Mystery engine knocking, vids & pics

Where is this knocking coming from? Lots of deposits on piston head, valves, and I found a crack in my cylinder head. Connecting rod does NOT have any up/down play that I can tell, even slapping it downward with my palm, and about 1/4" side to side play maximum. Please see pics and videos. Does not lose any coolant. No real oil burning unless I'm doing lots of freeway riding 

 

Any help with what is happening would be great. Thanks

 

http://sketchkeysartistry.deviantart.com/art/Drz400-head-crack-397449346

 

http://sketchkeysartistry.deviantart.com/art/DRZ400-Valve-Head-deposits-397449539

 

http://sketchkeysartistry.deviantart.com/art/DRZ-400-Piston-Deposits-397451358

 

 

 

http://www.youtube.com/watch?v=jb6UVNiNdoA

 

http://www.youtube.com/watch?v=4ywg_bkQrVs

Edited by Dirtsketcher

yep big end bearing is gone, mine sounded exactly the same when it happened and one day it decided to shat itself into pieces and died

yep big end bearing is gone, mine sounded exactly the same when it happened and one day it decided to shat itself into pieces and died

 

Even though there is no up/down play? I saw one guy here who demonstrated his bad crank and you could see and hear the rod hit the crank... mine doesnt move up or down.

There's way too much play in your rod. Might as well put a stroker in it for about the same money.

Per the service manual, the wear limit for the big end of the rod is 1 mm of thrust play (lateral between rod end and crank web) and 3 mm (0.12 in) of "rocking" when measured at the small end (laterally).  So if you can rock the small end of the rod 0.25" then the rod/crank needs to be serviced/replaced.

Per the service manual, the wear limit for the big end of the rod is 1 mm of thrust play (lateral between rod end and crank web) and 3 mm (0.12 in) of "rocking" when measured at the small end (laterally).  So if you can rock the small end of the rod 0.25" then the rod/crank needs to be serviced/replaced.

 

Thank you. Now about the cracks on the head... how would those form, and would that be responsible for the deposits in my combustion chamber? The bike never smoked.

Where is this knocking coming from? Lots of deposits on piston head, valves, and I found a crack in my cylinder head. Connecting rod does NOT have any up/down play that I can tell, even slapping it downward with my palm, and about 1/4" side to side play maximum. Please see pics and videos. Does not lose any coolant. No real oil burning unless I'm doing lots of freeway riding 

 

Any help with what is happening would be great. Thanks

 

http://sketchkeysartistry.deviantart.com/art/Drz400-head-crack-397449346

 

http://sketchkeysartistry.deviantart.com/art/DRZ400-Valve-Head-deposits-397449539

 

http://sketchkeysartistry.deviantart.com/art/DRZ-400-Piston-Deposits-397451358

 

 

 

http://www.youtube.com/watch?v=jb6UVNiNdoA

 

http://www.youtube.com/watch?v=4ywg_bkQrVs

Never seen a DRZ head cracked like that, or even close to that location..

 

Only three reasons come to mind based on the rest of your pics.

 

One: the part just failed, bad casting, or other metallurgy issue. 

 

Two: The head was damaged when the motor was frozen with an incorrect ratio or type of coolant was used in cold weather.

 

Three: the welch plug was at some point replaced, and the head was stressed / damaged during the install........ I really don't think this is likely. 

 

End state, no matter how it happened, the head needs to be replaced. 

AWESOME! So I'm in it about $1,000 or more as it sits.... great news lol

 

thanks for the info

Part of ownership man. I bought a used DRZ with 10k miles for $2,600. 900 miles later it blew a valve and destroyed the head. $2,800 in engine upgrades and I have a $5,400 DRZ 434 :jawdrop:

Edited by Bluelunatic

I have a similar sound that I'm hoping has nothing to do with this one.  Did you notice if it makes the noise when the bike is cold?  Mine really kicks in when the bike is nice and hot but a few minutes of cooling off will quiet it down.  Then it's back.  It was also a lot louder when I had some pretty burned oil in there.  An oil change also seemed to quiet the noise down.

GREAT NEWS!!!!! Those "cracks" from the pics I posted aren't cracks, they are leftover streamers from the silicone gasket on the plugs. THANK GOD!!

 

Those looked a lot like cracks though didn't they?? Man I feel so much better!

 

Also, I went and measured the rod play, and it is right at 3mm..... I overestimated the figure before at 1/4". Either way, I should get another bottom end or crank, yes?

Also I have another question for the hardcore mechanics out there. Given the amount of buildup in my combustion chamber, and that my rod has only 3mm of side to side play, COULD the knocking be coming from the deposits pre-igniting the AF mix... or from a lean mixture? I hate to blow $1,000 to fix something that can be adjusted or cleaned with a wire brush. Thanks.

Also I have another question for the hardcore mechanics out there. Given the amount of buildup in my combustion chamber, and that my rod has only 3mm of side to side play, COULD the knocking be coming from the deposits pre-igniting the AF mix... or from a lean mixture? I hate to blow $1,000 to fix something that can be adjusted or cleaned with a wire brush. Thanks.

1st if you have 3mm of side play at the big end of the rod, your crank assembly is junk. Service limit is 1mm.

 

2nd if your saying when you slide the rod over to one side and you then have 3mm of deflection at the small end as measured by a dial indicator, then you are at the MAX service limit. 

1st if you have 3mm of side play at the big end of the rod, your crank assembly is junk. Service limit is 1mm.

 

2nd if your saying when you slide the rod over to one side and you then have 3mm of deflection at the small end as measured by a dial indicator, then you are at the MAX service limit. 

 

Well, I didnt use a dial but I did eyeball the total wiggle length side to side of the small end... its just about 3 dimes width. I guess I have no way to get out of buying a new bottom end do I? Rebuild kits are even more expensive than a low mileage bottom end... I might just look for a good used engine. Thanks for the replies

Do yourself a favor and send it to Eddie. He does great work and is VERY fairly priced. He can probably fix you up for less than a grand and you will know exactly what you have. Or you could buy a random motor off flea-bay for a few hundred less, and hope for the best. I went route A :)

Edited by thebugslaaaa

So I played with it a little more when I went to drain the oil from the 4 different spots in the bike.... and noticed that at a spot right after TDC the crank has a tiny bit of play. I can make it barely make a tink sound and see the drive sprocket for the timing chain move just slightly. I pulled a few tiny silver bits from the screen in the frame, and there were tiny flakes of silver in the bottom of the oil pan. Not much, but they're there.

 

So it would make sense the knock could have been the crank bearing?

how many miles on your bike?

how many miles on your bike?

 

17K, babied since 6K, before that was neglected by my friend I got it from, probably like one oil change per season.

I think you should do nothing and then see what happens. That way you won't have to spend any money and buy a new bike when this one blows up.

Problem solved.

So I played with it a little more when I went to drain the oil from the 4 different spots in the bike.... and noticed that at a spot right after TDC the crank has a tiny bit of play. I can make it barely make a tink sound and see the drive sprocket for the timing chain move just slightly. I pulled a few tiny silver bits from the screen in the frame, and there were tiny flakes of silver in the bottom of the oil pan. Not much, but they're there.

 

So it would make sense the knock could have been the crank bearing?

 

http://www.thumpertalk.com/topic/840863-big-end-rod-failure-again/?hl=big+end+failure#entry8709980

 

Rod and and big end pin fail at the point where the rod just passes TDC, coz its where there is max stress on it from the piston trying to compress the ebig end rollers into the rod & pin

Its called compressive stress failure and is a common failure mode for caged needle roller bearings

 

you will feel a very slight up/down movement if you put the crank in the just past TDC position and pull/push on the rod in a vertical direction

It helps if you wash out the oil from the big end it contact cleaner before trying to feel for the play.

Edited by GuyGraham

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now