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Discussion Starter · #1 ·
I have done some serious reading on here since buying my 2000's 345 (my first ever riding mower). I wasn't happy with how it was mowing and ended up finding out it was was running on one cylinder. Once I got that fixed I noticed some oil residue causing smoke and was tightening up all of the bolts in the area, which were pretty loose, and then the head of this one labeled "4" snapped off. I don't notice any leaks and before I go creating a bigger mess by trying to take this all apart, remove the broken bit, and replace I wanted to see what you all thought on how urgent I should treat this.

Thanks in advance!
785367
 

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If it’s not leaking don’t mess with it. Those things always leak, and I find it less frustrating to replace the plastic with metal covers to finally be done with it.

Did it break flush with the head, or are there some threads hiding in the valve cover? If there’s a stud to work with you will be much better off when it does leak and you can’t ignore it any longer.
 

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It's not going to leak as the bolt broke on the upper side, but if that cover starts to pull away from the head, you will have to fix it as it will allow contaminates into the valve train.
 

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Discussion Starter · #4 ·
Thank you both for the quick responses! This is all new to me, so I thought I created a bigger issue while trying to fix another. It looks like there is a bit of the threads visible under the cover, so hopefully it will be semi easy to deal with if it starts leaking.
 

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You must have torqued that bolt quite a bit too much in order to twist it right off like that. If you're new to wrenching on stuff, get yourself a decent 1/4" drive and a 3/8" drive torque wrench, learn how to use them and learn some general torque specs. A small bolt like that is probably not spec'ed to much more that about 10ft-lb of torque, which is easy to exceed. Next time it could be much worse like a twisted-off sparkplug or oil drain plug, then you're getting into expensive repairs. 👍
 
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You must have torqued that bolt quite a bit too much in order to twist it right off like that. If you're new to wrenching on stuff, get yourself a decent 1/4" drive and a 3/8" drive torque wrench, learn how to use them and learn some general torque specs. A small bolt like that is probably not spec'ed to much more that about 10ft-lb of torque, which is easy to exceed. Next time it could be much worse like a twisted-off sparkplug or oil drain plug, then you're getting into expensive repairs. 👍
This is excellent advice and hopefully one which not only the OP, but anyone else new to wrenching takes to heart.

Sometimes, bolts which seem "loose" are actually not supposed to be over tight as the hardware can fail, as you have now seen. Fasteners threaded into aluminum are especially vulnerable to breaking if you aren't careful and some of the fasteners breaking can be a very serious problem or time consuming and expensive to repair. This is a plastic valve cover secured in place with a light duty fastener threaded into the aluminum cylinder head.

Actually, over tightening bolts such as these in a plastic part can warp it and cause the leak to worsen. Hopefully, for your sake, that doesn't happen in this case.

Proper torquing procedures, Learn them, Know them, Live them.......to avoid big headaches..............
 
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Those plastic valve covers should have a steel sleeve or bushing inside each hole that is the same thickness as the cover flange, as I remember them anyway. I can't see in the photo if it is still there. This was meant to let the cover just flatten the shaped "O" ring type seal, and not let the screw head (or flange) dig into the plastic. I suppose the covers can and do eventually warp between the fasteners from time and heat cycles. I have looked through my old Kawasaki engine manual and can not find a recommended torque for those capscrews. Kinda strange I think. My guess would be 70 in. lbs. An M6, 10.9 grade, should be good for more than that. I'm only guessing on the grade of those particular capscrews.

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Torque for those bolts is 53lb-in.
It looks like someone was in there earlier. It looks like they make a gasket and used some type of gasket sealant/cement.
Many of the bolts going into aluminum for that engine are lb-in torque spec. I would get a lb.-in torque wrench.
 

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Discussion Starter · #9 ·
Torque for those bolts is 53lb-in.
It looks like someone was in there earlier. It looks like they make a gasket and used some type of gasket sealant/cement.
Many of the bolts going into aluminum for that engine are lb-in torque spec. I would get a lb.-in torque wrench.
Thank you for the exact torque info. I went out and bought torque wenches after AJGreen recommended them. Although, I have not monkied with trying to get the old portion out and replacing. I would agree with you that it looks like the prior owner had put some sort of sealant between the two parts.
 

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53 in-lb = 4.4 ft-lb

Means that if applying force to the wrench 12 inches long from the bolt a push (or pull) of 4.4 lbs (at 90*) to achieve that torque.

I'd speculate that it's more likely that with the correct size wrench the users hand would be more like 6" from the bolt. At 6" distance the required push (or pull) would be about 8 pounds.
Still not very much to achieve the correct torque.
 
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