Hi all,

As I was replacing some bent pushrods, I decided to take the entire tappet assembly off, exposing the entire top of the head and valve springs/retainers/etc. I have verified with a few taps of a hammer per valve that they are opening and closing properly, as the spring bounces my hammer back into my hand as the valve closes.

With two of the intake valves, I noticed that these can be hammered down until you can hear the valve spring tension increase, and then it recedes back to a seated position on a hard whack, or very slowly.

This says a few things to me. The first is that there is crud built up on the valve stems from poor head lubrication and high engine heat that caused coking. The second and more invasive issue could be that the valve is bent.

Has anyone freed intake valves to the point that the valves were actuating correctly and the car ran well for a decent amount of time? What did you use? Chemical? Procedure?

I dont want to pull the head, but this might be this old girl's way of asking nicely what she really needs.

Thanks all in advance!

Jeff

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The only way you can ever really break something beyond repair is to give up trying to fix it.

I would first try fixing the lack of lubrication problem and then suspect worn valve springs or a bent valve. I have never heard of a slant six valve stem getting so much crud built up on it that it stuck in the valve stem shaft.

What bent the pushrods and were the bent pushrods on the stuck valves?

Pictures?

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Casually looking for a Clifford hyperpak intake for cheap.

Running an engine on old "bad" fuel is usually the reason for sticking intake valves.

If the fuel is old, discard it and run the engine on fresh gas.
If the tank is dirty, disconnect the fuel line from the incoming side of the fuel pump and run a hose from the pump and into a fresh can of gas.
You can add some "top cylinder oil" to tha fuel, to help lube the valves and rings.

As for the stuck intake valves, spray them with a light penitrating oil, then tap and rotate, that that can free them up enough to start and run the engine at low RPMs...
Once running, be sure cover the valve stems with lots of oil and inspect the rocker arm feed holes to be sure they continue to get oil once the valve cover is reinstalled.
DD

Listen to Doc. Old gas can ruin an entire engine.

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Joshua

I had the same problem when I first got my 64. Every few hundred miles a few valves would stick open. A squirt of oil and a hammer seemed to fit it but it would do it again. So I dug into it and found the rocker arm shaft was installed wrong and oil was not getting to were it needed to. Flipped the shaft and all is well now.

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50 chrysler,54 Plymouth, 64 Valiant conv 4 speed, 66 Valiant V8 wagon, 70 Challenger R/T 440+6 conv 4 speed,80 Colt, 98 Neon ACR,84 Honda V45 Magna
Taking care of 57 300C conv,48 T&C conv. Missing my 67 GTX and 36 Ply coupe

Along the lines of what 4speed said, you can run the engine with the valve cover off, and watch the rockers to make sure they are oiling properly. Sometimes you have to clean out the passages in the rocker arms. If you do a 'live' valve lash adjustment, it will give you an opportunity to observe their operation.

It may make more sense if i tell you the abuse this poor girl was subject to.

When I got the car, after finding out the fuel pump was bad evidenced by my first gusher of an oil change (gas/oil mixture). The bad part is that it looked like a previous idiot had plugged the fuel pump overflow with a bolt some time ago.

This means that there was terrible, crappy oil mixed with gas circulating for who knows how long, picking up nasty coked oil and grit everywhere it went. It also implies a myriad of potential impacts and money and...

But my faith in the slant stays strong. Knowing a rebuild is some time in the future, I think I will tinker and try to squeeze more life out of this 90k survivor.

When i removed the valve cover, the entire head was completely dry, and covered with dried, flaky previously cooked oil. This lends credibility to the "shaft was in the wrong position theory" that will be corrected. I have also taken the rocker arms out and cleaned the thoroughly (including passages). Has anybody ever had an issue with the oil channel at the rear bolt that lubricates the shaft/rockers?

The head is clean, and currently awiating its next cleaning and the advice that I can successfully resurrect some intake valves.

Oh and the pushrods? Four intake pushrods actually bent which led me to this current adventure, which I can also believe due to the lube issue. Interestingly, I only have two sticky valves and four bent pushrods...

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The only way you can ever really break something beyond repair is to give up trying to fix it.

Rocker shafts being installed upside down or backward is relatively rare. Since you are sticking intake valves it's much more likely you have bad fuel. Drain the tank!

At this point I would pull the spark plugs and spin the engine with the starter to see if oil comes up through the head passage. If it does then you're clear to reinstall the rocker shaft. The flat or notch on the end of the rocker shaft goes forward and upward.

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Joshua

I don't see it...........


How does bad fuel affect the intake valves?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Varnish won’t burn completly, just melts onto the hot valve stems and gums them up over time.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I just bent pushrod 1 and 6 on my 1979 D100... the vehicle had been in storage for 11 years. The tank was empty and when I put 5 gallons of gasoline in the tank it came out clean and clear. Within 80 miles it bent the pushrods. I pulled the head and all of the intake valves were gummed up like candied apples. I took another fuel sample and this time it was thicker and smellier than a comparison sample from the gas station. I am definitely going to clean the tank... I have a fuel cell in the bed of the truck right now. It took forever to get the head, carb and intake manifold clean. I bought a new fuel pump and rebuilt the carb. I will never ever ever assume that an old tank is clean again.

Yeah, im thinking that is what happened here Porter...my old girl had been sitting for probably a solid 9 months, judging from the condition the fuel was in when I first tried to start it. Plenty of nasty brown-ness in the fuel, seemed to clear up after a little more gas, and after she ran like a champ for a little bit, voila, sticky valves.

I was hoping that cleaning the tank could be put off a little longer but it looks like im going to have to just bite the bullet if I dont want any more problems. I would say that the amount that I had my slant running was probably equivalent to 80 miles or so as well.

What is the best way/product to clean the head and intake? I'm looking to go on the cheap so I was hoping to do the head myself if possible.

Totally random that it was 1 and 6 for us, or perhaps not?

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The only way you can ever really break something beyond repair is to give up trying to fix it.

After I scraped and wire brushed the head, I took a cherrypicker and lowered the bare head into a barrel of hydroseal carburetor cleaner for about 4 hours. I had to replace all of the intake valves and I re-honed the valve guides.

I think it was worse on 1 and 6 because the long intake runners cause the cylinders to run a little lean. The lean condition causes cyl 1 and 6 to run a little hotter and the extra heat bakes the varnish on the intake valves. Just a guess.

Either way...cleaning the head was a real pain in the butt.