jpoprock

Hey guys... I scored a seriously great deal on a Revo 3.3 w/ Platinum upgrades and an OS .18TZ engine with Slide Carb, AND after the auction, the dude said he'd sell me his RD Logics Starter Box II for $70. SOLD! I got all of this stuff for less than $300. But the dude didn't know much about the life left in the motor. He musta bought it from the original owner or something. I've been burned by bad motors in a deal like this before, and like a dunce, only started asking questions AFTER i won the truck. But I thought it was a huge score regardless, so I didn't care.

Anyway... what do I do once I get the motor, tear it apart, and find that it has little compression left? He said it has good compression though. The Traxxas ERP doesn't make it cost effective to rebuild a motor. But OS doesn't offer such a thing. And if you have to rebuild the .18TZ, the piston/sleeve/connecting rod can be sorta salty. A new motor runs about $175, piston/sleeve runs $93, CR runs $38, Piston Pin runs $10... so that's like $141 plus shipping! It seems that OS motors are not really cost effective to rebuild. So... if this motor I got is nearly toast... I'll need to just buy a new one, or send it off to be resized, and buy a new CR and pin. That would be worth doing I guess. I just never hear about guys "rebuilding" their OS motor, so I thought I would ask.

Thanks!

justin_92_92

My Feedback: (2)

Hey,
If you do decide to rebuild this engine. I can try to help on cost.

ridikt

i would just resize it and get a rod. i got a os .21v-spec that was crap, but got it for $70. i can get a rod for around $20-$25 and i believe rayaracing resizes for $20. thats my plan.

absolutemayhem

just wait til you get it.....take it apart and check the pinch......i can get a new TZ for $135 shipped from tower......best revo motor for the price.

justin_92_92

My Feedback: (2)

After going over the spec.'s of both the 18TZ and the 18TZ-TX......What would be the reason to spend more on the 18TZ-TX? Everything looks to be pretty close if not the same. But there is a $30 difference in price.


O.S. Max 18TZ
SPECS:
Displacement: 0.183 cu in (3.0cc)
Bore: 0.629" (16.0mm)
Stroke: 0.590" (15.0mm)
Practical RPM: 3,000-34,000
Output: 1.8ps @ 29,000 RPM
Weight: 7.8oz (222g

Distance between mounting holes same side: 0.43" (11mm)
Distance between mounting holes opposite side: 1.2" (31.4mm)
Distance from end of crankshaft to front bearing: 1.16" (29.5mm)
Distance from center of engine to front of crankcase: 1.4" (34.8mm)
Distance/bottom of mounting flanges/top of cylinder head:3.2"(81.2mm)
Width of mounting flanges: 1.5" (39mm)
Length of exhaust flange: 0.24" (6mm)



O.S. Max 18TZ-TX

SPECS:
Displacement: 0.183 cu in (3.0cc)
Bore: 0.629" (16.0mm)
Stroke: 0.590" (15.0mm)
Practical RPM: 3,000-34,000
Output: 1.8ps @ 29,000 RPM
Weight: 9.3oz (264g)

Distance between mounting holes same side: 0.43" (11mm)
Distance between mounting holes opposite side: 1.2" (31.4mm)
Distance from end of crankshaft to drive washer: .051" (13mm)
Distance from center of engine to front of crankcase: 1.4" (34.8mm)
Distance/bottom of mounting flanges/top of cylinder head:3.2"(81.2mm)
Distance/back of recoil to front of drive washer: 2.96" (75.43mm)
Width of mounting flanges: 1.5" (39mm)
Length of exhaust flange: 0.24" (6mm)

justin_92_92

My Feedback: (2)

Realized that the TX has a pull start on it.

jpoprock

The TZ-TX and the TX have the same specs I think. But it really comes down to "what are you putting it in" because depending on your answer, one may fit better in one vehicle, while the other may require some modding. It's almost best to buy the .21 that was made for the Revo and Tmaxx, even though I have heard that the .18TZ is as good if not better. Word is, the .18TZ is one of the best O.S. Motors for the money, PERIOD. But I don't know. It's all personal choice. It comes mounted to this Revo I'm buying, so I don't have to worry about the flywheel or crank. I think the OS to get for the Revo is the .18TZ "p" or something like that.

I've heard that the OS .18TZ is prone to connecting rod issues, just like the 3.3 supposedly is, but who knows.

I have talked to Rick Brake at RB Mods, and he can diagnose what a motor needs, if you send it to him with a note. Then he'll call you and give you your options. You pay him w/ a Credit Card, he does the work, then sends it back. RayaRacing does the same thing. So, if I end up needing a resizing, I'll choose one of those two. All of the motors that RB Mods sells are modified by Rick btw. And he's working on some mods for the Traxxas 3.3, namely a new, more durable connecting rod, and a turbo mod

AbsoluteMayhem... how can you get that motor from Tower at that price? Coupon? Must be. They are $149. With a coupon, they would be less, and really NOT worth rebuilding, unless all you needed was a resizing. That is the .18TZ P T which is "turbo". I'm not sure if they make a "non-Turbo" .18TZ. Or if Turbo is what you want for a Revo?

Thanks!

absolutemayhem

all 18tz are turbo, and yes the have coupons... i have not heard of con rod problems on the tz, im at 3 gallons and mines perfectly fine.....the front bearing is starting to leak ( not as bad as a 3.3) but these shoud be replaced every 4-5 gallons on every motor anyways.........yeah, not worth rebuilding... just buy new one..put on old carb, sell new carb for $50... i end up paying less then $90 for a new motor.

mebcop2000

Yeah Justin, I could have gotten the TZ-P for a lot cheaper, but then I would have had to buy a $100+ bumpstarter...... We'll be back to buy a motor for Melissa's shortly, but we're just trying to figure out which fricken one she wants.... 18tz, axial 28 spec 1s, Picco, hmmmmmmm

justin_92_92

My Feedback: (2)

well dayum, Getting those 3.3 the hell outa here huh LOL!

My 8.0 came in but I am waitting on taking it till the track is complete or almost complete anyways. If not I wont work on the track enough LOL.

mebcop2000

Let me know when you want some help over there.... seriously Justin

superman11

My Feedback: (1)

Is there any way to buy one with a slide carb and a pull start?

justin_92_92

My Feedback: (2)

The guy said he would be there this week to start the driveway and to flatten for the track. He said midweek. So mabey friday is mid week to him

I will give you a hollwer when he has it pretty well set and I can show you what I have in mind for the track layout. We could throw around ideas.

jpoprock

Hey guys! Got the OS yesterday. I didn't have a glow plug igniter, so I couldn't start it up. But I did take it somewhat apart to inspect it. To ME, it feels like it doesn't have ANY pinch when turning the flywheel. This is my curse. I don't think I'm EVER going to buy a use nitro motor ever again. But it looks like he's been running this engine on the truck, because it has the same sort of "track dirt" on the motor body, as it does the truck's chassis. So, maybe it does work. I can see the top of the piston, and it's somewhat "dark". But this motor comes apart a little differently than I'm used to. The way the glow plug attaches is different at least. I'm assuming I'd have to somehow pull the sleeve from the top, but that always makes me nervous. If it's hard to get out, my monkey wrench/pliers can scar it up, and that's not good. Do they make a tool that pulls those out cleanly? Or is there a better way?

If I need to rebuild this, I would probl need a connecting rod, piston, and sleeve only. It looks like the crank is good, as well as the bearings.

Also, this guy had been running it with a TRAXXAS carb. That might be ok, but the thing is, the traxxas carb doesn't fit all the way down in to the motor body! It stops with about 1/16th of an inch left! Now, I''m assuming it leaks, but maybe not. The carb sits very tightly in the hole. So can either seal it with KTV, or trim some of the bottom of the carb off so it sets all the way down in there. What would you do?

Thanks!

mebcop2000

To get the sleeve out I just put the piston at Bottom Dead Center (BDC), stick a plastic zip-tie in the exhaust port, and then spin the flywheel so that the piston hits the ziptie and pushes the sleeve up. Sometimes you gotta spin it kinda hard for it to work, but it has worked every time.....

jpoprock

Hey guys... Got the truck all ready to go, but this OS .18TZ will NOT start to save it's life! I have a fresh glow plug in it, new fuel line, and original carb. The bumpbox spins the fly wheel effortlessly, but the motor isn't drawing so much as a drop of fuel from the tank. I've tried several fresh plugs too.

I'm going to check the OWB, but the flywheel spins like mad, so I'm not sure that it's the OWB. It could be a fuel tank leak, but when I hold the truck upside down, nothing leaks out. The seal seems good. I checked to see if the carb had an air leak, and it doesn't. I forgot to check the tank for leaks before putting fuel in it, but I'm almost sure it doesn't have any. But I still need to verify.

I'm using the same type glow plug that was in the motor, which is the OS P6. This motor IS used, but I was told it had good compression still (and realize that it's buyer beware, and I've been burned on almost every used motor I've ever bought.. so no more for me!) But I'm not familiar w/ OS motors, so I'm not exactly sure how much pinch these should have, or how far the piston should go to the top. I couldn't figure out how to get the sleeve out, which is why I couldn't check it out.

The inside of the motor looked really good though. The previous owner was not the seller. He bought it off a local racer that needed the money badly, then sold it to me. Apparently, this truck was a winner at the local track, numerous times. But the seller really didn't have tons of info. I didn't really care though, because It's a Revo Platinum, and it's in 9/10 shape. And for what I paid for it, I could buy a new motor and still be plenty ahead! I just don't want to have to do that, if I can avoid it.

Any help would be appreciated!

absolutemayhem

even a worn out motor will still start,....is fuel coming out the exhaust ?

cummins driver

My Feedback: (31)

There is no one way bearing in use when you are bump starting an engine. If the flywheel is spinning like crazy, then the motor is spinning, and it sounds like you dont have much compression at all, if any. Did you prime it before you tried starting it? I like to prime mine until a little fuel gets into the carburetor. If the exhaust seal is bad, it wont push fuel to the carb by itself. Sounds like you may need a rebuild. I would just have the sleeve repinched for $20 and run it until it dies, and then buy a new one.

Eric

jpoprock

Yeah, my bad on the OWB. I'm so used to the EZ start system, that it just didn't dawn on me.

But I have this all figured out now! It seems that the motor block is cracked in HALF! I think it was probl damaged at one time, cuz it has a small section missing. I didn't notice when I got it. That's why it woudn't start. But that damage finally finished the job, and now the motor body is in two pieces! The nice thing is... I was able to get the sleeve out and check the pinch.. and it's really good it seems. LOL. When I pushed the crankshaft out, the inner bearing came with it (half of it), so that's toast too.

Now I'm faced with buying an OS .18TZ motor body and bearing and take a chance on putting the guts back in it, trading a dead 2.5R in for a TRX 3.3 for $115, or spending $135 on a .18 or spend TWICE as much on a .21 TM w/ Revo Manifold. Boy, tough choice there! I may get the .18, and keep these parts for back up. I have two dead 2.5R's, so maybe I'll use one of them and get a 3.3, then buy a .18. I'm just a backyard basher, but I like speed and power when I can get it. I just want to be realistic with my expectations/application, and price.

fabrimacator21

Where is it missing a chunk out of the block?

If the case is toast then I'd buy a block off ebay and throw it back together. If it starts then run it and if not, pull it apart and sell it.

If you end up buying a new motor look at the picco .26 red dot. More power for less money.

jpoprock

It had a small piece missing from the side of the block, it looks like. But now it's split completely in two. The piston head is sorta "pitted" and not "Smooth". I'm not sure what that indicates. But removing the piston and sleeve, then trying to push the piston thru the top... it won't do it. So, there seems to be pinch. This motor was used by a racer. So, it has probably been ran quite a bit, but well maintained. Hard to say. I could try the new motor body route I guess. I lost an inner bearing too though.

You can get the OS 18TZ from Tower for like $149, then less a rebate of $15-$25. So that is a great deal. I've heard the Picco Red Dot is great too, but it's like $210 before rebate... AND I think requires a big block conversion from New Era. OS .21 is like $300, and probl requires a big block conversion kit too. I'm not sure.

I do think I'm going to at least buy one TRX 3.3. For $115, why not?

I'm also thinking of ditching this bumpstart. It's a royal PITA for me. I can't be carrying that box all over the yard to restart my truck if it dies. Granted, if it's tuned good, it won't die usually. But if I run out of gas, or flip it 200yds from me, etc.. it will die before I get there. I'm thinking of trying a pull start, and if that is for the birds, I'll buy a Rotostart system.

nitro stan

the .21 tm is a direct drop in for traxxas trucks.
i would keep the bump box.roto starts dont fit in your pocket good. pull starts are for the birds, owb's go bad, springs break, or the cord breaks,they are good for teaching you to tune,get a lot of blisters in the process though

jpoprock

Well... for as many times as my truck wouldn't start... and I've basically left my EZStart wand on it, cranking, while I mess with the trigger and prime (I can eventually finesse it into starting again), the thought of pulling a cord a million times makes me cringe. But carting a bump box all over the neighborhood chasing my car that died for some reason, 200 yards away, stinks too! EZ start is really a good way to go. Esp with a 4600nimh battery and my own glow igniter.

It's weird though... I took the large flywheel off the OS and put it on my TRX 2.5R, and for some reason, the flywheel fit totally differently on the bumpbox. It was rubbing or something. Unless I'm mistaken, and put the wrong flywheel on it. I need to check huh? Because it shouldn't make a diff what motor it's on, as long as it's the large flywheel right?

absolutemayhem

WOW....... you drive 200 yards away!!!!!!!! most the time im within 50, if its a speed run 80

jpoprock

Well... maybe not 200, probl at most a 100, then I can't tell what's going on. And that's only when I'm doing speed runs! My Spectrum seems to have good range.