Preliminary compression test results are in Mike, Bill, all

I just bought a good compression tester today and had a chance to test the first two cylinders (#1 and #2, #2 is the leaker/problem), ran out of time before I could get them all done. I got 150 psi on both cylinders after 4 cranks on a cold engine. This is exactly what my mechanic got.

Comments? So does this point to the head/valve guide as the problem?

Thanks,

Bill

Reply to
William Oliveri
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This probably isn't going to be super helpful but: It points to your engine being just fine. If you have good compression, you have no odd valve train noise, and you have no blue smoke, no oil in the coolant, or vice versa, and the engine is running well... You don't have a problem. Unless of course all the other cylinders show higher compression than the first two).

Oil on one of the plugs threads (but not on the important part of the plug) with no fouling or missing probably means that some oil got into the plug hole threads (maybe from a previous valve cover leak, or while you were doing the valve job?).

Of course I might very well be wrong, but it seems to me like you're looking for reasons why you may have messed up the valve job, when no real symptoms have actually cropped up.

BTW I've enjoyed your posts, as a non mechanic who's also trying to learn about this stuff in preparation for future DIY projects. I think I'm learning almost as much from the answers to your questions as you are (all the way back to the original pinging at idle thread).

Reply to
Simon Juncal

Thanks Simon, However, I do get fouling on the plug. If it was only the threads I could care less. The plug is coming out soaked with oil and fouling.

Again, glad you're are benefiting from these exchanges.

Bill

Reply to
William Oliveri

Reply to
Will Honea

Pack away the tools, close her up and enjoy!

Oh, change that injector too so that # 2 will get a spark again...

I will bet when you swap that injector with the #3 one, that #3 will have the 'wet' plug.

Mike

William Oliveri wrote:

Reply to
Mike Romain

I guess I missed the beginning of all this! A plug with black, wet deposits that is fouled is either fuel fouled (As is the 99:1 liklihood in your case) or oil fouled (which everyone but you feels it is not!) You have hopefully already checked these items, but they are all VERY common and cause exactly the symptoms you describe: Bad plug wire(s); Cross-tracking in distributor cap; You've changed the plug, so that's taken care of: an injector with bad spray pattern or not sealing, but I doubt this one... No blue smoke - any black smoke? If that cylinder is running that rich, there would be black smoke. Now that I understand what the fuss was all about, my money's on the "lack of spark" side of the equation! A friend once gave away a perfectly good CRX Honda with a newly rebuilt engine because it fouled 2 plugs repeatedly. It had the original sparkplug wires on it! Spark plug wires aren't like they used to be back when I was a kid - One set for the life of the car! I have had bad single wires in sets quite a few times and have had one or two go bad within a year, but not real common. After 3 or 4 years, you'll almost always have a definite performance gain when you install new wires. That said, all the old-timers are gonna climb all over me - I used to doubt it myself, but am now a believer after gaining some (bad) experience!

Maybe you already went through all the ignition stuff - as I said, I missed the beginning. If you did, I'd suggest checking it very carefully one more time. There is also the remote possibility that you have the order wrong, but you should have had symptoms for that. Look for anything that can diminish the spark on that plug - the easy stuff 1st like wiping out any grease in the hole and on the top surface around the hole - if you use anti seize compound on the threads, a build-up is bad and some are non-conductive. If long enough, swap two plug wires (swap em at the dizzy and the plugs, remember!) and see if your wet plug moves with the wire. Cracks or cross-tracking in the distributor cap are common and you probably will only see indications if you watch it running in total darkness (away from city light.) Then there is the remote possibility of something mechanically wrong like a bad distributor shaft bushing or something like that - should be bad for all cyls tho. On the "almost totally unheard of" page is a worn point cam on one lobe only! This engine most likely does not use ignition points, BTW. The old Jeep V-6's had some point cam issues, but they had weird point cams anyway (3 lobes at a certain angle - other 3 lobes at a different angle!)

Now that you have the compression gauge, check it about once a year and keep a log book. Any time something changes in engine performance rather radically and somewhat suddenly, whip out the compression gauge and check it before you do any "What-if" worrying!

I'm betting against the bad injector theory!

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Reply to
Busahaulic

Thanks for the reply,

Here's a summary of events that started this whole thing. I had previously been told I was blowing blue smoke by a mechanic but I couldn't see it so I blew it off for the mean time but kept watch. Then one day I found a place to go 4 wheeling for the first time since I bought this jeep. Everything went fine on the trail but soon after I began to blow blue smoke which occurred if I let it idle for a few minutes and then pump on the gas. Also, my plugs (all of them) fouled out. After considerable help here and other places I replaced the valve seals to see if this would help. After completion I saw the engine ran great and when I looked at the plugs after about 15 minutes at idle, they all looked perfect. Also I had no blue smoke. Then I drove it for about 10 miles and I could feel the engine go out of balance and felt like it was missing so I checked the plugs again. #2 was oil soaked and fouled out. All the rest were fine. I say oil fouled because when I pulled the plug I could run my fingers around the plug threads and wet oil would come off on my fingers.

Jump to present and reply to your post below:

I checked the wires, changed them out (switched them), bought a new cap and rotor, still the same.

Got my leak down tester today and tried it out. The only bad thing is the hose to the spark plug hole didn't fit so I made a make shift coupler and connected it to my old compression tester hose. It worked but there was a slight leak in the coupling which I don't know how much it will affect the results. I think minimally but I will get a fitting tomorrow which will totally clear that up.

Anyway, here we go.

I did the first three cylinders twice, #2 is the problem cylinder with the oil leak.

#1 18% leak down, 21% leak down. #2 35% leak down, 35% leak down. #3 28% leak down, 31% leak down.

These are hugh numbers as far as I know. I think I should be under 10% and definitely be under 15%.

I also got a new compression tester yesterday and last night did a compression on the first two cylinders.

#1 150 psi #2 150 psi

Which was the same as my mechanic's results.

My heads spinning on this one. One thing I'm going to try, and it's a long shot, is I have some super duper carbon dissolver that you pour in the tank. Perhaps after the engine ran rich (when I had the carb on it, now I have fuel injection) and combined with the oil leaking before I changed the seals, perhaps I got some serious carbon build up in the chamber which is either clogging the injector or causing a valve to remain open.

I don't know but this is the easiest try first. I looked at the injectors to see about changing them and it doesn't look easy at all.

Bill

Reply to
William Oliveri

what are you using for carbon dissolving?

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Reply to
brad smith

BG 44K

Reply to
William Oliveri

Bill, those numbers mean crap on an old engine.

You bought a 'used' fuel injection system.

You have replaced 'everything' electrical relating to that engine.

You have excellent compression.

You have no spark on one cylinder.

In my opinion you are totally wasting your time mucking about until you swap that injector out.

Hey, but it's your time to waste, me I would rather be wheeling.

Mike

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

William Oliveri wrote:

Reply to
Mike Romain

Mike, have you ever change out an injector for a MPI kit? Doesn't look easy or simple, not like changing a spark plug otherwise it would be done already. Do you have any call outs so I can see just what I'm getting into?

Thanks,

Bill

Everything

Reply to
William Oliveri

The whole rail has to come off eh?

I really can't think of anything else that would cause the mis fire and wet plug.

Is there any way to check the electrical pulse coming to the injector? My books don't cover that, but you should be able to see if there is an electrical pulse happening at the injector.

I also believe you can check for a leaky injector. One that stays open thus flooding the one spark plug. I think if one is stuck, the fuel pressure will drop down fast after the engine shuts down. If the system is sealed good I believe it should hold pressure overnight.

Does your fuel rail have a place to attach a pressure gauge? If so I would put one on and watch what happens after shutting it down.

Mike

William Oliveri wrote:

Reply to
Mike Romain

Okay 'cause in your original post valve job messages you mentioned a "film of oil" and nothing about it actually running rough. Oil gets past the rings on even brand new modern engines.

You say the plug does foul, by foul I mean you get so much crud that the plug can no longer manage to get an arc across the gap (at least consistently).

Reply to
Simon Juncal

Yeah, it has a place to attach a fuel pressure gauge and I do have a fuel pressure gauge so I can try that. Also, I need to hook up my Check Engine light for the MPI kit. Perhaps there's some diagnoistic codes being spit out that I don't know about.

If the injector was clogged though, would it show any difference in pressure? I have not smelled any fuel smells, especially when I pulled the plug after a drive. If it was spewing too much gas I surely would smell something.

If the injector is clogged then I would get little gas to the cylinder and that would cause the intermittent spark, yes? Then the oil fouling later down the road, true?

If the injector is clogged from carbon and excessive oil due to the seals the best bet I would have now I guess would be the BG 44K to clean that stuff out.

I mean, If I look at the numbers that came back on my tests, you are right. The compression is good and the leak down on #2 is not far off from #3 but I'm not having the same problem with #3 so.......

Bill

Reply to
William Oliveri

Yeah, plug coated with oil, wet on the threads, black black on the element. Also, the engine runs progressivly poorer as the plug gets worse (from new to worse).

Bill

Reply to
William Oliveri

I am thinking an injector not shutting all the way off. It doesn't have to be all the way 'on', just have a chunk of junk in it so it doesn't go all the way 'off'.

The pressure leak down test is a quick and easy check for that anyway.

If it was clogged closed, well... I don't think I have ever heard of an injector that was clogged closed, they always are 'leaky' when they get old. A good soak in carb cleaner can clean them up.

I am thinking soot black on the electrode means too rich and a wet base means it is leaking after shut down.

I would try that test anyway. That will sure let you know if something is indeed leaking or not shutting all the way off.

Mike

William Oliveri wrote:

Reply to
Mike Romain

If you are not getting fuel to the chamber then it should stay dry - the carbon black on the plug is a pretty good indicator of running rich.

Before you pull the fuel rail (about 4, maybe 5 small bolts) go get a o-ring kit and grab a package of the plastic quick connects used on the lines - at least used by the OEM setup. If this MPI kit is pretty new, you might get by but if it's more than a year old, get a new set of o-rings to seal the injectors.

You can buy a noid (just a light bulb, really) that goes > Yeah, it has a place to attach a fuel pressure gauge and I do have a fuel

Reply to
Will Honea

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