X-300 keeps bending Push Rods.

[Diggin It]

Just put in the third set of push rods in a Kawasaki 17HP FH451V (or is it 491?). Always on the right side (from the seat), never the left. Obviously something deeper, but what, and is it something I want to bother with on a 13 year old machine (DOM 083006) with over 1,000 hours?

 

[RandyT]

Pull the valve cover back off, and look at the position of the valve guide inside of the valve spring. I bet it has migrated toward the spring keeper, and is stopping the valve from fully opening causing the push rods to not be able to fully open the valves.

 

[Diggin It]

Hmmm, will see. Not sure exactly what to look for, but I can compare to the other side.

Couple of other notes:

The first time I had to do this a year or so back after losing power on hills, I found that one ear of the push rod guide plate was gone completely. No sign of it any where. No hole large enough for it to get inside either. Replaced that.

Currently, it has been audibly 'puffing' almost like missing or maybe an exhaust leak. This is both before and after the latest push rod replacement. Clearance is adjusted to .004 as spec'd. Or at least as close as I can.

 

[Diggin It]

Got about an hour or so run time before it ate itself again, so obviously there's something else going on. I'll check that guide spring in the next few days, but I'm thinking I'll let it sit for a few weeks until the weather is a bit less horrible.

 

[Kish318420]

I would look at everything on that side, replace anything suspicious looking or out of spec. Looking at it on the parts site (JD). I'm wondering about the rocker nuts and the screws in the end of them backing out allowing things to shift. Are you using any thread lock (Locktite Blue - semi) on those or a similar product? or even the studs those are screwed to?

 

[Amvcane]

Diggin it, I think RANDYT has a very valid point about the valve guides moving and restricting movement on the spring side of the rocker. The pushrod side will still move through its full cycle and will bend.
Here is a video of a Briggs with the same problem, different engine showing what to look for concerning the valve guides. Taryls camera man does a great poking around the engine. Kinda feel like you are in the shop with them.

How To Fix A Briggs and Stratton V-Twin Intek Engine That Is Running Badly (Bent Push Rod) - YouTube
You can start video at 4:50 mins. To skip the comedy.

 

[Diggin It]

I would look at everything on that side, replace anything suspicious looking or out of spec. Looking at it on the parts site (JD). I'm wondering about the rocker nuts and the screws in the end of them backing out allowing things to shift. Are you using any thread lock (Locktite Blue - semi) on those or a similar product? or even the studs those are screwed to?

Replaced the stud/bolt and nut this last time. Used LT Blue.

Diggin it, I think RANDYT has a very valid point about the valve guides moving and restricting movement on the spring side of the rocker. The pushrod side will still move through it's full cycle and will bend.
Here is a video

I'll look at that area next time I get a chance. I only do static images, no videos.

 

[RandyT]

Diggin it, I think RANDYT has a very valid point about the valve guides moving and restricting movement on the spring side of the rocker. The pushrod side will still move through itç—´ full cycle and will bend.
Here is a video of a Briggs with the same problem, different engine showing what to look for concerning the valve guides. Tarylç—´ camera man does a great poking around the engine. Kinda feel like you are in the shop with them.

How To Fix A Briggs and Stratton V-Twin Intek Engine That Is Running Badly (Bent Push Rod) - YouTube
You can start video at 4:50 mins. To skip the comedy.

Had seen 3 in the shop already this year. One on a Briggs intek twin which if you know anything about the engine will eat the pushrod and you retrieve it from the engine sump sometimes in pieces, sometimes wrapped around the camshaft. A Kohler Courage 27 HP and a Kawasaki. Problem is due to heads getting too hot and the aluminum softens around the valve guide and they migrate out toward the valve spring keeper until the interfere with the moving of the valve when it opens and then bends the pushrod.

 

[ruffdog]

So, the head gets real hot, valve guide then pushes out toward keepers, then, the guide won't push back in so easily, push rod bends?

 

[RandyT]

Certainly a valid cause, but I have to wonder if something isn't missing in this thinking. If a guide can migrate out on its own without any outside force, why wouldn't the valve keeper push it right back down at the same time? I would suspect that this happens on an engine when it is shut down. A guide moves on a valve that is closed. The head cools and locks the guide in place.

It probably does get pushed back in somewhat, but the guide will migrate 3/8-1/2 an inch in some cases before it contacts the spring keeper. I have seen them migrate enough that the guide is tight against the keeper and the valve will only move about 1/8 inch.

So, the head gets real hot, valve guide then pushes out toward keepers, then, the guide won't push back in so easily, push rod bends?

Correct, If you remove the valve and press the guide back into the head without some type of knurling or something to hold it in place it will migrate back out within about 2 hours of pressing it back in.

So what force pushes out the guide?

I suspect it has to do with the compression or other vibration forces, in combination with possible deposits building up on the valve stem and causes extra friction which pushes the guide toward the keeper. The always migrate toward the keeper, never toward the valve head.

 

[Diggin It]

Upper Push Rod was not bent, but it was laying loose. Note the bend/crack in the Guide Plate. This is a new Guide Plate by a few months, replaced because the same tab was broken off, but at the bottom of the plate (the other Push Rod), not the top.

Lower valve guide is out quite a bit further than on the right side valves and it looks like the upper is out a bit too. I'm using upper and lower because I don't know any other terms for them. Exhaust? Compression?

Question is, what do I do about them? Can they just be driven back in using a small diameter socket as a means of keeping even pressure? Then, how far in? Is there a stop they hit against? Sure don't want to seat them too far.

 

[tomplum]

Bear in mind that the intake valve has the seal which makes the guide appear longer. The correct thing to do here is replace the head. It would be tough to knurl a hardened guide whilst it is in the head. You could try with something small, hard and sharp to mar the guide. Drive it back and stake it like you would a valve seat. The precise distance isn't really necessary. Look at a pic of a new head. Or look at the other head. You would want to anyways. As a general rule, the guides protrude closely to one another- but it isn't always the case. I don't THINK the manual gives specs on the positioning. I could be wrong. I've heard of guys drive the guide back into place and put a tack weld to keep it from pulling through. Certainly not worth it if you have to pull the head. On a side note I had a head last year that the guide did drift in towards the head of the valve - keeping it open. Only one I recall.

 

[Diggin It]

So, should I try to reseat it or not? Keep in mind:

• I can swap simple parts and make minor adjustments, but I don't know engines
• Machine is 13 years old and has over 1,000 hours.
• I don't have a local shop that I know of that can repair a Kawasaki. No way I'll pay the JD shop's prices.
• Remainder of machine including deck are in fair to slightly above fair condition. Might be able to be sold for parts, but probably not much value.
• I can get a Predator 13HP engine for $250 or so, but I'm not sure I even want to do that.
• I have a Briggs 13HP single cylinder scavenged from another mower, but I'm not sure about the running condition of it.

 

[4get gto]

So, should I try to reseat it or not? Keep in mind:

• I can swap simple parts and make minor adjustments, but I don't know engines
• Machine is 13 years old and has over 1,000 hours.
• I don't have a local shop that I know of that can repair a Kawasaki. No way I'll pay the JD shop's prices.
• Remainder of machine including deck are in fair to slightly above fair condition. Might be able to be sold for parts, but probably not much value.
• I can get a Predator 13HP engine for $250 or so, but I'm not sure I even want to do that.
• I have a Briggs 13HP single cylinder scavenged from another mower, but I'm not sure about the running condition of it.

Tough decision. I'm sure that head could be repaired but might be better to keep your eye open for a good used complete head and just change it out. Might get a couple more years out of it.

 

[Diggin It]

Well, if it's a simple as driving it back in and pinching or tack welding .....

Then there's a matter of getting the spring retainer keepers back in place. Two small wedge shaped pieces. Doesn't look like a fun task.

 

[Bigkrank]

I've bought a bunch of Kohler twin heads on ebay when we were modifying for tractor pulling purposes.

Example of a Kaw: Kawasaki FH491V J Deere X3/34 CYL HEAD VALVES (PLASTIC INTAKE STYLE) #1 USED | eBay

 

[4get gto]

Well, if it's a simple as driving it back in and pinching or tack welding .....

Then there's a matter of getting the spring retainer keepers back in place. Two small wedge shaped pieces. Doesn't look like a fun task.

You kinda said it all right there...

 

[tomplum]

Really any repair shop can do this repair whether or not they shy away from Kawasaki due to having no parts source or something. It sounds like this is making you stressed. I sure wouldn't put a HF engine or and old 1 lung Briggs on it having a a basically good engine otherwise.

 

[Richard001]

So, should I try to reseat it or not? Keep in mind:

• I can swap simple parts and make minor adjustments, but I don't know engines
• Machine is 13 years old and has over 1,000 hours.
• I don't have a local shop that I know of that can repair a Kawasaki. No way I'll pay the JD shop's prices.
• Remainder of machine including deck are in fair to slightly above fair condition. Might be able to be sold for parts, but probably not much value.
• I can get a Predator 13HP engine for $250 or so, but I'm not sure I even want to do that.
• I have a Briggs 13HP single cylinder scavenged from another mower, but I'm not sure about the running condition of it.

Well I watched the video about the guy working on the head and showing the raised valve guide. If you can get a use head at low cost, OK, but how do you know it doesn't have the same problem that your trying to solve?

I would think that drilling a hole into the side of the head that will align with the valve guide and into the guide. Of course you will have to remove the head, but you will have to do that anyway if you replace it.

Every one seems to think the head is junk with a valve guide that is drifting up and bending the push-rods. So what do you have to loose by trying to secure the guide with a pin. If it were mine, I'd remove the head, remove the valve, heat the head in a oven to about 300 degrees, then press or drive the guide back into place.

Then cross drill a hole thru the side of the head and thru the valve guide. You would have to carefully select the right size drill to match the roll pin you plan on using. Tap the role pin in place, making sure that it does not protrude into the valve area of the guide.

Reassemble.

Richard

 

[crazyal]

A coworker had the same problem and just pushed the guide back down into place. That was 4 years ago. He's out this week but I can ask how he did it. One school of thought is that it took 100 hours to move the first time so it might stay in place if pushed back for another 1000 hours. I would want to pull the head and remove the valve before trying. That would require a couple tools though (like a valve spring remover and a torque wrench). Probably could get what you need if you don't have it at Harbor freight.