HELP! Hyper 7 TQ Engine Problems During Break-in

[imashy14u]

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!

 

[cbaker65]

Are you still running it at break-in settings?

You will have different opinions about this matter ,but when I break in mine ,I ween the richness of the settings do
to eccessive fuel ,not only your engine is tight ,it also has to put up with too much fuel ,in which is harder on it ,also ,
try loosening up the glow plug to relieve some of the compression when you start it ,after it starts ,an as you throttle
on & off keeping it running ,you can tighten up the glow plug as it runs!

You can lean HSN about a 1/8 at a time ,if you already have 4 tanks ,then a 1/2 a turn wont hurt for the rest ,
also ,when you lean ,the engine may start to rev higher ,then ,you will have to adjust your idle set screw!

I hope this helps!...

 

[NCNitro]

I have never been a fan of idle break in. I have used the heat cycle method for years with great sucess. What bump box are you using? When breaking in my rb concepts ws7ii in my hyper 7 pcr pro I found the only box that would start it was the ofna chrome top starter box with the 12v gel cell. Even with that box it would still occasionally get stuck. I needed to push the car down just enough to bring the wheel up to speed then bump it. It might help if you loosen the glow plug just a bit then tighten it back up once you have it running.

 

[imashy14u]

Are you still running it at break-in settings?

You will have different opinions about this matter ,but when I break in mine ,I ween the richness of the settings do
to eccessive fuel ,not only your engine is tight ,it also has to put up with too much fuel ,in which is harder on it ,also ,
try loosening up the glow plug to relieve some of the compression when you start it ,after it starts ,an as you throttle
on & off keeping it running ,you can tighten up the glow plug as it runs!

You can lean HSN about a 1/8 at a time ,if you already have 4 tanks ,then a 1/2 a turn wont hurt for the rest ,
also ,when you lean ,the engine may start to rev higher ,then ,you will have to adjust your idle set screw!

I hope this helps!...

Hi cnbaker65, thanks for the reply.

After the 2nd tank I leaned it out about 1/8 of a turn and leaned it out another 1/8 of a turn after the 3rd tank, but didn't get to the 4th tank

The problem I have at the moment is that the piston is stuck at TDC and the only way to loosen it is to take the engine out of the car and turn the flywheel by hand, which takes a lot of effort as it's so tight. But I don't want to be doing that all the time, especially when after each attempt to start it on the box, it gets stuck again. Even with the glow plug off it gets stuck at TDC, so definitely the pinch is tight and not the compression.

Tried heating it with a heat gun by pointing it down the top of the engine/heat sink for about 10 seconds, but still doesn't get loose. Is 10 seconds with a heat gun enough time, or should I do it longer? The engine gets hot to touch, but not scolding hot. Not sure if I should be heating it up longer.

 

[imashy14u]

I have never been a fan of idle break in. I have used the heat cycle method for years with great sucess. What bump box are you using? When breaking in my rb concepts ws7ii in my hyper 7 pcr pro I found the only box that would start it was the ofna chrome top starter box with the 12v gel cell. Even with that box it would still occasionally get stuck. I needed to push the car down just enough to bring the wheel up to speed then bump it. It might help if you loosen the glow plug just a bit then tighten it back up once you have it running.

Hi NCNitro, thanks for the reply.

To be honest, I'm not sure what starter box it is, it's one I had from years ago when I used to play with nitro cars. I think it might be a Q-World one? I connect it to by car's 12V battery for power using aligator clips.

You're right, it get's stuck quite often when the piston gets stuck at TDC and I have to try and loosen the flywheel as the starter box doesn't have the power to turn it. I can't even turn it easily with my hand, so I wouldn't expect the starter box to either.

Tried taken out the glow plug just to turn the engine, but it doesn't work when the piston is at TDC, so it would be the tight pinch in the sleeve that is casuing the problem, rather than the compression.

 

[cbaker65]

Hi cnbaker65, thanks for the reply.

After the 2nd tank I leaned it out about 1/8 of a turn and leaned it out another 1/8 of a turn after the 3rd tank, but didn't get to the 4th tank

The problem I have at the moment is that the piston is stuck at TDC and the only way to loosen it is to take the engine out of the car and turn the flywheel by hand, which takes a lot of effort as it's so tight. But I don't want to be doing that all the time, especially when after each attempt to start it on the box, it gets stuck again. Even with the glow plug off it gets stuck at TDC, so definitely the pinch is tight and not the compression.

Tried heating it with a heat gun by pointing it down the top of the engine/heat sink for about 10 seconds, but still doesn't get loose. Is 10 seconds with a heat gun enough time, or should I do it longer? The engine gets hot to touch, but not scolding hot. Not sure if I should be heating it up longer.

Ooh ,I am not sure at this point what you should do ,I only had one engine do that once ,an the engine quit doing it after
some run time!

 

[olds97_lss]

Something you can do to help the process is to loosen the glowplug 1/4 turn and once it's running, tighten it back up. That will help lessen the force needed to crank it over.

Since you have a heat gun, preheat the engine prior to attempting to start. Get the crank case up to 180-200F, then start it while it's still hot. If you heat the cooling head, it should wick heat to the crank case and warm it up as well. This will cause the sleeve to expand a bit, which will also lessen the force needed to get it going more easily. I'm guessing 10 seconds isn't nearly long enough to do much other than warm the cooling head a bit.

Good engines have a tight pinch that takes time to wear down. Cheap engines are usually less tight after 4-5 tanks. A good one will likely be pretty tight for the first gallon or so of it's life. I've also found that they really start tuning well and put out good power after a gallon or so is run through them. Cheaper engines don't take that much run time to fully break-in. They also don't last as many gallons.

I also follow the heat cycle method. I only keep track of tanks just so I know how much I've put through an engine. But once I get it running, I run in slow figure 8's. As it starts to loosen up, I'll run up to WOT slowly and let off. I just do that over and over and adjust the needles to try to get the temp up to 180F. I'll run it for about 5 minutes, kill it, put the piston at BDC and let it sit until it's down below 100F. Then I'll heat it up again, start it, run it, etc. I go through that process for 6-8 tanks. Then I just run it for 2-3 tanks at a time, slowly speeding up, letting off. By the time you get 1/2 gallon through it, it should be ok to run it pretty good. There's about 3800cc's in a gallon of fuel. A typical tank is 125cc. So by the time you get to 15 tanks, your at half a gallon.

 

[imashy14u]

Something you can do to help the process is to loosen the glowplug 1/4 turn and once it's running, tighten it back up. That will help lessen the force needed to crank it over.

Since you have a heat gun, preheat the engine prior to attempting to start. Get the crank case up to 180-200F, then start it while it's still hot. If you heat the cooling head, it should wick heat to the crank case and warm it up as well. This will cause the sleeve to expand a bit, which will also lessen the force needed to get it going more easily. I'm guessing 10 seconds isn't nearly long enough to do much other than warm the cooling head a bit.

Good engines have a tight pinch that takes time to wear down. Cheap engines are usually less tight after 4-5 tanks. A good one will likely be pretty tight for the first gallon or so of it's life. I've also found that they really start tuning well and put out good power after a gallon or so is run through them. Cheaper engines don't take that much run time to fully break-in. They also don't last as many gallons.

I also follow the heat cycle method. I only keep track of tanks just so I know how much I've put through an engine. But once I get it running, I run in slow figure 8's. As it starts to loosen up, I'll run up to WOT slowly and let off. I just do that over and over and adjust the needles to try to get the temp up to 180F. I'll run it for about 5 minutes, kill it, put the piston at BDC and let it sit until it's down below 100F. Then I'll heat it up again, start it, run it, etc. I go through that process for 6-8 tanks. Then I just run it for 2-3 tanks at a time, slowly speeding up, letting off. By the time you get 1/2 gallon through it, it should be ok to run it pretty good. There's about 3800cc's in a gallon of fuel. A typical tank is 125cc. So by the time you get to 15 tanks, your at half a gallon.

Thanks olds97_lss!

I'll look at heating up the engine longer and hotter to expand the sleeve more and help loosen up the engine. Hoepfully I can get over this initial breaking in process and my son can enjoy the car.

 

[olds97_lss]

Even using a hair dryer works, just takes longer. But, it's less likely to overheat surrounding stuff. You can also put a sock on the cooling head to help hold in some of the heat until you get through break-in. Just get a cheap 6 pack of baby socks and cut the ends off. Use the elastic bit around the cooling head to help block air going through it, which holds heat.

 

[imashy14u]

Even using a hair dryer works, just takes longer. But, it's less likely to overheat surrounding stuff. You can also put a sock on the cooling head to help hold in some of the heat until you get through break-in. Just get a cheap 6 pack of baby socks and cut the ends off. Use the elastic bit around the cooling head to help block air going through it, which holds heat.