Maybe Just Coked?

Hi, I just posted on here a few weeks ago about a flashing engine light possibly caused by low compression getting worse. And it was determined that a used engine would be the way to go because the rings were so bad. Since then I did some research and found that low compression can also be caused by coked rings. I did have a wet compression test done that pointed to the rings as the culprit. But is it possible that the low compression is not bad rings but coked rings instead and that something like Auto-RX might might be worth a try? Is there any way to test for coked rings or are the results from the wet compression test enough proof that the rings are bad without a doubt?

Try it. What have you got to lose?

Coked rings are usually suffered by those who believe in 10,000 mile oil changes and who never add any oil between changes…But once the rings get varnished up and stuck in their grooves there is little chance any chemical additive or treatment will free them…

Now is when 10/40 oil and a can of “Restore” might offer some benefit…

Caddyman, Appreciate it. I’ll give those a try next oil change.

t s m, about 40 bucks. lol : )

My boat guy highly recommends Yamaha Combustion Chamber Cleaner. Read the directions to see if it works on cars! Conventional wisdom says if it cleans out lots of gunk it would be better before an oil change.

Yes, but if it works you’ll have saved THOUSANDS!!!
I’ve made worse bets!

All engines have several piston rings. One is a “compression” ring and the lowest is an “oil ring” designed to keep oil from getting into the combustion area. A chemical in the oil can clean the bottom ring, but have less impact on the compression (or upper rings). Therefore a chemical injected with the gas cleans the combustion area (values, and perhaps that upper compression ring). This means you might need to try several “cleaners” to see if you can improve the compression without tearing down the motor. Keep your expectations in line, they might not work, but it seems worth a try considering the alternative is a bunch of money.

You might try pulling all the plugs and then pouring some solvent or penetrating oil into each cylinder and let it sit overnight. SeaFoam comes to mind for this but just plain kerosene would probably work too. Crank over the engine before you put the plugs in to make sure you don’t hydrolock.

I once bought a “work” car for $150, a 70 Plymouth Duster with a slant six. The previous owner had lived a 1/2 mile from work and that’s all he used it for. The oil was like tar and it trailed a cloud of blue smoke.
I changed the oil and put in Valvoline 10w-30. I then drove the daylights out of it winding it up in each gear and changing the oil twice more at 500 mile intervals.
Every once in a while the car would give a big hiccup and lurch, emitting a big puff of smoke. Within a month, the rings were all unstuck and the car never burned any oil or smoked.

I’m going to buy a compression gauge and test before and after I add the cleaners. I’ll post the results, probably in a couple weeks.

keith, you think about a tablespoon of kerosene in each cylinder?

And another thing. With the low compression and smoke upon start up the plugs should be black from oil fouling right? They’re not. In fact, I’ve compared them to two plug charts and they match the “normal” plug picture. I checked both the set that had been in the car since 131,600 to 163,000 and the current ones that have been in since 163,000 to 168,000.

I would use about a 1/4 cup, but crank the engine w/o the plugs in to pump out any kerosene that didn’t leak down past the rings. You will need to do an oil change afterward.

You get oil fouled plugs when you burn about a quart/50 miles. If I remember correctly from your previous post, you were burning only about a qt/500 miles. Usually when you have coked rings, you burn a lot more oil than you are burning now.

Hmm…Yes, I am only burning about that much.

I guess it’s still worth a shot though.

You do mean 1/4 cup per cylinder and not a 1/4 cup divided between all four cylinders, right?

Yes, per cylinder.

BTW, did anyone mention that you should check you valve lash?

You mentioned it as a possible cause for the misfire in the “Check Engine” thread.

If I do decide to replace the valve stem seals and check the valve clearance, I’ll also check the valve lash while I’m at it.

You also mentioned that a faulty injector could cause a misfire. According to an invoice I have, the car has an injector pulse. What does that mean?

Valve lash = valve clearance. I would recommend that you check this even if you don’t do the valve seals. You will need a valve cover gasket kit for this, but considering the age of your vehicle, It probably needs that anyway.

Injector pulse means that the computer is sending a signal to the injector, that does not mean that the injector is working. With the engine running, use an automotive stethoscope on the injector, you should hear a faint clicking sound. If you don’t have one of these, a straw, a rubber tube or even a metal rod held on or close to the injector and close to your ear should transmit the sound. Check the other injectors for a reference.

Even if you hear the clicking sound, that is still not 100% proof that the injector is working correctly. Maybe 99%, but there is a small chance that it could still be leaking a little gas causing a rich condition on that cylinder, but you should see a black carbon build up on that plug if this is the case. It could also be plugged up causing a lean condition that would be harder to detect.

One more thing, I would avoid AutoRX. Based on testimonials about how dark the oil got right after using it on a BRAND NEW engine, I am suspicious that it burns at a very low temperature and is the source of the discoloration, not the cure. I don’t know if it would do any real harm, but I don’t trust it.

I tried AutoRX to help an oil burning problem. AutoRX didn’t help.

Sorry, I wasn’t clear. What is written on the invoice is “worried about injector pulse”

The injector pulse comes from the computer, however, if the coil on the injector is defective, either open or shorted, it will distort the pulse coming from the computer. Listen for the click.

An additive is certainly worth a shot in the event that a ring (or plural) are sludged or coked in place but with the latter I wouldn’t hold my breath while awaiting positive results.

Other causes of ring problems could be lack of spring tension from any overheating episode, scored cylinders due to excessive dirt/debris inhalation, seized ring(s) from overheating, and just plain old premature wear due to irregular oil changes and/or dusty environment and so on.

With a ring problem you have nothing to lose by trying an additive or any other trick. Nowhere to go but up as the saying goes.

The injector pulse comment is a bit hazy but if there’s a problem with an injector hanging open or whatever it’s possible to wash the cylinder wall down with raw gasoline. This will lower compression, cause premature ring wear (on that cylinder only), and can dilute the engine oil. (The oil may have a gasoline smell to it.)