Cracked valve seat

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Model T Ford Forum: Forum 2013: Cracked valve seat
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Gaines on Sunday, November 03, 2013 - 07:59 pm:

Is it possible to repair a crack starting at the valve seat area and leading to the side of the block in an exhaust port ?
It does not appear to be cracked all the way across.
New to the model T scene and any help would be appreciated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Sunday, November 03, 2013 - 08:40 pm:

Yes,but quite possibly costly. Unless it is a rare block,might be easier to find another. You can always rebuild it later.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Putnam, Bluffton, Ohio on Sunday, November 03, 2013 - 08:59 pm:

Yes it can be fixed by a machine shop. The crack can be pinned and a new seat installed. I have to disagree with Uncle Jack, about $25 per crack including the seat.
T blocks are famous for cracking in the center two exhaust seats from the valve to the outside of the block. Once repaired, problem gone.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Sunday, November 03, 2013 - 09:03 pm:

Dale,
Here are a bunch of ideas:
http://www.mtfca.com/discus/messages/29/25489.html?1179861450

Everything from run it to fix or junk it.

My block has cracks with seats and it works fine.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Sunday, November 03, 2013 - 09:13 pm:

Jack ,it all depends on the machine shop. Around here,some of them think they have a license to steal.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Vancouver, WA on Sunday, November 03, 2013 - 09:15 pm:

http://www.mtfca.com/discus/messages/331880/385494.html?1378063234


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tyrone Thomas - Topeka KS on Monday, November 04, 2013 - 10:49 am:

two engines i have replaced the seat with a hardened seat and poured in a bottle of a Micro head and block sealer. both blocks have been running trouble free for 4 plus years.


Top of pagePrevious messageNext messageBottom of page Link to this message  By J and M Machine Co Inc on Tuesday, November 05, 2013 - 09:46 am:

Dale :
Yes we do this repair all the time as the Model T and Model A for that matter are prone to the exhaust seats cracking. You need to find someone that does crack repair utilizing metal stitching.

www.jandm-machine.com


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Wednesday, November 06, 2013 - 01:00 pm:

Typically, with the type of hair-line cracks that usually occur in the #2 & #3 cylinder exhaust valve seats, if they point out in the direction of the exhaust manifold ports, all you generally have to do is install a seat and it will cure any potential issue. If the crack is big enough to catch your fingernail in, then maybe it needs to be stitched.

My ACTUAL experiences:

About ten years ago right after I bought my touring car, I did a valve job. I reamed the valve guides oversize and re-ground 3-angle seats in with a Sioux Valve Seat Grinder. The block did not have hard seats and the center two exhaust valve seats had the "typical" cracks mentioned above. At the time, I did not have the tool for installing hard seats in the block without pulling the engine, so I just left those seats just the way they were and didn't do anything about the hair line cracks. I installed new stainless valves, lapped them in, and timed the valves by piston position. I put roughly 15,000 miles on that car over the next couple years and had the head off to install new piston rings about four years later and pulled out those valves to examine what the seats looked like. The contact area between valve and seat was clean and polished and you had to look real close to see where the crack in the seat was. If I didn't know it was there, I probably would never had seen it. There was no hint of discoloration or leakage near the crack. HOWEVER, at this time, I did have the tooling to properly install a hard seat and decided to do so at that time "just in case".

I have also seen quite a few of these "typical" exhaust seat cracks on customers motors that I have had apart for one reason or another and no valve issue was noted previous to dis-assembly and no discoloration of signs of obvious leakage were present.

I have a suspicion, that these types of cracks may have occurred early on in the life of some of these engines and probably only rarely ever got "bad enough" to cause any issue.

Your results may vary...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Lovejoy, So Cal on Thursday, November 07, 2013 - 12:55 am:

Very interesting, I had those same crack's. Looked like they had been there a long time. Put seats in, but not really sure if I needed too now. Thanks Adam.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Thursday, November 07, 2013 - 01:58 am:

Here is one of the video's that Lock n Stitch put on Utube. These videos are in several parts so you have to find the following one.
www.youtube.com/watch?v=Pq0wfU4ZaKk‎
This may be the same video:http:
//www.youtube.com/watch?v=Pq0wfU4ZaKk. One of the videos shows how to lock the repair.


Top of pagePrevious messageNext messageBottom of page Link to this message  By J and M Machine Co Inc on Thursday, November 07, 2013 - 12:00 pm:

Quote:
Very interesting, I had those same crack's. Looked like they had been there a long time. Put seats in, but not really sure if I needed too now. Thanks Adam



When the seats loosen up/fall out from the crack growing from heat you'll have to ask the same question over again.

If we see a crack in an engine we fix it.
There is no "need to" it's "Has To."!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Thursday, November 07, 2013 - 12:20 pm:

Not fixing cracks in a block no matter where they are at, shows a great LACK of Engine rebuilding knowledge!!!!!!!!!

Cobble, Cobble, Cobble!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Thursday, November 07, 2013 - 12:55 pm:

O my 15 touring, I started to get water into the oil, and was told that crack like this was probably responsible. I have not yet pulled the head to check and don't plan to use it until fixed. I have another late 15 block to rebuild since the current one also has a big water jacket crack.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Thursday, November 07, 2013 - 01:06 pm:

80% of all these "typical" exhaust valve seat cracks that I have seen do not extend more than about 1/3 of the way out towards the exhaust manifold port. If they extend any further than that, I would recommend more of a repair than just installing a seat, but I rarely see them worse than that. The photo that J&M posted above is a far different story. Any crack that extends towards or into a cylinder should be properly repaired.

If the engine ever gets hot enough for one of these "typical" cracks that extend in the direction of the manifold to "grow" and cause a seat to get loose, the engine is likely to be so terribly overheated that a loose valve seat would be the most insignificant problem you would have.

The cast iron block (under ordinary circumstances) is not flexible enough to allow the counterbore for that the seat to "open up" and allow a seat to become loose.

With all this being said, I am not advocating that people don't have to do anything if they have valve seat cracks, or only have to put in a seat. What I am saying is that in most circumstances: If you are doing the rebuild yourself and, if that is all you are able to do, all you can afford to do, or all you are willing to do, then it is pretty likely that you probably won't have any further trouble. If you do have trouble, your T gets a trailer ride home and you fix it right at a later date, no big deal. HOWEVER, if you have it all apart and it is at the machine shop or re-builder, then of course, get it fixed!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Thursday, November 07, 2013 - 01:21 pm:

Amazing!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Thursday, November 07, 2013 - 01:34 pm:

Dale Peterson: Check your freeze plugs to see if they are leaking. Believe it or not, I have seen instances of a freeze plug leaking and the antifreeze getting into the engine thru a valve cover that was poorly sealed at the top! It doesn't sound like much could get in that way, but it was enough to make the engine oil milky!

Herm Kronke: Prattling on about "not fixing cracks showing a lack of engine building knowledge Cobble Cobble, etc." Herm, If someone was paying thousands of dollars to have an engine rebuilt, then yes, all cracks need to be properly repaired. HOWEVER, if a hobbyist has the head off his T that otherwise runs fine and just happens to see one of these "typical" cracks in an exhaust seat; Are you saying that the only rational thing he can do is pull his motor, strip it down and take it somewhere for repair or risk facing a catastrophic failure where his car will die a horrible death somewhere out in the middle of nowhere with buzzards circling overhead? JEEEZ!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Thursday, November 07, 2013 - 03:01 pm:

Yes! As you evidently don't know, cracks in blocks NEVER get better, they always get worse!

Not fixing a known crack when first found will cost more in the long run.

As J & M said, putting in a seat to stop a crack don't work. It is like using a big Cork as a cure for Diarrhea!

And every body knows a Model T will never boil.

And the Buzzards would only come in to effect from the owner shooting him self in the head from not repairing cracks. JEEEZ!



Is it possible to repair a crack starting at the valve seat area and leading to the side of the block in an exhaust port ?
It does not appear to be cracked all the way across. "END QUOTE"

You leave a crack go in an exhaust port, and you may not be left with anything to fix.

But who cares Adam, it won't cost use anything! Right!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Thursday, November 07, 2013 - 11:35 pm:

I usually keep around 50 blocks on hand so I don't ever repair one, I just grab another one off the pile. The only time I would consider spending any time or money on a cracked block would be on a VERY EARLY one.
A little off the subject of repairing blocks it seems that 26 blocks are very popular any more. I have one guy take five 26 blocks and another took three. Many others have taken one or two 26 block.
While moving some blocks inside the shop today I thought why am I keeping so many blocks, I seldom rebuild one any more!

blocks


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