Valve seat problem

[Randy SR]

On my way to pick up my grandkids this morning, the engine started making a racket. Got a tow home, pulled the head, and found a chunk of metal in the #2 cylinder. Upon looking closer, there is a chunk of the #2 exhaust valve seat missing, the same size as the piece of metal I found. Is it possible to replace one valve seat with the engine in the car, or should I just pull the engine and take it to a machine shop and have them replace it?

[Joe Bell]

They originally never had valve seats? was it added or is it a two piece valve that came apart?

[Randy SR]

I've got about 10 years on this rebuild, or about 2,000 miles. At some point in the past steel valve seat inserts were installed in the block. I cranked the engine over until the #2 exhaust valve was lifted and can see that it's a valve seat like the one that Lang's shows in their catalog. The valves are one-piece valves.

[speedytinc]

New valve seats can be easily be cut/installed without removing the motor. An over sized seat & regrind be had.

Good news: that can be done easily to first 3 cylinders on a T without even sliding the motor forward.
Bad news: why did one give way? Are others going to come out further down the road?

[Randy SR]

Re: good news/bad news. What tools do I need to do the job in the car? If tool costs are too high, it's probably easiest to take the engine out to someone who is equipped and knows what they're doing. As far as the bad news, I don't know why it came apart, and maybe I want to replace them all.

[TXGOAT2]

I'd consider replacing them all, and look VERY carefully for a crack across the valve seat. As for why it came out, it could be that the valve was not seating correctly and allowing the valve and seat to run very hot. A valve that was adjusted too loose and allowing the valve to slam down hard on the seat might cause it to loosen. A crack across the valve seat could cause the seat to loosen.

[speedytinc]

I'd consider replacing them all, and look VERY carefully for a crack across the valve seat. As for why it came out, it could be that the valve was not seating correctly and allowing the valve and seat to run very hot. A valve that was adjusted too loose and allowing the valve to slam down hard on the seat might cause it to loosen. A crack across the valve seat could cause the seat to loosen.

Yes, I would be concerned about loosing other seats. They dont fail typically ever & especially after so few miles.

Its probably not the kind of thing you will do yourself. A cutter set would be over $500 used. However, talk to your mechanic/machinest They may have the equipment to do it in car. Arrange to have it towed to him. You can even pre-clean the deck.

[Randy SR]

Good information; a couple of months ago I found the #2 exhaust valve was VERY loose, and adjusted it, so that may be my problem. Upon closer inspection, it appears there are inserts on the #2 and #3 exhaust valves only.

My magneto has not worked for a long time, the clutch is slipping, and the low speed drum has a definite groove in it. Looks like it's time to pull the engine, get the valve seat fixed, and rebuild the transmission. I bought the car in 2007, had a rebuild done on the engine in 2010 (lost babbit on #1 rod) but didn't know much about the car at the time. I know much more now, so will correct some things that have needed attention.

[Norman Kling]

While you have it out, inspect very carefully the area in the block between the cylinder wall and the valve seat. This area is very common to be cracked. It gets very hot and if the water is low and someone pours cold water into the radiator, it can crack very easily. If it is cracked, the crack might have gone all the way into the seat and caused it to crack and the piece fell out.
Norm

[Randy SR]

Norm, I will definitely check there. The valve seat failed between the valve and the exhaust manifold side of the engine, so not on the cylinder side.

[Duckwing]

Several years ago my wife’s brother installed a valve seat in my engine. He owns a motorcycle shop and brought his “machine” to my barn and did the job without removing the engine. I provided the valve seat. He installed it. Worked fine. He also has a powder coat business. Nice to have a relative with the know how/tools/facilities.

[Quickm007]

They originally never had valve seats? was it added or is it a two piece valve that came apart?

Hi Joe, did you know if they have any video how to adjust valve in the goal to have more torque? Thx

[Mark Gregush]

I am thinking that because you are replacing a seat, you may need to go to a larger OD to get press fit. Without knowing what OD size was used in the first place, they are not all the same, you might be better off taking to shop that can order the correct size needed. When first installed, pockets are cut to the interference fit and depth of seats used. Once the seat is installed, you may or may not need the deck surfaced.

[Randy SR]

It looks like only #2 and #3 exhaust valves have seats, so I will replace them both, and have a good look at #1 and #4 as well.

Radiator, headlights and bar, floorboards, and steering column are out. DIsconnecting drive shaft will be next, then engine mount bolts. Should be ready to pull the engine this afternoon!

[Randy SR]

Does anybody know where I can get a single .020 over aluminum piston? The affected one is pretty battered on the top, the others are all good, and the vendors only list them as a set of four.

[Mark Gregush]

If it is only battered on top, no big dents or cracks, I would clean it up and use. Otherwise you are going to have to match it to the ones you now have left in the engine. Not all pistons are made the same or have the same weight.

[TXGOAT2]

New pistons are very reasonably priced.

[Craig Leach]

Randy, thats correct pistons are not that expensive. I had a two piece valve become a two piece valve and brake through the head.I replaced the valves, and head and had a knock. Turned out the impact that didnt break the piston fractured the battit in the rod. Pulling the engine seem's like a lot of work. But sometimes a major go through is not that much and gives years of confident driving knowing every thing is right.
Good luck. Carig

[TXGOAT2]

Ideally, you'd pullit, fixit, and balance it. If you cannot avoid re-using the damaged piston, be absolutely certain that the rings do not bind in the ring grooves. You could not pay me to re-use a piston like that. The rod may be out of alignment, too. That needs to be carefully checked.

[Randy SR]

Great information from forum members as usual, i had not considered the rod or babbit issues. Engine is out now, today I will make an adapter (as seen on the forum to mount the engine to my engine stand and start disassembly.

[Scott_Conger]

I suppose I'm the contrarian of this crowd...

the size piece of valve seat that you're describing is not big enough to be caught between the piston and head...yes the piston top is dinged up, but the rod is not going to be bent nor is the Babbitt going to be damaged.

Regardless of age, 2000 miles is far too little miles for bands to wear to the point that rivets are cutting drums; it is all but certain that that grooved drum was there when the engine was last placed into service and a groove in and of itself is little reason to replace much less warrant a transmission rebuild. yes, some grooves warrant drum replacement, but many or most do not. Don't let anyone convince you to remove the groove via machining as that will take off too much metal to risk placing back into service. A light skim by a guy who knows what he is doing if the drum is not round on the bushing, but to remove the groove...that would be a No-No. If the high-speed clutch is slipping, that may be a simple and common adjustment. Inspection of the clutch pack will guide you on this.

From the evidence presented, if this was my car, I would have verified that the clutch was maladjusted or had a shot after-market clutch long ago. That wasn't done, but it is now a simple inspection without dismounting the transmission from the engine, and certainly not a mandatory rebuild. Additionally, seat failure is pretty darn rare and I would not be inclined to remove an existing seat preemptively, though there are arguments and inspections which could be made to verify the odds of that being a good or bad choice...it certainly is not a mandatory job without much more thorough inspection and evaluation. Finally as far as babbit and rod goes, your rings are seated, the pistons are happy being where they are and it is nearly inconceivable that anything was damaged by that small of a piece of metal which never got "squoze" between two solid mechanical parts. "Dings" in the top of the piston are absolutely no concern in a 20HP low-reving engine. I'd replace the valve because it is cheap and that means very cheap insurance.

Magneto? Again I doubt that despite the years (particularly when you say it quit long ago) there is anything wrong with the mag-ring or magnet gaps with as few miles as the engine has now or the engine HAD when it quit. These are not flaky things that mysteriously go "poof" in the night. With the engine on the stand it is easy to probe the contact and spin the engine and look for signs of electrical life. Now, if you ever removed the starter and the mag subsequently quit, then it is near certain that the mag ring is damaged.

Now, I'll sit back and watch while you're further talked into $3000 worth of work by everyone else.

[TXGOAT2]

" The affected one is (piston) pretty battered on the top" ..... Picture? A picture of the damaged piston and the loose piece of valve seat would be helpful, as would a picture of the underside of the head.

[Dan Hatch]

Have not read all threads , so do not know if this subject has been discussed.
When installing valve seats, you should do so BEFORE you bore clys. Installing seats can warp the cly bore. Specially on a T where bore is close to valves. Dan

[TXGOAT2]

At one time, I believe that a substance called litharge was used to help set valve seat inserts. Warming the block and chilling the seat insert might also be helpful. A seat that is jammed too tightly in the block risks cracking the block. An exhaust seat that is not set tight enough will likely overheat and allow the seat to further loosen. Ford V8s were originally equipped with hard valve seat inserts for many years. Most of them stayed put, even if cracked. It might be helpful to see if specifications for the V8 seat to block interference fit are available. The seat needs to be tight enough to stay in place under harsh conditions, and it needs to have full contact with the block to maximize heat transfer to the block.

[Dan Hatch]

If you look up seat in a catalog most tell you what size they are and what size to bore.
Also, sleeve retainer helps.

[Randy SR]

I got everything taken apart today. The forum search taught me to build an adapter for my engine stand, and make a $0 valve spring compressor.

The rods and babbitts all look good, looks like the only damage is to the top of the #2 piston and bottom of the aluminum head. I'm hauling the block down to a machine shop tomorrow to get a new valve seat installed, and will have them look over the other valve seat insert. All the valves look good, I will lap them and reinstall, except for replacing the #2 exhaust valve, even though I don't see any damage to it.

I took the transmission off so I could pull the crankshaft, and will be checking babbitt clearance on the main caps before putting it back in. Main babbitts look good. The band linings don't even look worn, nowhere near worn down to the rivet heads/. The low speed drum was grooved when I bought the car. So maybe a clutch inspection (and replacement if necessary), and readjust everything. Other than the clutch slipping, the transmission was smooth, no shudder or chatter, and shifted well. Might as well re-line the bands while it's apart, though.

An ignorant owner who shall remain nameless removed the starter without removing the bendix, and I can see where it chewed up the magneto coils. He is better educated now. Time for a rebuilt magneto coil ring.

My grandfather (1899-1984) got me interested in Model Ts, he drove them as a young man. He always said he could fix anything that broke with a hammer, pliers, and baling wire. Looks like I'll be close to doing that in this case.

[Scott_Conger]

Assuming the engine ran just fine before this mishap, the only thing you'll really accomplish with lapping the valves is widen the seats and lower them. If you have a lot of time on your hands and a bucket of grit, you can even ruin them.

The shop should fit a new valve to the new seat and check everything. Hoping that you numbered the valves, they should be able to happily drop back into the holes from which they came.

Again, your car simply has too few miles for things to have worn to the point of needing any remedial work (yes, I know the seat came out...broken parts is different than worn parts).

[Kerry]

Geees Scott, what are you using for lapping paste that you can widen and lower the seats!!

[Scott_Conger]

Kerry

I don't use lapping paste. I cut the seats with Neway cutters. Now, you may not increase seat width too much nor drop the seat too much, but you know what you're doing. Given the inclination and time, pretty much anyone with no experience can take an engine from good shape to a real mess, and I know that you've seen your share of them yourself and had to fix them.

My advice was given knowing the engine had only 2000 miles and failed for a very specific reason unrelated to burned valves. In the absence of any other information either in words or pictures, I stand by it. If it was an old engine or even an engine with unknown miles and perhaps one or more obvious issues coming on such as hard starting or low power, I believe my advice might be different. That however is not the case with the OP's description.

[Randy SR]

The engine ran fine before the valve seat came apart. I may not be a smart man, but I DID number the valves, and labelled EVERYTHING so I could put it back together exactly as it came apart. The affected valve has no marks on it, but I will change it just the same. I'm taking the valves down to the machine shop with me to make sure I get the right size, as I see that Lang's has a standard size and a 1/32 oversize.

How do you measure things to check to see if the clutch is worn out?