MLD-28 gasoline engine
12-17-2009, 09:05 PM
#901
RE: MLD-28 gasoline engine
ORIGINAL: dogshome
If you take the nut off, then refit the front part with the 4 out of 6 screws - you can then run the big bolt in the middle onto the end of the shaft and use it like a puller [8D]
You don't want to wind too hard, just put some preload on. Then use two medium flatbladed screwdrivers behind and it will pop off fairly easily.
To get the nut off at the start, you will need a 'long' 13mm socket and two soft steel screws in 2 of the six holes to work against with a big pair of pipe grips. It doesn't matter if you bend the soft screws (e.g. panhead or pozi type).
If you take the nut off, then refit the front part with the 4 out of 6 screws - you can then run the big bolt in the middle onto the end of the shaft and use it like a puller [8D]
You don't want to wind too hard, just put some preload on. Then use two medium flatbladed screwdrivers behind and it will pop off fairly easily.
To get the nut off at the start, you will need a 'long' 13mm socket and two soft steel screws in 2 of the six holes to work against with a big pair of pipe grips. It doesn't matter if you bend the soft screws (e.g. panhead or pozi type).
]
12-17-2009, 10:49 PM
#902
RE: MLD-28 gasoline engine
One of the pics posted here showed the crack very close to the pick up magnet and the crack on mine is not even close to the pickup so I'm thinking the cracks can vary in where they occur.
12-18-2009, 12:34 AM
#903
RE: MLD-28 gasoline engine
Mine is not near the pick up magnet either, but it starts right at the key slot. You have to take a look inside. I bet most cracks start right there. I am no expert but I think it happens in areas that have been cut or drilled. That's why one of the pictures posted shows a crack by the magnet hole.
12-18-2009, 01:02 PM
#905
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RE: MLD-28 gasoline engine
ORIGINAL: Planeclothes
Thanks. I followed your advise and it only took me a few minutes to remove the hub. Now the bad news is that my worse fears were confirmed. The crack starts right in the key slot. That is exactly the same spot where the old CRRC 26 hubs failed and cracked. My concern is that as long as this hub is not modified in some way, it will happen again, and again, and again...[]
ORIGINAL: dogshome
If you take the nut off, then refit the front part with the 4 out of 6 screws - you can then run the big bolt in the middle onto the end of the shaft and use it like a puller [8D]
You don't want to wind too hard, just put some preload on. Then use two medium flatbladed screwdrivers behind and it will pop off fairly easily.
To get the nut off at the start, you will need a 'long' 13mm socket and two soft steel screws in 2 of the six holes to work against with a big pair of pipe grips. It doesn't matter if you bend the soft screws (e.g. panhead or pozi type).
If you take the nut off, then refit the front part with the 4 out of 6 screws - you can then run the big bolt in the middle onto the end of the shaft and use it like a puller [8D]
You don't want to wind too hard, just put some preload on. Then use two medium flatbladed screwdrivers behind and it will pop off fairly easily.
To get the nut off at the start, you will need a 'long' 13mm socket and two soft steel screws in 2 of the six holes to work against with a big pair of pipe grips. It doesn't matter if you bend the soft screws (e.g. panhead or pozi type).
]
12-18-2009, 01:10 PM
#906
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RE: MLD-28 gasoline engine
ORIGINAL: airborne2.4
Wait a minute, you mean to tell me this could happen again after I change my hub?
Wait a minute, you mean to tell me this could happen again after I change my hub?
12-18-2009, 05:27 PM
#907
RE: MLD-28 gasoline engine
ORIGINAL: dogshome
I wouldn't worry too much. My hub is fine. A couple bad hubs with tight clearances and bad metal and sharp edges doesn't mean they are all bad.
ORIGINAL: airborne2.4
Wait a minute, you mean to tell me this could happen again after I change my hub?
Wait a minute, you mean to tell me this could happen again after I change my hub?
12-18-2009, 05:55 PM
#909
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RE: MLD-28 gasoline engine
I got one of the earlier engines, no cracks on mine. I have been with this thread from the beginning, and talk to the guys at Cermark regularly. These recent 3 or 4 incidences, have been the only ones that I have personally heard of. I would not worry. Maybe those were a Friday batch, who knows. If your replacement cracks, then get pissed 
12-19-2009, 01:32 PM
#910
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RE: MLD-28 gasoline engine
Hey guys
I finally got my new hub! After LONG wait. I'm going to put it in and I'll let you know whether I see any new cracks or not.
How much torque do you think I should put on this bolt when tightening it into the hub/keyhole?
Would you use a torque wrench or just as tight as you can? The hub wants to spin as you turn and I don't want to scratch up the new one. I guess I cloth with a pipe wrench won't hurt it too much
I finally got my new hub! After LONG wait. I'm going to put it in and I'll let you know whether I see any new cracks or not.
How much torque do you think I should put on this bolt when tightening it into the hub/keyhole?
Would you use a torque wrench or just as tight as you can? The hub wants to spin as you turn and I don't want to scratch up the new one. I guess I cloth with a pipe wrench won't hurt it too much
12-19-2009, 01:41 PM
#911
RE: MLD-28 gasoline engine
Will a strap wrench hold it? Or a soft balsa stick in the exhaust port? Pipe wrench and leather maybe... I'd be concerned that the teeth would find their way through a rag.
12-20-2009, 04:55 AM
#912
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RE: MLD-28 gasoline engine
Hi Guys,
Just purchased the MLD 28cc & a Cermark edge 540 26cc airplane, ran the engine on the ground 2 tanks of gas. Power was perfect and the engine ran perfect. then i put on the cowling, things changed completely, i tried to take off and the model just limped around the sky with practically 25-30% power even at full throttle. i then landed and removed the cowl. and then took off again, same problem. i then also noticed that there was considerable amount of bubbles in the fuel line at close to full throttle. i am at a loss guys help...............
Any suggestions?
regards
ravi.
12-20-2009, 07:24 AM
#914
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RE: MLD-28 gasoline engine
Is the 5" depth from the back of the mounting plate to the end of the hub or back of the prop? Can the engine be mounted without the standoffs?
Dimension: Width: 5 3/4", Height: 8", Depth: 5"
Dimension: Width: 5 3/4", Height: 8", Depth: 5"
12-20-2009, 08:59 AM
#915
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RE: MLD-28 gasoline engine
Trpastor, I agree with AA5BY, go to Walmart, and get a $5 rubber strap wrench. Teeth marks lead to possible future failure.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
12-20-2009, 09:00 AM
#916
RE: MLD-28 gasoline engine
4 3/4" are needed to clear the jug and another 1/2" to clear the muffler and there is a bearing boss on the rear of the motor so no, the engine cannot be mounted without some standoffs. However, if the firewall or box were relieved for the muffler, about a half inch could be reduced from the length requirement though I think it would certainly require a half fire wall and belly pan angled back from there to produce a tunnel so as to give the jug fins some space to cool.
12-20-2009, 09:41 AM
#917
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RE: MLD-28 gasoline engine
Thanks, will order one right away. However guys was wondering about the in flight problem to the engine, where the power drops significantly, and the engine goes rich upon takeoff, and the models literally limps across the sky.
ORIGINAL: w8ye
You need a Walbro filter clunk in your tank to eliminate the bubbles
You need a Walbro filter clunk in your tank to eliminate the bubbles
[img][/img]
12-20-2009, 09:44 AM
#918
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RE: MLD-28 gasoline engine
Hi Jimeni,
Thanks for your input, the clunk should take care of the bubbles, but what in your opinion is the cause for the mixture to change in flight, i flew the model with and without the cowl and both times the engine mixture changed completely,
was running perfect on the ground but in the air the engine sags and barely flies the model even at full throttle, does it need a velocity stack? am at a complete loss
regards
ravi.
Thanks for your input, the clunk should take care of the bubbles, but what in your opinion is the cause for the mixture to change in flight, i flew the model with and without the cowl and both times the engine mixture changed completely,
was running perfect on the ground but in the air the engine sags and barely flies the model even at full throttle, does it need a velocity stack? am at a complete loss
regards
ravi.
ORIGINAL: Jimeni
Trpastor, I agree with AA5BY, go to Walmart, and get a $5 rubber strap wrench. Teeth marks lead to possible future failure.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
Trpastor, I agree with AA5BY, go to Walmart, and get a $5 rubber strap wrench. Teeth marks lead to possible future failure.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
12-20-2009, 10:22 AM
#919
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RE: MLD-28 gasoline engine
Well, I'm going to beat a dead horse here, but. Could be one of your ignition connections. I had the same issue, tuned until I was blue in the face. Only happened at half throttle or better, but sometimes would show up at lower settings too. On the run stand, go to 3/4 throttle, and wiggle your crank sensor lead connector. There seem to be alot of these where they over crimped the pins, breaking the wires. I think the units are great, they just have some connector installation QC issues. If you dont find the problem there, the plug lead can do the same thing. If you have the exact same problem with or without the cowl, that almost eliminates airflow issues.
12-20-2009, 10:37 AM
#920
RE: MLD-28 gasoline engine
ORIGINAL: ravikoth
Hi Jimeni,
Thanks for your input, the clunk should take care of the bubbles, but what in your opinion is the cause for the mixture to change in flight, i flew the model with and without the cowl and both times the engine mixture changed completely,
was running perfect on the ground but in the air the engine sags and barely flies the model even at full throttle, does it need a velocity stack? am at a complete loss
regards
ravi.
Hi Jimeni,
Thanks for your input, the clunk should take care of the bubbles, but what in your opinion is the cause for the mixture to change in flight, i flew the model with and without the cowl and both times the engine mixture changed completely,
was running perfect on the ground but in the air the engine sags and barely flies the model even at full throttle, does it need a velocity stack? am at a complete loss
regards
ravi.
ORIGINAL: Jimeni
Trpastor, I agree with AA5BY, go to Walmart, and get a $5 rubber strap wrench. Teeth marks lead to possible future failure.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
Trpastor, I agree with AA5BY, go to Walmart, and get a $5 rubber strap wrench. Teeth marks lead to possible future failure.
ravikoth, the filter clunk is awesome, and cuts down on bubbles. It also does not choke off if your tubing slides a little and the clunk touches the back of the tank. Mine bubbles like mad, does not seem to bother it. Remember, its a pumped carb, and not a glow engine. Certainly worth a try though, those clunk's are the best.
The bubbles cause the fuel to be less dense changing your fuel mixture
12-20-2009, 10:38 AM
#921
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RE: MLD-28 gasoline engine
Thanks will check for sure, however th engine runs perfect on the ground and just turns limp in the air, so i still feel that it could be a air-pressure issue, would you recommend a vent line from the carb plate into the fuse?
regards
ravi.
regards
ravi.
ORIGINAL: Jimeni
Well, I'm going to beat a dead horse here, but. Could be one of your ignition connections. I had the same issue, tuned until I was blue in the face. Only happened at half throttle or better, but sometimes would show up at lower settings too. On the run stand, go to 3/4 throttle, and wiggle your crank sensor lead connector. There seem to be alot of these where they over crimped the pins, breaking the wires. I think the units are great, they just have some connector installation QC issues. If you dont find the problem there, the plug lead can do the same thing. If you have the exact same problem with or without the cowl, that almost eliminates airflow issues.
Well, I'm going to beat a dead horse here, but. Could be one of your ignition connections. I had the same issue, tuned until I was blue in the face. Only happened at half throttle or better, but sometimes would show up at lower settings too. On the run stand, go to 3/4 throttle, and wiggle your crank sensor lead connector. There seem to be alot of these where they over crimped the pins, breaking the wires. I think the units are great, they just have some connector installation QC issues. If you dont find the problem there, the plug lead can do the same thing. If you have the exact same problem with or without the cowl, that almost eliminates airflow issues.
12-20-2009, 10:53 AM
#922
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RE: MLD-28 gasoline engine
Mine ran perfect on the ground also. For some reason would only show up if wiggled, or in flight. I'm not saying these other issues cant be your problem, just from my experience with MLD/SPE ignitions, a connection issue is most likely the cause. It shows up in flight like the engine needs tuned. Try this first, before anything else, just to possibly save you from pulling your hair out. Then I would look at the bubbles. Do one thing at a time so you know what fixed it. From your description, airflow would be the last thing I looked at, personally. Had it changed with cowling on or off, airflow would be the 1st thing I looked at. Every single issue that I have had with SPE/MLD boiled down to a connection in the ignition system.
12-20-2009, 11:03 AM
#923
RE: MLD-28 gasoline engine
Ravikoth... Most atmospheric hole issues are caused by positive air pressure in the cowl because of inadequate air exit and as Jimeni pointed out you said the problem was with or without the cowl so that is not likely your problem. More likely is what Jimeni describes, a vibration affecting wires. It could be that the particular vibration that causes it is dampened by the landing gear while on the ground.
An interesting aside to this is that I've been doing some flight video recording with one of the very small cameras using a mount that I made to rubber band onto various planes landing gear. The camera is foam insulated from the mount but it does pick up some of the movement of the mount in the video. I noted very quickly that various planes have more/less landing gear vibration.
An interesting aside to this is that I've been doing some flight video recording with one of the very small cameras using a mount that I made to rubber band onto various planes landing gear. The camera is foam insulated from the mount but it does pick up some of the movement of the mount in the video. I noted very quickly that various planes have more/less landing gear vibration.
12-20-2009, 11:50 AM
#924
RE: MLD-28 gasoline engine
Ravikoth,
I had an filler valve that leaked air only when there was a positive G force in the air (up elevator). It would cause the engine to die or almost die when plane was given a little up elevator. Replaced the filler valve and the problem went away.
Just another thing to check.
Ralph White, Neoga, IL
I had an filler valve that leaked air only when there was a positive G force in the air (up elevator). It would cause the engine to die or almost die when plane was given a little up elevator. Replaced the filler valve and the problem went away.
Just another thing to check.
Ralph White, Neoga, IL
12-20-2009, 10:38 PM
#925
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RE: MLD-28 gasoline engine
Thanks, will definitely look into it.
regards
ravi
regards
ravi
ORIGINAL: AA5BY
Ravikoth... Most atmospheric hole issues are caused by positive air pressure in the cowl because of inadequate air exit and as Jimeni pointed out you said the problem was with or without the cowl so that is not likely your problem. More likely is what Jimeni describes, a vibration affecting wires. It could be that the particular vibration that causes it is dampened by the landing gear while on the ground.
An interesting aside to this is that I've been doing some flight video recording with one of the very small cameras using a mount that I made to rubber band onto various planes landing gear. The camera is foam insulated from the mount but it does pick up some of the movement of the mount in the video. I noted very quickly that various planes have more/less landing gear vibration.
Ravikoth... Most atmospheric hole issues are caused by positive air pressure in the cowl because of inadequate air exit and as Jimeni pointed out you said the problem was with or without the cowl so that is not likely your problem. More likely is what Jimeni describes, a vibration affecting wires. It could be that the particular vibration that causes it is dampened by the landing gear while on the ground.
An interesting aside to this is that I've been doing some flight video recording with one of the very small cameras using a mount that I made to rubber band onto various planes landing gear. The camera is foam insulated from the mount but it does pick up some of the movement of the mount in the video. I noted very quickly that various planes have more/less landing gear vibration.