Badly fouled spark plugs Options

[andreic]

Hello,

I have a problem on my newly rebuilt 1.8L engine, with L-Jet.

Yesterday as I was driving home the car simply quit about 5 blocks away from home. Until this point it was running very well. I had to have it towed home and now I started trying to diagnose it.

So far I've checked that the fuel pump operates when opening the flap in the AFM, so I suspect I got fuel pressure right. The starter spins the engine well.

I have strong spark on the main distributor cap wire (coming from the coil), and putting a brand new spark plug into one of the spark plug wires I have spark at that too. (Originally I was too lazy to pull an actual plug from the engine.) But this morning I tried pulling a spark plug from the engine, and it is completely black and covered in carbon. Not wet, just covered in a thick layer of solid black material.

I can't check right now whether the spark plug from the engine is fouled badly enough to not give a spark at all, or if it still is OK. (I need to wait for my son to come back in the afternoon to help me, this is a 2-person job.) But assuming the spark plugs are the problem, can somebody offer a guess as to what could have caused the engine to foul the spark plugs so badly and so quickly as to stop the engine while driving? Before that there was no indication something was wrong.

Other slightly strange things.

a) I've noticed the car burns a lot of gas. I barely get 20 mpg in mixed city/highway driving.

b) I have about 600 miles since the rebuild, engine ran well all along.

c) The only other issue with the car is that I can not get the idle right: it seems to idle at 1800 rpm most of the time, but if the engine is well warmed up (after about 1/2 hour of driving) or if I hold off the clutch as I come to a stop until the rpm's come down to 900, it'll idle at 900. I've tried two different throttle bodies, thinking it may be the throttle that sticks, but it behaves the same way with both. I started to suspect that the distributor is sticky and does not retard the idle sometimes.

Any suggestions, highly appreciated.

Thanks,
Andrei.

[earossi]

I've been looking at your posting and all of the comments you have received. Please consider that you may have two or more issues going on that may or may not be related.

Of those to consider, the one that I am fairly certain about is that you have not properly broken in the rings. Properly done, you should have seated your rings in the first 500 miles. Actual mileage to seat rings depends on ring material. If ring material is iron, seating takes place fairly quickly. If you installed chrome rings, then seating can take a lot longer. Regardless of ring material, if you fail to seat the rings rapidly, they will build a glaze in your cylinders.

Another issue that promotes glazing is whether or not you "oiled" the cylinders before installing the pistons. Newly ringed pistons should be installed in cylinders that are properly honed and are "dry". Oiling the cylinder walls allows the rings to slide over the cylinder walls rather than to seat. Although the oil will be removed in the first few seconds of run time, you have nonetheless promoted glazing.

Once a cylinder is glazed, I do not know of a way to remove the glaze other than removing each cylinder. The glaze is not very hard, and can usually be removed with Scotchbrite. There have been suggestions in write-ups that you can run some abrasive material through your engine to rough up the glazing; but, I have never read of someone reporting back that such a scheme worked.

Which brings us back to proper engine break-in. The temptation for someone who has not rebuilt a lot of engines is to soft pedal a newly rebuilt motor. Which is exactly the reverse of the way to break in an engine.

A rebuilt engine, once started, should immediately be run up to about 2500 rpm and held at that speed (without a load) for about 10 minutes. Doing that forces the new valves and bearings to seat in properly. That first run is also the time when any debris in the engine will wash out into the oil. So, after the initial run in, you should change out the oil and filter.

The second phase of engine break-in can now be initiated. As someone posted above, you should take the car out and drive it like you stole it, limiting engine speed to about 5000 rpm. The driving cycle should include putting a high load on the engine by "bogging" the car in higher gears. Usually 3rd or 4th gear works well. The procedure is to shift into a gear and then allow engine speed to decay as car speed decreases. Then, just short of stalling, apply full throttle which will cause the engine to begin to pull out of the stall. This puts a very high pressure load on the piston rings, forcing them to move "out" into the cylinder, which promotes ring seating. Maintain full throttle until you reach the rev limit mentioned above. Repeat this "lugging" cycle about 6 or 7 times during that first run.

Then continue to drive the car "like you have stolen it" for 500 miles, paying attention to not allowing the engine to over rev (past 5000 rpm) during that period. Rapid engine acceleration is what you want, but not to exceed the rev limit. You won't hurt the engine doing this. So do maximum acceleration movement through the gears without going above the rev limit.

At the end of the 500 mile break-in period, change your oil once again (as well as your filter). Then you should be good to go until a normally scheduled oil change is due.

Another poster mentioned oils including break-in oil and brand of oil to run. The difference between break-in oil and your normal oil is that the break-in oil will be a single viscosity (usually 30 weight) and break-in oils have very high levels of zinc and phosphorus. The high zinc is required to properly break in any contact surfaces such as engine tappets running on camshafts. Once you have properly broken in an engine, at the 500 mile point, you should replace the break-in oil with your oil of choice.

Regarding oil brands, there are much better oils on the market other than Castrol. I don't want to touch off a firestorm debate on oils, but though Castrol is OK, you should look for a better product. Whatever oil you choose should have higher levels of zinc and phosphorous. Government regulations have forced oil formulators to reduce zinc and phosphorous levels to very low levels, which are OK for modern engines, but will ruin the older engines such as we run in our 914's. The zinc and phosphorous additive put into most oils is called ZDDP. which is an acronym for the chemical formula of the additive. Proper levels of ZDDP are usually 1300+ ppm, rather than the 700-900 ppm currently being run in oils meant for street use. You will find the proper ZDDP levels in oils labeled "for off road use only". Or, you can purchase Mobil 1 synthetic motorcycle oil which comes in the 20W50 weight our engines were built to use. That oil (don't recall its trade name) can be purchased at your Harley Davidson store, or over the internet. It's formulated to run in air cooled engines and has the higher ZDDP needed.

Gasoline contamination of the oil does occur during the run in period; however, to build oil volume rapidly (as you described) is an indication of something else drastically wrong having to do with your fuel management system. You are obviously running way to rich. Gasoline that has made its way into your oil system is usually at a very low rate and will vaporize as oil temperature increases and be pulled off the system by vacuum.

And finally, your statement that the car was running perfectly and then suddenly stalled indicates to me, that you have suffered some electrical or technical malfunction. But, that malfunction is more than likely divorced from engine break-in.