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I have a 21hp Briggs Intec on my Husqvarna riding mower that got a lot of water in the tank, I've gotten all the water out of the system and took the nikki carb down and cleaned it out. Now it fired up but was backfiring really bad and wouldnt run much. I found bent pushrods on one cylinder due to backed out valve guides. My question is what is the chances of something like a cam or tappet is damaged too or should I just figure its all right there at the head? I understand the pushrod is basically the sacrificial lamb so that other vital components does not get damaged, but I just wanted some assurance. Also is it a waste to even try to fix the old head or just buy a new one. Looks like the other cylinder is ok. Thanks!

Most likely it is just the head that is damage. I have seen fixes for repairing these head but since I cant get new valve guides I have tried those tricks. To me if the valves stuck in the guides enough to cause them to move then the valves and guides are damage.

StarTech said:

Most likely it is just the head that is damage. I have seen fixes for repairing these head but since I cant get new valve guides I have tried those tricks. To me if the valves stuck in the guides enough to cause them to move then the valves and guides are damage.

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I have a friend that is a machinist, but after I've checked the prices on a new head, it makes better sense to just put new ones on it. Its a good mower. I think it just got hot or something.

Most of the time, moving valve guides are from over-heating the engine. I would install a new head vs "fixing" that one.

Check and clean the engine cylinder block cooling fins ALL the way around each cylinder. This is a yearly thing printed in your engine manual.

Taryl has a video on this repair.

slomo

slomo said:

Most of the time, moving valve guides are from over-heating the engine. I would install a new head vs "fixing" that one.

Check and clean the engine cylinder block cooling fins ALL the way around each cylinder. This is a yearly thing printed in your engine manual.

Taryl has a video on this repair.

slomo

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Thanks. I can't make it through Taryl's video. The stupidity ruins it for me.

Then skip the first 2-3 minutes.
It is a standard enhancement method in education to shove as much silly humour as you can into a lesson.
Students remember the stupidity like "mufkin" or "Kroller" and use that as a link to the important facts
And I find his humour quite purile but it does work & I understand why it is there

hotroddr32 said:

Thanks. I can't make it through Taryl's video. The stupidity ruins it for me.

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Amazing you can't find the huge pool of knowledge in Taryl's videos. The time he spends on EACH video must be impressive. Editing, acting and prop work..... Haven't watched one of his videos where he put out wrong info yet. IMO, he is one of the best OPE repair guys on youtube.

slomo

I think a lot of it is that when I go to youtube looking for the solution to an issue I have, I'm focused on getting to the point and the comedy is a bit more than I want to deal with when I'm focused on repairs or trouble shooting. He definitely puts a lot into his videos and does know what he is talking about. Maybe I'm just too impatient.

i had an Intec engine to do a similar thing. The Intake push rod was bent. The steel exhaust push rod didn't bend. It however shoved the valve adjustment stud bolt straight up and ruined the threads since the head is aluminum, i figured there was no way to repair the threads, so i got a used head at a local repair shop for 40 dollars where someone had brought in a blown engine. i put it on 3 years ago and the engine is still running. to this day though, i don't know what caused it. The used head was on a 2012 engine and the older engine was a 2006 engine, since the part numbers showed the same, it worked fine

hotroddr32 said:

I think a lot of it is that when I go to youtube looking for the solution to an issue I have, I'm focused on getting to the point and the comedy is a bit more than I want to deal with when I'm focused on repairs or trouble shooting. He definitely puts a lot into his videos and does know what he is talking about. Maybe I'm just too impatient.

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Or like me that fooling around is big pain just to get to the point. It is a waste my time to watch stupid stuff beside I got too things that got to be done each day. Anyway I don't his videos any more.

StarTech said:

Or like me that fooling around is big pain just to get to the point. It is a waste my time to watch stupid stuff beside I got too things that got to be done each day. Anyway I don't his videos any more.

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I thought you had Taryl teeth and the wig Startech? One of you guys turned me on to him. Taryl is off the chain. Don't care what you impatient babies think LOL.

Guess you guys need to watch boring donnyboy. Right off the bat, need a 5/16" wrench and a #2 Philips screwdriver. Look she runs great. The end.... LOL

In all honesty, I used to FF to the repair part. Now I watch the comedy part too. Better than Netflicks.

P.S. you guys know you can fast forward youtube videos right? Hold the cursor just right, you see the video in frames? Surely Shirley??

slomo

I got the head off this evening and the exhaust valve will barely opens. Intake looks a little more normal, but that pushrod was bent too. Why would that one be damaged? Also, I don't see anything wrong on the other head, Seems like the guides there barely sit higher than the second coil on the springs. Would it be safer to go ahead with replacing both? I wonder what the chances are one being damaged and the other not.

1.Remove all the dirt, grass and oil mess from the cooling fins, ALL the way around each cylinder. Overheating will cause this.
2.Post up a lot of pictures of the bad head and valves. Good light and a steady camera. If you have a cell for a camera, TURN IT HORIZONTALLY and rest off a bench while snapping the shot.
3.What was step #1 again?
4.Pictures of the good head and bad head for comparison.
5.Repeat step #1. Even the thinnest dirt film will insulate the aluminum slowing heat transfer. These are air cooled engines that get to full op temp in roughly 60 seconds. Use a good degreaser like Dawn and a nylon brush.

slomo

Pic below is the bad head followed by the other suspected good one. I don't see much wrong with it, but the guide on first one has definitely backed out.








Bad head

Confirmed, valve guide has left the building LOL. I would pull all the valves out to make sure the good one is okay, hasn't started to move either.

Most of the time this is from overheating. You have to keep those cooling fins totally clean and clear.

If this was mine. I would take it to an automotive machine shop. Shouldn't cost too much. See if they can push the guide back or get their opinion on replacing the head. They are the pros on this stuff.

hotroddr32 said:

I got the head off this evening and the exhaust valve will barely opens. Intake looks a little more normal, but that pushrod was bent too. Why would that one be damaged? Also, I don't see anything wrong on the other head, Seems like the guides there barely sit higher than the second coil on the springs. Would it be safer to go ahead with replacing both? I wonder what the chances are one being damaged and the other not.

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"barely sit higher" LOL That little guy is about to jump out of the head.

slomo said:

Confirmed, valve guide has left the building LOL. I would pull all the valves out to make sure the good one is okay, hasn't started to move either.

Most of the time this is from overheating. You have to keep those cooling fins totally clean and clear.

If this was mine. I would take it to an automotive machine shop. Shouldn't cost too much. See if they can push the guide back or get their opinion on replacing the head. They are the pros on this stuff.


"barely sit higher" LOL That little guy is about to jump out of the head.

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"Barely sits higher" referred to the guides on the head still installed on the motor.

I had the same problem with a BS 20 horse engine, valve guide worked its way out resulting in a bent push rod. I pushed the guide back in and using a punch peened the edges around the guide, straightened the push rod and put it back together. The engine ran fine and never had the same problem.

Moving guides are a symptom & not the problem, excepting the 0.01% manufacturing faults.
The guide moves because the head gets too hot.
Head gets too hot because
1) cooling fins are obstructed
2) engine is run at less than full speed
3) timing is too far advanced
4) carb is way too lean.