'93 pinging/knocking disaster

Without hearing the noise for myself, I'll go out on a limb and suggest that the noise you are hearing is indeed a piece of carbon (you should see the size of some of the "mushrooms" that grow on the backside of the intake valves). In addition to some of the other stu you have read, it is also possible that a faulty lower intake gasket may be the source of your ping - this has been a common problem on the 4.0 OHVs as well as the SOHC motors. I still wouldn't discount the EGR totally since the early systems were rudimentary compared to the latest offerings. They are easy to test...... apply vacuum to the valve diaphragm and the motor should stumble badly or even stall. There remains the possiblility that the EGR is fouled with carbon and is restricting flow (this includes the EGR passages).

As for who will pay for removing the errant carbon particle..... sad to say the view will be that it was your carbon particle to start with and it is still your carbon particle now..... that large pieces can break off and become troublesome (though it is rare for them to hang around for too long) should have earned a mention in the preservice discussion. What you might try is intoducing a water spray into the manifold (it can be done carefully and slowly through a vacuum hose) to see if this will further reduce the size of the piece and allow it to pass through the exhaust valve.

Don't lose heart with the car... remember that it is nearly 11 years old and nothing is forever. My '92 has over 170,000 km (105,000 miles) and is a treat to drive on regular gas. Easy to park and dependable, it is our second vehicle and receives the most and roughest use (especially from yours truly).

Good luck

-- Jim Warman snipped-for-privacy@telusplanet.net

owner , well maintained and cared for . Developed bad

about it a month ago with a few responses . Did

plugs,wires, maf sensors dirty, carbon build up etc . Went to

with any codes , sensors were probably ok , not the

most part with high octane , looked like it was a

out for me an all data service bulletin on the

PM-3 to flush out the carbon in motor . Agreed on a

to pick it up I was told after the cleaning it

days and see if it goes away . He thought maybe it

something up inside .After a good day of driving it

pissed and am quickly starting to hate this truck that

'open up the motor' to fix it he would but no

suggestions as I don't know what to do and how to handle

station guy and don't think he did anything wrong on

SOMEBODY PLEASE HELP ME

Hello, Jim. Although not totally on-topic, your comment about water to get carbon out was something I wanted to follow up on as it is the second time I've heard that suggested lately and it may apply to me. Among other vehicles including my '97 explorer with 150K miles (the most reliable vehicle we have out of 5 road vehicles), I also have a '74 GMC horse truck with a 2 bbl carburetor 350 V8 that has had an internal tapping sound for years. The carbon build-up in one cylinder is so bad that we use a shortened spark plug to keep from mashing it. The truck still runs fine (with that tapping sound), especially after we recently replaced the old timing chain, but it would be nice to clear out that carbon. What method do you recommend for injecting water and what cautions should be observed? The other guy suggested a water spray in the carb, but warned it could shock the engine and break something, so we left it alone. Thanks.

=Vic= Bear Gap, PA

Jim Warman wrote:

well maintained and cared for . Developed bad

it a month ago with a few responses . Did

maf sensors dirty, carbon build up etc . Went to

any codes , sensors were probably ok , not the

part with high octane , looked like it was a

me an all data service bulletin on the

flush out the carbon in motor . Agreed on a

pick it up I was told after the cleaning it

and see if it goes away . He thought maybe it

something up inside .After a good day of driving it

am quickly starting to hate this truck that

up the motor' to fix it he would but no

suggestions as I don't know what to do and how to handle

guy and don't think he did anything wrong on

SOMEBODY PLEASE HELP ME

My dad was a mechanic, and he taught me the water trick back when carbureted engines were the norm. Your just take a quart or so of water, and with the air cleaner off, and the engine idle increase slightly, you pour the water slowly into the carburetor intake, slow enough to not stall the engine. Presumably the water changes to steam and that is what takes a whack at the carbon build up. He also recommended a product made by GM for the same purpose. "Top Engine Cleaner"

A Google search on "GM Top Engine Cleaner" came up with these articles among others:

No one will say for sure or guarantee what will fix this problem . If I figure in tune-up , wires , EGR , maf sensor ,etc, etc etc, and aggravation , your right , I'm probably better off using premium gas . I USED to like this truck . Modern technology , computer controlled emissions , piece of s*it pings like crazy , at

, well maintained and cared for . Developed bad

about it a month ago with a few responses . Did

maf sensors dirty, carbon build up etc . Went to

any codes , sensors were probably ok , not the

part with high octane , looked like it was a

for me an all data service bulletin on the

to flush out the carbon in motor . Agreed on a

pick it up I was told after the cleaning it

and see if it goes away . He thought maybe it

something up inside .After a good day of driving it

and am quickly starting to hate this truck that

'open up the motor' to fix it he would but no

suggestions as I don't know what to do and how to handle

station guy and don't think he did anything wrong on

SOMEBODY PLEASE HELP ME

I had pinging on my '93. It turned out to be a "leaking" intake manifold gasket. Pull the #5 spark plug and look for a white carbon coating on the plug. Compare it to the other plugs and it will be noticeably worse as far as carbon build-up if the intake manifold is leaking.

In some cases, I understand that folks replaced the intake manifold gasket, which takes quite a bit of effort and time.

I found that I could retorque my lower intake manifold bolts and that it would get rid of the pinging. Be very careful in retorquing the bolts because the torque is low (180 INCH-Pounds, I think). Carefully retorque gradually in a pattern and don't retorque the full amount at once.

This is my story. I'm sure there are many other reasons for pinging, but the '93 model is known for the poorly designed intake manifold gasket which causes oil or water to leak into the #5 cyclinder, causing carbon build up on the spark plug.

So, replacing the spark plugs and retorquing the intake manifold gasket helped my pinging, which, as yours did, gradually got worse and especially was worse in hot weather.

owner , well maintained and cared for . Developed bad

about it a month ago with a few responses . Did

plugs,wires, maf sensors dirty, carbon build up etc . Went to

with any codes , sensors were probably ok , not the

most part with high octane , looked like it was a

out for me an all data service bulletin on the

PM-3 to flush out the carbon in motor . Agreed on a

to pick it up I was told after the cleaning it

days and see if it goes away . He thought maybe it

something up inside .After a good day of driving it

pissed and am quickly starting to hate this truck that

'open up the motor' to fix it he would but no

suggestions as I don't know what to do and how to handle

station guy and don't think he did anything wrong on

SOMEBODY PLEASE HELP ME

in tune-up , wires , EGR , maf sensor ,etc,

gas . I USED to like this truck . Modern

at 75,000 babied miles you would think they

? Blame Ford ? I sure think so !!! Yeah so

hmm...by your reasoning, if you didn't drive it for another 20 years, a car with 75K miles should still drive the same? you can hardly attribute how well a car *should* be driving solely to the number of miles it has on it. regardless of the miles, some factors ARE time-affected. rubber hoses and belts develop cracks, oil and lubrication can dry up and seize, etc., not to mention rust...

john

Hi, Vic.... for carburetted and TBI motors, the water can be drizzled into the intake manifold via the throttle plates. The "Top Engine Cleaner" that me indicates is also good (just not as cheap as water). The downside to anything like this is that there always remains the danger that too large a carbon deposit can be knocked loose and leave us with a problem like Ron NY - yes, even the water can knock some big chunks loose. Also bear in mind that, should the offensive piece finally leave a cylinder, it can enter another depending on cam timing, manifold design and such....

Bring the idle up to 1000 - 1500 rpm and drizzle the water or TOC into the carb or TBI in small amounts slowly (don't forget my disclaimer) - as the water flashes to steam, it works like a little jackhammer to help knock carbon apart (water expands tremendously when it changes from liquid to steam). The TOC is better at removing the deposits from the back side of the inlet valves.

The water is one of those ages old tricks that has old mechanics remembering the times it worked better than they remember the times it didn't...

HTH.

-- Jim Warman snipped-for-privacy@telusplanet.net