dropped valve??

74loaf · « **on:** November 20, 2011, 03:43:43 PM »

so I popped off my valve cover today on cylinders 1&2 of the 74 bus since it has been idling lately with a miss.... I figured I would find a valve needing to be tightened.... instead what I found was a rocker arm over an intake valve that had so much play in it I could literally stick my finger between it and the valve. and the adjuster was still tight!

Not sure if you can tell from the pics, but the valve is actually stuck about a half an inch in the head. the spring is still compressed, but the valve isnt coming all the way back out. what would cause this? dropped valve guide?

attack chicken · « **Reply #1 on:** November 20, 2011, 04:21:02 PM »

Dropped valve seat. The valve seat is a hard steel ring that is pressed into the head,when conditions are right..ie heat,age,quality of original fitment..the seat will fall out of the head when the valve opens and then when the valve closes it won't go back all the way. It won't come off the valve unless it breaks or the valve breaks, it just pounds the life out of the head everytime the valve is opened and closes. The valve spring pressure is probably between 200-300 psi which makes for a pretty good hammer. Type 4 engines and 140hp Corvair engines are known for dropped valve seats. That's my guess.

Ret.Bugtech · « **Reply #2 on:** November 20, 2011, 05:25:48 PM »

Quote from: attack chicken on November 20, 2011, 04:21:02 PM

Dropped valve seat. The valve seat is a hard steel ring that is pressed into the head,when conditions are right..ie heat,age,quality of original fitment..the seat will fall out of the head when the valve opens and then when the valve closes it won't go back all the way. It won't come off the valve unless it breaks or the valve breaks, it just pounds the life out of the head everytime the valve is opened and closes. The valve spring pressure is probably between 200-300 psi which makes for a pretty good hammer. Type 4 engines and 140hp Corvair engines are known for dropped valve seats. That's my guess.

A intake seat falling out is pretty rare. I have seen my share of exhaust valve seats falling out. No matter because the head has to come off. You might get lucky and find a nut or screw behind the head of the valve. I have seen that before. Seeing how you have one those rebuilt engines from" $^#%&@$%*^#$" there is no telling what you are going to find. Keep us posted. Your name will be posted on the Type- 4 "Wailing Wall of Shame"

Russ · « **Reply #3 on:** November 21, 2011, 02:59:35 PM »

Didn't we tell you not to buy a GEX motor?

74loaf · « **Reply #4 on:** November 21, 2011, 04:03:09 PM »

next up... trying to remove the head without pulling the engine.

Zen · « **Reply #5 on:** November 21, 2011, 04:06:20 PM »

Quote from: 74loaf on November 21, 2011, 04:03:09 PM

next up... trying to remove the head without pulling the engine.

Ummmmm . . . no. Save yourself a LOT of extra work and go ahead and pull the engine.

Ret.Bugtech · « **Reply #6 on:** November 21, 2011, 04:51:30 PM »

Quote from: Zen on November 21, 2011, 04:06:20 PM

Quote from: 74loaf on November 21, 2011, 04:03:09 PM
next up... trying to remove the head without pulling the engine.

Ummmmm . . . no. Save yourself a LOT of extra work and go ahead and pull the engine.

Like Zen said. To much prying and bending even on a lift, but it's your Coal Truck, use C-4 if you want to.

volksnick · « **Reply #7 on:** November 21, 2011, 10:56:49 PM »

anything is possible...

Ret.Bugtech · « **Reply #8 on:** November 22, 2011, 08:00:21 AM »

Quote from: Bignick on November 21, 2011, 10:56:49 PM

anything is possible...

Sure it is. I don't care how you do it.

volksnick · « **Reply #9 on:** November 22, 2011, 03:31:13 PM »

I'm not going to lie, I disassembled a type 4 last year and it was sitting on the bed of my pick-up... it was a P.I.T.A. with all the room around it.I couldn't slide the head off because of a stupid piece of tin that wouldn't come off. After I solved the rubik's cube, I was able to pull the fan shroud off and then get the tin off. Only then, would the head slide off. It sucked, but the whole reason I was disassembling it in the bed of my truck was because I couldn't pick it up... there's no easy way

Ret.Bugtech · « **Reply #10 on:** November 22, 2011, 11:23:39 PM »

Quote from: Bignick on November 22, 2011, 03:31:13 PM

I'm not going to lie, I disassembled a type 4 last year and it was sitting on the bed of my pick-up... it was a P.I.T.A. with all the room around it.I couldn't slide the head off because of a stupid piece of tin that wouldn't come off. After I solved the rubik's cube, I was able to pull the fan shroud off and then get the tin off. Only then, would the head slide off. It sucked, but the whole reason I was disassembling it in the bed of my truck was because I couldn't pick it up... there's no easy way

If you are really careful you can bend that piece of tin out of the way and just barely slip the head off without removing the fan shroud. Just make sure you bend the tin back in place. Still can be a pain in the butt, but I just hated to pull the shroud off when it had A/C. Matter of fact I hated to do anything on those pieces of crap.

74loaf · « **Reply #11 on:** November 23, 2011, 12:28:35 PM »

Quote from: Ret.Bugtech on November 22, 2011, 11:23:39 PM

Quote from: Bignick on November 22, 2011, 03:31:13 PM
Matter of fact I hated to do anything on those pieces of crap.

Sounds like he wants to do some type 4 head work whenever I get the head off. LOL

Ret.Bugtech · « **Reply #12 on:** November 23, 2011, 08:14:56 PM »

Quote from: 74loaf on November 23, 2011, 12:28:35 PM

Quote from: Ret.Bugtech on November 22, 2011, 11:23:39 PM
Quote from: Bignick on November 22, 2011, 03:31:13 PM
Matter of fact I hated to do anything on those pieces of crap.

Sounds like he wants to do some type 4 head work whenever I get the head off. LOL
Well if it dropped a valve seat, can you say NEW HEAD. I can do valve work if you can find the valves.

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