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These are two intake valves from my 292 rebuilt 5K miles ago. It started using a ton of oil. a qt every 300 miles. I suspected valve seals so put new seals on about 500 miles back and the oil usage stayed the same. I pulled the heads and oil was pulled in the intake chambers in 4 out of 8 ports. The machine shop supposedly knurled the guides when the machine work was done. There is no sign of knurling in the two guides I took the valves out of. Is the carbon build up on these intake valves due to oil cooking on the valves after the engine is shut off. I have never ever seen an intake valve in this condition. I thought I had pulled the exhaust valves by mistake. Any thoughts on this?
I am no expert but, the knurled valves take out movement in the valve stem which may cause the valve seals to leak or fail early. (I am not a fan of knurling valves) You recently installed new seals which would have to have failed with that much oil loss, if that is the problem. If the seals are still tight on the stem and the valve seats are good ( I cannot tell from the pics) then there must be another reason for the oil loss. How is the fit between the valve stem and the valve guides?
You can wiggle the valve stems in the guides and oil will ooze out as you are wiggling the valves. There is no sign of the guides being knurled as I was told by the machine shop, and the guides definitely have not been replaced. So the guides have 100K miles on them. When I pulled the intake to remove the heads, I looked into the chambers and oil was pooled in the intake chambers of the ones the valves were close on. Definitely have to be coming through the guides.
You can wiggle the valve stems in the guides and oil will ooze out as you are wiggling the valves. There is no sign of the guides being knurled as I was told by the machine shop, and the guides definitely have not been replaced. So the guides have 100K miles on them. When I pulled the intake to remove the heads, I looked into the chambers and oil was pooled in the intake chambers of the ones the valves were close on. Definitely have to be coming through the guides.
Thats really too bad. When I first read the post my thought was possibly a bad PCV valve but you seem to have nailed it down to the guides. Time to find another shop to deal with/
Thats really too bad. When I first read the post my thought was possibly a bad PCV valve but you seem to have nailed it down to the guides. Time to find another shop to deal with/
I did get a set of heads from Tim McMasters. Tim put in bigger valves for better breathing. John Mummert makes aluminum heads but there was no way I could afford those or even justify them. There are a few shops around the country that are very knowledgeable about these Y's and if I got heads from any of them, I would have been confident in their abilities. Tim was very helpful. Obviously the local machine shop here which has a very good reputation doesn't understand Y's.
I did get a set of heads from Tim McMasters. Tim put in bigger valves for better breathing. John Mummert makes aluminum heads but there was no way I could afford those or even justify them. There are a few shops around the country that are very knowledgeable about these Y's and if I got heads from any of them, I would have been confident in their abilities. Tim was very helpful. Obviously the local machine shop here which has a very good reputation doesn't understand Y's.
The wiggle test tells the tale. The Mummert heads are pricey and way more HP than would be good for a mostly stock truck.
The wiggle test tells the tale. The Mummert heads are pricey and way more HP than would be good for a mostly stock truck.
No thread activity in a while, just wondering if you resolved the issue. Your post makes me have less faith in my rebuilt y-block. I had machine work done years ago, but my truck wasn’t ready for running it yet so it has not been started. The shop did screw up the oiling ports when they put in the cam bearings, so my faith in them is in jeopardy, even though they always done well for
mu machine shop work on the past. I’ll probably be running the truck this year, so I’m hoping for the best.
I put the heads on that were done by McMaster. I put on close to 500 miles on the engine before the snow flew and it consumed little to no oil. Spark plug inspection shows no oil fouling just a light tan to greyish color. I will no more in the spring when I start driving it again but am confident the issue has been resolved.
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