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air leak sealing questions

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symmetricon

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A couple weeks ago i posted some engine problems, and thought it was a bad tune. I then retuned it it ran better, while doing so i found out that i had broken the front pinion in the diff. So i ordered the necessary parts and fixed it, also put in some lst shock.So today i started it up, it didnt want to start. So i got it running and of couse it died and then wouldnt restart. After much pain got it to start again, and it wouldnt keep running. Well when i initialy had problems with it randomly killing and not fireing up again i thought it might have an air leak. Well after my troubles today i took out the motor and found an air leak where th crankshaft seals with the bearing. Do i need to take the hole motor apart? And then how do i reseal it?
 
Is it the bearing seal itself or what? Unless it's really bad, it shouldn't affect your tune to the extent that your dealing with. The more likely culprits are the backplate seal, carb neck, carb cinch bolt, HSN banjo fitting or the o-rings on the HSN or LSN.
 
The air leak is between the crankshaft and the bearing where the crankshaft meets and exits it, not where the case and bearing sit, not the bearingand its seals. When i took the motor off of my xl and checked for air leaks i pluged the carb and exhaust port whith my fingers and then blow into the fuel line and there it was. I could actually feal it blowing out at my face. I then put some soapy water and checked the hole motor out and the only place where it leaked was where the crankshaft exits the bearing.
 
I think i just need to replace the bearing, what do yall think, and then how do i seal the new one up with the case and crankshaft?
 
You don't seal a front bearing, ever. I'd send it back to HPI if it runs that bad. If the crankshaft does indeed leak that badly at the bearing race, they need to replace the engine.
To answer your other question the bearing is just a press fit. Heat is required to remove and replace them properly.
Randomnly dieing and not restarting sounds like you are running it too hot or the pinch is gone already.
Some leakge at the front bearing is normal, what you described sounds past the norm though.
Axial made that engine for HPI. They hands down make the worst bearings I have ever seen.
Buy a Mach .26 double sealed front bearing or order some good quality bearings from www.avidrc.com or acer racing.
I have put the Mach bearings in quite a few different engines with good results.
Me personally, I'd send it to HPI and tell them about alll the trouble you had. I would not spend a cent on it.
Also Axial carbs are notorius for leaking where the composite and aluminum halves are pressed together. It does not leak until the engine gets warm. Degrease the carb and seal around that joint.
 
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I always check my engine temps keep it below 250. And i can seriously feel the air blowing out through the bearing. I guess ill be calling hpi tomorrow.

Sorry i dont mean to sound stupid but what is the pinch?

Ok i looked up what pinch means and the motor still seems to have pinch, I've only run 2 gallons throught it.

I've tuned and retuned, the darn thing wont stsy running.
 
Sounds a lot like an axial that I did have... and sent back to the mfr, then received back saying there was nothing wrong with it... I didn't check for a leaky bearing, I just replaced it. Still ran like junk. Started fine, idled fine, but regardless how I tuned, ran really hot (260F+) with no power and a lean bog when past 1/2 throttle.

Sold it recently as a parts engine. Hopefully HPI stands behind what they sell better than axial did with me. If they had given me a new engine back and it performed as well as many of the ones I've read about, I would have bought another... as it is, I sold it for $30 to a guy in Canada that wanted it for parts. Just over a gallon through it, still shiny new looking inside and hard pinch at TDC. Now I avoid axial like the plague.

This, after all, is a hobby and is supposed to be fun. Fighting with an engine is no fun.

Replaced it with an LRP28S3. Awesome engine. Hands down one the best performing BB I've owned. Will probably buy another for my savage when spring comes.
 
It has truely been a test of patience, I've been so close to grabbing a hammer and....or bringing it to work to meet the plasma cutter. The first gallon ran pretty well,and then started to run even better. Then went to hell. We will see what hpi think. Ill keep posting. Thanks for your input.:)
 
That's about how long my axial lasted... Ran it in a XTM mammoth ST for a bit over a gallon. Sold the truck, kept the engine. Stored the engine in a baggy pickled with ARO for about 6 months. Tried it in my savage, ran like crap. Put it back in a baggy for few more months.

The best it ran after that point was when I fitted an OS carb on it as a last ditch effort. The carb was for a 21 and I had to make a sleeve around the carb neck and sealed it really well with RTV. I installed it in my aftershock and ran it for a few tanks. It ran much better with "ok" power, but you could tell the new carb wasn't giving it enough flow.

Considering I spent $100 on the engine new at my LHS, it probably cost me another $200 in aggravation. So, instead of wasting anymore time with it, I got rid of it so it wouldn't remind me of the headache.

Had a similar experience with an STS30... Not quite as long as I've learned to not put up with such nonsense. Sold it the to the same guy at the same time I sold the axial. Apparently Canadians have better luck with Axial and STS than I!

Hopefully your story ends with a better ending! ;)
 
The LRP .28s3 will probably be the next motor if i can't get this issue resolved, its very well priced too compared to alot of other motors.
 
Good plan!
Make sure you get the roto start backplate setup. Towerhobbies lists everything you need to convert it to roto.
The LRP is super tight at first, you can forget using a pullstart.
 
I didn't/haven't had a problem with the PS on mine... I made sure to heat the engine up to 80F and loosened the GP 1/4 turn before trying to start it for the first time.

That being said... I'm sure the next time I go fire it up, the pull start will snap off in my hand!
 
olds97_lss said:
I didn't/haven't had a problem with the PS on mine... I made sure to heat the engine up to 80F and loosened the GP 1/4 turn before trying to start it for the first time.

That being said... I'm sure the next time I go fire it up, the pull start will snap off in my hand!
Click to expand...

Yep! You asked for it.:p:
Mine was a bump version and i caught hell breaking it in.
At the same time a friend put one in his Savage. Did the same as you, preheated it, loosened the GP and broke the pullstart twice in one day!
He's no idiot either, damn good mechanic. He swapped it over to the roto and never looked back. That was his first and last pullstart engine!:hehe:
 
I called HPI and explained to them the situation. The customerservice tech was very nice, he asked me about the breakin process, and i told him how i broke the engine in. I broke it in exactly how the manual said too, 1 tank idleing, then 2 tanks w/light driving. He then told me that i must have an older manual, he said " the new manual says to idle at least 3 tanks idleing". I dont know if this would make any kind of difference but... He told me to send it in and they will test it. If there is anything wrong with it they would replace it. But they will be on vacation from the dec 25- jan 5. Oh well, i guess ill pass the time with a new heli and fix up my vxl pede
 
Hope they take care of you. Go ahead buy a new mill in the meantime.:D
Why settle for one when you can have two?
 
symmetricon said:
I called HPI and explained to them the situation. The customerservice tech was very nice, he asked me about the breakin process, and i told him how i broke the engine in. I broke it in exactly how the manual said too, 1 tank idleing, then 2 tanks w/light driving. He then told me that i must have an older manual, he said " the new manual says to idle at least 3 tanks idleing". I dont know if this would make any kind of difference but... He told me to send it in and they will test it. If there is anything wrong with it they would replace it. But they will be on vacation from the dec 25- jan 5. Oh well, i guess ill pass the time with a new heli and fix up my vxl pede
Click to expand...
Let us know what the results are from HPI. Intersted in seeing how they stand behind there product.
 
Hey guys, i was wondering what u think si the best mill out there for the ol xl, the lrp 28, sts 30, o.s.30vg, picco 28...... Also will my pipe work on any of those?
 
The polished HPI pipe will work on any big block engine.
The picco .28 would be the best choice, it requires a lot of patience to breakin, as do most soooo...
The LPR would be my next choice
SH .28 Pro 6 port is very similar and can be had with the roto already installed.
I'd stay away from STS, poor quality.
The O.S. 30 is not that impressive but is a good engine.
 
The LRP runs better with a bit more restrictive pipe.

I ran the HPI polished pipe with it on my aftershock and it did well, but I borrowed a buddies LST2 pipe (Losi HT tuned) and it really evened out a mid throttle bog I had and gave me good power throughout the entire RPM range. The polished pipe seemed to give me most of my power down low.
 

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