per hour. For 570 hours on my engine, the total number of pressure pulses on my engine is over 61 million. So even with the pressure being low, the cumulative effect of such a large number of pressure pulses is significant.
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post #23 of 38 Old 07-14-2019, 10:32 AM
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Re: Briggs Intek pushrods

That's where you need to step back about 13 steps and not worry about it. My brain does the same thing sometimes and delves deep into the whys and stuff all in all it doesn't matter too much. But pondering does occasionally help me come up with some out-of-the-box fixes.
Lots of things are- or are not in theory or on paper but don't work out that way an actual practice or real life.
Very very few engines run at 3600 RPMs anymore anyways. It is amazing how they have lowered the specs over the years. Most of these engines respect from the factory between 3150 and 3450. With most being on the lower end.
Still though, there's a lot going on in a short period of time.
From my experience with these in many many occasions I would have to say it must be the pulses and the vibrations. I have seen a good number of valves stick in the valve guide where they couldn't even be moved by hand and to where they were so slow to close from the valve spring pressure ,the piston smacked them before they could get out of the way on with valves in a position where the piston can hit them.
This would be a lot more pressure exerting on the guide to make it move one way or the other or to at least loosen it up and these were never loose.
After the valve stem was cleaned and lubricated or run on a wire brush to let everything slide freely, there were no future problems with the guide moving out of place.

It's really just more about the heat. When they overheat the aluminum expands so much you could push the guide with your thumb. Then, when it cools back off it tightens back up. Every time it moves or slips even a little bit it wipes a little bit of the aluminum off and makes it a little bit easier for it to move the next time it gets hot and at an even lower temperature.
I believe the explosive pressures inside the engine, even though the valve should be totally shut when the explosions are occurring oh, but there is the movement which is fairly fast of the air blowing out of the open valve and out the exhaust port, I feel this pressure and movement is what causes the guides to always move out away from the head of the valve.
I could certainly be wrong about this as it's just a guesstimate. It very well could be the effects of fast movement or inertia. The guide that is sitting still and the valve is being pushed quickly and repeatedly so therefore the guide could be pulled up just like a hammer handle is if you hold the handle on the bottom with the head towards the floor and take another hammer and smack the bottom end of the handle. It looks like you are pulling the hammer head up onto the handle and that is the end result but in reality the heavier hammer head is staying exactly where it is and you are quickly and forcefully moving the handle so fast that the heavier metal head cannot keep up with it so a little bit of movement occurs. This could be the forces at science involved with the guides coming out and asked if which way they slide.
But as I started this reply, none of it really matters. The science involved for the reasons aren't going to help us fix the problem or prevent it. We're not going to be able to slow the speed or the impact Force down on the tip of the valve stem or make the guide what would be the engine whole head move at the same time and speed as the rocker arm. All that matters in these situations is the quickest, easiest way to fix that is a long-term or permanent solution
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post #24 of 38 Old 07-15-2019, 09:00 AM Thread Starter
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Re: Briggs Intek pushrods

"That's where you need to step back about 13 steps and not worry about it. "

So very helpful.

Last edited by Bus Driver; 07-15-2019 at 10:29 AM.
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post #25 of 38 Old 07-15-2019, 10:21 AM
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Re: Briggs Intek pushrods

Bus, you been here what, 10 minutes, and are questioning Toby who's been for 'round 6 years?
This is the FRIENDLIEST web site, so those posting at least try to chill when they get bothered or disagree with a given post. Not worth the heartburn.
We all are here to help one another with problems and solutions gained over years, or accumulated to centuries of experience. No need to get bothered at a suggestion. It's just that, a suggestion.

By posting a question, quandry or problem, you are asking ALL site members for their input, so don't be bothered when someone answers. OR, don't ask...

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post #26 of 38 Old 07-16-2019, 12:13 AM
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Re: Briggs Intek pushrods

Quote:
Originally Posted by Bus Driver View Post
"That's where you need to step back about 13 steps and not worry about it. "

So very helpful.
... you, me, whoever. Notice I said I do the same thing.. Over-analyze, but as I mentioned it can be good for unique fixes.
Not picking on you just saying that while you and me might think all about the pressure forces under a valve head on the guide.... we are like 13 steps beyond what most owners ever consider.
Kind of a plus for us.
I have found though that on many situations I have stopped worrying about the why's ~some~ and just do what I know works.
That's how the guides and seat repairs are to me. I guess I've done too many.
Sorry if it brushed you the wrong way but clapback will get you nowhere.
The rest of the post had a lot of good info following along with what you pondered in your post.
I'm here to help others, learn stuff, go off topic and tell stories, make small talk, and tell people when they are doing something the hard or wrong way-- HELLO YOUTUBE!
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post #27 of 38 Old 07-31-2019, 02:46 PM Thread Starter
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Re: Briggs Intek pushrods

Had opportunity to look at the Briggs repair manuals for the Intek and Vanguard engines-- separate manuals. Will paraphrase the info to avoid copyyright issues. Just 4 lines of text for valve guides for the Intek. Briggs gauge #19381-- apparently if it fits into the guide, the guide is considered to be worn out. Replacing the cylinder head is the repair. That's it.
Vanguard uses similar gauge #19382. Valve guides are replaceable for the Vanguard-- using tools and techniques specified by Briggs. Reaming the guide to size is the final step.
So our home-brewed remedies are what I call "farmer-fixes".
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post #28 of 38 Old 07-31-2019, 07:19 PM
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Re: Briggs Intek pushrods

Quote:
Originally Posted by Bus Driver View Post
Had opportunity to look at the Briggs repair manuals for the Intek and Vanguard engines-- separate manuals. Will paraphrase the info to avoid copyyright issues. Just 4 lines of text for valve guides for the Intek. Briggs gauge #19381-- apparently if it fits into the guide, the guide is considered to be worn out. Replacing the cylinder head is the repair. That's it.
Vanguard uses similar gauge #19382. Valve guides are replaceable for the Vanguard-- using tools and techniques specified by Briggs. Reaming the guide to size is the final step.
So our home-brewed remedies are what I call "farmer-fixes".
I've been telling people for years there is no Factory or manufacturer authorized repair for this. I say it's the backyard mechanic and old guys who know what they're doing repair. I fully believe when you fix one with a Groove around the guide peening it nicely and use Loctite, it is better than any new head you could put on there. The only Advantage people have to put a new head on and the reason it doesn't break or slip quickly is the new head is nice and clean with no debris or buildup or greasy Grime to hold in the heat. If you clean them off properly when you have them apart a good repair is better than a new head.
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post #29 of 38 Old 07-31-2019, 10:31 PM
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Re: Briggs Intek pushrods

Quote:
Originally Posted by TobyU View Post
I've been telling people for years there is no Factory or manufacturer authorized repair for this. I say it's the backyard mechanic and old guys who know what they're doing repair. I fully believe when you fix one with a Groove around the guide peening it nicely and use Loctite, it is better than any new head you could put on there. The only Advantage people have to put a new head on and the reason it doesn't break or slip quickly is the new head is nice and clean with no debris or buildup or greasy Grime to hold in the heat. If you clean them off properly when you have them apart a good repair is better than a new head.
Since new head has no improvements I'm thinking it might be a good idea to do the peening repair on the new head right away.
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post #30 of 38 Old 08-01-2019, 11:07 AM
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Re: Briggs Intek pushrods

You could also drill through the aluminum and into the guide but not all the way through and cut a short pin to drive into there and then peen the aluminum from the hole back over on top of the pin. You can do this on two spots if you wanted to at like at 9 and 3.
It's just more work and I've never had one fail after fixing by just peening so I haven't ever worried about doing it a different way.
Went back and forth for quite a bit either in this thread or another one about someone wanting to remove the head and weld on both sides from a YouTube video they found. That could make it substantially stronger than just peening also but you still could have a little bit of movement because it would be hard to get the weld tight on the aluminum as it would melt some of it because you're having to weld to a steel guide. Also it could warp the guide slightly and you have to make sure the valve slides smoothly in the guide with no tight spots.
Between both of these types of over the top repairs oh, I feel that Drilling and pinning would be the best way to prevent any possible movement but I just don't think either one is necessary. They're both over the top and one requires you remove the head. I just did one of these Monday without removing the head in about 40 minutes start to finish.
The two most time-consuming parts of the job are getting the valve Keepers back in and cleaning off all the debris on the head under the shroud. You could fix one of these and never even take the shroud off but that's kind of a gamble since majority of the time the reason they fail is because of lack of air flow and proper cooling.
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