The Stovebolt Site Forums The Shop Area Engine Shop Broken valve guide

Looking for some answers on a broken valve guide on my 235 fresh rebuild. History of the truck the motor was rebuilt by me my first one ever. I had the head rebuilt at a local machine shop along with everything new installed in the motor except for the crank and rods and they were all reconditioned by the same machine shop. The motor went through the Breakin period without any problems and i did use zppd with the oil.

It's been about a 7-year build on the whole truck and I finally got to drive it a few weeks ago. As I was putting around to town I got about 15 miles into the motor and I heard a noise the truck started missing and I immediately shut it down. A few seconds before it made the noise my water temperature was 185 and my oil pressure was 40 PSI as I was constantly monitoring it while driving it. Upon tearing the motor down figure out what the problem was I seen the valve guide was broken. When it broke down I let the truck warm up for about 10 to 15 minutes before I took it on a little stroll around town and I was not running it hard just City driving down my little rural town about 35 miles an hour.

Other facts to be considered the motor was rebuilt probably about 3 or 4 years ago. There was no bad gas in it the valve's didn't have any varnish on it no rust on it . Everything was adjusted correctly to the best of my knowledge and everything in the head was new except for the rocker assembly which was all clean and inspected.

Not to point fingers I just would like to know what may have caused this to happen the parts I got for the head I believe we're from Patricks. Any ideas just for my knowledge would be great thanks again

http://i61.photobucket.com/albums/h50/Jes89048/20190312_132750_zpswrhhte62.jpg

Most valve guides are cast iron, unless you go to the trouble and expense of installing bronze ones. It's pretty easy to get one a little out of alignment as it's driven into the head and cause a hairline crack as it tries to align itself with the hole bored into the head. I usually store guides in a freezer overnight and heat the cylinder head a little before driving the guides into place, or if I want a really snug fit I'll bore the holes in the head a little undersize and cold-soak the guides in a bath of dry ice and alcohol before driving them into place. Depending on how good your relationship is with your machine shop, I'd suggest asking them to share in the expense of correcting their mistake, maybe buying a gasket set, etc. in addition to replacing the broken guide. How long ago was the machine work done?
Jerry

The engine was rebuilt and i had the machine shop do the cylinder head work about 4 years ago. It would have been done sooner however i had a leg amputation so things were put hold till i was able to finish it up and get plates one it. When i inspected the head there was a lot of oil you could see running back to the block. Everything looked lubericated. All of my engine parts except the pistons, rings and main cap bearing were purchased through patricks. I looked at patricks web site and its no longer there. By the way are you still making and selling the vibration damper install tool . if so i am interested in purchasing one now if you still are doing that.

Well I had to have two valves replaced and actually 2 valve guides we're broken Plus 2 bent pushrods. I was extremely nervous because that was the first motor I had ever rebuilt especially the inline 6 which is not common to the younger guys or at least in my town. The shop where I took the truck to said the Machine Shop made the valve guides too tight and didn't leave enough tolerance so it was nothing done with my amateur rebuilding skills it was the Machine Shop that created the error. So I will have it fixed they say the valves are all operating properly now and we're at the right tolerances so the motor should be a lot quieter and back in business within a couple days I just wanted to share an update.

Thanks for the update.🛠

Thats not uncommon, valve guide clearances are pretty tight. Machinist could have been having a bad or really busy day, or just over looked it trying to get it out the door, stuff happens. If they help with the cost, you are good to go, if they don't, find a different shop next time. Glad that it going back together, and hope you get some drive time finally.

Joe

I had to return my head to my machine shop when I got it back. A couple of mine had hairline cracks. I called them on it and they tried to make me pay again...uh, no. Fix it.
I hate it that these days a guy usually has to be mean to be treated fairy.

I am definitely in the school of leaving the original cast iron stock guides in place and installing bronze liners. It's a little easier to get the proper clearance for the valve stem, and if for whatever reason the clearance is a little tight, I think the bronze is more forgiving.