Great deal on a Craftsman Riding Mower

[user 122190]

Do you have any idea why the push rods got bent?

Were they bent on both cylinders and just one?

Motor ran good first day, like crap the second. And yep, the same exhaust valve rod was bent again. It look like the valve guide is sticking out a ways. I'm going to pull the head, and verify. Steel valve guide, aluminum head = bad design.

I'll investigate, but it is looking like, it is a new engine or this machine goes to the scrap yard. Fudge! Double Fudge!!!

I see on Ebay and Amazon a replacement engine is $900. Is it worth it? I gots to think about it. Might be best to just dump this and take the $300 hit.

 

[Sportfury70]

Metal does funny things when exposed to heat cycles. Even though you tapped the pushrods straight, they will forever be imperfect and prone to bending again.

Maybe splurge a little more and get some new pushrods and retainers. Shouldn’t be more than $20-$30

If you have the patience, grab new head gaskets too. Pull the heads all together and disassemble so you can lap the valves and inspect the cylinder bores while your at it. Shouldn’t take longer than an afternoon so.

I’m not sure if that engine uses a poly camshaft lobe, but that’s something else that could cause an issue if they get damaged or worn out.

 

[user 122190]

Metal does funny things when exposed to heat cycles. Even though you tapped the pushrods straight, they will forever be imperfect and prone to bending again.

Maybe splurge a little more and get some new pushrods and retainers. Shouldn’t be more than $20-$30

If you have the patience, grab new head gaskets too. Pull the heads all together and disassemble so you can lap the valves and inspect the cylinder bores while your at it. Shouldn’t take longer than an afternoon so.

I’m not sure if that engine uses a poly camshaft lobe, but that’s something else that could cause an issue if they get damaged or worn out.

I'm going to look into some high heat "loctite/glue" and see if I can tap the valve guide back into its proper position and get it to hold during normal operations. New pushrods are not excluded from a fix. This is all under investigation right now. As far as time goes, I gots lots and lots of that.

 

[Okie]

Most likely cause of push rod bending on a Briggs OHV"

Valve is sticking in the guide. (the push rods are made wimpy enough to bend and maybe not damage other things when a valve sticks) One of the push rods is steel, the other is aluminum.

What causes a valve to stick in a guide?
overheating due to clogged cooling fins, bad fuel, ethanol gas, rpm's constantly too high, lack of lubrication, running slightly out of time and overheating.

Cure:
Sometimes just remove the gummy syrup from the INTAKE stem and clean the gas tank and add new non-ethanol gas. Intake usually sticks due to old gas instead of the exhaust valve.)

Replace the heads with know good heads.

Usually won't last if push rods are replaced or straightened without finds the original cause of the valve/valves sticking.

I would probably just go ahead and remove the head that BOTH PUSH RODS WERE BENT AND CLOSELY INSPECT THE GUIDES AND STEMS for cause of sticking.

Completely overhauling the engine with sticking valves is kinda like whipping on a dead horse and throwing good money after bad.

If you want a second or 3rd opinion you might go here register and ask. (mainly a small engine forum site)
Some guys and moderators here that have walked in your shoes and they have free service manuals in their library and usually fast responses. Sometimes you have to click on the back arrow ONCE to get past a advertisement to get the forum link.

http://ppeten.com/forums/viewforum.php?f=3&sid=fe9807f658661be38d04cd99447f1cf4

 

[user 122190]

The problem and solution is in reach.
I could possibly fix this myself, but I have a greater then 50% chance of making the situation worse.

I have a referral to someone that can do the job, and do it right. Good news is that the problem seems to be minimal as there is little else that I can see wrong.

From what I know, in the picture the value guide is protruding out creating a block and keeping the valve from fully opening, hence the bent rod. It is press fit in and needs to be pressed back in place, and then welded (or some other way) to keep it from moving back out.

Doesn’t seem that difficult, but I don’t have the tools, nor are my welding skills at all capable of doing fine work. The good news is EVERYTHING else looks fine, except some clean up. Years and years of grime is coating the head and very likely caused the head to over heat.

On a similar good note, I did get my 250V 50A wired up to run my ARC Welder. I'll be welding soon enough, but welding a valve quide is a few welds away (>30 and then some).

 

[Okie]

Good to hear you found the cause of the bent push rods.

Lots of carbon build-up on the piston. Was the engine smoking any when you got the momentary run?

Did you see any of the reasons I posted above as to why when looking at the valve stem and guide as to why the valve hung/stuck in the guide and caused the guide stick to the valve stem and move? (like gummy stuff on the valve stem or valve)
I've seen Automobile heads do that when running on propane or when using ethanol gas in old model vec's. (lead gas kept the stems and guides lubed good, especially the exhaust guides..

 

[user 122190]

Nope no smoking at all. And the valves movement in the guide is very smooth. The valves look great including the face and the corresponding head surface. Really other then the carbon build up it all looks great.

One of my referrals passed on doing the work. I've two others that are possibles. The more I think about this I'm becoming more confident I can do this. Tomorrow I play with the welder. I can weld a lip on the guide if I can muster up the confidence to remove the guide.

 

[Okie]

Edited a mis-print: that should have read I've pinned Valve seats instead of guides

Just a thought.
Wonder if the guides could be pinned in place on their side. (drill through the aluminum and part way into the guide after the guide has been pressed back into place)

I've staked and used small steel machine screws to stake valve guides SEATS on small aluminum block engines in place with very good results.

I'm kinda lucky that I have couple of lawn tractor and small engine junk salvages close by to get salvage prices and parts for small engines and lawn tractors reasonable.
Main thing is I ALWAYS get a price up front for a part first BEFORE I even go look at their junk.
If I don't like their price I don't waste my time shopping with them.

 

[user 122190]

Edited a mis-print: that should have read I've pinned Valve seats instead of guides

Just a thought.
Wonder if the guides could be pinned in place on their side. (drill through the aluminum and part way into the guide after the guide has been pressed back into place)

I've staked and used small steel machine screws to stake valve guides SEATS on small aluminum block engines in place with very good results.

I'm kinda lucky that I have couple of lawn tractor and small engine junk salvages close by to get salvage prices and parts for small engines and lawn tractors reasonable.
Main thing is I ALWAYS get a price up front for a part first BEFORE I even go look at their junk.
If I don't like their price I don't waste my time shopping with them.

I've thought of a set screw from the side. I'm still considering that. Also red or green loctite after roughing up the guides surface, and then welding. Or a combination of two or all three. It is about getting the guide out with a brass punch, which I need to buy. And can I get the guide back in without a hydraulic press, i.e. using a vice.

 

[Okie]

Since no low priced replacement heads available or donor engine for parts and new heads to expensive for an old engine and to stay away from machine shop or pay someone else to try and they are not going to offer a warranty and you say you have time to piddle:

If you pinned the guide/guides in place you would not have to remove. Just get the guide in correct place and do a drill from the side. (even at a angle, then drill and tap so as the end of the pin just divits into the side of the guide) Take a steel pin from a grease sert and tap into place or similar to the way I do valve seats is I take small steel USUALLY 4-40 machine screws and drill tap the block so as the edge of the screw head holds the steel seat anchored in place. (the pressed in valve seats pop out due to the difference in the expansion rate of the aluminum block and the steel seat)
I do this while the engine is still mounted on the machine usually.

One concern about yours is something has caused (and maybe still causing) the valve stem to seize in the guide with enough friction to actually move the pressed in guide and that is why the wimpy hollow push rods bent. I'm not sure if it's a weak design flaw of the guides in the aluminum heads or another cause???? (like the design issue with the pressed in steel valve seats in aluminum block)
If the push rods had been stronger and not bent, things would have broke and went south fast.

The Red locktite will usually release when it gets heated.

I've got some stuff (do not remember the name, and expensive in a small oz bottle) that I tried around valve seats that were coming out that turns to a hard ceramic and was designed for such around loose valve seats, (apply before PEENING) around the edge of the seat, but I also seen it fail to securely hold the seats on some engines.

 

[user 122190]

I've got some stuff (do not remember the name, and expensive in a small oz bottle) that I tried around valve seats that were coming out that turns to a hard ceramic and was designed for such around loose valve seats, (apply before PEENING) around the edge of the seat, but I also seen it fail to securely hold the seats on some engines.

I like the idea of peening. Today's priorities are welding stuff/junk for practice, then clean the head, press/tap the quide into place and then think on this some more.

Looks like a new head is around $150 and change. Since the entire machine is worth a grand, I figure I can spend another $700 to get this fixed and running and still break even. So a new head is Plan B, if I seriously fubar what is currently a "simple" problem to fix, albeit I'm not quite sure what is the best solution.

 

[Okie]

You might try a post at PPETN link I sent you for more GOOD ideas. (for 2nd opinions before you put it on the operating table)

Some of those guys and moderators are into those type engines every day.

 

[user 122190]

My referred engine guy from yesterday, who declined, suggested that this was likely to go to a machine shop and an oversized guide might be required. Is there Indy 500 pit mechanics with extra time on their hands. I mean the race is still 6 days away, surely they can fix this little problem during a potty break.

I'm absolutely sure I stressed that this was a 2003 John Deere Riding Mower. After that I began thinking this is something I need to fix myself.

 

[user 122190]

I got the head back. I took it to a local guy who has a little machine shop. He pressed the guide out, scored it, applied red loctite, and then staked/peened it. He said it pushed out simply enough, but went back in requiring a lot more force. I'm thinking it will hold. Guy charged me $20, so an inexpensive attempt at a solution.

I'll start putting the engine back together today. I've some cleanup to do, and I need to do a good job as I don't have a replacement head gasket, but the old one is still intact and looks fine.

 

[SS396driver]

Picked this craftsman up for $250 about a week ago it’s like new needed a belt

 

[user 122190]

Picked this craftsman up for $250 about a week ago it’s like new needed a belt

Yup. That's what I'm talking about. $30 belt and the machine can be sold for more then $1000. Easy money!

 

[Sawyer Rob]

Yup. That's what I'm talking about. $30 belt and the machine can be sold for more then $1000. Easy money!

Really, they sell that high there?

You "might" get $600. for it here, IF everything works perfect and it looks like new.

SR

 

[user 122190]

Really, they sell that high there?

You "might" get $600. for it here, IF everything works perfect and it looks like new.

SR

I bought for $150 the same riding mower and sold it a month later for $1100. Just cleaned it up, and made it pretty. Last time I checked riders are limited, need to be ordered, and the price is high compared to pre-pandemic prices.

 

[Sawyer Rob]

I know where there's one right now for 800., it's Kohler powered and looks like it came off the showroom floor, I'm not kidding, it looks new.

It's been sitting there for quite a while, so around here they obviously sell a lot cheaper.

SR

 

[wrenchit]

What is the Model and type of the engine?

Some of them dogs have a dual throat type carb and intake. (one side of carb could be suspect if the dual throat type is why I mention such)

Do you have any idea why the push rods got bent?

Were they bent on both cylinders and just one?

Push rods bent because the head was overheated and the valve guide worked its way out. 90% of the time from mice nest blocking off the air cooling fins , or a bunch of grass plugging them up.
You can try to tap it back in but unless I know the person, I wont do it because it may last years or an hour before it comes out again. The warranty on driving them back in ends when the machine goes past the door of my shop. Its best to just replace the cylinder head and be done with it, while you have the tin covers off clean it out as best you can to eliminate it from happening all over again.