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Points Pushrod Help


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#1 Sawdust OFFLINE  

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Posted March 15, 2014 - 09:45 AM

I found out my 1976 MTD 990 needs this replaced. It's not sliding in & out at all when I rotate the engine. I found the pushrod but not the bushing $36. :mad2:  Is it common to replace the rod & not the bushing. I'm also considering the electronic conversion. I know somewhere in the earlier days of B&S flywheels had to be repolarized & would be done free by B&S. I found on here a few conversions but not much about replacing the rod & bushing, so I'm assuming most just convert instead of replacing.  I know how to do it but I read where the cost is just as much as the conversion so this might be a no brainer to just convert. Anyone that has done this I'm open to your experience. Thanks!

 pr1.jpg


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#2 olcowhand ONLINE  

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Posted March 15, 2014 - 09:57 AM

Is the current push pin loose in the guide, or is it stuck?  If it's stuck & you can remove it, then a little emery cloth would get it moving slick again.  If it's free in the guide & still won't move with the cam lobe, then it's possible the cam lobe has worn down & either a new cam or having the flywheel re-polarized & going magnetron would be your only choices.


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#3 Sawdust OFFLINE  

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Posted March 15, 2014 - 10:27 AM

Is the current push pin loose in the guide, or is it stuck?  If it's stuck & you can remove it, then a little emery cloth would get it moving slick again.  If it's free in the guide & still won't move with the cam lobe, then it's possible the cam lobe has worn down & either a new cam or having the flywheel re-polarized & going magnetron would be your only choices.

Its stuck & I thought about that but can this just be pulled out & slid back in without going iniside?



#4 olcowhand ONLINE  

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Posted March 15, 2014 - 12:25 PM

Its stuck & I thought about that but can this just be pulled out & slid back in without going iniside?

 

Yes, it should pull on out, IF it isn't stuck too bad.  I can't remember if the guide comes out from the outside or if it has to push out inside the block.


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#5 Sawdust OFFLINE  

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Posted March 15, 2014 - 12:40 PM

I was able to pull it out slightly but with some resistance. When I turn the engine CCW the pin comes out & as I push on it while turning CCW I hear a slight rubbing noise. When I turn the engine CW the pin goes back in but does not come back out while turning CW. I also seen on Youtube the sleeve is suppose to be set at five business cards deep when installing a new one. My sleeve is sticking out a little more than 1/4" is this right.

 

The pin as it sits while turning CW

p1.jpg

 

It comes out while turning CCW regardless where the cam shaft lobe is

p2.jpg

 

Is this the right position of the sleeve 

p3.jpg



#6 Jack ONLINE  

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Posted March 15, 2014 - 12:44 PM

I am not sure if what you need is in here or not. But if you haven't seen this there is a lot of
really good info here. There is some B&S stuff near the bottom. I am thinking they may also make a
"flared" pushrod to repair a B&S with a worn cam. Check it out.

http://gardentractor...om/ignition.htm
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#7 Sawdust OFFLINE  

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Posted March 15, 2014 - 01:45 PM

I am not sure if what you need is in here or not. But if you haven't seen this there is a lot of
really good info here. There is some B&S stuff near the bottom. I am thinking they may also make a
"flared" pushrod to repair a B&S with a worn cam. Check it out.

http://gardentractor...om/ignition.htm

I seen that last night Jack. It looks like a good remedy if mine is as bad as I think. This GT I'm not really worried about keeping original basically what ever works good & looks good is what I'm going to do. It's going to be my do what I ever I feel like GT  :D I would like to keep the points. I have heard some pros & cons on the electronic system so I'm a bit skeptical. I may have to cover this project up for right now & go back & start painting my MF12 because of good weather. Thanks



#8 JDBrian OFFLINE  

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Posted March 15, 2014 - 02:45 PM

If the sleeve is supposed to be nearly flush it almost looks like the rod got seized in the bushing/sleeve and pushed it out of the block. You might try removing the whole works. 


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#9 allisb10page OFFLINE  

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Posted March 15, 2014 - 04:16 PM

I have the same problem with a B&G on a B-10 of mine.  The shaft unfortunately has to be inserted from inside the block.  I will be curious to hear how it goes for you...allowing me to know what I am getting into.  Hope it all goes well.


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#10 Sawdust OFFLINE  

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Posted March 15, 2014 - 11:39 PM

On page 20 of the Ignition section of the B&S Repairmans Handbook shows this plunger & bushing can be changed from outside. I don't know how to copy & paste a single page of the PDF file so I will try to explain. It says to pull the plunger rod out as far as possible then break off. Tap the brass bushing with a 1/4-20 tap about 1/2" to 5/8" deep. Take a few washers & place them over the bushing then screw a 1/2" long bolt into the bushing that you just threaded. This acts as a puller for the bushing & I assume the rest of the plunger as well. There is a caution to not let any shavings or pieces fall into the case area. To install insert the new plunger into the new bushing. Take the old bushing or something that fits over the new bushing & tap into the case. It also mentions the shoulder of the bushing is to be flush with the casing as mine sticks out 1/4". I have found the new plunger part # 298125 on ebay but not the bushing. I have searched several parts suppliers but they don't list my Type number. Off to do more searching  :wallbanging:  Thanks to everyone who is trying to help.



#11 Sawdust OFFLINE  

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Posted March 17, 2014 - 08:15 PM

Well I got some good news & bad news, good first. I tried pulling & twisting slighty but couldn't get the brass bushing to move at all. I didn't really spend too much time trying because I didn't want to damage or collapse the bushing. I did use the method explained in the B&S Repairmans Handbook & this method surprisingly was simple.  http://gardentractor...-engine-manual/

 

This pic shows the part of the plunger rod I snapped off then I pushed it in to make room for tapping

p2.jpg

 

I used a 1/4-20 tap & threaded 1/2" deep

bushing7.jpg

 

Make sure you back out to clear the threads even though the brass is soft. I put oil on the tap to hold the shavings in the flutes. I also removed the tap a few times & blowed the tap clean & vacumed the hole a few times as well

bushing6.jpg bushing4.jpg

 

I threaded the bolt in all the way then backed it out about an 1/8" then sized up some washers to make a puller

bushing5.jpg bushing1.jpg

 

This pic shows how long the tip was that I broke off

bushing9.jpg

 

The plunger after I removed it

bushing8.jpg

 

I'm really not sure how this got bent. If you remember my bushing was not pushed in as far as it should have been. I'm thinking the plunger got sloppy because of not enough bushing to ride in & got caught on the cam lobe. Now the bad news. I used a 1/4" dowel rod with a narrow piece of cloth & pushed into the cam lobe & turned the drive shaft slowly to clean the lobe. I looked inside & my cam lobe has a distinctive groove in the center. To me it looks damaged. The edges of the riser looks good but the middle of it has a groove. It dosen't look like friction wear but because of the bent plunger I'm thinking it has cut a groove into the lobe. This looks like a candidate for electronics or maybe a project for next winter. While I was cleaning the lobe I noticed some slop back & forth in the camshaft. I'm not sure what is exceptable but I'm thinking a complete rebuild this winter.  :tapping_fingers:


Edited by Sawdust, March 17, 2014 - 08:17 PM.

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#12 olcowhand ONLINE  

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Posted March 17, 2014 - 08:18 PM

Wow...I had NO idea that would be that long!  Never had one out of a Briggs, and just going by push pins in Kohler engines, I expected it to be much shorter!


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#13 Bruce Dorsi ONLINE  

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Posted March 18, 2014 - 07:04 AM

 my cam lobe has a distinctive groove in the center. To me it looks damaged. The edges of the riser looks good but the middle of it has a groove. It dosen't look like friction wear but because of the bent plunger I'm thinking it has cut a groove into the lobe.

 

What model & type # B&S engine?  .....I may have a cam or another engine for you.


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#14 Sawdust OFFLINE  

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Posted March 18, 2014 - 09:52 AM

What model & type # B&S engine?  .....I may have a cam or another engine for you.

Model 326431  Type 0204-01 I have several sources for parts but right now I won't know what I need until I open up the case & inspect. My curiosity tells me to do a complete rebuild but that one little small voice says go electronic just to see if it runs. I have a MF12 waiting to be painted & the weather looks good so I will probably switch over to that project & save this one for winter. I'll let you know if I need anything...thanks.






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