NGH 35 Carb Won't Pump = Fix - RC Groups
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Sep 15, 2016, 05:25 AM
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NGH 35 Carb Won't Pump = Fix


After getting fed up with messing about with this engine which was installed on an Acrowot XL which was always cutting out at inexplicable moments which was resulting in too many dead stick landings for comfort I put the model in "the other shed" and forgot it for a while till I could investigate with a clearer mind.

Today was that day and after removal of the engine from the model i proceeded to take things apart - then it hit me why this engine was so unreliable...

I can only hope this problem is related to just a small manufacturers batch that my engine was in but just in case there are a few other poor souls out there who were getting as frustrated as I was - Here is the fix to get you engine working. Regards Peter.
NGT GT35 Gasoline Engine Problem & Fix. 1 of 2 (2 min 41 sec)
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Sep 15, 2016, 05:38 AM
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PS. Just in case - you can't turn the carb around to make the airways fit - see pictures - control throws would then be all wrong.
Also to show the pump on the carb is working correctly here is a follow up video showing the fuel being pulled through the fuel tube towards the end of the engine run after the modification was made.
I have to say that the engine will now self prime as well which it would not do before.
I suspect my fitted carb was introduced by the manufacturer as a "stop-gap" so I hope the batch my engine came from was small but just in case I have to show the manufacturing error can be fixed.
I can only hope it does not affect many of you in the USA.
Regards Peter
NGH GT35 Gasoline Engine Problem & Fix 2 of 2 (0 min 50 sec)
Last edited by brucepeter2007; Sep 15, 2016 at 05:40 AM. Reason: Put in wrong link - correct one inserted now.
Sep 15, 2016, 05:34 PM
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Tucci's Avatar
You just may be my hero right now.
I suspected this may be the problem with an NGH 35 I have.....

THANKS!
Sep 16, 2016, 09:41 AM
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Hi Tucci.
So pleased the video has helped you but so sorry your affected.
I am still hoping the NGH35 problem production is small...
For interest the additional information below could be of help...
My carb only has stamped round symbols located on the air intake side and I had to remove the venturi to see them.

There are two numbers indented within circles on the air intake side of the carb under the fitted venturi - one number on each side of the flat.

Numbers on my carb are 62 and the other is a 2.

For reference here is my NGH GT35 engine serial number is 351512042.

Regards Peter
Sep 16, 2016, 03:37 PM
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keither's Avatar
Thanks! I'm just about ready to test fly my GP Giant Ugly Stick with the
NGH 35 engine. Its on the test bench now, and i have never started it.

So now I'm going to check to see if mine has the same problem as yours
before I even try to start it.

I also have a NGH gas 4-stroke 38cc engine that i like, and it also had a problem after about 20 good flights; the intake manifold cracked rjight at the attach point to the head. There's no welding this type of aluminum casting so I had to buy a new manifold from a UK seller; and now she's running great again. It turns an 18 x 10 prop at 6600 RPM and idles at 1100 rpm sounding like a Honda minibike!
cheers
Keither
Sep 19, 2016, 01:24 PM
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Hi there. Yours is a 4 stroke which have known exhaust problems - which you have just found out I'm sorry to say...
Sep 25, 2016, 07:26 AM
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Tucci's Avatar

Are these things just trash?? Warning: This is a book.


This is more for me to document my progress (failures) as I struggle with these POS engines. Feel free to offer advice.


So I have two of these seemingly useless NGH GT35R engines. One was NIB, the other appears new outwardly, but has an undetermined amount of run time. Can't have too much time on it though. I'll call these engine 1 and engine 2, respectively. Engine 1 is as stated, NIB. Engine 2 was on this profile airframe I traded for and has a DLE carb on it. Here's what they do.

When mounted with the cylinder pointed down and the fuel tank below the carb, they will start on the prime and immediately stall. With a gravity feed set up, they both perform slightly better, but the needles have to be set so rich, that there is no RPM and idle is horrid. After I get them running, and then lean out for RPM and idle, they won't start again.

Sounds like a pumping problem, right? So I found this thread and I was excited. Checked out engine 2, and sure enough the pulse hole did not line up properly. Fixed that, same thing. Engine 1 did not need the mod.


They absolutely hate life when mounted upside down, which is unfortunate since that is how 99% of planes require.
These are my first piston valve engines. So maybe it's inherent to the design? Also, I noticed some fuel leakage from the front bearing area while trying to start. The leak goes away when running. Could this contribute to the problem?

Here's what I did yesterday.
In light of this inability of the engine to run inverted, I mounted engine 1 on the test stand right side up and set up a gravity feed fuel system. It was running in short order and tuned easily. Ran 380 mL through it on the stand, then switched to a low mount fuel tank. Still running well, although cold start is a little tricky. I have to flip it on choke until it pops, and then flip it 3 more times under choke to get it really wet.

So now engine 1 runs well on the stand. Yay. I put it back on the plane. After 15 minutes of flipping I was able to get it started. Once it was running, I had to play with the high needle just a bit to smooth out the high end. That's where my arm said no more flipping today.
Sep 25, 2016, 11:10 AM
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Update:

Tried it again this morning. No start upside down. flip the plane upside down so the engine is right side up, starts immediately.

Screw these things.
May 02, 2017, 03:26 AM
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Hi Guys,

Old thread but I thought I'd post my experience as well.

I have just purchased my NGH GT35R and after difficulty in getting the fuel to draw I found the same issue, the pulse pump hole is misaligned from the walbro carb.

Currently I'm thinking of just drilling out the standoff plastic spacer and gasket to open up the suction path.

Any thoughts?

https://i.imgsafe.org/8343aae1f9.jpg
https://i.imgsafe.org/83456ab9ab.jpg
https://i.imgsafe.org/834663ce77.jpg
May 02, 2017, 03:36 AM
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This is a much better way to get the pulse than what was suggested in the thread.
Plastic spacers and thermal isolators are easily modified, I always check for alignment and that is what I do when I need to ensure I get the pulse. You can drill a hole in the spacer in the correct position and remove all the material between the two holes or just dig a channel, either way will work.

Edit: no need to change the gasket if it aligns well with the thermal spacer.
May 02, 2017, 03:57 AM
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Agreed, Yes that is what I'm planning to do.

I'll let you know how it goes.

Here's a video showing the misalignment, this is the video I used for a partial store credit RMA with Hobbyking.

https://www.youtube.com/edit?o=U&video_id=XrS4iCVfPwM

I still think its crazy that such a manufacturing oversight can occur.
May 02, 2017, 04:38 AM
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It's unfortunate but really only a minor issue, now we expect everything to be 100% from day 1, these small issues can be annoying but expected.
May 02, 2017, 04:44 AM
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Just another day ( probably a Friday ) at the NGH factory . Now where is Mr NGH when u need him .
May 02, 2017, 06:34 AM
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Tucci's Avatar
One thing I have to say about these 35s, they have plenty of power if you can mount them with the cylinder up. Although they won't start inverted, I did end up modifying the profile airframe to accept the engine with the cylinder pointed up. Flew it a couple times, and the engine was a great performer.

Then I ran it out of fuel and crashed it. Sold both engines.

They also might be OK if you had a starter to turn them.....
May 02, 2017, 07:35 AM
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Quote:
Originally Posted by Tucci
One thing I have to say about these 35s, they have plenty of power if you can mount them with the cylinder up. Although they won't start inverted, I did end up modifying the profile airframe to accept the engine with the cylinder pointed up. Flew it a couple times, and the engine was a great performer.

Then I ran it out of fuel and crashed it. Sold both engines.

They also might be OK if you had a starter to turn them.....
Hey Tucci, is old age creeping up on you that you're becoming nostalgic all of a sudden??