willysmjeeps.com

Hi guys,
I'm very new to this site and really look forward to learning a lot. I just bought a '51 M38. It's has a slight clicking in the number 4 cylinder? I went to adjust the valves and discovered the last valve had some rust on it where all the rest were covered in oil. The valve spring also has a lot of play I it compared to the others. I used a feeler gauge and the valve seems to be spaced at the correct .016 spacing.Can anyone shed some light on why the valve is clicking and will it hurt the engine to drive it with this issue?

Was the last valve you refer to the rear valve? #4 Exhaust.

Was the rust on the face or stem?

Are you checking clearance static cold?

Do your ALL exhaust valves have rotator caps ?

Is the side play of the valve stem in the guide excessive?

Is the side play of the cam follower in the block bore excessive?

Thanks for getting back to me so quickly Wes. To answer your questions:
Yes, it was the #4 exhaust.
I believe the rust was on the top of the stem just below where you check the gap.

The engine was cold when I checked the clearances. I used the .016 gauge and the clearance was tight on all the valves

All the exhaust valve look complete with rotator caps

The side play when I move the spring is much more noticeable on #4 exhaust than any of the others

The cam follower doesn't seem to have much side play.

My biggest concern is that I do not want to damage the block or head if there is a serious issue. It's not like I will be putting a lot of miles on this jeep. I was just hoping that the clicking could be resolved by adjusting the valve.

Then it could be the worn guide in #4 Exh or a soft pair of springs. Are you certain the ticking was not coming from the fuel pump or elsewhere on the engine?

To add to Wesk Comments---you say you are moving the Spring around. You could have a broken spring or soft spring as Wesk pointed out.

Looking at your picture---the valve to lifter doesn't look "square". Look at the valve beside it and notice how everything is centered on the valve stem and lifter. Check the face of the lifter "adjuster" for wear. I once had an engine which had the correct clearance on the valves, however, there was a noticeable indention on top of the adjuster. The feeler gauge was on top of the ridge around the indention giving me a false reading.

After looking at the picture very closely, it appears the rotator cap is not square to the end of the valve stem. It appears the distance is longer on the right than the left. It could be one of the keepers is missing. Sometimes they can be tricky to get set in completely. Jim

Come to find out it was actually a broken valve spring. I'm just waiting on the correct tools to arrive and it will hopefully be an easy fix. Thanks for all the help guys

I was able to replace the #4 exhaust valve spring without removing the head thanks to a great youtube video. Once I figure out why I am not getting fire to the plugs I hope to hear her run again.