Go Back  R/C Tech Forums > General Forums > Nitro Off-Road > Offroad Nitro Engine Forum
2 Attachment(s) You are subscribed to this thread HELP! Hyper 7 TQ Engine Problems D >

2 Attachment(s) You are subscribed to this thread HELP! Hyper 7 TQ Engine Problems D

Like Tree1Likes
  • 1 Post By xlrsd

2 Attachment(s) You are subscribed to this thread HELP! Hyper 7 TQ Engine Problems D

Reply

Old 08-11-2019, 06:32 PM
  #1  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Unhappy 2 Attachment(s) You are subscribed to this thread HELP! Hyper 7 TQ Engine Problems D

Hi guys,

Sorry for the long post that's coming up.

Haven't played with Nitro care for at least 10 years and just bought a brand new Hyper 7 TQ Buggy with the Hyper 21 3-port engine for my son to try and introduce him to the hobby. It's been a nightmare trying to start the engine to do the break-in process. My son hasn't been happy about it and I'm worried it's going to put him off the hobby even before he's started.

Was going through the break-in process of idling the engine for 3 tanks and then 2 tanks of easy driving, as per the manual that came with the car. Anyway, before even getting the engine started on the first tank, we broke the pull start, it wouldn't recoil. It broke because of the hard pulls, especially with the tight pinch of the piston and sleeve. Took the pull start off the engine to have a look and the spring popped out and it was a nightmare trying to put it back in. So decided to remove the spring and the cord winder and just put the cover back onto the engine and plug up the hole where the cord goes through. I had a starter box, so decided to use that to start the car. Tried numerous times to start the engine, but it wouldn't start. There would be times when the piston would get to TDC and get stuck due to the tight pinch of the new engine, so I would turn the flywheel by using a screwdriver and prying it from the bottom to make it turn as it was too tight to just use my fingers. Of course, each time this happened, it would slightly damage the flywheel. the tightness was there even when I removed the glow plug. Anyway, did this a few times and eventually the engine started and we left it idling for the full tank.

Once the tank was almost empty, we stopped the eninge and left it to cool down for 5 minutes, making sure the piston was at BDC and "loose". Go to start it again, same thing happens. It would crank a little and then get stuck at TDC and have to pry the flywheel to loosen it and then tried starting it on the box again. Did this again and again and it would get stuck again and again. During my attempts to start the engine, I would remove the glow plug to release the compression, heat up the engine with a heat gun and try to crank the engine, but it would do the same thing of getting stuck at TDC. Even running the engine for one tank, it didn't seem like the tightness had reduced. So kept prying the flywheel to loosen it, then trying to start it on the box. Eventually after about an hour of trying, it finally started and we idled it for the second tank.

Time for third tank and what do you know, the same thing happens. Spent another hour doing what we have been doing just to try and crank the engine and start it. While during this time with all the prying of the flywheel, most of the small teeth on the flywheel have broken off from the the force required to turn it using the screwdriver. Eventually it started and I'm thinking surley it will be all nice and loose by now after three tanks, so I can just turn it with my fingers. NOPE!

Going for the 4th tank and again the same issues. This time it seemed like the tightness is even worse! with all the prying, the flywheel pretty was much shot and doesn't have any teeth left in the areas that corresponds to the piston's TDC. I even broke two screwdrivers trying to pry it and tunr it. I removed the engine from the car to turn the flywheel with my hand. It required alot of force to turn it and eventually it got loose, so I'm thinking it should be ok now. Put it back onto the car and try to start it and it happens again and the piston gets stuck at TDC with no way of being able to turn the flywheel without taking it off the car again. At this point I'm p1$$ed off and gave up.

Has anyone had this problem before and if so, how did you sort it out? I'm really stumped on why the pinch is so tight. I know new engines are tight, but not this tight, especially after 3 full tanks of idling. I've given up on trying to sort it out and pretty much thinking it's a $500 dud that I bought. The unfortunate thing is my son has waited so long to play with it and his disappointment really shows. I'm going to take it back to the hobby shop I bought it from and see if they can help. I might need to get the flywheel changed, because it looks terrible. Knowing my luck, they will say the engine is stuffed and not covered under warranty!
imashy14u is offline  
Reply With Quote
Old 08-11-2019, 06:46 PM
  #2  
Tech Regular
iTrader: (1)
 
frewster's Avatar
 
Join Date: May 2014
Posts: 495
Trader Rating: 1 (100%+)
Default

You need to preheat the engine if it's that tight. Most RTR engines aren't super tight so they work fine with a pullstart but it appears yours is tighter than the PS can handle. There are engine heaters that go on the engine made by SkyRC, Protek, Competition Heat, etc but the easiest thing is to get a cheap heat gun and use that to warm up the engine before starting. I always warm my engines up to 160-180F before starting. Also make sure the engine is primed because if it isn't you'll be trying to start it all day.
frewster is offline  
Reply With Quote
Old 08-11-2019, 06:51 PM
  #3  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Default

Thanks frewster.

I have tried pre-heating the engine with a heat gun. That worked a bit before the 2nd and 3rd tanks, but now after the 3rd tank it won't budge even after heating the engine.

I really don't know what else I can do. I can't keep taking off the engine from the car to loosen the flywheel as it pretty much happens everytime I try to bump start it.
imashy14u is offline  
Reply With Quote
Old 08-11-2019, 07:07 PM
  #4  
Tech Regular
iTrader: (1)
 
frewster's Avatar
 
Join Date: May 2014
Posts: 495
Trader Rating: 1 (100%+)
Default

I'm sorry! I read too fast and typed too soon. I didn't see that you had already preheated it. Is it possible to have it replaced under warranty? A pullstart engine shouldn't be this tight.
frewster is offline  
Reply With Quote
Old 08-11-2019, 07:17 PM
  #5  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Default

Hi frewster, no problem. Apprciate your help.

Yes, I agree a pull start engine shouldn't be this tight. It's crazy tight!
imashy14u is offline  
Reply With Quote
Old 08-11-2019, 07:48 PM
  #6  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Default

Originally Posted by frewster View Post
You need to preheat the engine if it's that tight. Most RTR engines aren't super tight so they work fine with a pullstart but it appears yours is tighter than the PS can handle. There are engine heaters that go on the engine made by SkyRC, Protek, Competition Heat, etc but the easiest thing is to get a cheap heat gun and use that to warm up the engine before starting. I always warm my engines up to 160-180F before starting. Also make sure the engine is primed because if it isn't you'll be trying to start it all day.
Frewster, with heating the engine with a heat gun, how long should I heat the engine for? I only pointed the heat gun down the top of the engine for about 10 seconds as I didn't want to heat it too much as it was getting hot to touch, but not scolding hot. Should I heat it longer? Some say heat it for about 10 minutes with a hair dryer, but a heat gun is much hotter, so 10 minutes won't be needed I would think.
imashy14u is offline  
Reply With Quote
Old 08-11-2019, 08:58 PM
  #7  
Tech Regular
iTrader: (1)
 
frewster's Avatar
 
Join Date: May 2014
Posts: 495
Trader Rating: 1 (100%+)
Default

Originally Posted by imashy14u View Post
Frewster, with heating the engine with a heat gun, how long should I heat the engine for? I only pointed the heat gun down the top of the engine for about 10 seconds as I didn't want to heat it too much as it was getting hot to touch, but not scolding hot. Should I heat it longer? Some say heat it for about 10 minutes with a hair dryer, but a heat gun is much hotter, so 10 minutes won't be needed I would think.
10 seconds is much too short. I move it back and forth between the crankcase and the head. I probably do that for 1-2 minutes. Being hot to the touch doesn't mean that the heat has soaked into the internals which is where it actually needs to hear up. Infrared temp guns start around $10 and while the cheap ones aren't perfectly accurate (no adjustable emissivity etc) they do give you a decent idea of temp. It would be a good investment. The RC specific infrared ones are more expensive but pretuned for more accurate engine temp readings.
frewster is offline  
Reply With Quote
Old 08-11-2019, 09:51 PM
  #8  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Default

Originally Posted by frewster View Post
10 seconds is much too short. I move it back and forth between the crankcase and the head. I probably do that for 1-2 minutes. Being hot to the touch doesn't mean that the heat has soaked into the internals which is where it actually needs to hear up. Infrared temp guns start around $10 and while the cheap ones aren't perfectly accurate (no adjustable emissivity etc) they do give you a decent idea of temp. It would be a good investment. The RC specific infrared ones are more expensive but pretuned for more accurate engine temp readings.
Oh ok, maybe i am not heating it up enough. Where would I point the temp gun, down the heat sink into the glow plug?
imashy14u is offline  
Reply With Quote
Old 08-12-2019, 04:36 AM
  #9  
Tech Adept
iTrader: (3)
 
Join Date: Jul 2011
Posts: 249
Trader Rating: 3 (100%+)
Default

Originally Posted by imashy14u View Post
Oh ok, maybe i am not heating it up enough. Where would I point the temp gun, down the heat sink into the glow plug?
you can do a little heat directly in to the heat sink and glow plug, but I always focus the heat gun more on the engine case, just below the heat sink. As this is where the piston and sleeve are internally, and those are the parts of the engine internals you most want to heat up, to loosen the “pinch”. Although this can be accomplished by just blowing straight down the heat sink, I think it takes less time to get it to a good starting temperature by blowing the heat on both sides of the engine case below the heat sink.
Micah78 likes this.
xlrsd is offline  
Reply With Quote
Old 08-12-2019, 04:53 AM
  #10  
Tech Adept
Thread Starter
iTrader: (7)
 
imashy14u's Avatar
 
Join Date: Jul 2007
Posts: 206
Trader Rating: 7 (100%+)
Default

Originally Posted by xlrsd View Post

you can do a little heat directly in to the heat sink and glow plug, but I always focus the heat gun more on the engine case, just below the heat sink. As this is where the piston and sleeve are internally, and those are the parts of the engine internals you most want to heat up, to loosen the “pinch”. Although this can be accomplished by just blowing straight down the heat sink, I think it takes less time to get it to a good starting temperature by blowing the heat on both sides of the engine case below the heat sink.
Thanks xlrsd. I’ll take that into account.
imashy14u is offline  
Reply With Quote
Old 08-15-2019, 03:46 AM
  #11  
Tech Rookie
 
Join Date: Jun 2019
Posts: 5
Default

Use pipe grips to move the flywheel out of TDC when it gets stuck.
Redtopracer is offline  
Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service