Hpi F4.6 engine/ Cracked crank??

[chronic]

My savage is a couple weeks old. I was having troubles with it at idle, and noticed it was literally spewing oil all around the front main bearing. So I removed my engine at work today.

My buddy who had time between his run cycles offered to take the clutch off and check it out.
My clutch bearings were effed. He said when he pulled the clutch bell off the bearings fell on his work bench.
Then he wanted to remove my flywheel to check the main bearing, and when he removed the wheel, the friggen crank cracked and a piece of the end came off. I'm not sure how much, but some of the threaded end broke off??

Any opinions here? I'm totaly confused, my friend is really upset because it broke when he was playing with it, I don't understand what the hell is up here.

 

[Jeremy]

ouch that sucks dude .. I would think that your friend was way too forceful in removing the flywheel.. yea I hope you ordered a new crank ..

if you go to a parts store you can get a small "puller" so next time you wont have that problem .. sorry about your bad luck

 

[samisavage]

I would maybe try and contact HPI. See if maybe they can send you new parts, I donno would think it would be a warranty issue, shouldn't have busted that easily. Donno, maybe a shot. Maybe not. Kinda Iffy situation.

 

[kube1]

Actually i did use a puller. The tapped end for thw screw literally broke off. I realize it is a hardened shaft and not as relient to shock as tempered steel but i don't think it should have broken like that. Anyhow, I'm picking him up a new crank tomorrow. Whatever.

 

[MTBikerTim]

the bearings shouldn't have fallen apart that easy. But I have found that bearings don't like nitro fuel much and fall apart real quick.

 

[rex_hvn]

i don't know wot it would cost to get it going again but i know that if you look on ebay for a K4.6 you can pick one up for aroun 120 and then you have a brand new motor all you are doing (no offence) is working on something that may have more problems

Just a thought :dunno:

 

[Shaun]

Ya Rob A.k.a. "nitronutzz" On Ebay Has The 4.6 Engine!! He Has The Pullstart And The Roto Start Version And Like Was Just Said There Only Like $125 Bucks!!

 

[kube1]

i think you guys are misinterpreting. the bearings that fell out were the clutch bearings. they had piled up and his clutch was running off center. the engine bearings looked fine.

 

[JohnH]

I had heat issues with my clutch bearings. with them running off center it could have cracked and weakened the end of the shaft. as far as I can tell not your fault but there must have been an alignment issue with the spur or it was slipping bad to over heat the bearings. I went to ceramic bearings on the bell. I would call HPI if you can't get a crank cheap then get a new motor as for cost for that much money a few more dollars you can get a hotter motor.

 

[Crash]

couple weeks old it should be worth savn, don't buy the crank untill you open the engine. If you need anything else to rebuild motor a new one may be the way to go. a new hpi 4.6 k will only cost you about 115 bucks. I rebuilt my hpi 4.6 k and I spent over 140 dumb move on my part.

 

[MTBikerTim]

I had heat issues with my clutch bearings. with them running off center it could have cracked and weakened the end of the shaft. as far as I can tell not your fault but there must have been an alignment issue with the spur or it was slipping bad to over heat the bearings. I went to ceramic bearings on the bell. I would call HPI if you can't get a crank cheap then get a new motor as for cost for that much money a few more dollars you can get a hotter motor.

This was the sort of thing I was thinking as well. I would say whatever caused the bearings to fail probably caused the crank to fail.

 

[Keithv]

Hey Chronic, not sure if you saw my post from a few days ago. My clutch bell bearings disintegrated last week too and the spur gear got dstroyed. As far as I can tell the crankshaft is fine though. I called HPI and they are sending out new bearings and a new spur gear. I would call them before you buy anything, it should all be covered by the warranty.

 

[chronic]

Well, I should have a crank on the way. And, we may have saved this one for the time being. So, i'll see how it goes.

Although, I'm kind of bummed with this motor excluding the the crank thing. Clutch bearings I brushed off and thought what ever.

But the front main bearing was leaking...and believe it or not. Trying to find a sealed bearing for the f4.6 engine is damn near impossible. Infact most stores were telling me I HAD to buy the crank case kit with the two bearings and block???? But of course, I still had to order them.

I found a bearing, Its the right size, but not the same. I don't think its sealed. I guess I'll find out the hard way.

Started to eye ball those hpi engines on ebay. It would be nice having a spare for when a million things go wrong at once.

 

[Shaun]

Ya U Really Cant Beat $125 Bucks For A Brand New Hpi 4.6 Engine!! And As I Stated Before Rob A.k.a Nitronutzz Has Both The Pull Start And The Rotostart!! I Just Bought The Xtm 457 But haven't Dropped It In Yet!

 

[chronic]

Woo, she lives again! And strong...****!


This bearing wont do, it spins a bit of oil. Very minute though...So, if I can't find a proper one this weekend. I will just have to make due.

However, through this mess of things. I made my truck a balsy little unit.

I ported the snot out of my crank. I made the entery almost inline with the crank cases carb port. I also polished the back end of the crank, eliminated some corners and carved in nice smooth rounded edges. I don't think I am done yet as I like what I am seeing.

I got a ribbed hpi muffler, and with the minor polishing I did to the sleeve, everything I did to the screwed up crank, and this exhaust. Wow! Once the motor starts to spin, it gives me some power that wasn't there before.

I didn't touch the carb settings through this epidemic, and its got alot of something that wasn't there before I ripped the engine apart. Its really impressive. To hell with a new engine, I want to make this one healthy and happy.

 

[Keithv]

Did you polish the sleeve yourself? and if so how?
Thanks chronic

 

[chronic]

I didn't do much to the sleeve, mainly the crank. But what I did do was polish the bottom lip so it was a nice clean smooth radius and almost sharp. I got rid of the square bevelled corners.
I started touching the transfer ports, polishing the edges of the guides facing the front of the sleeve away from the exhaust thinking the air flow up from the crank may slide around it then stop once it hits the sharp back side flowing up into the cylender. But that was the idea, after dabbing the sleeve on the scotch brite wheel I decided...No, I'll leave this for now until I learn more. The f4.6 engine has all the porting that guides show, already done. I think all a guy can do is exaggerate them and polish edges?


So yeah, haven't really done anything to the sleeve yet. I kind of want to get another piston/sleeve and crank. Then go nuts on the stuff I have now having two sets.


But for the time being, until I get a new crank. I'm going to go mental on this one. tomorrow I am going to maybe take the crank out again and finish my vision. I'll try to take some pics.

 

[Keithv]

what are you polishing it with?

 

[chronic]

The sleeve I used an....arbrite wheel? Scotchbrite, what ever you want to call it. And the crank I used a pencil grinder, a carbide burr for removing material and a ball grinding stone to kind of smooth it out. Then I just used fine sand paper to polish it up as best I could before I threw it back together. Tomorrow I'll use a dremel finish it all.

 

[Keithv]

ahh ok. thanks.
keep us posted on your progress

 

[chronic]

Sure, as long as everything holds together lol. I'm apprehensive about a few small things. But what ever, I'm a noob over thinking.

Tomorrow I will bag this thing, I should put my stock muffler back on too just ot determine how much the porting did!