compunerd

I recently got a Savage X 4.6, broke it in as directed, tried to tune and so on. However, the engine always seems to creep into the 300+ degree range after ½ a tank or so of fuel! I’ve even taken the truck to my LHS and paid them $25 to tune it thinking I was just doing it wrong, but no, it still overheats.

I also read on here that the engine might not be sealed properly and so sealed the engine at the backplate, bottom of the carb, and around the HSN as directed to. This didn’t seem to really do anything to fix the problem…

It’s also not uncommon for the truck to kind of hiccup in performance. Sometimes kinda stuttering when driving around, especially under high throttle.

My one other idea is that I have bad fuel? But I don’t really know the signs of bad fuel, I just know that it apparently absorbs moisture pretty easily from reading posts here. I’m about ½ way through a 1 gallon jug right now (after going through a quart early on) and the problems kinda seem like they have been worse recently. Could moisture in the fuel cause problems like this? I’m using the HPI’s Power Fuel, 20%.

Any help on this will be greatly appreciated!!

Argess

It sounds like your truck is running too lean. That accounts for the heat. Sticking brakes and running in heavy grass will also cause overheating.

The hiccups, or stuttering may mean you are actually having detonation in your engine.

You should screw out the HSN a bit to richen it. Maybe 1/2 turn further out, and then back in a tiny bit at a time for good performance.....or maybe even further out, but it sounds like you're close to OK, so try teh 1/2 turn out for now.

Sometimes, the HSN is set too lean trying to get decent performance when the real problem lies with an LSN setting that is too rich. I find the LSN setting is usually between the factory flush setting and no more than 1 turn in from that. Too rich an LSN and too lean a HSN is a very common source of overheating.

Shenanigans

My Feedback: (12)

If your always creepin up in temps at 1/2 tank your HTL'n (half tank leanin).  Search half tank lean and about a hundred posts will come up talking about it......tune your engine at half a tank, you will run a little rich when its full, but thats better for your engine than running lean when it drop to half a tank.  There are many ways to reduce/cure HTL.

Argess

Yes, Shenanigans is right about the 1/2 tank leaning problem. When I read your post, I missed that part and thought your engine, once warmed up, just kept heating due to tuning.

Yes, there are lot sof ways to cure it. My favourite is here, but Search away and pick a solution you like:

http://www.rcuniverse.com/forum/m_74...tm.htm#7498522

Part of the above mod includes shortening the pressure line as much as possible. Just doing that can help quite a bit. Some other forum members have had success by shortening both pressure and fuel lines as much as possible, and that's free to try and hardly costs anything to undo, although I suspect it only works with some engine/pipe combinations. The linked one will work with any combo.

compunerd

Ok, I will tune at half tank and see if that fixes my problems temporarily, if so, I guess I'll be modding the fuel tank!

Thanks!

compunerd

So I went to try and tune at half tank and realized that even at factory settings the engine was running around 250 degrees once warmed up. This was with less than 1/4 of the tank of fuel used!

I even tried a new bottle of fuel that I opened today, so it doesn't seem like a bad fuel issue.

I didn't try and tune it at that point since it seemed to be running hot at factory settings, really trying not to burn this engine up.

Anymore ideas?

thechap76

My Feedback: (26)

what fuel are you using...i see back in the post you had said top fuel ? fuel makes a big difference...

bigdogkanicsar

half tank lean issue crops up from what i call a jacuzzi effect.
when the tank is full you won't notice it cuz the bubbles in the tank caused from vibration don't really go as far as the pick up in the tank.
however when you get to about a half a ank the bubbles from the jacuzzi effect are reaching the pick up in the tank putting air bubbles in you fuel line and causing a lean condition and/or lean jitters on deceleration and sometimes the hiccups on acceleration.

to keep this to a minimum you need to find a way to isolate the fuel tank by way of finding some kind of rubber grommets( rubber o-rings ) on the posts where the tank mounts to the frame.

i hope this helps

compunerd

The fuel I use is HPI Racing Power Fuel 20%.

thechap76

My Feedback: (26)

they make a tank relocation kit to move the tank to the front of the truck...but to be honest ive not had any luck with the kit...are you running the truck with the body off or on...a new engine has a very tight "pinch" which doesnt help the condition ur describing ...ive got 3 savages and all of them ran warm for the first 10 tanks or so...i just run em as rich as i could. and made sure the fuel lines were aas short as possible without kinking the lines causing another lean issue...also try not to burp the throttle or let it sit in 1 place at idle to longkeep it movin and run it with the body off...also try not to run it in tall grass it makes em work harder which just increases engine temps and try to tighten ur slipper up it too can help keep engine temps down....hope this helps ya

compunerd

A new symptom?

I went to use my truck today and it started right up immediately (never happened before!).

Unfortunately it seemed the idle was really high, the engine was obviously in the higher RPM's range and the wheels were spinning, so I tried to back the idle screw out to fix it. When I backed out the screw though I observed no change!

I killed the engine 2 times so I could set the idle lower while it was off and try again but every time I started it back up the idle was very high and so I just shut it off...

I should point out that it didn't overheat today (it wasn't going long enough), but I'm wondering if this was at all related to the other problems I've been having.

Shenanigans

My Feedback: (12)

If lowering the idle screw has no effect on the idle you need to check your linkage.  Make sure the carb is completely closing to the idle stop when in neutral.

thechap76

My Feedback: (26)

sounds like the clutch spring broke man....that would exsplain the overheating problem as well

compunerd

I haven't gotten a chance to take the engine out and look at the clutch springs yet, but could someone explain to me how that would make the engine idle faster, overheat, and the idle speed not change when I adjust the idle screw?

bigdogkanicsar

just out of curiousity, before you fired it up for the first time, did you check the needles and make sure they were at factory default?
i only ask cuz a lot of times they are not set exactly where they should due to manufacturers quality control not always being on top of things like they should.
another thing is to check the throttle/brake linkages and make sure they are set properly.
they could be hanging the throttle open while running causing the idle screw adjustments to be non-effective.

Argess

Since it started easily, idled high, and the idle stop screw has no effect, I suspect you bumped up the throttle trim on your transmitter.

bigdogkanicsar

yep, that's another thing, and the heat range worries me and makes me think that the low speed needle may have been a little off out of the box

compunerd

First of all, the throttle trim was definetly the cause of the engine starting right up and idling high. (I'm kinda frustrated with this thing and just jumped to the conclusion that that was somehow related to the overheating) However turning that back down didnt do anything to keep my engine temp somewhere reasonable when the fuel/air mixture was still obviously rich.

So I removed the clutch bell on the front of the engine and the clutch shoes look fine and the clutch springs appear to be fine as well.

I'm waiting to try any mods to the fuel tank until I can get to the half way point on the tank and not be over 250!

Anymore ideas would be very much appreciated! Thanks.

Anthoop

You keep talking about temperature being too high, you are obviously using some kind of temp gun...is it accurate?
In your first post you say the engine sort of stutters at open throttle which would seem it is rich, forget the temperature is it giving off smoke? Does the engine actual feel/smell hot?
Personally I would set LSN,HSN and throttle gap to recommendations, check correct plug, check head shims and use a decent fuel (Byrons or Odonnels for me) and go from there.

bigdogkanicsar

i agree
some fuels are kinda weak on consistancy.
and not all temp guns are super accurate

compunerd

I use the Duratrax Flashpoint infrared thermometer. It's set to 77E and appears to measure the temperature at the glow plug to within 1 degree of room temp when the truck is cool and indoors.

Other than that the engine heat sink definitely feels hot although above about 150F I can't really gauge temp very well with my hand!

1QwkSport2.5r

The rule of thumb that I go off of is don't base your tuning on temps alone. This will destroy your engine. Some engines do run hot even when set properly. If you're using a good quality fuel (I like fuels with some castor oil in them) and tune by the sound and smoke of the engine, it will be just fine. If you're getting a nice stream of smoke and the engine is cleaning out and winding up cleanly, then you're set right and just run it. I start at base settings and tune my high speed mixture first (Low- flush with slide shaft High - 4 turns out). Once the high speed is set, then move to the low speed mixture and idle speed. From base idle mixture, lean in 1/8th turn increments running to WOT between adjustments. As the low speed is leaned, the idle will increase. Lower your idle speed until the truck will idle smoothly and not creep forward. Keep leaning the idle mixture and idle speed until you attain a nice clean transition between idle and WOT. Once your idle mixture and idle speed are set, (this is how I run my engines) I run my High speed mixture 1/8th turn rich. All of this done at 1/2 tank. I only use temp as a reference. I use Byrons, Odonnell, or Trinity fuels 25% nitro and MC59 Plugs and in 99% of the time this works fine.

Most common (I know some of this has been repeated over and over, sorry..) is needle compensation. Rich low end and lean high end or vice versa. Always set the high speed mix first as when the engine is running at RPMs above idle, the idle circuit is "bypassed" and has no effect on high-rpm operation. If the engine loads up and is real rough and smoky, the low speed is too rich. If the engine stalls from idle to WOT, the idle is lean.

Idle RPM has an effect on idle mixture - too high of an idle speed will make the engine pull fuel from the high speed circuit.

Once the engine is running smooth and linear, check your temp. If the carburetor is set right, this temp is a ball-park reference point. Dont tune the engine to run at a specific temp.

an 80%/20% blend of castor/synthetic will make a world of difference on engine operation, longevity, and temperature.

One more thing - When you think the engine is overheating, spit on the glow plug. If it boils off immediately, it is bona-fide overheated. If it takes 4-6 seconds to dissipate, its fine. My SH .28 P6 Pro runs between 250-280*F and my Mach 427 runs 275-290*F on average. Also - nitro over 25% usually requires an extra head shim or a thicker single shim.