rooker

My Feedback: (1)

I have been trying ti tune my Tmaxx w/2.5 in it. It is giving me a fit!! It will run for a minute or so pretty good, then starts to loose power. Once it starts to loose power it is not long then it dies. I have to let it sit for a few minutes before it will start back. The last time I caught it before it died and the temp was 320. I have good smoke coming out of the pipe and have the HSN out almost 5 turns, factory setting is 4? It has to be an air leak????

rooker

My Feedback: (1)

If I take the EZ start off the motor is it going to fall all to pcs?

t-max97

My Feedback: (9)

No the ez-start will not fall apart, you have to take out three screws to open the ez-start. have you checked your low speed needle?

rooker

My Feedback: (1)

I have it flush with the ring.

DaveG55

If I remember right you bought this truck used, correct? If so then you need to cheeck the piston and sleeve for pinch. What you have sounds like the classic symptoms of a worn out engine. Take the piston and sleeve out and see how far you can push the piston into the sleeve. It should stop about 1/8" from the top. If it is even with the top or past the top of the sleeve then you have a worn out engine.
If so you can rebuild it or, a better option, replace it.

rooker

My Feedback: (1)

Yes you have a good memory, it is used. Lightly used however.
thanks, will look at it maybe tomorrow, I will let you know

Will a worn engine cause it to run hot as well? it was 320 last time I checked. I called Traxxas, tech said it sounded like air? Either way I am going to tear engine down. I never have looked inside one!! Gives me a good excuse.

RCnutz

worn piston and sleeve or major leak through front crank bearing. I'm willing to bet though that the whole engine is a beater.
When you buy used rc cars/truck always be very suspicious about "lightly used". These trucks can clean up to look like they're almost new and yet have several gallons of use.

Don't rebuild it! Just pay the 120 and get a new engine in trade for yours. Most hobby shops provide the exchange service for traxxas. Better yet you can try a different engine that isn't made of bee wax. Also the 2.5 cooling head is a major design flaw like with all air cooled traxxas engines. On a hot summer day it just doesn't have enough surface area to cool the engine. If you do go with a traxxas engine buy an American CNC cooling head. They go for under 20 on ebay. Don't bother with Nova Racing their cooling head is just more expensive and won't do anything extra for cooling.

Good Luck!

rooker

My Feedback: (1)

Took it apart today.  She is toast.

crispyspa

Was the picture uploader not working? I'm not seeing any pictures.

rooker

My Feedback: (1)

I did not try to post any pics.  Just took it apart and spun it over.  There is not even a glimpse of pinch.  No resistance at all at the top of cylinder stroke.

crispyspa

What?????? Why?????

xxxtsuperstud18

you gotta show the guys the carnage man. thats why your on rcu

rooker

My Feedback: (1)

I will get some pics, trying to find my cable for the camera to computer.  It doesn't look bad, just no pinch what so ever.

rooker

My Feedback: (1)

What do you see???

crispyspa

AHHHHHHHHHHH!!!!!!!! focus man...focus!

DaveG55

Very blury but it does look awfully close to the top. I have seen worse though. Heck, I've got a very expensive outboard boat engine that the piston actually sticks about 1/16" out the top. Haven't rebuilt it yet, and don't know if I will, because the piston and sleeve cost about $130 last time I checked.

rooker

My Feedback: (1)

If I upgrade to the 3.3, will I need to beef up the drive train or will it handle the 3.3?

Mr Max Wheelie

IMO if ur gonna do an engine upgrade go with something other then the 3.3......i had no luck with them at all.....i found them very finicky  and i spent countless tanks of fuel on just tuning everyday.....if it had of been just one 3.3 i would say i had a bad one but ive had 2 that i blew up and 1 that i still have and im having the same problems with.......now one mite say ''problems with 3 engines maybe you just dont know what ur doing''......i thought that too until i bought the picco which runs great consistently with very little time wasted from day to day on tuning.......3.3 trx $140.......4.27 picco $200.....either way you go i would say yes you will need to upgrade ur drive train to at least tmaxx 4909 specs.........remember guys b4 you jump on me this is just MY OPINION!!!.........good luck with whatever you choose dude!

DaveG55

About doing upgrades to the drive train, My personal opinion is don't do anything until stuff starts to break. Once things start to break is plenty of time to upgrade. I cannot see dumping a butt load of cash into the drive train because stuff might break. But that's just me and I'm a big fan of "if it ain't broke, don't fix it" so you can take that for what it's worth.

I've never owned a 3.3 but my 2.5's have all been great little engines. IMHO the best all around engine for the Maxx was the OS .18TM but since it's not made anymore my next engine will probably be the Picco.

rooker

My Feedback: (1)

Drove 50 miles to HS, so I want call it a LHS, just HS.  Owner recommended a 2.5 to put back in the truck.  Will be here next week.

RCnutz

Just my 2 cents. The problem with the tuning on the 3.3 and 2.5 is the cooling head. Get an ACNCM cooling head or nova racing and replace the stock. It will do wonders!
Also on the 3.3 the con rod can be upgraded before break in to the Davis Diesel one and it seems to work pretty well. I don't expect my engine to blow prematurely due to the con rod.
3.3 is great if you change cooling head.

Just a note: If you put a 3.3 in a 2.5 it will twist the heck out of the drive shafts. Diffs will hold up because they are the same material and design. The other thing that will suffer is twist in the chasis since the 2.5 plate is a bit thinner I think. I did that years ago on one of my Tmaxxes and the chasis kept flexing and stripping my spurgear

Snook Man

JMO...While the 2.5 cast silver cooling head lacks in cooling perfomance, the 2.5R and 3.3 cooling heads cool just fine.
There would be no differance in the tuning of the engine with either the stock, nova or acncm heads cooling heads.
The only differance would be the cooling efficiency. If you cant keep the temps within operating range with the stock head, you need to tune up your tuning/troubleshooting skills.

rooker

My Feedback: (1)

The engine I am getting is the 2.5R, it should cool better?  Hopefully  can tune it with no issues.  If I can tune an Acme, to be sure, I can tune a good carb!!