Kawasaki twin cylinder issue

[Marv 952]

Compression check revealed about 30. Removed head and found both valve pushrods on the affected cylinder are bent. I have never seen an engine that was built with bent rods. So, the question becomes what caused them to bend. Stuck valves comes to mind. but these are nice and free. Help me out here. I am reluctant to just replace the rods and hope for the best.

Marv

[Jeff-C175 7,203]

25 minutes ago, Marv said:

Compression check revealed about 30. Removed head and found both valve pushrods on the affected cylinder are bent. I have never seen an engine that was built with bent rods. So, the question becomes what caused them to bend. Stuck valves comes to mind. but these are nice and free. Help me out here. I am reluctant to just replace the rods and hope for the best.

Marv

 

If the pushrods are bent the valves would stay closed and you would have compression I would think.

 

What if the piston became detached from the rod and came up and hit the valves?

 

Any marks on the top of the piston?

 

 

Edited June 15, 2022 by Jeff-C175

[Jeff-C175 7,203]

It's not a water cooled engine, is it? (hydro lock)

 

Or... Broken cam gear?  A la "interference engine" ?

 

 

Edited June 15, 2022 by Jeff-C175

[Marv 952]

10 hours ago, Jeff-C175 said:

 

If the pushrods are bent the valves would stay closed and you would have compression I would think.

 

What if the piston became detached from the rod and came up and hit the valves?

 

Any marks on the top of the piston?

 

 

 

10 hours ago, Jeff-C175 said:

It's not a water cooled engine, is it? (hydro lock)

 

Or... Broken cam gear?  A la "interference engine" ?

 

 

Jeff, No marks on piston. With both valves closed , no intake air so no compression I think. T tappets do move when flywheel is turned, I haven't checked them for timing yet though. The piston moves normally in the bore when flywheel is turned. Air cooled. The engine has been running on one cylinder for a while. The owner has been cutting grass with it that way. says it has been weak when going upgrade. Real head scratcher.

Marv

 

[953 nut 56,478]

16 minutes ago, Marv said:

The owner has been cutting grass with it that way. says it has been weak when going upgrade.

A single cylinder twin will do that to ya!         Have you attempted to move the valves to see if they are stuck?    Was there any appearance of overheating or lack of lubrication on the head for the dead cylinder?

[gwest_ca-(File Mod) 11,161]

Have often wondered if the valves are not closing fast enough leaving excessive tappet clearance. It would only have to happen once.

I can hear the difference in a Kohler single cylinder when Marvel Mystery oil is added to the fuel. A shot of 2-stroke oil in the fuel should work also.

Worth a try. Helps the valve train keep up.

[Jeff-C175 7,203]

3 hours ago, Marv said:

no intake air so no compression I think

 

That makes sense I guess?  Could even develop a vacuum in the cylinder under correct conditions...

 

Did a quick Google and found this guy has the same trouble... haven't finished reading it yet to see if there's a solution:

 

https://www.lawnsite.com/threads/23hp-kawasaki-bending-push-rods-what-to-do-next.392768/

 

OK, I just read it all... the guy doing the work had no clue and the guys helping him only helped just so much... but it sounds to me that your valves may be sticking and the 'top cylinder lube' that Garry suggested is a good idea.

 

Since you've got the head off, you may as well remove the valves, clean up the stems and guides, even though they feel free.

 

Edited June 15, 2022 by Jeff-C175

[Jeff-C175 7,203]

1 hour ago, gwest_ca said:

Marvel Mystery oil is added to the fuel

 

What proportion do you use Garry?

 

 

[Snoopy11 5,717]

Anthropomorphic beagle present.

 

Sticking valve @Jeff-C175... on the money with valve stems... (not sure what model engine this is... my personal Kawasaki has hydraulic lifters which if they are not pumping up enough or completely collapse can leave enough of a gap to bend pushrods). Unfortunately, in this case, it could be the lifters themselves, or even the oil pump... (clog in oil supply... etc...)

 

Bent pushrods is solid lifter engines are mostly caused from valves out of adjustment... but can be from bad valve springs... excessive head temperatures, bad/bent rockers, and overall metal fatigue.

 

In Briggs engines, when this happens, the pushrods can actually fall down into the engine oil pan (I won't go into detail), but it tells you how important it is not to run the engine in this condition.

 

I'd have to know the model engine, and the specs to give a true analysis here...

 

Don

[kpinnc 12,943]

9 hours ago, Snoopy11 said:

In Briggs engines, when this happens, the pushrods can actually fall down into the engine oil pan (I won't go into detail), but it tells you how important it is not to run the engine in this condition.

 

I know next to nothing about Kawisaki, but Vanguards use aluminum intake pushrods and steel on the exhaust side. If you put them in backwards, the aluminum ones can't tolerate the heat and will fail.

 

Seems simple enough, but they are actually hard to distinguish one from the other without a magnet.

 

Do Kawasaki engines have anything like this?

[Bill D 2,042]

I saw this on Taryl's YouTube channel.  The valves overheated and got stuck in the guides.  Take them out and sand and polish the valve stems to increase the clearances.   I've also seen the guides move in the head from overheating causing bent push rods.  The valve moved freely in the guide, but the guide was out of place causing the valve not to close and bending the push rods.  What model engine?  Taryl had videos on both the stuck valve and the bad valve guides.

[johnnymag3 2,554]

I run Marvel in the gasoline of all of my gas engines...….1.5 Oz to 1 Gallon Gasoline....

 

7.5 Oz. to 5 Gallon gas can.....mix it up every time I fill the gas cans,,   Great results !!!

[Snoopy11 5,717]

15 hours ago, kpinnc said:

Do Kawasaki engines have anything like this?

I can't speak for all Kawasaki engines, but from the twin that was on my Scag... and the one that is on one of my other machines, intake and exhaust were identical steel...

 

I do have a Briggs v-twin (not a Vanguard) and the pushrods are both steel...

 

Don

[kpinnc 12,943]

19 minutes ago, Snoopy11 said:

I do have a Briggs v-twin (not a Vanguard) and the pushrods are both steel...

 

 

I always thought it was a silly thing to do. I guess only needing half of them made from steel saved a few dollars. Freaking Engineers! 

[Snoopy11 5,717]

1 minute ago, kpinnc said:

I always thought it was a silly thing to do

Ha ha... yeah... trying that on an engine with any kind of heavy duty valve springs would be... eh...

 

Well... I'll put it this way... it would be good while it lasts... (the 4 seconds that it would last)...

 

Don

[kpinnc 12,943]

2 minutes ago, Snoopy11 said:

Ha ha... yeah... trying that on an engine with any kind of heavy duty valve springs would be... eh...

 

Funny thing is they have steel tips. Just aluminum in the center.

 

I've never had one fail so far. Some aftermarket kits have steel for both. Might try a set next build...

 

 

[Jeff-C175 7,203]

2 hours ago, kpinnc said:

Freaking Engineers!

 

Freaking ACCOUNTANTS !  

 

 

[ranger 1,769]

We used to see this now and again on VM diesels if the oil wasn’t changed regularly. The hydraulic lifters would ‘pump up’ and bend a pushrod, or break a rocker arm. Sometimes the opposite, the lifters would collapse, allowing the pushrod to detach from the rocker and engine would lose a cylinder, and sound like an old Lister/Petter.

p.s. My old AJS 650 cc twins, (motorcycles) had ‘Duralumin’ pushrods with steel ends.

Edited June 16, 2022 by ranger

[Marv 952]

Thank you all for your replies. Jeff, that is very interesting reading you came up with, thanks. I have this one all disassembled (head and valves).  As soon as I get new parts I will put it all back together. Will post results.

Marv

[Lagersolut 697]

On 6/15/2022 at 10:44 AM, gwest_ca said:

Have often wondered if the valves are not closing fast enough leaving excessive tappet clearance. It would only have to happen once.

I can hear the difference in a Kohler single cylinder when Marvel Mystery oil is added to the fuel. A shot of 2-stroke oil in the fuel should work also.

Worth a try. Helps the valve train keep up.

 

I've been adding 2 - 3 oz of Marvel to my 5 gallon cans of non ethanol gas for over 25 years .

[Marv 952]

Update:

The exhaust valve guide had moved. Apparently when the engine was hot, then when it cooled it stuck in place. So, the next time the engine started the valve did not have enough travel room. The movement of the rocker arm was stopped by the valve guide so the pushrod bent. There were no specifications on valve guides because they are not replaceable on that engine. Purchased a new head. Comparing the old and new I found the new guide extends 9/32 inch and the old one was 19/32. See picture. While replacing the head, three of the head bolts stripped, that is the threads in the block. Torque is 34 lbs. The threads gave away at 24. Wound up having to helicoil them. After reassembly it started and ran. After shutdown it did not want to start. Short cooling period and it started ok. Turned out that the ignition coil on that cylinder was intermittent.

Marv

Ps: Don't know what happened here but the pictures would not upload. Never had that problem before.