engine over heating!!

[dj_doogle]

please help me i dont want my engine to get damaged!!! why is my engine overheatin??? help me please how do i stop it from doing this???

 

[frickenjoey]

Are you over lean? How far have you turned your high speed needle in? Also how hot are you getting? What engine is in it? Nitro content....temp of glow plug? Sorry to answer a question with a question but need more info to help you out.

 

[ThunderTiger]

As Joe Said,^^^^ we need to know engine, fuel etc to be able to give a related answer to the question you ask.

Try something like: ' hi i have "x" type engine" using "x" percent fuel, it keep overheating, could you help me please'

 

[dj_doogle]

the engine is a pro-12bzx and its in a thunder tigerand my file is 20%.. thanks

i cannot tel u the temps but it is getting that hot is u put a bit of spit on it, it sizzles away straight away!

 

[ThunderTiger]

Ok, heres a check list:

HSN: check it's not set too lean. (refer to manual for "initial" Setting andreset to these and re tune a 1/8 turn at a time.) Tune the HSN until it bogs of fuel starvation at WOT Then close in clockwise 1/2 - 3/4 turn and you should be in the ballpark without being too lean.

LSN: Check that this is also not too lean. Again, refer to the manual for initial settings, reset to these and re tune a 1/8 turn at a time. Tune the LSN until it bogs or sputters on opening the throttle Then adjust 1/8 turn at a time and you should be in the ballpark without being too lean or too rich.

This all assumes, that you are working from the base settings.

And also assumes I'm not making a right monkey out of myself !!!!! lol.

 

[frickenjoey]

So it sounds like you are a bit too lean....there is a couple good tuning guides on this site one of them is below. They are very helpful. Read though this it may have exactly what you need!
https://www.rcnitrotalk.com/forum/showthread.php?t=60832

Assuming you're at the manufacturers recommended starting point with the idle opening gap already set and the engine running- the first thing that must be set is the HSN. The HSN (main needle) controls the maximum amount of fuel flow through the fuel inlet/spray bar. Since it does control total fuel flow- the HSN setting WILL AFFECT the LSN setting. Therefore, you MUST adjust this setting 1st before finalizing your LSN adjustment. Setting your LSN 1st will only cause you to have to reset it again once you alter you HSN adjustments. You must typically match this maximum fuel flow through the carb with the maximum amount of air flow through the carb. Maximum airflow through the carb can only be achieved with the carb at WOT and the engine at max RPM. It doesn't matter how fast you accelerate at this point- just get the engine to maximum RPM's doing several high speed passes and make a judgment based on maximum speed and smoke trail. Adjustments should be made at hourly increments. Once you get to a point where top speed is no longer improving, richen the HSN between 1/8-1/4 of a turn out just to ensure adequate lubrication at that maximum speed.

*If the engine suddenly cuts out at high RPM's - you too lean
*If the engine lacks high RPM response with excessive smoke- your too rich

If your engine's is starting to run excessively hot even while your fuel mixture is excessively rich...try switching to a cooler glow plug, one step cooler than the one your using. ( If you're using Dynamite plugs like an MC-59, switch to an MC8, then to an MC9 if necc- if you're using OS plugs and using an OS8, switch to an OSA5, and then to an OSR5 if necessary. DO NOT JUMP FROM ONE MANUFACTURER TO ANOTHER WHEN EXPERIMENTING WITH GLOW PLUG HEAT RANGE. THERE IS NO INDUSTRY STANDARD FOR THEM TO COMPLY WITH SO KNOWING WHICH PLUG IS HOTTER THAN THE OTHER BASED ON IT'S GIVEN RATING IS NOT SOMETHING THAT CAN BE DONE BETWEEN 2 MANUFACTURERS)

When the throttle is anywhere between 1/2 open to fully closed, the LSN enters the fuel inlet/spray bar and restricts the amount of fuel that can flow through it. Less fuel is required at this point since the smaller carb opening is also restricting the amount of air that can flow through the carb. The deeper the LSN enters the fuel inlet, the more it restricts fuel flow- to match the restricted air flow.

There are many methods people use to set their LSN. For me- I typically clear out the engine by doing a high speed run, bring the truck in and allow it to idle, then watch and see how it responds at idle speeds. If the idle speed drops right away or slowly drops within a few seconds ( or if temperatures start to drop too fast) = the LSN is too rich allowing too much fuel through which is loading up the engine lowering it's RPM. If it starts to climb in RPM ( or if temperatures also start to climb) then it's set too lean. Adjustments should be made at hourly increments with a high speed run in between each adjustment to clear out the engine. Once I get the engine to idle for at least 20 seconds or so without excessive load up, once again, I'll clear out the engine, bring it in and idle the engine for 5-10 seconds- then hit the throttle to watch how it accelerates. It should accelerate smoothly and powerfully from idle all the way to max RPM's with a nice healthy smoke trail leaving the exhaust. Even finer LSN adjustments can made in even smaller increments to fine tune this setting. Once your satisfied with your overall performance- you can adjust the idle speed ( if necessary) by using the Idle stop screw. This basically adjusts how far the carb's slide barrel will close. The LSN will affect the idle speed/quality if it's not set correctly- so it is important you're able to achieve and hold a steady idle at the manufactures suggested setting (usually at around 2mm) before making its final adjustment. Remember- you're not entering a contest which engine can hold the lowest idle speed so just set it to where it's comfortably below clutch engagement to prevent premature clutch wear.

Note: the ability to hold a prolonged and reliable idle is greatly affected by the heat range of the glow plug.. the hotter the better as far as idle quality. As far as high speed/max RPM running- the heat range of the glow plug will affect overall timing advance in which a hot plug might over-advance the timing causing detonation and/or reduced power output- the key is to experiment with something that will give you the perfect balance for overall bashing- cold plugs for tracks with long straight-aways and extended high RPM use, and med/hot plugs in tight tracks where lots of decelerating at closed throttle followed by WOT acceleration is performed.

The Midrange adjustment does NOT control an actual needle- nor can it be set rich or lean (LSN shape and design has more of an impact as to how much more gradual fuel flow is allowed through the fuel inlet at mid throttle). It actually controls at what point of the carb opening, the LSN fully leaves the fuel inlet. Since the HSN should typically be set slightly on the rich side- the point at which the LSN leaves the fuel inlet will create a sudden small rush of fuel. This sudden richness can be beneficial to expert tuners by manipulating at what point it occurs in the throttle opening. To adjust the Midrange point, both the Mid and the LSN need to be rotated TOGETHER in opposite directions. This transition point takes place at 1/2 carb opening. If you want the transition point to happen at a later throttle opening- you'll need to adjust the mid range clockwise (deeper) into the carb body while adjusting the LSN counterclockwise in the same amount of turns. If you fail to adjust the LSN at the same time- you will affect your Low speed setting. The opposite holds true if you want the transition to occur at an earlier throttle opening. The affect of the Midrange adjustment is very minimal and is better off being left at the manufacturers base settings.

Remember- there are other factors involved in maintaining and regulating operating temperatures of your engine- while a excessively lean or rich mixtures will affect your overall operating temps- it is NOT the only factor involved. If your engine is approaching excessively hot temperatures while still spewing out lots of raw fuel/oil out of the exhaust due to an excessively rich fuel mixture, there is likely to be another problem with your engine (air leak, too high or too low compression ratio, wrong glow plug heat range, etc). Engines are set up and shimmed at the factory to work in most/average operating environments. If you live in an area that is always excessively hot (95F +), it may be necessary to ADD an addition shim to reduce the compression of the engine to keep everything in safe operating range. If you live in area that are excessively cold year around...you might even want to consider removing the thinnest shim (.1mm) to INCREASE compression or even consider using higher nitro methane content to keep temperatures up where they need to be.

 

[ThunderTiger]

Joey, that link will help my missus too, thank you. you saved me the headache of explaining it to her !!!!

 

[frickenjoey]

Mine has no mechanical inclination at all.....which is why she probably keeps me around... ;-)

 

[Metalhead Matt]

Great spread, Frickenjoey. Killer info.

 

[dj_doogle]

thanks alot! i wil try that 2morrow when it it light lol