Valve seat removal

I'm doing an overhaul on a dodge 2.2 engine. Things were going relatively smoothly until I got to lapping the #4 exhaust valve. All the other valves went OK. It seems the valve seat is too worn or something. I can get a replacement valve seat for less than $10, but I don't know how to remove the old valve seat.

I checked online and there were a few suggestions. There are special machines, but I can't justify that kind of cost for something I'll only use once. Another method used a milling machine, which I don't have. One method was to weld a bead on the seat, and once it cooled the seat would contract or you would have enough of a lip to punch it out. Unfortunately, welding is not among my many skills. One suggestion was to put the cylinder head into the oven at 450 degrees for 30 min. and the different thermal expansion between the aluminum cylinder head and the steel valve seat would let the seat drop out. Problem there is I don't want to remove the other valve seats.

I am considering trying a heat gun to heat up seal and surrounding area, hoping that would loosen the seat enough to pry out. Another idea is to try a dremel tool to cut out enough of the seat to try to punch it out, but if I cut too deep I'll have to buy another cylinder head. I suppose I could just keep trying to lap the valve and hope I can get a good seal.

Any ideas would be welcome.

A new head at a yard that hasn't been overheated.....or a machine shop....they will see if it's warped and needs milling...a reply to: VictorVonDoom

Try some mcgyver tricks. Use a can of butane on the seat to shrink it.
Be careful, the residual is flammable as hell, even a little while after it looks evsporated.
Not sure flashpoint if you hit w heatgun shortly after so wear a helmet.

I suppose I could just keep trying to lap the valve and hope I can get a good seal.

This is why you should stop right now. ^^^

I've been wrenching on my cars as a hobby and to keep them up to shape for forty years and that's one thing I won't do myself. Take it to a machine shop. It needs to be checked for cracks and warpage anyway, this is very common for post-1980 engines, especially four cylinder engines. If the head checks out ok just have them do the valve seat if you're hell-bent on not having a real valve job done. Sorry if it sounds blunt but think about what you're doing. Do you really want to risk not doing it right and having to tear it all apart again and spend even more money?

a reply to: VictorVonDoom

short answer - sub-contract the job to a specialist cylinder head business

i spent 4 years rebuilding mercedes comerical engines - and it wasnt worth the effort to attempt valve seats myself

DIY " bodges " on critical jobs aways come back to haunt you

I appreciate the replies so far.

I should have mentioned that I already took the head to a machine shop. It was hard finding a machine shop willing to take it on. When I told them it was out of an 83 k-car most said they wouldn't touch it. The place I took it to had it for 3 weeks and never got around to it, so I just brought it home. Plus, they were going to charge $100 more than getting a reman from Autozone.

I figured I could do the job myself, and I can, I'm just stuck on the this one point. I've already bought a new camshaft, bearings, rockers, seals, etc. so all that money would be wasted if I gave up and bought a reman head at this point.

I may just do what I usually do in situations like this: stare at it until I get an idea. One just occurred to me as I was typing this. Maybe I could grind a small notch into the cylinder head just behind the valve seat that would allow me to get a pin punch behind the valve seat and knock it out. That shouldn't hurt anything, even if it doesn't work.

a reply to: VictorVonDoom

First thing you need to consider is that aluminum expands 2 times more than steel at equal temperatures which means that if you install the steel valve seat into an aluminum head wrong, the seat could drop out when the motor is running causing major carnage(broken valve, busted piston, gouges in cylinder wall, busted head….etc).

Are your valve guides ok, is there any wear on the valve stems, have you checked the clearance with a dial indicator? If there is any play (side to side slop) in the valve when it’s in the guide it may be impossible to get the valve to seat properly. You may need to install new guides and valves if there is too much wear on them.

If you don’t have the equipment or the experience in rebuilding heads, take it into a machine shop that does. They can also check the head for cracks and warp. Aluminum heads can warp a lot if the motor was ever overheated. It will cost you a bit more money but your wallet will thank you later.

originally posted by: VictorVonDoom

Maybe I could grind a small notch into the cylinder head just behind the valve seat that would allow me to get a pin punch behind the valve seat and knock it out. That shouldn't hurt anything, even if it doesn't work.

DO NOT do this, you will destroy the head. The seat requires a tight fit to keep it in place.

a reply to: Grayarea

I wouldn't think so, but maybe I could grind a small notch in the valve seat itself that would allow the pin punch a little footing to knock the seat out. Tomorrow I'll make a little sketch to show you what I'm thinking.

So many Johnny-don'ts around here.

If you're rebuilding a dodge I'm going to assume you don't need this engine to work- you just want it to.
I'm also going to assume you're doing this because you can, not because you need to.
Last assumption, if you've got a k-car you probably have some other junk laying around.

So, here's how I'd tackle that valve seat.

One, get yourself a mapp gas torch. If you don't own one, get on that. Yellow bottle, same thread as the little green propane tanks.... same torch head too. You'll learn to love this torch setup.

Two, find some junk aluminum and torch the # out of it. You'll find out that mapp gas CAN melt that aluminum- just not very easily. Feel the heat, and be mindful when torching your aluminum head. I doubt you'd be able to soften up a head enough to damage it with a handheld torch... but I've never tried. Aluminum will suck the heat away too fast, probably.

Now, head back into the same junkyard you got that k-car from (back yard?) and find a propane grill you don't care for. Cut off the gas line- you want the fitting that goes on the tank, and a few feet of tube. Find a tank that's at least half full, too.

Jimmy jack a way to put that tank upside down while you can still get to the on/off valve.
When you open that valve, the regulator and line are going to get very cold, very quickly. Liquid propane is a real bitch, don't get it on you. Anything it touches will get VERY cold as it evaporates.

So- now you have a torch that gets things hot as hell, and a liquid that gets things very cold.
Heat expands metal, cold makes it shrink.

First thing I'd do is heat the # out of that valve seat. the heat will sink into the metal around it. If you can touch the head with your bare skin after this, its probably not hot enough.
Then, uh... carefully... spray the valve seat with liquid propane. Note that it might explode a little bit.

Eyebrows not withstanding, get a dental pick or similar and I bet you can scoop that seat right out.
Then, go have a beer and relax for half an hour while the smell of burnt hair wafts away.

source:
third generation shade tree problem solver
15 years experience

Well, gentlemen, it's official. I'm a dumbass.

I looked at the problem with fresh eyes this afternoon. Hmmm, I wonder. I figured I would need to get a new valve, seat, and guide anyway. So I went and got a new valve, minimal lapping, and Bob's your uncle. It seals just fine. The problem wasn't the seat, it was the valve.

Where's Red Forman when you need him?