97 Ranger aero project.

[Xist]

Great post, Old Mechanic!

[user removed]

Well it looks like I will be buying the tires this weekend. Wife handed me a $70 off coupon today for Costco. Problem is the wheels will not be in my posession until Sunday the 16th, the day the coupon expires. Going to stop there (Costco) tomorrow and either buy the tires or pay for them in advance. Coupon also gives $30 off on installation, which means it would cost me $26 to get them mounted and balanced with a lifetime warranty on the balance, or if that won't work, I'll just put them on myself at my buddies shop and use his balancer if Costco doesn't want to work with me. I think the tires are the same size as a 2010 Prius. Basically that means I'll have the wheels, tires, and pizza pans a lot quicker than originally planned.

The truck has not burned any oil in 1000 miles since I changed it to 5-20. The oil is still about as clean as it looked when it came out of the jug.

Still got a little spark knock, think I'll just run the windshield washer hose to a vacuum fitting on the intake and run some alcohol-water mix through it using the washer pump at higher speeds to blast the carbon out.

regards
Mech

[ron]

old mechanic , my sons 2000 ranger 6cyl has spark knock ,Ive tried every thing I know to get rid of it but still knocks under load i.e. up a hill merging into traffic when you have to push it .I used the squirt gun approach to decarbonize it. if you get yours to stop the knock let us know how you did it . thank you in advance

[roosterk0031]

94 explorer 4.0 had spark knock as well, I ran 91 octane last 20,000 miles I owned it as was cheaper than possible fix's my mechanic hand in mind. Under warranty they tried lost of stuff and ended up replaceing MFS which stopped the knock and cut MPG down 2 mpg until 100+K when pinging came back.

[ron]

here in california the high octane fuel isnt worth the it,it sill knocks using it . im going to try the windshield washer high rev water injection that Old Mech used . I did ours at idle

[user removed]

I haven't used the washer system yet. If you do it, then you need to atomize the water through a nozzle of some kind so it is not just water in liquid form blasting into the intake.

My truck will knock under a specific range of load, typically at low speeds in higher gears which is the way I like to accelerate in gears. I can just let off the throttle slightly to keep it from knocking to the point where it could damage the engine.

I hardly ever use the washers anyway which makes them the obvious choice as a supply of water. I intend to use some alcohol with the water when it is injected.

Since my truck has just over 126k miles on it now, it's safe to assume there is some carbon accumulated in the combustion chambers. A simple injection setup will allow me to see if there are any results. That being said there are some things that need to be understood. Slight spark knock is a good indication that you are running as much timing advance as you can which is actually OK, but when you get into heavier spark knock you can do real damage to the engine so be careful and avoid introducing a lot of water without any spray pattern into the intake. Also make sure you are injecting the water in such a way that it is evenly distributed between the cylinders and you do NOT inject enough to cause a liquid lock or you can destroy your engine.

My intention is to make a very small orfice in a piece of steel or aluminum and insert it into the hose going to my vacuum fitting so it can not be ingested into the engine.

Most cars have a means of adjusting the timing advance to reduce or eliminate spark knock, by changing the ignition signal or changing the computers signal to the ignition coils. The days of just adjusting the distributor are mostly gone but if you have a distributor then just move it slightly in the direction of rotation to retard the timing.

A good way to check to see if you might be able to stop the knocking is to try higher octane fuel, or a different brand of fuel. That may be the best solution, but the approach needs to be systematic. Good EGR volume is critical to stopping spark knock.
Your plugs should be fairly fresh and I would (and have) used some fuel system cleaner. One of the best is BG 44k which has been recommended by Mercedes for a long time, but I have reservations about believing that any cleaner can really remove all carbon deposits from an engine.

Even a weak oxygen sensor can cause spark knock and sometimes it takes several different things to get it resolved. Maybe just be patient and see how mine goes before jumping into it with consequences that I would not like to thing I was responsible for causing with my recommendations. Mass quantities of water injected in the wrong place could cause problems with the various sensors involved in air flow measurement so it is best to introduce water downstream of those same sensors.

Mom has a phrase that says "yard by yard, life is hard, inch by inch it's a cinch". Basically start with a little and gradually increase the volume instead of starting with a flood and wrecking your engine or other parts.

regards
Mech

[ron]

I have already used the squirt/spray bottle at idle I just thought that the higher rpms would give better result and shake the carbon loose. thanks for the info on the oxygen sensor Ill look into them.It could just be related to the young rt foot. I drive it and dont have the problem I also get 2-3 mpg better mileage

[radioranger]

I have an idea that might help and be maybe a lot less risky , just soak a sponge and put it in the air cleaner box and run it , should pull the moisture right out of it readily , any comments , cheap and not much chance of damage i figure.

[user removed]

I have used a Binks #7 paint gun and shop air and water in the gun. Clamped the throttle linkage at 2k RPM and set the paint gun to flow into the intake with the air filter removed. This was done to 81-83 Datsun 280 ZXs which developed a carbon knock that sounder like terminal engine damage. The flat top piston (only used those 3 years) was only about a millimeter from about 40% of the cylinder head surface, a little more than the thickness of the head gasket. When enough carbon accumulated to fill that gap you got a knock that sounded like a rod knock.

That pocess was developed after many heads were removed for decarbonizing to get rid of the knock, which was in turn developed after several engine tear downs with no obvious damage except the flattened carbon deposit where contact was being made.

Those old engines used flap potentiometer air flow meters and were the first oxygen sensor 3 way feedback systems used by Nissan in their cars in the US. Instead of charging many hours labor to tear down and inspect an engine that had no other issues we developed the spray gun technique that took less than an hour and required no disassembly other than the air cleaner assembly.

Looking into the cylinders with a fiber optic light showed the carbon gone from the piston crown, and the repair lasted a long time and could be done many times, but we ususally never had to do it twice and it was usually close to 100 k miles when we had to do that cleaning.

I hesitate to do that anymore, not sure what the sensors might suffer as damage from the process. The hot wire mass air flow sensors and different cylinder heads in the V6s that Nissan put in the 84 and later 300ZXs never had the problem. The earlier 280s did not have the flat topped pistons so they would not develop the same carbon knock.

It cleaned the pistons to almost the same level as a blown head gasket did when the coolant was leaking into that cylinder, practically spotless.

regards
Mech

[slowmover]

Why not a piston soak as well for the carboned rings? I've used Lube Control LC-20 as an overnight remedy on a number of cars (1970's through 2001) with real success.

MolaSoak: LC-20 + Schaeffers #131 Neutra

I've also used Auto-Rx Non-Toxic Sludge Remover and Cleaner for Engines and Transmissions in combination with above.

For an old neglected engine they do well without the problem of nasty solvents. I like them in general use as well (per directions), and also FP-60 Fuel Power (products which I and my family have used over forty years).

And, BTW, I'd guess you know that BG-44K is not the same formulation as years ago. Good, but maybe not as effective. The above aren't cheap, but far from as expensive.

My first thought on de-carboning an engine is still a coke bottle with calibrated thumb to control water flow and the other hand working the throttle linkage. Guess it shows my age. Seeing an AMPCO Top Lube bottle on a firewall was always a reminder of same.

Good luck as it goes. Quite encouraging so far.