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Valve check

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M

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What is the best and easiest way to check the condition of valves? One method I have found is as follows:

"Get a tube of Prussian blue. Loosen the valve spring and blue the face of the valve and then turn it one quarter around the valve seat. If the seat shows a clear line of blue, you have a perfect fitting valve. If there are points where the blue does not touch, you have worn or warped valve or a faulty seat."

Is there another way? And can anyone send a photo showing the valve spring that is to be loosened?
 
I wouldn't do that. You have to pull the head to do this check. It's not worth pulling the head unless there is a problem, and I seem to remember you posted that the engine has been overhauled recently.

I would leave the valves alone unless there is a problem with them.

I suppose if you were champing at the bit to do a valve test, you could do a leakdown test. But, again, only if you suspect a problem with the valves or rings.

I thought you were learning to not worry so much; now you're backsliding!
 
Ed,

The exhaust valves will be the first to go since they operate in so much heat. The engine will run terribly with even a single bad exhaust valve. At low speed it will run very rough...so much so that it will buck and pop while coasting. It will sound better at higher rev's, like on the freeway.

So I guess I am trying to say, you will have no doubt something is wrong.

John
 
Dr. John.

Yes... guilty.. I'm backsliding. The "problem" is that my #1 spark plug keeps carbon fouling (heavy soot on it) while the other three are normal. I had the mixture checked and adjusted, but that didn't have any effect on the problem.

I say "problem," but even with the fouling spark plug, the car runs well. I keep coming back to the idea that a valve is not seated properly. And if that is the case, eventually the valve will be damaged.

I checked with the shop that had the engine rebuilt -- new valves, etc. -- and was told that the problem surely shouldn't be with the valves. They readjusted the fuel mixture. (And, as I said, this made no difference.) They also said -- and I find it a bit strange -- that because it is #1 plug and so near the radiator, that that cylinder runs cooler than the others...

The mystery of the fouling #1 spark plug is just something that I'd like to solve... although it may just remain a mystery until something comes of it.

Advice?
 
As John says, a compression or leakdown test will show you if the valves are leaking. But I think it's unlikely to be your problem.

#1 does run just slightly cooler, but temperature is not that critical, so it should not be causing soot on #1 plug.

Unfortunately you are in a tough situation. Your shop is obviously not going to help you; so you are faced with either learning to do the tests and adjustments yourself, or finding a different shop.

Just a side story, some years ago my wife's Caravan broke a timing belt, and rather than mess with it myself I had it towed to a nearby shop (nationwide chain). When I got it back, it ran smoothly enough, but was way down on power. I had to take it back 3 times to get it right! When I insisted on showing the mechanic the procedure for setting the valve timing, I realized that he could not read English! But after some heated discussions with the service manager, he served as translator and they finally got the valve timing right.

I never checked the plugs on the Caravan; but from a similar experience with an old Honda 4-stroke motorcycle, I know that late valve timing can cause the plugs to soot up.
 
Randall,

Unfortunately, you are right. I don't think the shop is going to give me much help.

I can -- and did -- check the balance of the carbs and the fuel misture myself, and I'll give that another that.

I checked the #1 and #2 valve gaps, and they seemed fine.... .010 each.

I checked the lead wire to #1 plug (it was OK), and I replaced the spark plug (but new one fouled also).

As for valve timing, I don't know what's involved with that or what to do. Is it difficult? What's involved? If it is not too difficulty, I can try it myself.
 
I'm certainly not an expert, but valves are not the only things that can make a plug foul. Weak spark due to a bad wire or fouled dizzy parts could also make a plug foul. I read in your post that you changed that plug so it wasn't the plug itself. If fuel is not the problem and the leak-down test is passed...look at electrical.
 
LexTR3 said:
As for valve timing, I don't know what's involved with that or what to do. Is it difficult? What's involved? If it is not too difficulty, I can try it myself.
Click to expand...

Without taking the timing cover off, and possibly pulling the head, you can only do a ballpark check of the valve timing. And if the engine is running well, that probably isn't the issue, and should affect all cylinders.

Have you checked the contacts in the distributor cap? Is the cam lobe worn for #1?

Another option would be to try out a Colourtune, that would let you compare the mixture in #1 to the other cylinders. But since #1 and #2 are fed by the same carb, it is hard to see how they could be different.
 
Ed,

If you are getting oil fouling, look to 2 places:

1- Rings. You'll have to do a leak-down check to make sure they are sealing. A compression check is the next best (and cheapest) way to check. By the way, the leakdown will tell you if you have bad valves, head gaskets, or cracks. Comression check doesn't give you much info on where the problem is...and it has to be pretty bad to show up.

2- Intake valve guide. If the valve stem is loose in the guide, it may be sucking oil. You can actually check this without a lot of dimantling...if you are interested, let me know. If this is a recent rebuild...the guide should be good, unless they screwed it up. Guides don't wear that fast.

John
 
Have you thought about using a Vacuum Gauge ? It cannot pinpoint exactly what cylinder is having a valve problem, but it certainly can give you an indication that a problem exist. Plus, it is a non-invasive diagnostic test.
Compare what you see to the scenarios illustrated here:
https://www.secondchancegarage.com/public/186.cfm
Or here:
https://www.centuryperformance.com/tuning-with-a-vacuum-gauge-spg-148.html
And while you're at it consider this :
https://automotivemileposts.com/garage/v2n8.html
 
The points are new, the distributor cap is new and the contacts are pristine, the fouling is not oily, only sooty.

the lead wire is new and there are no breaks.

The engine was rebuilt a year ago with new rings, etc., etc. Complete "valve job" was performed.

There is no noticeable color to the exhaust.

#1 is sooty, but #2 is textook normal.

The car runs like a "new" car....

One of life's mysteries...
 
Now THAT's a happy suggestion.

Actually, I avoid stop and go driving as much as possible and head for the open road as soon as possible, although I don't drive above 55 mph and usually around 45-50 mph. Also, I don't go out unless I am going to drive at least 20 minutes to an hour or more.
 
Switch to a hotter plug?
 
I talked to some mechanics about switching to a hotter plug. They advised against it for a number of reasons, including the fact that #s 2, 3, & 4 are doing exactly what they need to do. It is only #1 that is "fouling." They advised me to stick with the Champions that I've been runing in the car.

BTW, and for what it may be worth, one mechanic took a look at the photos of my "fouled" plugs and said they they look "sooty" but not "carbon fouled." This distinction is a bit too fine for me.
 
To me, "fouled" means that the plug is so dirty that it is shorting across the electrodes causing a miss to occur, whilst "sooty" has no such implication.

But that's just me.
 
Sounds logical to me. But I am just going on looks, and I can't tell the difference between "sooty" and "carbon fouled."


But even if "sooty" and "carbon fouled" are essentially different, I'm still puzzled why #1 is "sooty" and the others are textbook normal.

BTW. I took 4 new NGK BP5HS plugs with me to the shop when I went there to look into this problem, and they advised me not to use them.
 
Some guys are like that. The plugs they use are "THE BEST" :rolleyes: and everything else is ....well, do I have to say it ?
 
Yes, you are right, but these guys have been working on and driving Triumphs for 20-30 years. They have nothing against NKG plugs, but said that the "5s" are too hot. I had no counter argument, so I went with the Champions. If I thought I wouldn't do the car any harm, I might try the "5s" anyway.... but I'm in the dark here.

#1 and #2 are fed by the same carb, so I don't know why one is clean and the other "sooty." Both cylinders have Champions (they all have Champions). I've put three new champions in #1 in the last week to test it. All come out sooty. The only link I can find is the valve serving #1, but no one seems to think this is the cause.

Again... one of life's mysteries...
 
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