Help Identifying Engine and Run-Away Issue

[TimmyB1183]

Hey everyone, first post here and I can't find what I was looking for specifically via search. Sorry if you all know of the info elsewhere. I got this truck from a guy I work with who's not mechanical in the slightest and was very overwhelmed.

I did get it to fire yesterday, but it immediately took off, even with the TH Trim on my FlySky GT5 set to full brake.. I pulled the fuel line to shut it down.

1. What engine is this? I see HPI and 3.5 stamped into the side of the bottom end, but all the "3.5" I search for parts for show a black heat sink not the annodized purple. I'd like to get a different exhaust, a new air filter insert, and some new return springs etc, but want to make sure I get the right stuff. I've ran into getting the wrong things too many times on my 56 Chevy not knowing the backround on that Frankenstein either and it's a headache I'd like to avoid here lol

2. Seeing the throttle open that much with no power on, I'm assuming is the reason for the runaway.. what's the spec for a baseline idle? Something like 1mm or 2 open? I'm assuming that I should close it all the way and gently crack incrementally with the throttle linkage disconnected from the servo just to get it going, then hook it all up.. It also looks to me like the brake isn't properly configured. The brake rod has a lot of slack between that rubber stopper and the threaded end.

Thanks in advance for any help you can provide.
I can't wait to get this thing going.
Tim

 

[guinnessdublin]

Yes idle open far to much, start with 1mm open can use a paper clip for rough gap opening!
Bin current air filter & get 2- stage version, replace fuel line & get HPI metal version exhaust!
Have agood read through manual to familiarise yourself of how savage goes together!

https://www.hpiracing.com/assets/manuals/pdf/882.pdf

https://wheelspinmodels.co.uk/i/1163/

https://wheelspinmodels.co.uk/i/1045/

 

[Jam 1]

I dry set all the throttle settings and Brake settings with everything hooked up and powered on, 1mm gap for idle gets you close, I recommend reading thru all the Nitro Engine threads there is alot of great info there...

https://www.hpisavageforum.com/threads/nitro-engine-factory-settings.11154/

https://www.hpisavageforum.com/threads/list-of-useful-nitro-engine-threads.13941/

As always use a new barrel type air filter, the one you have is not good at all... Motor saver and others still offer good airfilter setups...
Any other questions you can always just update your thread and someone will usually respond shortly....

 

[xtremsavage]

The info previously stated is great advice. But, to answer your question about the motor, it's looks to be the F4.6 stock motor. I could be wrong though. But, it also looks like a non-X version savage also judging by the trans box, so it may be a an older savage 25 too.

 

[TimmyB1183]

I dry set all the throttle settings and Brake settings with everything hooked up and powered on, 1mm gap for idle gets you close, I recommend reading thru all the Nitro Engine threads there is alot of great info there...

https://www.hpisavageforum.com/threads/nitro-engine-factory-settings.11154/

https://www.hpisavageforum.com/threads/list-of-useful-nitro-engine-threads.13941/

As always use a new barrel type air filter, the one you have is not good at all... Motor saver and others still offer good airfilter setups...
Any other questions you can always just update your thread and someone will usually respond shortly....

Yea as soon as I touched that filter element I knew it was junk and removed it all together, I didn’t want any disintegrated filter getting in the carb. I’ll order an intake and a new exhaust today most likely, thanks for the Motor Saver heads up.

XTremSavage - Thanks for the tips, so it could be a F4.6 even though it’s got a 3.5 stamped into it? Haha shits confusing!

EDIT: Looking for an exhaust, I see some exhausts for Savage X, I’m assuming that’s what the base model is even though it doesn’t show an X? Sorry for all the n00b questions here

 

[xtremsavage]

Yes, if the TVPs have an "X" design in them(most likely grey in color), then it's the "newest" model savage. If they are silver without an X design, then it's the older version.

 

[guinnessdublin]

Suspect original design going by photo?

 

[TimmyB1183]

Yes, if the TVPs have an "X" design in them(most likely grey in color), then it's the "newest" model savage. If they are silver without an X design, then it's the older version.

So I’m not seeing X’s in the chassis plates. Older version it appears to be. The only X’s I see are in the shock towers.. Almost there to knowing what I’ve got here haha, still confused on the purple heat sink 3.5 when all the 3.5hpi power plants I see online have a black heat sink.. intake is ordered, looking for an exhaust now to replace the plastic one. Figures too, the guy I got the truck from just quit, so I can’t even get any info out of him next time I’m at the office..

EDIT: Just now saw the .25 on the side of the block. So at least we’re narrowed down to the Nitro Star 4.1 Idk what the hell the 3.5 is on the lower part.

 

[xtremsavage]

Judging by those last pics, it definitely looks like the older Savage 25. If you can, post another pic looking down between the bumper (front or rear) & the duff housing/ shock tower.

 

[TimmyB1183]

Judging by those last pics, it definitely looks like the older Savage 25. If you can, post another pic looking down between the bumper (front or rear) & the duff housing/ shock tower.

How are these?

 

[xtremsavage]

Just what I needed to see. Did even have to zoom in or anything. As soon as I seen the cross brace, I knew is was the older original Savage. And more than likely the motor is a original that came in the Savage 25. And the 3.5 stamped in the side has something to do with the motor size, displacement wise.

 

[TimmyB1183]

Just what I needed to see. Did even have to zoom in or anything. As soon as I seen the cross brace, I knew is was the older original Savage. And more than likely the motor is an original that came in the Savage 25. And the 3.5 stamped in the side has something to do with the motor size, displacement wise.

Xtrem thanks for the info! I wonder if the 3.5 has to do with the block and then depending on the head used determine if it ends up a 4.1/4.6 etc

 

[Jam 1]

Xtrem thanks for the info! I wonder if the 3.5 has to do with the block and then depending on the head used determine if it ends up a 4.1/4.6 etc

The 3.5 block is a big block. the crank, sleeve and piston assembly determines the actual displacement, timing, and carburetor sizing , etc, to make it run

 

[xtremsavage]

Xtrem thanks for the info! I wonder if the 3.5 has to do with the block and then depending on the head used determine if it ends up a 4.1/4.6 etc

The "3.5" stamped on the block has something to do with 1 of the specs if the motor. I can't remember which one though. As far as the model/version you have, when it comes time, try to find some "parts" trucks on ebay or someplace like that and start replacing the front & rear differentials & transmission case to the newer X style. They are easy access for maintenance. The type you have, you practically have to disassemble the entire truck to maintenance the diffs & trans.

 

[TimmyB1183]

Hello all, glad to report I got the runaway issue fixed, got the needles almost all the way dialed in, the car has a big fart at 100% remote throttle that I have to figure out. It absolutely hammers at about 80% throttle and hit the 2speed fine.. problem now is, I smashed my trash can with it lol.. snapped the battery box mount and chassis joint bars off. Bent the poop out of the aluminum side rails.. hopefully I can find parts to rebuild!!

Edit: Does anyone know if the aluminum chassis plates for the XL or flux swap to the older Savage 25?






Edit

 

[Jam 1]

short answer to your question is NO, the XL and Flux xl are different in WB and how the parts fit, if it was mine I would strip it completely down, get the required parts to fix it and hammer the plates back as flat as you can, you can get Savage X parts and convert it to those specs if you want, it will require a few parts but it is doable and pretty easy to accomplish.

One last thing is Stay away from solid objects they like to jump in front of speeding RC's and break them....

a few years back I did something similar to my XTM Monster MT with a concrete light pole, sadly the pole won but I was able to fix it with my parts stash...

 

[TimmyB1183]

Damn! Yea I was busy jumping out of the way of the truck, as I’m still not used to how twitchy it is steering wise since I’ve been battling the runaway issue. I’ve only gotten to drive this thing maybe 2-3x and for 10 min or so each. So as I hopped out of the way to save my ankles, as it went past me, it went right into the trash can before I could turn around and see where it was going lol.. sounds like a plan, I’ll see what I can find for the old style or I’ll just swap stuff to the X model. What all would be required for an X swap? More than just the side plates?

 

[Jam 1]

Bulkheads, radio box, maybe a few others. my Savage is an X I got from a guy here, it came minus a few parts, but I sourced what I needed a few years back and built it up. that is half the fun for me is fixing up old RC's and adding them to my collection of toys, I bet I have almost a hundred cars, trucks, and assorted things, it is an addiction....

 

[TimmyB1183]

I’m getting the RC bug myself, I’ve always been into things with engines period, but now that the 56 is away for the winter it’s time for other toys. I been looking at Traxxas TRX4Ms lately too for some fun indoors or outdoors.

Overall, it doesn’t look as bad as I thought. Need to put the frame in my vise to straighten the rails out, but I was expecting much worse. Definitely need a radio box since the steering posts snapped the plastic off the bottom, I lost the front driveshaft outside somewhere and the bulkhead mounts broke off. Putting together a cart now. What do you all recommend for shock upgrades/steering upgrades, may as well while it’s in a few pieces.

Also, any idea what would generally go in that small tabbed bracket next to the transfer case? I can’t find an exploded view diagram of these things anywhere, so those exist?