Trouble starting, glow plug dies fast, always needs tuning (help me before I sell it!)

[jgorm]

Hey Guys,
I've been screwing with my savage after about 5 years in the shed when the starter pin broke for the 2nd time. Just when I think everything is running perfect, it will act up on the next tank. Then it will bog under heavy accelerating and I have to adjust the carb. My biggest problem is starting the damn thing. Sometimes it works fine, then sometimes it is a 1hr waste of time. It always takes me about 10 minutes to get it running. It was running fine and I was doing some fine tuning, then I filled it up from a half tank to a full tank and then spent 30 minutes trying to start it before I gave up.

I'm using a d battery glow plug starter and I notice that it seems to kill the battery really fast. If I have the glow plug hooked up for more than about 10 minutes it seems like its not working well and the voltage goes from about 1.6 to 1.4 (on vom, not the crappy gauge) and when I remove the plug it looks like its not glowing enough. The top coil hardly ever turns red when I have the plug removed and in the igniter . I rigged up some pipe so I could stuff 2 D batteries in there and it starts WAY better, but I kept screwing with it to get a good connection. Sometimes I have to use a torch or heat gun on the heatsink to get it to start. My next plan is to get a 4 D battery holder and run 2 in series, 2 in parallel, with a harbor freight VOM attached to monitor the voltage and a remote attachment for the glow plug with a switch to turn it on.

I'm not new to tuning, just new to nitro. I tune mustangs on my dyno as a side job and would say that I could tune 5 supercharged mustangs in the time i've spent messing with this truck to get it running correctly.

I have some questions that hopefully you experts can help me out with before I sell this POS and buy a brushless truck that will actually work when I want it to.

1. How long does it typically take for you to start your truck?
2. How many minutes would you estimate that a 1 D battery glow plug should last while its hooked up?
3. Are there better glow plugs that run hotter?
4. Is it typical to have to mess with the tune every time you drive it?
5. what percent of the time to you spend starting and tuning, vs driving and bashing?

My nitro fuel is less than a month old.
The engine has about 5 tanks of fuel run through it and the compression feels strong.
I use the electric starter with a fresh battery or my dewalt drill if it dies (the starter spins it way faster than the drill)
Once its warmed up and running it idles and starts back up just fine, but if I wait a while it gives me crap.

 

[olds97_lss]

Is the engine 5 years old? Have you replaced the engine or anything in the engine?

O-rings dry out and shrink over time. Especially when not used. This alone would cause a myriad of tuning problems. Air leaks, tune creep, clogs from deteriorating o-ring bits...

Also, what's your ambient temp? Much below 45F and tuning can be a pain regardless what you do usually.

 

[jgorm]

yeah, the engine is at least 5 years old. I dont remember when I bought it. Its a S-25 with the 4.1cc. I have not done anything to the engine. It was running great a couple weeks ago. I'm in san diego so its never below 50F when I'm driving, it's 56F and dark now. If some of you don't mind answereing these questions, it would help me decide if I should give up on nitro and get a electric truck.

1. How long does it typically take for you to start your truck?
2. How many minutes would you estimate that a 1 D battery glow plug should last while its hooked up?
3. Are there better glow plugs that run hotter?
4. Is it typical to have to mess with the tune every time you drive it?
5. what percent of the time to you spend starting and tuning, vs driving and bashing?

 

[srusinek]

I myself run a lipo warmer which is way better than my sub c ignitor. If the warmer is charged and I prime it properly, it takes about maybe 5 minutes to start it. I do have to let it warm up a little bit and its all good. I'd say a d cell warmer would not last more than an outing in my opinion. I run the r5 plug in my xl which is the stock plug. My engine usually keeps a tune unless I change fuel or have a drastic change in temps from my last outing. I don't spend a lot of time tuning since my engine does hold a tune. One thing you might try is sealing your engine with rtv sealant and associated green slime for the o rings on the needles. I will admit nitro is not for everyone but for me its more satisfying to hear that engine go over 20k rpms.

 

[2revo1maxx]

I would order a whole new o-ring set for it, then install them with green slime or dielectric grease. Set the carb back to factory settings and try running it with some new fuel lines and a new plug. I would also check the fuel tank for any leaks as well as the exhaust. I use a AA ignitor for mine and the battery will last for at least 10-15 start-ups, if not more.

 

[hulkmaxx]

+1 on what 2revo said. I would bet its an airleak. Don't give up on the nitro just yet. Those 4.1 engines are a really great engine. Once you get it sorted thet usually hold a good tune if they are broken in properly. It should not take no more than a few min to get the truck started. And I would ditch the glow plug warmer you have, and get a good rechargable one. i recommend the hotshot igniter. And you should not be burning up glow plugs that QUICK either.

---------- Post added at 12:31 PM ---------- Previous post was at 12:22 PM ----------

Hey Guys,
I've been screwing with my savage after about 5 years in the shed when the starter pin broke for the 2nd time. Just when I think everything is running perfect, it will act up on the next tank. Then it will bog under heavy accelerating and I have to adjust the carb. My biggest problem is starting the damn thing. Sometimes it works fine, then sometimes it is a 1hr waste of time. It always takes me about 10 minutes to get it running. It was running fine and I was doing some fine tuning, then I filled it up from a half tank to a full tank and then spent 30 minutes trying to start it before I gave up.

I'm using a d battery glow plug starter and I notice that it seems to kill the battery really fast. If I have the glow plug hooked up for more than about 10 minutes it seems like its not working well and the voltage goes from about 1.6 to 1.4 (on vom, not the crappy gauge) and when I remove the plug it looks like its not glowing enough. The top coil hardly ever turns red when I have the plug removed and in the igniter . I rigged up some pipe so I could stuff 2 D batteries in there and it starts WAY better, but I kept screwing with it to get a good connection. Sometimes I have to use a torch or heat gun on the heatsink to get it to start. My next plan is to get a 4 D battery holder and run 2 in series, 2 in parallel, with a harbor freight VOM attached to monitor the voltage and a remote attachment for the glow plug with a switch to turn it on.

I'm not new to tuning, just new to nitro. I tune mustangs on my dyno as a side job and would say that I could tune 5 supercharged mustangs in the time i've spent messing with this truck to get it running correctly.

I have some questions that hopefully you experts can help me out with before I sell this POS and buy a brushless truck that will actually work when I want it to.

1. How long does it typically take for you to start your truck?
2. How many minutes would you estimate that a 1 D battery glow plug should last while its hooked up?
3. Are there better glow plugs that run hotter?
4. Is it typical to have to mess with the tune every time you drive it?
5. what percent of the time to you spend starting and tuning, vs driving and bashing?

My nitro fuel is less than a month old.
The engine has about 5 tanks of fuel run through it and the compression feels strong.
I use the electric starter with a fresh battery or my dewalt drill if it dies (the starter spins it way faster than the drill)
Once its warmed up and running it idles and starts back up just fine, but if I wait a while it gives me crap.

1. It should take no more than a few min to get truck started.
2. Those battery powered igniters don't last long I keep one as a back up thats it. but you should get at least 10 to 15 starts on it. They dont glow as hot as a rechargerable one though.
3. Yes there are several diff types of glow plugs i run medium to hot in my trucks that is what works in the area where I live.
4. Once its broken in properly and you get a good tune you should not have to tune it every time but temps and weather may require some tuning every once in a while. Those 4.1 hpi ebgine generally if broken in propeerly hold a good tune. My savage x truck has neVer been retuned since the time I broke it in and tuned it for performance like 2 rears ago. I used Hpi recommend break in to the T.
5. I bash more than I tune. ALSO spend more time replacing broken parts on my rigs because I like to see how high my rigs can fly


HOPE THIS HELPS

 

[lesclaypool]

1. How long does it typically take for you to start your truck?
2. How many minutes would you estimate that a 1 D battery glow plug should last while its hooked up?
3. Are there better glow plugs that run hotter?
4. Is it typical to have to mess with the tune every time you drive it?
5. what percent of the time to you spend starting and tuning, vs driving and bashing?

1. When it's cold 5-6 pulls, when it's warm 2-3 pulls
2. Should last a whole day of bashing easily
3. Plugs come in different temp ranges from cold to hot, but any 'properly' working glow plug should at least get it running
4. You'll need to mess with tune every time you drive it, unless ambient temps, humidity, elevation, fuel, trucks mechanical condition(bearings etc), and running conditions, and throttle finger all stay identical...so in other words, yes you're going to have to mess with tuning every time you run
5. 5 minutes to warm it up, go over everything, and start it - hours and hours of bashing.

I'm just laying it out there honestly. I would listen to the other recommendations made so far, and throw a new plug in as well. Pre-heating the engine with a hair dryer will really ease the starting. Also - be sure to pull the pressure line off the pipe and blow into it until fuel reaches the carb(to prime before starting). Then put that ignitor on, and fire it up. You may need to 'feather/blip' the throttle while starting, or open your idle gap up via your trim, but once it's running set it back to neutral.

 

[2revo1maxx]

Also remember this: A well tuned engine should seem a little sluggish and rich until it reaches operating temperature.

 

[bgbdwlf2500]

It definitely sounds like an air leak. Also ditch that d cell ignitor for a rechargeable one they suck and tend to not get hot enough. Also, don't run traxxas top fuel. Some say it works fine I've never gotten a truckto run on it

 

[jgorm]

Thanks guys, I'm going to at least put in one serious attempt to get it working all the time. I had some motivation last night while drinking beer in the garage. I modified (destroyed for regular use) my D battery glow plug igniter to use the top part as my remote attachment to the glow plug. I mounted a switch on my roto start to turn the plug on and off. I ordered this off of ebay http://www.ebay.com/itm/DC-DC-POWER-CONVERTER-VOLTAGE-ADJUSTABLE-1-2V-18V-/261045837080 to be able to convert the 7.2v to 2 or 3 volts (for a extra hot plug). I'm going to hard wire a harbor freight vom to the frankenstein mix to be able to switch between the main pack voltage, the voltage to the plug, and the resistance of the plug if needed. This way I'll have one 'tool' and a easy and quick way to troubleshoot all aspects of it and with 2 batteries that I can charge in 15 minutes I wont have to worry about running out of juice. I had a rechargeable glow plug igniter, but I'm good at killing them fast when its not running and then I'm done until they charger for many hours. That's why I bought the D battery one, then I could just pop a new one in.

How important is it to seal up the back case? It seems that the area below the piston shouldn't matter at all. I'll pull the needles out of the carb and check the O rings. Maybe I'll add some vacuum grease to seal them up. I had to patch my gas tank because the shock tower screw busted a hole in in from one of my wrecks. It's sealed up good, but I'll double check it and maybe pressure test it under water.

Also remember this: A well tuned engine should seem a little sluggish and rich until it reaches operating temperature.

Thanks. Sometimes I think I'm too quick to go for the needles. I've also been tuning on a full tank, but I read more about needing to tune with a half tank. I'll try that the next time I get it running.

 

[olds97_lss]

These little engines are very fussy regarding air leaks anywhere. Fuel line, carb neck, carb o-rings, backplate, front main bearing, cooling head, fuel tank lid, fuel tank hole... A leak from any of these areas will cause an engine to not run right all day long.

The general run down for sealing a nitro engine:
https://www.rcnitrotalk.com/forum/showthread.php?t=72487&highlight=seal


Regarding your 5 questions:
1. 4-5 pulls after priming and putting the heater on for about 15-20 seconds.
2. can't say as I use 2650mah AA's in my heater. It lasts all day long easily on a single battery.
3. Temp of glow pugs is solely for tuning purposes only. Has nothing to do with ambient temps. Has everything to do with engine timing and nitro content. I find that my big blocks like medium plugs when running 20-25% intro content. I use MCCoy MC8's and oddonnel purple. Both are medium. Higher nitro requires cooler plugs. Lower nitro requires hotter plugs. Using the wrong temp plug could make your engine run very poorly due to the fact that it's not cumbusting the charge in the cylinder at the right time. Too hot and it blows early as the piston is coming up, so the engine fights itself. Too cold and it fires after the piston reachs TDC or right near at TDC which means your losing the power of the charge out the exhaust.
4. Yes, but only with small adjustments. ALmost always less than 1/8 turn on any needle gets my rigs running right for the day, unless the ambient temps changed drastically (30F+ change from when I last ran).
5. A typical outing for me lasts 2-3 hours. I spend less than 5 minutes starting/adjusting anything in that 3 hours time span.

Just general info, alkalines don't deal well with high current applications. On energizers site, they only go as high as a 500mah draw. At 500mah, the battery rates around 10000mah. I did some looking around for what I could find about current draw of a glow plug ranged from 2A-5A. Even at the lowest 2A draw, that is 4 times what energizer even rates for. Which looking at the chart would put the battery around 3000mah. NiMH cells allow higher current draw due to their chemical design and physical makeup. Typically the physically fatter the cell, the more current you can pull from the cell and push into the cell. The larger the cell overall, the more capacity it has (Mah). Now, I don't now if the high current draw causes the alkaline to fail/dump earlier than math would suggest, but if it didn't, at 2A draw you would get 1.5 hours glow time out of it. With my AA heater using a 2650mah cell, I'd get 1.3 hours.

All that said, since using my NiMH AA driver, it glows brighter than my alkaline c-cell driver does. The NiMH cell can handle the current draw better so I get better performance out of the smaller cell. I still keep the c-cell driver in my carry bag just in case I forget to charge my AA's before I go out.

 

[2revo1maxx]

You may want to spring for a new tank at some point, and the backplate is a critical area to seal up if there's a leak. An air leak on the block usually means a fuel leak on the block.

I can get my aa duracells for free, but they last quite a while anyway.

 

[jgorm]

These little engines are very fussy regarding air leaks anywhere. Fuel line, carb neck, carb o-rings, backplate, front main bearing, cooling head, fuel tank lid, fuel tank hole... A leak from any of these areas will cause an engine to not run right all day long.

I checked the fuel system. I pinched off the line near the carb, and blew into the pressure line. It held pressure for at least 15 seconds before I let it out, so no issues with the tank and lines. I did wonder about having the fuel line going next to the head and heat sink. Is that ok? should it be not touching the engine?

I can't see the backplate and front main bearing having anything to do with how the engine runs. If I were to guess, I would leave them vented to release any blow by. All real engines have a vent for the crankcase for that purpose (most pull vacuum to burn off the vapors for emissions). What am I missing?

 

[2revo1maxx]

You're missing the whole concept behind nitro engines.
The front end of the crank has a 'scoop' in it where fuel and air mix enters the block. It's actually a rotary valve, and a leaky front bearing is not much of an issue, you're right about that....However, a sloppy front bearing will allow the crank to eat into the soft aluminum and compromise the fit between the crank and block.

When the piston comes down the fuel mix is pushed up through the sleeve ports, and this is only possible because the rotary valve is closed at that time. If you have a backplate leak you will most likely notice a fuel leak. A backplate leak will also allow air to be drawn in, especially when your carb slide is closed. That means tuning issues. You also have to check the fit of the starter shaft and backplate, because like the crank scoop, it also relies on a thin film of fuel and oil mix to keep it sealed up.

 

[jgorm]

You're missing the whole concept behind nitro engines.
The front end of the crank has a 'scoop' in it where fuel and air mix enters the block. It's actually a rotary valve, and a leaky front bearing is not much of an issue, you're right about that....However, a sloppy front bearing will allow the crank to eat into the soft aluminum and compromise the fit between the crank and block.

When the piston comes down the fuel mix is pushed up through the sleeve ports, and this is only possible because the rotary valve is closed at that time. If you have a backplate leak you will most likely notice a fuel leak. A backplate leak will also allow air to be drawn in, especially when your carb slide is closed. That means tuning issues. You also have to check the fit of the starter shaft and backplate, because like the crank scoop, it also relies on a thin film of fuel and oil mix to keep it sealed up.

Let me see if I have this correct.

In this picture I'm guessing that the port directly to the right of the rod bearing is part of the intake? Is this correct for these nitro engines?
[ame="http://www.youtube.com/watch?v=xV9jnWVeSB4"]2- stroke engine - YouTube[/ame]

I know my backplate is not ideal. I broke off 2 screws the first time i had it apart and the shafts are still stuck in the block. I'll open it up and rtv the hell out of it. I'll inspect the o rings and seal up everything in that thread. thanks for the tips!

 

[bifft it]

you can drill those screws out and re-tap the holes a bit bigger. i been doing that with the aluminum differential cups. one of every 4 seem to get a screw twisted off

 

[2revo1maxx]

Yes the fuel/air mix travels up from the crank case.
through ports to the combustion chamber.
Your video is a totally different type of 2 stroke engine.

 

[olds97_lss]

It takes a very small air leak to cause big issues. Trust me... I've had many leaks over the years. The most elusive and worst I had were when the mounting ears had cracked causing hairline cracks in the crankcase. Took me a while to figure out where the oil was seeping from and why it ran so badly.

All it takes is one leaky o-ring to give you a lot of fits with tuning. As the engines heat up, things expand which can make phantom air leaks as well. Leaks that aren't there on the bench when cold, but once warmed up, tune becomes erratic. These can usually be found by using compressed/canned air blowing all over the crank case when running. If your RPM changes, wherever your blowing air, you have a leak.

 

[jgorm]

you can drill those screws out and re-tap the holes a bit bigger. i been doing that with the aluminum differential cups. one of every 4 seem to get a screw twisted off

I've tapped tons of things, and even bought a micro tap set for this type of thing, but there is not much metal around the screw holes and I think they were dead end holes that make tapping a short distance very tricky.

These can usually be found by using compressed/canned air blowing all over the crank case when running. If your RPM changes, wherever your blowing air, you have a leak.

Great tip! I'll blast everything with 120 psi and see whats up. I use carb cleaner to find vacuum leaks on real engines and it works well.

 

[olds97_lss]

Carb cleaner on this will ruin things. It dissolves plastic, which is all over an RC, so avoid using that. I got some on a lexan body once, turned it into swiss cheese!