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Baileygunns

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  1. Bashing
What do we do here? lol...

I'm going to guess you all are about to tell me to get a new piston and sleeve. The cross hatch in the sleeve is about polished out near the top and there is a slight score (I can feel it with a finger tip) going down the side of it. Do I need a new head too or can I polish it out?

If this was my 450R, I would toss the piston have the cylinder redone and deck and polish the head.

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This is a Revo I took on trade. I've ran about 2/3 of a quart of 20% fuel through it. I've burned up 5 glow plugs trying to tune it... Is this the reason I can't tune it or is this what happened because I can't tune it? I went back to factory settings on all the needles but was still running lean. I took the motor out to seal it and that's when I found this damage. This thing also has one of those Integy dual exhausts on it. The plan is to take it off and go back to the stock exhaust. I have the resonator but need a stock header. From what I have read here the dual exhaust is no help with tuning and lean conditions.
 
I'd use traxxas's ERP and just replace the whole engine. That engine was not taken care of at all and IMO, time/$ spent on it will be time/$ wasted.

I'd bet if you take it further apart, you'd see more internal damage. That doesn't look like typical pitting from detonation, but rather like something got in the engine or it was run so hard and lean that the piston skirt itself is breaking apart and tearing the surfaces up on it's way out.
 
Looks to me like it started out with a glow plug filament broken off and kicking around in the engine after a new plug was installed. Any time a bad plug is missing part of its filament, the engine MUST be opened up and completely cleared of any debris.
The engine will probably run just fine if it's tuned properly.
 
Wow... If that ain't two conflicting stories, lol...

olds97_lss said:
I'd use traxxas's ERP and just replace the whole engine. That engine was not taken care of at all and IMO, time/$ spent on it will be time/$ wasted.

I'd bet if you take it further apart, you'd see more internal damage. That doesn't look like typical pitting from detonation, but rather like something got in the engine or it was run so hard and lean that the piston skirt itself is breaking apart and tearing the surfaces up on it's way out.
Click to expand...
Correct me if I'm wrong... The piston skirt is on the bottom of the piston.. Now you're saying it came apart and some how made its way past the piston and sleeve in large enough chunks to cause that type of pitting on the head and top of piston before it made it's way out of the engine? I totally agree it is not pitting from detonation but indeed from something bouncing around in there before it made it's way out, I doubt piston skirt. I'll still pull the engine down and look closer.

Rolex said:
Looks to me like it started out with a glow plug filament broken off and kicking around in the engine after a new plug was installed. Any time a bad plug is missing part of its filament, the engine MUST be opened up and completely cleared of any debris.
The engine will probably run just fine if it's tuned properly.
Click to expand...
Rolex, I'm tracking what you're saying. The first thing I thought was the coil from a plug was in there and and the engine was ran like that. You think all that pitting is OK to run with? What about the score on the sleeve? How much is to much? Also the lack of cross hatch in the sleeve. The cross hatch is there to hold oil and lubricate the piston while traveling up and down.

I think tossing in the hat and buying a new engine is a little extreme... Pricing out the parts, new piston/rod/sleeve and a cooling head is much less than the EPR. Even if I added a crank to the bill it is still cheaper to rebuild myself.

Hopefully some more will chime in with opinions here... As of right now it's a coin flip.
 
I think the bearing went bad, causing the rod (which was probably worn already) to scrape the bottom of the case. It's happened to me and my head looked exactly like that one. I would ERP it.
 
It's very difficult for debris to make its way to the top, but I've seen several engines with that kind of damage from broken filaments. 30,000 RPM or better can leave a lot of scars when tiny metal particles are bouncing around in there. You have no residual fuel color on the piston, and that tells me it must have run extremely lean. Depending on how severe the scratch in the sleeve is, you might still consider cleaning it out and starting with both needles about 1/8 turn lean from factory settings and tune from there.
Going through 5 glow plugs is pretty easy when a piece of another filament hits the new one.
 
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Well, come to think of it, the air and fuel is rushing through there so I'm sure it can carry some filings to the top of the piston.
 
Only one way to find out for sure.....Mr Gunns. I've had just about every part of a 3.3 fail at one time or another, yes even the head, but they're still pretty good 'rtr' small blocks.
 
^^ You are absolutely right... Only one way, lol.

If you look real close at the pic of the head you can see the small "C" shaped indents which is what first make me think coil from the plug. They look to be the perfect size and shape for pieces of the coil.

Question still remains, should I try and smooth out the head?


I just went out to the bench and pulled the clutch bell off... Bearings are cooked in that, centers falling out, lol. Pulled the back of the engine off and found some metal shavings on the one way bearing and bottom of the block. Different then what was on the top end, much more fine. The piston has up and down play on the wrist pin and it has a nice scar down the side of it. How does the crank come out? That 8mm nut that holds the bump start wheel feels frozen.
 
Baileygunns said:
I think tossing in the hat and buying a new engine is a little extreme... Pricing out the parts, new piston/rod/sleeve and a cooling head is much less than the EPR. Even if I added a crank to the bill it is still cheaper to rebuild myself.

Hopefully some more will chime in with opinions here... As of right now it's a coin flip.
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NOT trying to be rude, but can you give me the links for the parts you are finding that are much cheaper (when adding all together) than purchasing a new mill... piston/sleeve and wrist pin kit is like $80 and new head is around $45, those two alone are more than the traaxas trade in deal, i can get a NEW mill complete w/ carb for $110+ tax from 3 LHS's in my area, just have to put flywheel and clutch and cluthbell on... like i stated above not in anyway trying to be rude, but i got a mill that needs rebuilt and if i can purchase parts cheaper than a complete new mill i need to order them , cause i on TIGHT budget

Thanks for any info
Jeff
 
Dude you need a whole new engine. Sounds like your bearings started it all. The pieces that made it to the top are smaller because the fuel air mix won't carry the larger ones up there as easily. Plus they most likely would get ground up between the piston and sleeve on there way up there. You might have a good crank, but I wouldn't even count on the block being any good. Grab the flywheel with channel locks to loosen the nut and you might have to heat and tap it off or use a puller.
 
Oh , in you first post you said you had the integy dual exhuast pipe on it...
from everything i have ever heard about dual tips, you never get it to tune right , it will ALWAYS run lean, and as all will tell you runing lean is very bad, makes engine run hot and too much heat is a engine KILLER,

been there done that got two mills in the junk box from it, one from being a newbee and one from being STUPID trying to get that last little bit of HP and crossing too far over the fine line...
 
wildjokerracing said:
NOT trying to be rude, but can you give me the links for the parts you are finding that are much cheaper (when adding all together) than purchasing a new mill... piston/sleeve and wrist pin kit is like $80 and new head is around $45, those two alone are more than the traaxas trade in deal, i can get a NEW mill complete w/ carb for $110+ tax from 3 LHS's in my area, just have to put flywheel and clutch and cluthbell on... like i stated above not in anyway trying to be rude, but i got a mill that needs rebuilt and if i can purchase parts cheaper than a complete new mill i need to order them , cause i on TIGHT budget

Thanks for any info
Jeff
Click to expand...

No offence taken... eBay is where I was looking

$50 buy now for piston and sleeve
http://cgi.ebay.com/Traxxas-TRX-3-3...Control_Parts_Accessories&hash=item33620f0ec5
$65 with piston, sleeve and rod
http://cgi.ebay.com/Traxxas-Slayer-...Control_Parts_Accessories&hash=item564113fa54

$15 for the head
http://cgi.ebay.com/Traxxas-TRX-3-3...Control_Parts_Accessories&hash=item51966b553f

New crank $11
http://cgi.ebay.com/New-Traxxas-T-m...Control_Parts_Accessories&hash=item2c58fca6f0

Now those are by now prices... You can win an auction cheaper.

Piston rod and sleeve just ended for $37
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120650465702&ssPageName=STRK:MEWAX:IT
 
Thank you Sir.
its good to know these things....
i do have a stock 3.3 i need to rebuild and i am flipping the coin on a rebuild and add ceramic bearing or just using the trade in deal for a new mill...
keep us informed on which way you go and total cost... it would help others out too:D

jeff
 
I'll have to put some thought into it... This thing doesn't rank to high on the priority list. I'm just about done building a honda 250EX from the ground up for my wife and I'm always adding to my 450R... I traded a pit bike that had been sitting in the garage for a couple years untouched for this Revo. I think I got the shat end of the deal on that trade, lol.

I'm a true motor head and love to rebuild and modify... If I'm around here long enough you guys will learn 2 things.. I finding things insanely cheap and I like doing it myself, lol.

I'll keep you guys updated.
 
I've seen 3.3's go for 80-90 bucks new w/o a pullstart. It's the best bet, trust me. I know you want ceramic bearings, but it's a waste putting them in a 3.3 that hasn't been broken in, plus they're insanely expensive.
 
Metalhead Matt said:
Whatever you do, pick up a pipe that will work correctly.
Click to expand...
That's for sure... I just hit the pipe I have with some Mother's polish and the Dremel... Next stop... eBay!

I'm watching some engines on eBay right now... Seems like every few hours some one lists a new one for $.99... It may take awhile but I think I'll be able to find something cheap and go from there. This will give me time to play around with chassis and suspension mods. Polished chassis anyone? lol...
 

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