cazlin

Yesterday I was out bashing in the snow with one of my 4910s and right at the end of my 2nd tank, POP!
Running 20% Traxxas top fuel.




Amazingly, nothing seems damaged.
The bearings are fine, no grind, smooth and tight. Has plenty of compression. I broke this motor in 7 years ago using the same methods for the 2.5, but then shelved it once I got a new 2.5. Built this 4910 last week out of spare parts so I used this motor. It sat for a loooong time, but it was in a sealed plastic bag and soaked in after run oil.

I have been looking for another crank, cant seem to find one. Does anyone have/know where to get one? Getting oem parts from megatech is almost impossible for this motor.

Does anyone have any experience with this motor/series?

Has anyone had the crank shear off like this before on any motor?
This engine has less than 2 gallons on it, and I just recently started tuning it for more performance. It was cold today, so the motor never got above 150F.

Maxximize

Well, I don't have any experience with that exact engine, but I can sometimes find things that are hard to find Anyways I did a quick search and found a complete M16 on Ebay for $30. It has the purple head, but I'm not sure if it is the T Maxx model or if the crank is a T Maxx crank. Going by the picture, it is attatched to a T Maxx engine mount though. Here's the link to it. Clicky I found a black head one on there too, but it was removed from an HPI Rush so I'm guessing it has the long crank. Your best bet for an engine that old is Ebay for sure. I own an HPI Rush that I get parts for exclusively on Ebay due to it's age and the fact that HPI dropped support for it. Sometimes it's just playing the waiting game for the part I need.

cazlin

I found the ebay post you are referring to. That was posted Monday, I searched all over the place yesterday for parts.... I guess this is my only option other than buying a better motor.

Maxximize

Yea that was the only thing I could find also. Well, it's never a bad thing to have spare parts that's for sure. You could always get a Pro .15. Those are pretty cheap these days. The O.S CV-RX .18 with rotary carb will drop right into a Maxx using the Traxxas adapter nut for the clutch and uses a side exhaust. The crank may have to be trimmed a few threads for a perfect fit though. I can't quite remember exactly. There is another version .18CV-RX(s). I'm not positive which one fit best, but it looks to be the non s one to me. I think they have another version with slide carb and rear exhaust too.

cazlin

I love the OS CV motors, I put my old .15 CV back on this truck,(in the background of the picture) temporarily. Has over 6 gallons on it. Hard to keep running though after it gets over 180F(very little compression). I purchased that ebay link since its below $30, can't beat that for a working .15+ motor. Only reason I ever purchased this Megatech Q16 is because it was under $90 new at my local HS back in 2005. After break in, I always ran it hard so can't complain really.

Maxximize

Yea those CV engines are awesome! I remember the old hyper CV engines, those things screamed! That price is hard to beat, might as well even just for parts. I remember doing that same thing back in 2004, except I had an Orion Wasp .18 Maxx engine. It cost about $90 or so on sale, and is somewhere in one of my parts boxes. I am actually thinking of doing the same thing you did and using all the old parts I pulled off my Maxx when I made for big blocks and using my old Orion engine for it. I've even got an old MIP stinger rear exhaust somewhere to sue for it Anyways, hopefully that engine will work for you.

cazlin

You should definitely build another one! Its amazing just how many parts you accumulate, lol . I thought about rebuilding this CV15 instead, but its just too wore out. I think a piston/sleeve rebuild would just nuke the poor thing. Just started it up in my garage for the first time in years... and it idled.

Maxximize

Wow, that is one clean truck! I like that fuel tank, what one is it? I am in the process of putting an Ofna 9.5 tank on my big block Maxx, still finishing that old project off. After that it's time to get my old HPI rush back on the dirt, then I should inventory my spare parts. I was thinking of a rear wheel drive only 2 speed Maxx on buggy shocks with my .18, that would be interesting. I know I have 2 chassis plates, 4 stock wheels, a TRX 2.5R and the Orion, 2 complete pipes, an old black forward only tranny, and a crate of other parts from the 13 or so years I've had the truck. My big block Maxx is basically built from scratch and has no stock parts left on it except the center front drive shaft and the servo mounts A truggy Maxx would be a neat project for sure!

cazlin

Haha, it wasn't clean yesterday.

This truck (originally) was the first nitro I ever owned. I think the only original parts are the rear tires and chassis lol. Everything else has broke/replaced over the years.



I just emailed http://www.megatech.com/support.php so we shall see what they have to say about the crankshaft.

The tank is from an old Nitro Rustler. 75ML I believe. I drilled the holes to fit it on the stock 4910 chassis. Its a lot easier to work on the motor this way and lighter IMO.

I actually did the exact same thing, 2WD forward only but in the snow the back end is too light. I also have JB welded the rear diff on this truck. I installed a front diff and now it handles much better in the snow/ice.

The megadeath motor is on it in this picture, haha. Post pictures if you decide to build a 4910 I am currently building another 4910 with a 2.5R motor. Still waiting on a few parts from ebay...

I have a video of when the Megatech motor broke the crank if you are interested. Made a strange nosise, I immediately knew it had failed.

Maxximize

Awesome truck! My current one was my first monster truck, and my second nitro. I bought it when I was 14 years old after shelving my HPI nitro Rush in favor of it. I still have the Rush too, but it needs some work and parts are hard to find these days. How long are your run times with a tank that size? I like how it sits on the chassis, and might use one like that when I decide to build a Maxx 4910 truggy. I want to go stripped down with it, make it as light as possible for speed running. I definitely will post pics of it, once the big block is done and it warms up a bit I can go look through my parts in the garage. I'd like to see that vid, never seen one of these engines blow before.

cazlin

https://www.youtube.com/watch?v=pKcVMJpL--0


Crank splits at 5:37


I usually get 8 minutes, 5-6 minutes running rich.


I have the original HPI Nitro MT, really hard to find parts. I need the main spur gear, its the single speed plastic gear with no slipper. Do you know if something like this would fit the MT?
http://www.ebay.com/itm/HPI-1-10-Bul...item5d501ecac7

Quickywd01

My Feedback: (3)

My engine did that too. I think your engine wasn't up to operating temps causing the failure.

cazlin

Was your engine that failed a Megatech .16 too?

Quickywd01

My Feedback: (3)

No. 2.5R, replaced it with another 2.5R which still works but I have a .26 red dot in it.

Maxximize

Hmmm yea that's interesting. It could have been the cold temps coupled with the age of the engine causing metal fatigue. Hard to say really, never know anybody that happened to with any engine.

8 Minutes on a tank that small isn't bad at all, that may be an option for my lightweight Maxx idea. I was going to do the Ofna 9.5 tank mod like my big block has, but 150cc of fuel for a small block is really overkill and adds weight too.

About the spur, I'm not really sure about how HPI parts cross over to different models. It's really too bad they don't continue to make parts for their older vehicles that break often like spurs and tranny gears. I have the same issue with my Rush, 1 spur left and none anywhere at the moment. I can find the slipper clutch parts on Ebay, just no spur gears.. Haunting Ebay will likely be your best bet for the Nitro MT as well. Of course, you could buy a spur that looks like it may work and see firsthand, that is really the only way to know. I was actually considering attempting to use Savage spurs on my Rush, they are smaller, but the same gear teeth (1M) and Savage clutch bells work for the Rush and MT both. I think all HPI nitros use 1M gear teeth so they will all mesh with each other at least. Of course you need the adjustable engine mounts to use any gearing other than stock like a larger clutch bell from a Savage. The Rush uses a different, larger spur than the MT does stock, and I think a smaller clutch bell. I think HPI may have the parts listed on their website for the MT. At least that would give you a part number for your original one. I'm not sure if they were made, but a steel spur would be a good bet for trucks like ours, a hardened Savage clutch bell is all that is needed for a steel spur.