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10-25-2019, 12:16 PM | #1 |
Junior Member
Join Date: Jul 2015
Posts: 10
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Number 8 Exhaust Valve sticking
This summer the the No. 8 exhaust valve started sticking while going down the road on several tours this past summer. The problem is intermittent but seems to be happening more each time and stays stuck longer. I use Marvel oil additive in the gas and I use zero ethanol gas. Several buddies have suggested spraying a lacquer remover into the No 4 cylinder to remove the varnish on the exhaust valve. Has anybody had this issue and what was your remedy for the sticking valve?
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10-25-2019, 12:24 PM | #2 |
Senior Member
Join Date: Apr 2013
Location: Northwest CT
Posts: 1,092
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Re: Number 8 Exhaust Valve sticking
Lacquer thinner is great at dissolving stuff so might be worth a shot. Definitely worth trying that before taking stuff apart. MMO usually seems to do the trick for most people but maybe you have more varnish than most. Whats the history on the engine?
I've only ever had issues with valves sticking on engines that hadn't run in a long time. Exercising the valves with WD-40 always freed them up. |
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10-25-2019, 12:31 PM | #3 |
Senior Member
Join Date: Mar 2019
Posts: 121
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Re: Number 8 Exhaust Valve sticking
I only have four exhaust valves in my model a ?
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10-25-2019, 12:33 PM | #4 |
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Join Date: May 2010
Location: Oregon
Posts: 5,969
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Re: Number 8 Exhaust Valve sticking
You might also have a weak or broken spring.
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10-25-2019, 12:34 PM | #5 |
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Join Date: Dec 2014
Location: Santa Maria, CA
Posts: 985
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Re: Number 8 Exhaust Valve sticking
Time for some Bardahl..."Frees sticky valves"!
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10-25-2019, 01:23 PM | #6 |
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Join Date: Jan 2019
Location: Germany, near Aachen
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Re: Number 8 Exhaust Valve sticking
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do you know "Valve Clean" from Liqui Moly? I recommend trying this. Note: MMO max. 3 ounces per 10 gal.
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Beste Gruesse aus Deutschland, Werner Ford Model A, Roadster, 1928 Citroen 11 CV, 1947 Hercules W 2000, 1976; (with NSU-Wankel Rotary Engine), Canadian version |
10-25-2019, 01:23 PM | #7 |
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Join Date: Apr 2013
Location: Big pine Ca 93513
Posts: 797
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Re: Number 8 Exhaust Valve sticking
start the moto put some Rislone (oil additive to clean sludge etc)in intake at high revs let carb suck it in until it kills engine let it sit for 15 min..try it again. works on intake valves...in your case remove #4 plugs pour some this stuff in plug hole with ign off crank moto and let it sit for a while..
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10-25-2019, 02:00 PM | #8 |
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Join Date: May 2010
Location: Largo Florida
Posts: 7,225
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Re: Number 8 Exhaust Valve sticking
About the only good thing I can say about WD40 is that it has worked good for sticky valves. Thru the plug hole it can be sprayed at the valves, [not just in the hole]. I remove the side cover and spray the stem. Turn the engine over to make sure its unstuck. I also think mixing ATF with the fuel helps keep them free.
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10-25-2019, 02:12 PM | #9 |
Senior Member
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Re: Number 8 Exhaust Valve sticking
HHHUUUUMMMMMMMMMMMM!!!
I thought everyone knew that a Model A engine has 8 valves and number 8 valve is an exhaust valve. Guess I was wrong.... |
10-25-2019, 02:29 PM | #10 |
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Join Date: Aug 2015
Location: Southern Alberta
Posts: 582
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Re: Number 8 Exhaust Valve sticking
ive allways added a bit of 2 cycle oil to the fuel to help a sticky one
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10-25-2019, 04:12 PM | #11 |
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Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 1,159
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Re: Number 8 Exhaust Valve sticking
Incidentally, this is a disadvantage of unleaded gasoline. Each outlet valve shaft moves in the so-called "mixed friction area". The lubrication of these valve guides allows only lead, no oil survives these extreme temperatures!
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Beste Gruesse aus Deutschland, Werner Ford Model A, Roadster, 1928 Citroen 11 CV, 1947 Hercules W 2000, 1976; (with NSU-Wankel Rotary Engine), Canadian version |
10-25-2019, 05:00 PM | #12 |
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Join Date: Apr 2017
Location: Sacramento
Posts: 1,262
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Re: Number 8 Exhaust Valve sticking
or instead of using snake oil you actually pull the head and valve cover,find the root cause and save yourself potentially huge issues from a broken spring or a broken guide..
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10-25-2019, 05:48 PM | #13 |
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Join Date: Jun 2017
Location: Walla Walla, WA
Posts: 1,045
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Re: Number 8 Exhaust Valve sticking
How does one narrow it down to a particular valve that is sticking? Diagnostic equipment?
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10-25-2019, 05:56 PM | #14 |
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Join Date: May 2010
Location: Alabama
Posts: 8,099
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Re: Number 8 Exhaust Valve sticking
The main reason that I avoid removing the head is the risk of broken head studs
A quick and easy way to get snake oil of choice to the valves is through the vacume line with the engine running . I disconnect the vacume line from the firewall . I either bend the original vacume line for the procedure or make up another vacume line so I don't have to bend the original . With the engine running . Connect one of the vacume line to the vacume port on the intake manifold . Stick the other end of the vacume line in the bottle of the snake oil . The vacume of the engine will pull the snake oil right in to the valves and stems. Sometimes valves are so tightly stuck that more drastic action is necessary. I have in some cases removed the valve spring on the stuck open valve . I then break out the vise grips with the round gripping area. Sometimes I remove the manifolds so that I can spray penetrant on the valve stem above the guide through the intake or exhaust port . I then carefully grip the mushroom end of the valve stem with the vice grips . No need to grip the valve stem with enough pressure to scar up the mushroom . It WON'T be stuck tight enough to require that much pressure . Move the vice grips left and right while spraying penetrant on the upper and lower valve stem . Pretty soon the stuck valve will loosen up enough That you can remove the vice grips. I then reach in with my hand and continue to turn and push the valve up and down until the valve moves to my satisfaction . I then reinstall the valve spring and side cover . If it works out , the valve will be unstuck without removing the head There is no risk of the HORROR of a broken head stud . |
10-25-2019, 06:21 PM | #15 | |
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Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 7,504
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Re: Number 8 Exhaust Valve sticking
Quote:
Let's not get 'em in a tangle over it.
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10-25-2019, 06:33 PM | #16 |
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Join Date: May 2010
Location: Largo Florida
Posts: 7,225
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Re: Number 8 Exhaust Valve sticking
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10-25-2019, 06:34 PM | #17 |
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Join Date: May 2010
Location: Largo Florida
Posts: 7,225
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Re: Number 8 Exhaust Valve sticking
Exhaust valve in cylinder #4 I believe is called valve #8.
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10-26-2019, 06:42 AM | #18 |
Senior Member
Join Date: May 2010
Location: Mpls, MN
Posts: 27,582
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Re: Number 8 Exhaust Valve sticking
A can of Sea Foam in the oil, and another in the gas should fix it.
Just a can in the oil fixed a long time stuck hydraulic lifter in an Olds in less than 5 miles driving. |
10-26-2019, 09:33 AM | #19 |
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Join Date: Apr 2017
Location: Sacramento
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Re: Number 8 Exhaust Valve sticking
Not arguing Purdy,just don't understand..the horror of a broken head stud is worse than the horror of a broken valve guide?. I'd be as happy as a clam if a chemical fixed the problem but an assumption is made that the valve is sticking.Assumptions can lead to expensive lessons,finding the root cause of the issue negates assumption.
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10-26-2019, 10:02 AM | #20 |
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Join Date: May 2010
Location: Alabama
Posts: 8,099
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Re: Number 8 Exhaust Valve sticking
Because the broken stud must be removed without causing damage to the cast iron threads in the block
. The valve guide is held in place by the valve spring . With the valve spring removed , the guide is easier for me to remove than a broken stud . .Sometimes the head has to be removed , no matter what . I just try to avoid removing the head unless it is absolutely necessary . I'm not trying to be a smartazz . I have seen that Railcaarmover knows his stuff . This is just my preferred method and why . Last edited by Purdy Swoft; 10-26-2019 at 01:13 PM. |
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