Need Help, 6th valve no pressure

[88supra_lawn ornament]

Did a pressure test and all the valves came out relativly fine except for 6, it read only 20 pounds of pressure, need possible problems that may not involve ripping the sucker apart.

Any suggestions would be greatly appreciated.

Thanks
Kyle

 

[mrnickleye]

I assume you mean #6 cylinder that has 20psi..... Does the engine run?....Perhaps one of the valves is too tight on #6, or you have a burnt exhaust valve.. Whats the compression on 1-5 cyls ??? I gotta know to help....After you post the #s, I'll give you some info.

 

[siman]

wow if that is the static compression.....you have a hole in your piston! LOL :nono:

 

[88supra_lawn ornament]

Here are the numbers that i got.
190, 190, 210, 200, 210 AND # 6 CYLINDER IS 20 LBS

The car does run, however I can not get the rpm to rise above 3K at best. everything else seems to be in ok condition, and the car is an 88 turbo model if that helps with the info.

Thanks
Kyle

 

[supraturbo1987]

Sounds like you have a stuck open exhaust valve or are missing an exhaust valve (or part of one) or have a hole in your piston. I would go with the valve problem though...happened to me on #6 with a motor that had 2K miles...

Trev

 

[mrnickleye]

Probably stuck open valve. But....Pull the spark plug out, and put a 19mm socket and ratchet on the crank bolt to bring the piston up to the top. Use a very bright flashlight to look into hole, and maybe you might see a hole in piston(most holes will be at spark plug because that is what would burn the hole there).

If you can't see, take a coat hanger and poke around on the piston top to see if it suddenly goes way in (hole). Probably not hole.

Pull valve covers off and check that valves are working properly. Yes?? then likely a very burnt valve.