Mike, here's the plugs after about a 10 to 15 mile run after new distributor and fresh rebuild

They look pretty damn good Bill. Except you count backwards! ;)

Seriously, the plugs look fine, but run it a bit more and check it out again. If Mike is right about you having a bad injector, I'd hate to see it mess up your new engine. It still might be a good idea to have the injectors flow and impedance tested to make sure they are performing properly.

Chris

Chris and all,

I've never broken in an engine before. What can I expect? Will the engine feel different at different mileage? What mileage can I say it's truly broken in and the parts are 'harmonized'?

Right now there's a feeling of vibration at idle and I'm wondering if it's normal and later these things will go away.

BTW, the engine rebuilder told me he used molly rings and to expect loosing oil between every oil change as the molly rings are porous and so there will be some burning of oil.

Comments?

Thanks,

Bill

The best way to break in an engine is to drive it under moderate throttle conditions for about the first 500 miles or so. Do this with varying engine speeds. Don't take a 500 mile highway trip at 65mph in other words. Avoid towing and do not overheat the engine. Watch the coolant and oil levels closely to avoid running either one low, and to check for fluids where they don't belong. After that, change the oil and drive it as you normally would. Also, if the camshaft is new, you normally run the engine for 20 minutes or so with the engine varying from 1500 to 3000 RPM under no load. Too late for you to do this now, but you should be ok there. You didn't go out and beat the hell out of it.

Moly rings are slightly porous on the surface and you may see a small amount of oil consumption, but it shouldn't be excessive once the rings are properly seated. If the honing was done properly, the moly rings will seat quicker than the cast rings. Cylinders for moly rings are honed with a finer stone than cast rings.

As far as the vibration, check it out as you are driving to see if if disappears in a certain RPM range, or gets worse. I wouldn't worry about it until the engine is properly timed and the fuel injection is confirmed working properly. One bad injector, or anything else that causes the cylinder to slightly misfire can be felt as a vibration.

Chris

Well, the R&R place 'should' have done the brake in procedure you're speaking about. I gave them an outline from the machine shop and when I questioned them about it they said they did it. However, one point I found they did not do was to NOT put coolant into the radiator water for the first

50 miles. I asked the machine shop about this and he said (if I understand correctly) that he wanted water to go to every nook and cranny in the engine and that with coolant in the water it would be less likely for that to happen. After the first 50 miles go ahead and put coolant. I'm going to double check with him on the reasons when I see him again but that's how I understand it.

Anyway, when I reviewed the R&R work before they were done I saw they put coolant in. I again showed them the outline the machinist gave me which I gave a copy from the git-go and they replied, strange, and took the coolant out.

I think they had broken in many engines and just followed their method without looking at the outline given to them.

The 'vibration' is felt only at idle. When I drive it I don't feel it. Plus, I still have drive shaft vibration from the lift kit so at about 40 mph I get vibration from the drive shaft which is different from what I'm talking about.

This engine was balanced with both the flywheel and clutch plate and harmonic balancer as I understand it.

Bill

They sure aren't doing too bad. Like the others say check again and/or it would still be a good time to make sure on those injectors.

Mike

William Oliveri wrote:

Right, I'm definitely going to keep an eye on the plugs and I'm definitely not going to forgo checking those injectors out for sure.

I'm going to take it to a local jeep shop for checkup ASAP.

Thanks for the input.

Bill

I always put water in first in case of leaks. After I run it for a very short while & no leaks, I put in the antifreeze - friendlier to the earth & (more important) friendlier to my wallet. don't know about the "nook & cranny" thing.

That's after only 15 miles?! The plugs out of my BMW were cleaner than that after 50,000 miles.

I don't want to be the bearer of bad news, but me thinks you have issues.

Never mind.

My plugs came out with much less brown on the tips, but I suppose that the brown is not an indicator of trouble. They are all the same color, but the ones to the back of the motor look a little darker to me.

IN A RELATED DEVELOPMENT I took the plugs out of CRWLR, and the #3 plug is black and loading up.

You guys might remember that I wsas asking about a high speed miss that has developed. The motor runs well at low speeds, normal city and rural road driving, but misses after several minutes on the interstate. I was wondering about what a floating valve might feel like. I have never had a valve float, but if one did float, I think it should feel alot like what I am getting. The black plug tends to support that I have something in the motor getting ready to take a bye. .

I will reserve judgment on Bill's plugs until some miles get on them.

I would be checking the plug wire and inside the distributor for carbon tracks first on your miss, buildup. Even a bad plug. Maybe swap them with a different cylinder to see what happens.

Then a fast compression test can tell a bunch...

A floating valve usually will be noisy, but not always.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

CRWLR wrote:

Have you still got your scope?