View Full Version : 91ST motor, the head keeps coming loose?
10-02-2008, 01:52 PM
The head on my 91ST keeps coming loose and I'm not sure why. I've checked it and none of the bolt threads are worn and I use locktite everytime i put it back togetter but for some reason it keeps coming loose over time. Is this a normal thing to keep checking and doing maintenance on or is there something wrong?
10-02-2008, 07:31 PM
what color loctite are you using?
10-03-2008, 04:53 PM
10-03-2008, 05:12 PM
sounds like the motor is detonating you might be to lean!! what fuel are you running
10-03-2008, 06:02 PM
Blue loctite is removable with heat.. red loctite is for High heat applications.. Also remember to tighten the head bolts in a sequence across from each other, not radial. Just like an automobile.
10-03-2008, 11:30 PM
Yup I do use the radial method, but maybe will try the red loctite. It is a new fuel then I'm use to so maybe I am running a little to lean? Its Power Master 30% heli. The settings were way different from the magnum 30% heli i was running but that may have been from the head starting to loosen?
10-04-2008, 12:28 AM
was that a typo? you mentioned you do tighten the bolts in a circle. Vs alternating across from each other. use red sparingly, and make sure you do not use Permanent loctite. Semi perminent sparingly will deteriorate slow enough to last about long enough for you use the engine and be able to crack it apart when its time to rebuild if you dont replace. Good luck. yes, switching fuel brands can be a pain at times because of the different lubrication package each one uses. Thats why its always best if you can to stick with one flavor. Hard to say about the head being loose before you switched, though leaning out usually is a sign that something is leaking air aside from improper tuning.
10-05-2008, 04:32 PM
Sorry ya that was, i do go back and forth like a car tire to tighten the head down. Ok I will give it a go and see how it makes out using the semi permanent loctite.
red loctite has no place on any kind of rc model period!!!
03-15-2009, 07:52 AM
Do not use red locktite !!!
The engine was not designed to use locktite on any of the bolts, the motor has to be detonating and causing a serious vibration for the head to come loose, install a new head gasket and shim the head out until your detonation is gone and your problem will go away.