IC engine clean / lubricate

[Tim Donald]

I have just stripped down the carb on a Thunder Tiger Pro .46 that was having trouble with idle.  It is an engine that I got second hand and I think has been left for quite a long time without use (it's not been run much from new).  It's also something I wanted to do as a learning experience with an engine that I'm not too precious about.  The carb had a bit of gunk but was not too bad so I am re-assembling and was wondering if I need to oil the parts and if so with what sort of oil?  I have 3-in-one, WD40, engine oil and glow fuel with synthetic readily available to hand.  

I will probably go on to take the main engine apart and check / clean once I get hold of a puller to remove the drive washer collet.  Any tips for that would be appreciated too !  

Thanks.

[Nigel R]

'trouble with idle' is as likely to be 'not ever quite set up right' as anything else.

 

That said. If it's already oily, I wouldn't add any extra oil!

 

Don't use 3 in 1.

Don't use WD40.

Engine oil? From cars? Won't necessarily be glow engine friendly. Some oils will negatively affect the silicone O rings that are fitted to our small motors.

 

I think an air tool oil or light machine oil would be about right.

 

Jon of Laser can confirm (or refute) that recommendation.

[Tim Donald]

Thanks Nigel.  I had the local engine wizz at my club look at it but the idle needle never seems quite right so just cleaning the carb in case that is the cause.  The engine does run enough to fly with but something stops it idling consistently.  

[Jon H]

Some 2 stroke oil will be fine for engine assembly. The sort of stuff you mix with petrol for the strimmer or chainsaw will do just fine. This is soluble in methanol (not all oils are) and will wash away once you start running fuel through the engine. if you use a fuel with klotz oil in it you might even be able to buy a bottle of that same oil for this sort of work, and if so inclined you could even use the same oil as an after run for long term storage. 

 

wd40, 3in1, cellulose thinner, petrol...all things not recommended for glow engine cleaning. 

 

Air tool oil is often suggested but have no experience with it directly. I had one engine that came from the US which was allegedly inhibited with air tool oil but i cant say if it was or not. In any event, whatever it was the oil had dried out and all the bearings had to be changed. 

 

When it comes to idle issues the first port of call is tank placement. Top of the tank, centre of the carb. If that relationship is wrong (tank to high usually) it will never tune correctly so i would check that once you get the engine back together. I had a TT46pro years ago and it was a good motor. never gave any trouble

[Tim Donald]

Excellent,  thanks Jon.  I've got all sorts of two stroke oil for mowers / strimmers so will use some of that.

I checked the tank height in the plane and it seems ok but will mount the engine on a test rig now until the problems are sorted.  I also watched a youtube video and it said that on the TT .46 engine the idle screw has to be set almost fully in for some reason.  Strange though because I had a few flights ok before the problems and did not change the idle screw.  Could be the plug too I guess so will try a new one.

[Jon H]

As always, you cant tune an engine by counting turns. 

 

Its common to see recommendations about tuning engines based upon numbers of needle turns, relative position of components or other cosmetic or visual clues. Ultimately none of these things matter though and the only option to run the engine and tune it using the performance of the engine to inform you on what to do. It would be the same as trying to tune a stringed musical instrument by counting the turns on the tuners or seeing if they were all aligned in some cosmetic way. Needless to say, this wont work!

 

If you have trouble with engine still after the rebuild post a video showing the issue as the sound of the engine is a big aid to diagnosing the problem. Just keep the camera out of the prop blast as wind noise is not informative 😉 

[Engine Doctor]

Hi Jon. Air tool oil is an excellent oil to build and store engines. It doesn't dry out like many oils. I have engines In my collection that were stripped , cleaned and re-assemble with this oil many years ago and they still turn freely. It only works on clean engines . If any other oil or contaminants remains in the engine they will stiffen up . 

Cenga oil is IMO best but most air tool oils are pretty good as they are made to resist any moisture that is in the compressed air flowing through the tools and it doesn't attack "0" rings .

Used that for vintage rebuilds that are likely to sit on a shelf for some years now. For engines that are being repaired or refurbished for running I use two stroke oil and prefer Carlube . It's also a handy additive for diesel fuel . I used it for years in my cars at ratio of 300 : 1. 

It quickly mixes and clears out of an engine and never had any problems. Obviously there are other makes available .

 

 

[Richard Wills 2]

4 hours ago, Jon - Laser Engines said:

 if you use a fuel with klotz oil in it you might even be able to buy a bottle of that same oil for this sort of work, and if so inclined you could even use the same oil as an after run for long term storage. 

 

 

I only use the same oil that is in my fuel for lubricating while assembling or afterrun purposes.  In my case Klotz tecniplate.

[Nigel R]

16 hours ago, Jon - Laser Engines said:

I had one engine that came from the US which was allegedly inhibited with air tool oil but i cant say if it was or not. In any event, whatever it was the oil had dried out and all the bearings had to be changed. 

 

Doesn't sound like air tool oil, as ED says that should not dry out.

[Jon H]

6 minutes ago, Nigel R said:

 

Doesn't sound like air tool oil, as ED says that should not dry out.

 

Yep agreed. That or it was some shabby quality stuff 

[Engine Doctor]

17 hours ago, Jon - Laser Engines said:

had one engine that came from the US which was allegedly inhibited with air tool oil but i cant say if it was or not. In any event, whatever it was the oil had dried out and all the bearings had to be changed.

I would guess that Jon's engine had just been oiled with air tool oil  (ATO) but still had old oil/ fuell inside , possibly castor. ATO won't stop an engine siezing if old oil is present unless it completely flooded with the stuff. It only works on clean parts .

[Jon H]

Yea absolutely. Its why i think after run oil is a waste of time as you will never displace all the contaminants in the engine unless you fill it to the brim. 

 

 

[GrumpyGnome]

That's good 'cos I sometimes feel I'm mistreating my engines by not using after run oil...

[Jon H]

1 hour ago, GrumpyGnome said:

That's good 'cos I sometimes feel I'm mistreating my engines by not using after run oil...

 

Nah. The best defence against corrosion is still running optimum tuning on both needles, run the engine dry if you can (more important with 2 strokes than 4) and use the engine as regularly as possible. 

 

I think i mentioned before that when i store my engines i blast them with the hose pipe to clean them, then stick them on the bench and fire them up. Set all the needles to the bench and run at high power to get them really nice and hot. Pinch off the fuel, attempt restart until no fire, set to TDC, wipe down, then pop it in a plastic bag in a box under the bed. I have not had any problems with an engine stored in this way and they all fire straight back up even after years of sleeping.