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stuck valves/engine


jcmiller

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I have a straight 8 that was "reconditioned" 20+ years ago and then stored in a garage. I can manually turn it over, but only part way before it sticks. In one direction it makes a screeching type noise when it sticks, much like the sound a lug nut makes when it has been on really tight and first comes loose. When it sticks in the other direction it does not make that same sound.

I took the valve covers off and observed the valves while turning the engine back and forth and it looks like all the valves move up and down except for three that are stuck in the up position. It doesn't seem like valves in the up position would keep the engine from turning over. I sprayed the valves ends and springs down with PB Blaster and have put various lubricants in the spark plug holes. Is it safe to keep working it like this, or do I need to go to the next step, which sounds like it means removing the head?

(It has oil and I soaked the cylinders for a while with Marvel's before doing any of this.)

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Recommend you remove the head for a start. You may need to remove the pan as well. What are your plans for the engine? Before you can use it, you will have to take the head and pan off to inspect for rust etc.

It may be a simple matter to get the valves working. A head gasket and oil pan gasket are cheap investments, to avoid ruining your engine.

It would also help if you could apply oil under pressure to the lubrication system. This can be done through the oil pressure gauge fitting.

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Thanks Rusty. My plans depend on several variables. I have a '46 New Yorker that needs a straight 8 and transmission. I bought this and one other as potential replacements, but they are both C49s. If I can find a transmission/fluid drive, and one of these is in good shape, I may try to use one of them in the car. Or if I find an engine/tranny combo of the correct vintage, I might try to sell or trade both.

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The valves may not be all the way up and the camshaft is keeping the crankshaft from making the full turn.

Take the head off.

Back off the adjusters on the stuck valves and lube the stems with a mix of ATF and acetone or lacquer thinner.

If your valves have a slot or 2 indentations for lapping them you can try to spin them, tapping will also help.

You may have to try to get the valve keepers off.

I had to do this on a 1926 Chrysler 6 that had been sitting for 50 years.

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I took the head off. I have three sticky valves. I was able to gently tap down two of them. The third has not yet responded to light tapping. I hosed it down with PB Blaster and will let it soak for a while and try again later. The two that went down stay in the up position when I turn the engine, which now turns freely (yeah!!).

Being a novice, I'm not sure how to read the condition of the engine. But to me the pistons and cylinder walls look really good (no wear lip). The valves are a mixed bag. I've attached a few pictures of the best and the worst of what I see. The worst piston/valve combo matches the worst cylinder head recess.

Are valve stems lubricated from the bottom during normal operation?

Rusty - Can you provide any more details on how you would apply pressurized oil? Is there a special tool for that?

Thanks for the help folks.

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I don't like the looks of those valves. You may need to replace the badly pitted ones.

Prelubing an engine is something they do before starting a rebuilt engine. Basically, you have a sealed container of oil, attach it to the fitting where the oil pressure sender goes, and pressurize it with compressed air. 5 or 10 PSI should do it. This is to force oil into the lubrication system, and make sure all the bearings are lubricated before starting the engine.

You can make something up or buy a small garden sprayer and attach a fitting to the hose.

I would be afraid of rust in the crankcase given the amount of rust in the cylinders. Have you taken off the pan?

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You guys are killing me! I'm trying to celebrate getting it to spin freely and you're giving me new tasks! :)

It looks worse in the pictures than in reality. Those were taken right after the head came off. Most of that rusty looking stuff was powdery and wiped right off. I'll post more pics this weekend.

Thanks for the details on the oiling. I've not removed the pan at this point. It's not easily done with my current setup. For now, I'm going to try to get those three valves moving and think about whether to remove any of them for closer inspection and possible replacement.

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  • 7 months later...

I finally decided to borrow a spring compressor and remove those three valves.  I just removed one tonight.  The valve stem looks great except about the last inch near the valve face.  There must be corrosion in the guide, however, because after pouring some Marvels down it, the valve still does not move up and down easily.  So, what can I do short of taking this to a machine shop, to clean up the guides?  I was thinking of trying to find a very skinny wire brush.  Thx, Jeff

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Oh no not valve grinding compound! You could polish the valve stem with chrome polish or silver polish. The guide should not be cleaned with anything abrasive. A small gun cleaning brush or a brush used for cleaning oil passages when rebuilding an engine would work. One made of nylon or at worst, brass bristles. You could use 0000 steel wool but be careful to clean up all residue.

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Thanks for weighing in.  I bought some nylon brushes and cleaned out the guide with kerosene.  It works much better but still binds when the valve is most of the way down.  I think this is because of the corrosion on the valve stem near the valve proper.  I may need a new valve.  I'm going to drop by an automotive machine shop today to see if they think it is shot.

 

 

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Edited by jcmiller (see edit history)
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If the valve stem  is rusty polish it with 0000 steel wool. Unless the pitting is very severe it will not affect the working of the valve or its life.

 

Lap the valve and seat with fine compound if they are pitted. Pits will cause burning of the valve and seat, especially the exhaust .

Edited by Rusty_OToole (see edit history)
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I stopped by the machinist today. He said to put the valve in a drill and run it against 320 grit sandpaper. I did that and the valve seems to be working nicely now. Two more to go. The keepers are kind if hard to position. Would you know immediately if they aren't seated properly?

Thanks again for the help. I'm looking forward to getting the head back on this engine.

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  • 3 weeks later...

I'm just writing to report that I was able to remove the two remaining valves and they now move freely.  One was extraordinarily difficult to get out.  I had to get a neighbor to help and we used two pry bars on opposite sides of the valve to force it upwards and out.  Despite being stuck to such an extent, the valve looks good, much like the one pictured above.  I borrowed parts of a gun-cleaning kit to scrub out the valve guides. The kit had a brass bottle brush, a long rod, and a handle.  The one that was stuck is a little tight when you first start putting it in, but it moves freely and without resistance within its normal operational range.  Thanks again for the tips along the way.

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