Please help. I think I have a piston problem with my PRO-70BX

[dj_sparky]

I just recently traded a Thunder Tiger EK-4 with a Pro-70BX engine. First off, this engine was way bigger than I expected!

Anyhow, when I look into the piston from the pipe manifold, it seems to leak air when it's pushed up and/or down. Nevertheless, it doesn't seem to have compression. Is this normal for this engine?

Any tips on what I can do?

 

[Metalhead Matt]

It should be hard to rotate past the top with the glow plug in it.

 

[dj_sparky]

There's hardly any resistance whatsoever when pushing the piston upwards, and when it reaches the top it leaks out air.

 

[Metalhead Matt]

Where's it leaking air from? May be a bad glow plug seal (copper ring) or the head bolts may be loose.

 

[Mickstix]

Yea, also head could be warped, bad button or button washer (if it takes one).. Any number of things..

 

[dj_sparky]

The air is leaking out from the exhaust gate (The place where the pipe is placed onto. The pipe manifold.) when I push the piston upwards (Which has no resistance whatsoever). Is it leaking past the piston ring?

 

[Mickstix]

Well, that could be normal? I believe, depending where the piston and crank are in their cycle, it'll let air out the exhaust chamber.. I think your best bet is gonna be to just hook it up to the juice and see what it does.. I sounds as if you may be light on compression, but unless your a guru on nitro (I'm certainly not) you should just see if you can get it to run and see how she does.. Best of luck and let us know what happens!

 

[dj_sparky]

Thanks. Don't know how these large engines are supposed to be, but I'm guessing lots of them have compression problems.

Found the source of the problem, which was a bump in the manifold that surrounds the piston head the to ensure a tight seal (Where you screw the cooling house onto). And the cooling head screws were loose as well. Along with a couple of ribs, which seemed to have broken loose.

Anyhow, I got it started, but only for a few seconds and full throttle before I discovered this. Will keep working on it.