Engine Running Really Hot

[aznitro]

Hi All,

I got a new LRP Z.28R Spec 3 in a HPI savage, and just put in a new 3 speed tranny, but it's now running really hot. I also put on a K&N style air filter. I'm thinking that the air filter and the 3 speed tranny are making it run really lean, but not sure. I don't want to try and compensate for too much air by making it richer, but maybe I should...

I was hoping maybe someone with good experience or perhaps the same setup might have some input as to how to get the temp down.

Any info would be greatly appreciated.

Thank you.

 

[aznitro]

I just tried some tests...

From cold, I ran it for a specific distance with the K&N style air filter and got the temp.
230 - 260

Let it cool down and then put the stock hpi air filter on and ran the same distance and the temp was the same. So that pretty much ruled out the K&N air filter.

After letting it cool down, I started it back up and just let it idle for a bit to see if it would heat up high and it didn't.

Then I tried richening the HSN and ran it for just a little and took the temp and it came down a bit, but not much. I tried richening the HSN like an 1/8 turn and the same for the LSN and I'm still stuck in the 230-250 range.

Is there anything else I should try?

Thank you

 

[ohmygahitscoby]

Take off the K&N filter. That thing wasn't designed to filter out small dust and debris. Get a Motor Savers Air Filter. I thought that 230 was ideal, but I'm not certain. If you have a nice stream of smoke coming from your exhaust, your tune is perfect.

 

[Cupooterluvr]

Take off the K&N filter. That thing wasn't designed to filter out small dust and debris. Get a Motor Savers Air Filter. I thought that 230 was ideal, but I'm not certain. If you have a nice stream of smoke coming from your exhaust, your tune is perfect.

+1. Those K&N filters may work on your 1:1 car but on a nitro they will let so much dust and dirt in that your engine will be useless in less than a tank.

230-260 is an ideal running temp.

 

[aznitro]

Thanks for the feedback guys...

I did take that K&N filter off and put the hpi one on. I'm starting to get frustrated with these temps though... it doesn't seem right. When too hot, it has a distinct smell. barely running it for 1 min and it's hitting 240+ temp. It's so frustrating having to spend more time troubleshooting than actually running it. Even the tuned pipe is hitting 230 all the way down and it never got that hot before, that I recall. Do any of you think that the 3 speed tranny may be causing the engine to reach max rpm?

 

[ohmygahitscoby]

Just out of curiosity, did you check your engine for air leaks? If you haven't already, you should seal it.

With the 3-speed tranny, it should shift (if you're on first gear) into second gear before it reaches max RPM, and same going from 2nd to 3rd.

 

[samrsnow]

What tank do you have? Stock one i'm guessing? Junk it if so and get one of these http://www.neweramodels.com/item.cgi?session_id=wtpmmjvsgduxlxkyqmgvjbqjmicbxjtp&part_id=1704 and then make the pressure line long. And if you have a fuel filter put if on the pressure line.

That's what i did on my truck and my engine runs cool all day. (210 to 230 range)


EDIT: Check for air leaks also.

 

[olds97_lss]

My LRP runs around 230F all day long in my aftershock. Just mostly finished break-in of my second LRP in my savage with a 3-speed.

What fuel tank are you running? Have you checked the tank and hoses for leaks?

What pipe are you running? I've noticed my LRP's like a pipe that is quite a bit more restrictive than the HPI polished or HPI ribbed pipe. The Losi LST HT pipe works really nicely with it on my aftershock. Need to scrounge for another on ebay for the savage.

What fuel are you running?

What glow plug?

What gearing (CB/spur)?

Do your gears shift in a positive fashion that you can distinctly hear it shift? If not, it's either not shifting and wrapping out why too high too often, your slipper is slipping, your OWB's in the trans are slipping, your clutch shoes are slipping or your flywheel is slipping on the crankshaft.

Sorry for all the questions. I can tell your frustrated and more info for us is better to help you figure out your problem.

With mine, I'm running the LRP28S3 with an MGT tank, byrons 25% fuel, OS#8 plug, 49/16 gearing, 3-speed trans, HPI Savage teflon 3-shoe clutch. I have the slipper tightened down all the way and it still slips a lot when it shifts into second and even more when it shifts into 3rd. Once it starts slipping, it heats up the slipper and then slips a lot more. I didn't have this problem when I had an XTM24.7 in it. The LRP just has a lot more power, which is good, but can be troublesome as I've found out.

 

[aznitro]

Thanks all for your input.

I just checked for leaks and what I found was this...

Took hoses off of pipe and carb and covered one hose and tried to blow through the other hose and was solid seal from end to end.

Took the tuned pipe off and covered header hole and pressure nipple and blew through the exhaust out on bottom and was solid with no leaks.

Then i hooked up a hose to the carb nipple and covered the air intake hole and blew through the hose, and I'm able to blow a small amount of air through the carb. However, I am still trying to find out where the air is going, and if thats normal or not. Is it normal? or should I not be able to blow air through it with the intake hole covered?

Also covered air intake hole and left all hoses hooked up and slowly pulled on the pullstart to feel how it turns the engine. There seems to be a small escape of pressure if I pull slow and stop as it's getting tighter on it's rotation and I can feel and hear the pressure escaping very slow. Sounds like it's comming from behind at the pullstart.. is that normal?

So this is what I've been able to determine with my short nitro rc experience.

Are there better ways to check for leaks? What and how is checked? What should allow small parts of pressure to flow through, and what shouldnt? These are the answers I don't think I know.

Any info appreciated.

Thank you

 

[ohmygahitscoby]

The small air you're blowing may be going out the exhaust port.


To check for air leaks, get some soapy water and put it over the carb hole, the inlets, the backplate, and anywhere else a leak can happen. If you blow through the fuel line and you see that a spot is bubbling, there's your leak.

I'd recommend sealing your whole engine though. Doing a break down of the engine and cleaning everything is good, then when you put it back together start sealing her up. There are engine sealing videos online.

 

[aznitro]

Thanks olds97_lss and samrsnow.

I'm not sure what tank it is. It was on the truck when I bought it from the previous owner.

Olds... I don't mind the questions at all... I appreciate you taking the time to help. So here goes...

Clutch bell: 17T
Spur: 49T
Plug: O.S. A5 (sold to me by guy at hobby bench today)
Fuel: Monster trinity r/c fule (20% nitro 12% oil)
Tranny: savage 3 speed preassembled 1 day old
Engine: LRP Z.28R spec 3 1 week old (1/4 - 1/3 fuel left in first gallon)

Here's some pics from phone, just took them in the work shop so not so great...
http://www.myspacewrench.com/sharing/html/Chris/4286/NitroRC/


Thanks again everyone for your help!

ohmygahitscoby - I did plug both the air intake hole and exhaust hole while blowing in tube.

I'll try the soapy stuff. So I should not be able to blow through though? At all?

 

[ohmygahitscoby]

No you shouldn't. It may be really hard to distinguish if you're blowing through a small air leak though.

 

[olds97_lss]

Plug: O.S. A5 (sold to me by guy at hobby bench today)
Fuel: Monster trinity r/c fule (20% nitro 12% oil)

Personally, I'd take the plug back and get an OS #8. The A5 is one of OS's coldest plugs which is usually ran with 30%+ nitro content and extra shims in the head.

The OS #8 is a medium/hot plug that has worked pretty good in my other and in my current LRP so far. I'm going to try a McCoy MC8 though once I finish break-in. It's a little cooler than the OS#8 and did wonders for the XTM24.7 I took out of my savage.

Running a plug as cool as the A5 causes you to lean it more to get it to run right on lower nitro fuel. This in turn kicks the crap out of power and raises temps quickly.

The temp of a glow plug combined with the percent of nitro is a way to control the combustion timing. If you run a hot plug on high nitro (OS #3 with 25% or higher) it will ignite too early in the stroke while the piston is coming up. This will cause pitting on the top of the piston and head button, high temps and low power since the engine will be fighting itself just to run.

The symptoms are similar when you run too cool of a plug for the fuel your burning, your scenario. Except it's the exact opposite. The ignition of the fuel/air mix in the chamber is happening while the piston is already on the down stroke. So you get the bang, but a lot of it is lost out the exhaust and not in the force to push the piston down. Plus, your running it leaner than you should due to the fuel not burning well since it's not at it's peak compression and the plug is too cool to keep it burning right.

Higher nitro fuel ignites easier and causes a bigger boom. That requires a cooler plug like the A5. Adding head shims lowers the compression a bit, but that is more than made up for by the extra nitro. Too high of compression with high nitro also causes early combustion regardless of plug temp.


If the A5 is what your running and 20% fuel is what your running, that could be your main source if problems. I noticed in my manual that LRP suggests 25% fuel as well. I've ran that in my other one most of it's life with a few tanks of 20%. That extra 5% makes this engine a whole different animal. Granted, the 20% wasn't bad, but the 25% let it idle smoother and transition through the RPM's more cleanly. Now I only run 25% regardless of my engine or vehicle.

 

[aznitro]

Thanks olds, I'll try changing the plug and get different fuel. I think there's also a leak at the base of the carb. What do you recommend for the fuel brand and to seal the carb/engine?

Again... thanks a million olds we really appreciate your input.

 

[olds97_lss]

I run byrons fuel and really like it. My LHS doesn't carry byrons 25%, so I buy 20%/12% oil and 30%/11% oil and mix them 50/50 in gallon jugs.

To seal the carb, you just need to take the carb off, clean it and the crank case hole really well with DA. Then get some [ame=http://www.amazon.com/Permatex-81878-Sensor-Ultra-Copper/dp/B0002UEOPA]permatex high temp sensor safe RTV[/ame] and put a bead of it around the carb neck base (where the neck meets the carb body), then put it back in the crank case, push down on it hard while tightening the cinch bolt.

 

[aznitro]

I took the carb off and noticed that the cinch bolt cramped the o-ring and the leak is not at the base of the carb like i thought, but rather on both sides of the cinch bolt things. I went and got that permatex stuff and pulled the backplate off and put a light bead all the way around nice and neat and sealed it nice and tight. I also put that sealant around the cinch bolt holes and on the carb base. Now letting it cure... if it still leaks... I'm going to go mad... The cinch bolt pieces are a poor design.

And FYI.... anyone buying one of these engines... make sure all your screws are tight! Forget what your LHS guy says "it's new... no need to seal or nothing just put right in"...
I found that one screw was lost off of the pullstart, and all 4 screws on the backplate under the pullstart were somewhat loose, all 4 cooling head screws were also somewhat loose. I had to check everything... don't rely on factory BS.

My opinion of this lrp so far... is not good at all. GOODLUCK GETTING PARTS! like say... an o-ring... I got some from 3 places.. and none fit. Same for screws...

Whats worse, I beleive there is still a leak somewhere, just dont want to put to much pressure blowing in it until the sealant cures.

Thanks again olds for your help.

I wish this thing would just let us drive it already... had it 3 weeks... and in that time 90% (not exhaggerating) of the time was spent working on this, buying that, getting ripped off here, can't find the part there.... my son and I are so frustrated... I'm like $600 into this truck and can't drive it... this sucks.

 

[olds97_lss]

Wow, sorry to hear the bad luck.

Once you get it running... don't worry much. You will be all smiles with the power and consistency you get. I know I am with my first one and the second is shaping up to be just like it.

I've had my first one for almost 2 years now. Haven't had a need for parts, but then again, I've probably only ran 5 gallons or so through it. Since it's on my "shelf queen"... well, as close as I'll ever get to a shelf queen. Although... my savage is now turning into one as well.

I'm not like rolex though, I run my queens hard.

 

[Scrogg]

Dynamite platinum series O-rings will fit your carb.

 

[olds97_lss]

Any other cross brand parts that fit the LRP?

 

[Scrogg]

MC-59 is the correct plug for this engine. It may take up to 1 and 3/4's of a gallon of fuel for the engine's pinch to totally relax. Once this happens it will run cooler, make more power and stop detonating from the excess compression.
That was my experience with the LRP. also the LSN being too rich will actually make this engine sound really lean. Get a decent top speed out of it with the HSN, then start leaning the LSN until it sounds clear after you let off the gas. Then lower your idle speed. Mine fooled me with this condition. i kept richening the LSN and it kept sounding leaner. My buddy bought a LRP at the same time as me and showed me the error of my ways. He leaned the LSN quite a good bit it and started running smooth, clean and cool. This engine needed very little adjustment to the HSN until it had well over a gallon on it.
He used O'Donnell's 30% Race Blend, I used Trinity MHP 30%. Both ran well on these fuels.