Crankcase vent blocked?

[ZSPOT]

When I purchased my '98 a while back, I noticed they had the vent tube disconnected, and a vacuum cap over the vent nipple. When I test drove it, it ran fine and didn't smoke one bit.

Fast forward to fixing a few issues to include the vent tube, and a leak test that yielded 6lbs for 10 min no problem. Now that it's all back together, it smokes pretty bad and the idle is very high at 1.5 turns out from tight. It idles fine with about 3/4 turn out.

Was the blocked vent tube a quick fix for a bad crank seal? And wouldn't a leak test have found this? Any other suggestions welcome too.

 

[tbrooks]

Yeah it could have been hiding a leak. Some times a hot or cold engine, can be the difference in an air leak, but yes a leaktest should have found it. Are you talking about the idle screw or air screw?

 

[nick20555]

Yes, the leak test would have told you if you had a bad crank seal if you did it correctly.

The crank case vent's purpose is to relieve pressure and the crank case heats up and the air inside wants to expand so if it was plugged then I would think that would mess with pressures in your bottom end.

 

[ZSPOT]

Idle screw is all the way in,... air screw is 3/4 turn out.

I didn't go as far as replacing the crank seal, which I'm guessing is what my next step should be. Should I do the other side while I'm at it?

 

[nick20555]

Turning your idle screw in increases your idle speed. If your idle is to high then back it out some. You may not have a problem other than your idle screw needing adjusted out

 

[ZSPOT]

Gotchyah. The previous owner had the idle screw that way, and sealed with rtv. Thanks!!

 

[Blaaster]

This is the prescribed way to set the idle speed, taken from the service manual.

There should be no air leaks and the float level must be within specs.

Warm up the engine first.

Your idle screw will be in the carb body!

 

[Blaaster]

If one seal requires replacing, the other one will have the same amount of use, so it is a good idea to change both.

 

[nick20555]

If one seal requires replacing, the other one will have the same amount of use, so it is a good idea to change both.

I thought since his leak test came out leak free that he wouldn't need to replace the seals?

 

[ZSPOT]

Thanks Blaaster!!

I think it may just be my inexperience with carb adjustment. It makes sense. Would the air screw being too rich be causing the extra smoke though?

 

[Blaaster]

I thought since his leak test came out leak free that he wouldn't need to replace the seals?

The question asked in post 4 was being answered!

 

[Blaaster]

Thanks Blaaster!!

I think it may just be my inexperience with carb adjustment. It makes sense. Would the air screw being too rich be causing the extra smoke though?

Running rich will produce more smoke that normal.

At idle speeds oil often pools in the crankcase and the throttle needs blipping to purge it out.