Nitro engine - help with the basics

[James76G 10]

While I decide what direction to go with my Tamiyas (Nissan King Cab and Monster Beetle) I have picked this up locally. It's an HPI Nitro MT2

I have no experience of nitro myself, but this was £free so I thought it a great opportunity to learn. 

It hasn't been touched for 10 years and while the engine turns over and appears to have good compression, the carb is stuck. By which I mean the rotating barrel doesn't move, so currently it's stuck on idle. So questions:

1. What is the best way to unstick it? I've taken the carb off and it's currently soaking in some alcohol but all other suggestions welcome. 

2. What fuel to buy. 16% Optifuel? 20%?

3. Glow plug works when connected to a battery, so presumably should be good to start it. Or do they go bad after time?

Thanks in advance. 

[KEV THE REV 2315]

The carb is stuck with old fuel , see how the soak goes . If it frees it up then great . It will probably need a service at some point . The engine turns over , but could still have old gunk in the bottom of the casing . Check / clean the air filter foam / cartridge element and use some drops of air filter oil  . Once assembled you could try kicking it over with the rotostart you have there if you have a glo-plug heater  . 20% is a good staring point on fuel. If it fires up you will need run it around to get it hot and not bog down at low speed too much  , run it some and check your tuning . It will smoke as it cleans out the old fuel from the engine and exhaust pipe  . Some smoke on running / acceleration is ok , running with no smoke could mean a too lean a carb setting and potential overheating - leading to a seize . Take it easy on running it . Once you have finished running the engine you need to drop in some after run oil to prevent the old fuel gunking up the works again . Check for leaks from the joints of engine crank case / head carb gasket . Maintenance / overhaul of engine / damper oil , gaskets etc will be required as the whole truck has sat for a decade

[Juggular 4964]

4 hours ago, James76G said:

1. What is the best way to unstick it? I've taken the carb off and it's currently soaking in some alcohol but all other suggestions welcome. 

2. What fuel to buy. 16% Optifuel? 20%?

3. Glow plug works when connected to a battery, so presumably should be good to start it. Or do they go bad after time?

Free is the best price! 

But 10 years is a long time... well... come to think of it, my nitro trucks haven't ran for about that long too.  But mine were treated with "after-run oil."  Now that you have a nitro engine, that would be a good investment. 

As you may know, nitro fuel has 3 parts. Nitro, alcohol (methanol) and lubricant. Methanol is actually what burns. Nitro supplies extra oxygen for combustion.  Lubricant can turn sticky after years.  If that's the case, rubbing alcohol should undo it. 

Rust could be another way it can get stuck.  Few drops of fuel is always left in the engine. If so, methanol in the fuel tends to attract water from the air.  Obviously, rust doesn't melt in alcohol, so if that's the case, you'd have to use plastic-safe lubricant to undo it.  But I would not recommend WD40.  It's not entirely safe if there are rubber seals inside.  If possible, I would use plastic safe stuff. (I think "evapo-rust" might be safe to use, but I'm not 100% sure on that).  

15-20% nitro should be fine.  I think I did use 20% the most, when I was running them.  When you get it, it would be best to keep it capped at all times.  It's a magnet for moisture, and water molecules can ruin any fuel fast.  I think developing a habit of treating it with "after-run oil" after every run would be a good idea too.  We always think "I'll run it in an hour again" and something else grabs our attention and years fly by.  I suspect after-run oil neutralizes methanol in the fuel. So there wouldn't be anything to pull water into the engine. 

Glow plugs are consumable items.  They burn out after a while.  Every nitro guy carries a few in their tool boxes. 

 

[KEV THE REV 2315]

17 minutes ago, Juggular said:

When you get it, it would be best to keep it capped at all times

Yes indeed . I keep it indoors out of sunlight too , as you said it breaks down with age and loses some of its potency over time if not used

[KEV THE REV 2315]

The carb will need to be primed on the start up . I can't remember if the MT2 tank has a primer button . If not , pull the pipe off the exhaust nipple on the exhaust pipe and blow into the fuel pipe , you will see the fuel travel along the inlet pipe to the carb from the fuel tank , re-fit the pipe onto the exhaust , switch on radio TX first then RX , attach glo-heater and crank on the Roto -Start . You can check the throttle opening by eye down the barrell of the carb with filter off , there should be a very small gap ( idle setting) . If it is wide open , back off the idle screw , reverse the proceedure for no gap at all , re-fit air filter

[James76G 10]

Thank you both for the comprehensive replies - all very helpful.

Current situation is that the carb barrel came unstuck after a soak of some 3 hrs. I cleaned out all the varnish inside and oiled it lightly so it now rotates nice and smoothly and reassembled it on to the main body of the engine. 

I've since ordered some 20% fuel and a glow plug igniter. The MT2 tank does have a primer button which I have been using to eject the old fuel that's been sat in the tank for the last 10 years, so that's good. 

Will upload a quick video when it fires up for the first time in a decade. I am expecting lots of smoke - can't wait!

[KEV THE REV 2315]

Cool - can't wait . I had an MT2 some years back it was a great truck

[KEV THE REV 2315]

Before you go out to the woods with it , you might want to fit a failsafe to the throttle servo on the RX to prevent any runaways if you lose signal or battery , unless your RX has a failsafe already

[James76G 10]

Quick update, the engine would catch but won't run

I removed the glow plug, put some fuel straight in, and it ran fine, albeit for about 2 seconds. This suggested a problem with the carb settings and so I checked the manual for this HPI T15 engine and it says both LSN and HSN should be flush with their housings. Neither were, so I adjust them to the base settings and expected the car to fire right up. But still nothing.

Glow plug is bright and fuel is new Optifuel 20% so all good there.  I am trying this without the air filter fitted though, as the foam within looks like it will get sucked in to the engine. I assume that its absence isn't going to prevent a start?

[KEV THE REV 2315]

The air filter won't prevent it starting . Have you tried priming the carb like I said by blowing into the tube that is attched to the exhaust so that you see fuel travel to the carb . Have you got an old inline fuel filter fitted ? , it could be blocked . Check that and the idle setting . When I crank my nitros I ease up the throttle trim whilst starting the engine to open the carb up slightly , then back off to the trim neutral position . If the filter is blocked , you can clean it out by unscrewing the filter to reveal the gauze inside .

[James76G 10]

5 hours ago, KEV THE REV said:

The air filter won't prevent it starting . Have you tried priming the carb like I said by blowing into the tube that is attched to the exhaust so that you see fuel travel to the carb . Have you got an old inline fuel filter fitted ? , it could be blocked . Check that and the idle setting . When I crank my nitros I ease up the throttle trim whilst starting the engine to open the carb up slightly , then back off to the trim neutral position . If the filter is blocked , you can clean it out by unscrewing the filter to reveal the gauze inside .

Thank you Kev, I had primed the carb albeit with the built in plunger. There is no fuel filter so no issues there. 

Anyway, good news, I got it running. It has taken ages to get it to go but then it is waking from a 10 year slumber. In the end I just kept the roto start running until it was running properly. Here's the video on YouTube

This got the wheels spinning which shows that I have an issue with the front diff/gearbox as one of them isn't turning, so that's next on the list. Still, getting ever closer to the first proper run. 

 

[James76G 10]

Quick update on this. 

I fixed the issue with one of the wheels not turning, which was simply that the driveshaft was not engaging in the output cup properly due to some missing red o-rings. A few £ later and that's sorted. 

Yesterday I thought I'd take it for a run but although it will start (albeit reluctantly) if you give it any throttle it just stalls. A lot of fuel seems to be coming out of the exhaust which suggests it's running rich but all the adjustments are set as per factory. 

I've put it back on the shelf for now, but I am beginning to hate nitro...

 

[M 800STD 586]

Factory settings are just a guide, don't expect it to run perfectly.

Have a look at this...