BrianStasC-101 5 #1 Posted April 8, 2023 Hello all I have gone down the rabbit hole with my C-101 tractor. Bought it and noticed a moderate smoking on startup and after some research it has led me to believe I have worn valve guides. After pulling the head I can see someone has honed the cylinder wall and done rings and the compression is great the smoke only occurs on startup. A friend of mine that restores antique tractors told me that unless it smokes after warming up it is likely the valve guides. I was wondering if anyone here has experienced this issue and has any advice on how to go about replacing them as information on the subject is quite sparse. I'm assuming with the correct reamer for the replacement guides I could ream them and then drive and finish ream them. any advice on this topic would be very beneficial to helping me sort this out. Thanks. 1 Share this post Link to post Share on other sites
WHX?? 51,728 #2 Posted April 8, 2023 When you pulled the head was it "washed" or did it have carbon build up. Washed or clean head or piston top means rings. I have more than a couple k motors that smoke like the dickens but goes away for the most part when working. Was there any noticeable side to side play in the valves. Share this post Link to post Share on other sites
BrianStasC-101 5 #3 Posted April 9, 2023 @WHX?? There is carbon buildup present in the head no washing present. I will have to unspring the valves and check for side to side play. My dad is a kohler buff and he told me to get a new intake and exhaust valve and check side to side play and try to lap them in and see how it goes. If not I fear I may be riding the fine line near a machine shop visit to have the valve guides redone unless there is something else I am missing. Hoping I can get her sorted because it is a very nice tractor and will hopefully be with me for a long time. I'll attach and image of the old girl. 2 1 Share this post Link to post Share on other sites
oliver2-44 10,694 #4 Posted April 9, 2023 Pull the valves and measure the stems in the guide area and the lower unworn area. Diameter spec also in the Kohler manual. If they are worn in the guide area you might’ve able to just replace the valves like your dad suggested. This may not fully fit it, but could make it a lot better. (I did this on my sons 312-8 and now it just has a tiny puff of smoke on startup and runs great). Share this post Link to post Share on other sites
RED-Z06 2,567 #5 Posted April 9, 2023 Its not extremely common, on a horizontal flathead, to get smoke from guides,because gravity keeps the oil out of the ports. On ohv for example you will have oil present on the rickers, stems, springs, keepers..and it can seep down past a bad seal/guide and cause a smokey startup. But on a flathead, the oil stays in the valve spring box, and gravity keeps it there. Im interested in how much slop you have in your valves, they would need to be pretty loose id think, to blow case pressure up from the valve spring box. Share this post Link to post Share on other sites
ri702bill 9,377 #6 Posted April 9, 2023 Brian - welcome. All good info so far. A couple of things come to mind. I wonder, since this engine has been apart before, if the breather plate was installed wrong with the oil drain hole at the top, not at the bottom where it needs to be?? Once you have the breather assembly off, familiarize yourself with checking the valve clearance between the tappets and valve stems - more on that in a bit. Use a good valve spring compressor to allow removal of the split keepers with a pencil magnet. Important - keep the spring, rotator / plate, and keepers with the respective valve - do not mix them up. Take a good look at the area where the head of the valves seals on the insert in the block - may be time for a valve job anyway..... Determine if you need to replace the valves, guides, or both... New Guides need to be final reamed with them installed (like a sleeve bushing, they DO close up a minute amount when pressed in). IF you go with new valves - as supplied, the stems are too long. This allows grinding the end of the stems squarely to set your valve clearance. Lap the valves and seats, clean out all the grit, check the clearance again - if good, reassemble. Install the breather plate correctly... Share this post Link to post Share on other sites
WHX?? 51,728 #7 Posted April 9, 2023 1 hour ago, ri702bill said: Important - keep the spring, rotator / plate, and keepers with the respective valve - do not mix them up. Why is that Bill? I don't do that just with tappets. Share this post Link to post Share on other sites
ri702bill 9,377 #8 Posted April 9, 2023 (edited) It is my understanding that the cam lift is different on intake & exhaust - that spring has seen a certain repeated deflection all it's life - You don't want to deflect it more now... One of my 7 HP K161 engines had only one rotator, the other valve did not. That right there affects the valve spring installed height.... Bill Edited April 9, 2023 by ri702bill 1 Share this post Link to post Share on other sites
squonk 43,752 #9 Posted April 9, 2023 Funny thing about those rotators. I have seen them on both valves, 1 valve and none at all. They are supposed to be on the exhaust only. 1 Share this post Link to post Share on other sites
ri702bill 9,377 #10 Posted April 9, 2023 (edited) And that's where it was.....makes sense - it's always the exhaust valve that takes a beating up thru normal use.... Edited April 9, 2023 by ri702bill Share this post Link to post Share on other sites
