PT 422 fuel tank

[SpringHollow]

I assume you have tried the weld a nut etc to get them out. If you are looking at replacing the heads, do you have anything to lose trying to remove the head and drill them out with a left hand drill bit sized to just miss the threads? Half the time it comes out once you drill part way. Replace with oversize threads if need be. Worst case, you then replace with a new head and cover.

Ken

 

[marrt]

I've got a couple broken valve cover bolts and I get about 20 minutes before oil starts seeping onto the hot parts. Can't get the broken bolts extracted from the heads. Only solution seems to be new heads and valve covers, as they don't make new heads with old-style valve covers for the Kohler. I've tried a couple rounds of sealant, but that doesn't work for more than a few hours, then back to the 20 minute rule. Grrrr.... gonna have to break down and do it.

I recently threw away the Kohler that came out of my first PT (same engine you have). Was saving it for parts but got tired tripping over it.

I assume you can't weld a nut to the broken stud? That's usually that best method as the heat tends to loosen the bolt as well.

If that doesn't work, you can get a few left-handed cobalt drill bits from Mcmaster-Carr and, starting with a small drill first, work your way up. Once the hole in the bolt is large enough, it releases pressure on the threads and the left-handed drill will catch and spin it out.

You're probably dealing with galvanic corrosion between the bolt and head. Since you're at the verge of buying a new head, you can be more aggressive. If the drill method doesn't spin the bolt out, just drill it to slight oversize and re-tap (or put in an insert like a Heli-Coil to keep the same size bolts).

I guess another option would be to drill a small hole next to the broken bolt and insert a screw. You might consider using an anaerobic sealer, rather than RTV or similar. They work well on metal to metal contact. I think Loctite may even make a sealant that will, essentially, enable you to permanently "glue" the cover to the body.

And finally, do you have a machine shop near by? Machinists are experts at broken stud removal.

 

[MossRoad]

Well, see, here's my predicament. They are snapped off deeper than I can weld a nut onto them. I've done that before and that would have been my first thing to try if not for the depth.

2nd. I bought left hand twist drill bits and it didn't come out. So I put an EZ out in there to get it out, and the EZ out snapped off in there on one of them. So now there's a piece of hardened broken EZ out in that one.

3rd. I have one broken on each head. So both heads will need to be replaced if I can't get them out. On that one, I may be able to just keep increasing the size of the left hand bit until it's gone and skip the EZ out. So I may be able to salvage that one.

4th. I need the machine weekly, because, my lawn grows so fast. So I don't want to attempt it, FAIL, goober up the thing so much that I can't put the valve cover back on, and have no spare head to replace it with.

Still thinking....

 

[BigDaddyEureka]

If you're really out of options @MossRoad sometimes you can drill a very small hole NEXT TO the stud hole to loosen the grip of the stud in the hole, then get it out, then drill a larger hole and use a helicoil. TOTALLY a PITA, and 100% not recommended when there's any other option. Sometimes this happens in a shipboard engine where the engine is built into the ship...so it's an option, but definitely not a great one.

 

[marrt]

Well, see, here's my predicament. They are snapped off deeper than I can weld a nut onto them. I've done that before and that would have been my first thing to try if not for the depth.

2nd. I bought left hand twist drill bits and it didn't come out. So I put an EZ out in there to get it out, and the EZ out snapped off in there on one of them. So now there's a piece of hardened broken EZ out in that one.

3rd. I have one broken on each head. So both heads will need to be replaced if I can't get them out. On that one, I may be able to just keep increasing the size of the left hand bit until it's gone and skip the EZ out. So I may be able to salvage that one.

4th. I need the machine weekly, because, my lawn grows so fast. So I don't want to attempt it, FAIL, goober up the thing so much that I can't put the valve cover back on, and have no spare head to replace it with.

Still thinking....

Number 4 is your biggest problem. With time, you can keep escalating the risk of destruction until it comes out or you ruin the head. But not if you need the tractor weekly.

You can bust out an EZ out with a punch and lots of patience. Can’t hurt to hit it a few times to see what’s up. I’ve used this technique successfully before. If this is a “cheap” EZ out, it may be brittle anyway (and may be the reason it broke).

On a milling machine, you could drill it out with a carbide bit...but you need a very rigid setup for this to have a chance of working (i.e., it will never work with a hand drill). Even then, you'd probably need to ruin a couple cobalt bits to get the top of the EZ out flat enough so the interrupted cut doesn't break the carbide bid.

I'd attack the head w/o the stuck EZ out first, using the left hand drill bits as you suggested. If you get that fixed, I'd remove the other head and take it to a friend with a milling machine. You're a friendly guy so you must have a couple friends with milling machines...or, at least, a friend of a friend. I have a milling machine but was working on it and needed to use a milling machine to fix my milling machine. I asked around and found two within a couple miles.

 

[MossRoad]

I have friends that ask ME to fix stuff.

I know people with lathes, but not milling machines. I better tell them to step up their game.

 

[johara1]

Too bad we are so far apart .... I have a mill...... jim

 

[MossRoad]

I have a kid in Pittsburgh. But that's a 6 hr drive each way. Thanks, though.

 

[johara1]

What size bolt broke off? We use to take out broken head bolts out of Mack engines with a piece of steel pipe and a welder. Put the pipe down in and weld it inside and turn them out with a pipe wrench ..... jim

 

[MossRoad]

What size bolt broke off? We use to take out broken head bolts out of Mack engines with a piece of steel pipe and a welder. Put the pipe down in and weld it inside and turn them out with a pipe wrench ..... jim

It's a pretty small bolt. I don't think it's even 1/4".