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Hey guys, getting really frustrated. The long and short of it is: I pulled my 2.5 last summer and had it rebuilt, got an ax 5 out of a 2000XJ with the external slave. I went to a "reputable" machine shop/engine builder, and broke it in properly. When it continued to use oil well past break in, sometimes a quart every 500-1000 miles depending on load, etc., I called the builder. Now, it was cold weather, and I wasn't going to get to into it, but he assured me it was probably valve seals and he could take care of that easily. Now, he's just a machine shop, and not a garage, so anything more than seals would mean I have to take the head off, or the engine out, and bring it back to him. I have a neighbor, a good guy, who is an ASE mechanic, former Ford dealership pro who's now teaching at a vo-tech. He was more skeptical, and thought maybe it was valve seats, but the builder didn't knurl or re-use them, he put new ones in. Anyways, we thought the first step, before taking anything apart, was to do a leak down test. My friend had a junky Harbor Freight unit lying around, and it didn't work very well, but we noticed that cylinders 2-3, which had fouled Champion plugs, hissed when we applied shop air at TDC, and you could hear the air coming out of the oil filler. He said that I should go to a shop, get a documented leak down test, then go to the builder with the numbers. He was fairly certain that the rings on 2-3 were bad. So, not knowing any mechanics very well, I took it to a place called "Motorworks." They do a lot of Jasper installs there. I dropped the MJ off, and they called back, saying compression was 135-140psi and consistent, and that the leak down test was "normal." When I asked him what normal was, he said "in the green area." I said 'meaning what?' He said "less than 40% in all cylinders." Well, I didn't like that answer, found out that he was a manager and did the test, but did not admit to being a mechanic, which makes me wonder if he did the test correctly. I haven't picked the truck up yet, but I feel like I'm going to spend some money and not get a real answer. When I asked him why I would foul 2-3 and use oil, with good compression and acceptable leakdown, he said "I have no idea." He suggested I get NGK spark plugs ("b/c Champions are crappy") and "run some good gas in it." I mentioned that the vehicle came from the factory with Champions and calibrated to run at 87 octane. I'm picking the truck up tomorrow. Anything else I should ask him? I'm pretty bummed about this whole thing. Engine builder keeps insisting I check the valve seals. Could that do what is happening here?? THanks! Tom :wall: :wall: :wall: :wall:

Hey guys- Long time, no see. Now that it's getting warm(er), time to think about the summer projects. I have to do the heater core, rebuilt an AMC20 I found, and have the valve stems replaced :wall: . Anyways, I found a 21 spline np242 for sale cheap - needs a rebuilt. My 231 is noisy and soon to be the ONLY drivetrain component that's not new(er)/rebuilt. Is it a straightforward replacement? Other than the shifter plate change, will I have to mess with the linkage or the driveshafts? I'd rather get the 242, have it rebuilt, and then do a one day swap and not have too much downside, rather than taking out my 231 and waiting for it to come back. Pro's? Any con's? Thanks Tom

Thanks, guys, I should have figured that out. I think there's a drum for it lying around somewhere!

Hey guys- I have an amc 20 4.10 from an MJ in my garage, and was wondering what brake shoes it took (it has none on it): autozone.com lists 2 kinds for an 86 MJ but gives by size, not axle type With 10 x 2 1/2" brakes With 10 x 1 3/4" brakes which did the AMC20 have? Anyone know? THanks! Tom

:agree:

LOL the machine shop cut my flywheel without me asking when I had my 2.5 rebuilt. The clutch has never engaged smoother.

Just so everyone knows, Dan (bigd) got back to me on this and made good. We're square. Thanks Tom

Hey, now that you're back, you wanna pay me for the starter I sent you? You didn't hold up your end of the bargain, and even when you came back online, you haven't replied to me. Sorry to clog up the board with this, and I hoped we wouldn't have to worry about bad buyers/sellers here on a close-knit group, but it's everywhere I guess. :hijack:

Lessons I learned: Even if you seem stuck, and are frustrated, as long as you have another vehicle to drive, never EVER take a 20 year old car/truck/whatever to the mechanic! The information here is great, and most people have probably seen your problem before. That said: I got the 2.5 to go into closed loop, but it had NOTHING to do with the temp sensor. NOTHING. The mechanic who did my fuel pump, while rooting around for wires, cracked the hard vacuum line going to the MAP sensor. Once I fixed this, the car began running correctly. So there is more to open/closed loop than simply temperature. I was using oil like crazy. A few years back, when the old motor was blowing by like crazy, I was scrambling to do anything to stop/slow it. I pulled the rear grommet from the valve cover, where vacuum is applied. The 2.2mm opening was almost closed from years of crap. I took a drill bit and bored it out, to make sure I was getting adequate vacuum. Well, that opening was 2.2mm for a reason. On the new engine, with great vacuum, I was losing oil through the CCV system. Replaced the grommet, stopped losing oil. Thanks for the help -- I can finally move forward with the truck and enjoy driving it! Oh, and the other thing I learned is if you have access to a DRB II with the Jeep module, it really helps in diagnosis! LOL :rotf:

Not that I've been able to see so far! No puddles, or even drips, under the truck :ack: , even when parked after a highway trip.

Not that I've been able to see so far! No puddles, or even drips, under the truck :ack: , even when parked after a highway trip.

So it's very variable. I'm going to start by getting the CCV system operating the way it was designed, and if it continues, I will have the builder run some tests on it. It's running great -- really smooth, and with a lot more power. Hopefully the oil consumption comes down to a minimum. :pcwhack:

So it's very variable. I'm going to start by getting the CCV system operating the way it was designed, and if it continues, I will have the builder run some tests on it. It's running great -- really smooth, and with a lot more power. Hopefully the oil consumption comes down to a minimum. :pcwhack:

Here's what the builder told me to do: filled it with 10-W30 Castrol, initial startup and run at 2400RPM for 20 mins. Shut down, change oil. Change oil again 500 miles later. I've used 10W30 Castrol each time. He did not specify a weight, only that it be dino oil. It's possible the rings haven't seated yet, is that just a matter of time, or something I have to do? Thanks Tom

Here's what the builder told me to do: filled it with 10-W30 Castrol, initial startup and run at 2400RPM for 20 mins. Shut down, change oil. Change oil again 500 miles later. I've used 10W30 Castrol each time. He did not specify a weight, only that it be dino oil. It's possible the rings haven't seated yet, is that just a matter of time, or something I have to do? Thanks Tom

I know! I'm hoping it's that the rings didn't seat. After I replace the grommet, if it continues, I'm going to drive it to his shop and let him do leak down tests. I've had bad rings before and usually get oil-coated plugs. I would expect smoke, or something! It's strange.

I know! I'm hoping it's that the rings didn't seat. After I replace the grommet, if it continues, I'm going to drive it to his shop and let him do leak down tests. I've had bad rings before and usually get oil-coated plugs. I would expect smoke, or something! It's strange.

OK, I have about 1200 miles on the rebuilt 2.5. It was rebuilt by a good shop, so I know they didn't put the rings in wrong or anything. No smoke, no leak, no fouled plugs, no oil in the air filter, but I'm using oil. The builder told me to check the PCV system. I told him I had a CCV and no PCV valve, he was surprised and said to check vacuum at the dipstick, that there should be 4-5" of vacuum there. Well, there wasn't, but I have good vacuum to the valve cover -- and that's my question. The grommet with the 2.2mm orifice in the back of the valve cover got pretty crummy looking a few years back so I took a drill bit and honed it out to open it up a bit. Could I be sucking up a good bit of oil from the roller rockers? That's the only thing I can figure so far. If I take the truck on a good highway run, maybe 40 miles round trip, I'm using almost half a quart! I'm going to start with this grommet. Is it too soon to worry with 1200 miles? I'm using dino oil by the way, no synthetic yet. Tom :huh???:

OK, I have about 1200 miles on the rebuilt 2.5. It was rebuilt by a good shop, so I know they didn't put the rings in wrong or anything. No smoke, no leak, no fouled plugs, no oil in the air filter, but I'm using oil. The builder told me to check the PCV system. I told him I had a CCV and no PCV valve, he was surprised and said to check vacuum at the dipstick, that there should be 4-5" of vacuum there. Well, there wasn't, but I have good vacuum to the valve cover -- and that's my question. The grommet with the 2.2mm orifice in the back of the valve cover got pretty crummy looking a few years back so I took a drill bit and honed it out to open it up a bit. Could I be sucking up a good bit of oil from the roller rockers? That's the only thing I can figure so far. If I take the truck on a good highway run, maybe 40 miles round trip, I'm using almost half a quart! I'm going to start with this grommet. Is it too soon to worry with 1200 miles? I'm using dino oil by the way, no synthetic yet. Tom :huh???:

I was looking at these for my 2.5, but it's a start towards finding a good hi-flow for your truck: http://www.performance-air-filters.com/ ... parts.html http://www.autoanything.com/exhausts-mu ... 55808.aspx

Thanks, Jeff. Wondering if I put the right sensor in the right place! I'll check my wiring diagram LOL :oops:

Hmm -- OK, I see what you're saying. I didn't think of that; I thought the diagnostic connector was a reading of what's going to the CPU. It makes sense to me that signal goes sensor-->CPU-->diagnostic connector, but I have no proof of that. I was tooling around under the hood last night and found a crack in the vacuum line to the MAP sensor. I electrical-taped that up and it ran a LOT less rich. Driveability is still kind of poor - it hesitates pretty badly, almost like it's running lean now! Tonight, planning on hooking up the DRBII again to see if I'm now getting into closed loop. Also going to test fuel pressure at the TBI and adjust, if necessary, after the fuel pump was changed. I played with the volt/ohmeter a bit last night. I'm getting battery voltage to the 02 sensor, the MAP, MAT, and temp sensor are getting the correct voltage (4.x volts). I tested resistance on the MAT and temp sensors, and they dropped after warm up. I didn't write anything down LOL -- kind of helter skelter. But nothing was wildly abnormal. Here's one of those dumb questions JUST TO MAKE SURE: there are two similar looking sensors, the CTS (coolant temp) and MAT, both on the intake, one on top and one in the side. Which is which? I'm sure I put the right ones where they go when I had the intake off, prior to install, but I'm just re-tracing all my steps! Thanks! :dunce:

There's only one coolant temp SENSOR. I know what the gauge sending unit is, and my truck didn't come with an aux fan from the factory. The sensor is telling the ECU what the temp is. I know this because we had the DRBII hooked up and it said "coolant temperature: whatever degrees." The DRB was plugged into the diagnostic connectors under the hood. This is why I'm having the confusion: according to the DRB, the truck warmed up into operating range, and beyond, but never left the open loop. See what I'm saying? It was getting temp readings from the coolant temp sensor. So I imagine it's working. It happened to correlate with the gauge as we were running the diagnostics on the idling engine. From that, I'm concluding that it's not only operating temp. flips the truck over into closed loop. :wall: :D Tom

Wrong. First, you don't have a fuel bowl. Second, the O2 sensor doesn't flip into closed loop mode, the ECU does. And it does so when the operating temperature reaches the "normal" range, which is around 165 to 168 degrees, as reported by the temp sensor in the side of the block (not the one on the back of the head ... that one only feeds the gauge). If you aren't getting into closed loop mode, your ECU is simply ignoring the O2 sensor and running in "warm-up" (open loop) mode all the time. You most likely either have a bad temp sensor or a bad ECU. Start by checking the wiring between the temp sensor and the ECU to be sure you have a circuit. OK, thanks. If the DRBII scanner is telling me that the coolant temperature was 200-205 degrees (before my fan kicked on), shouldn't it have come out of the open loop? Wouldn't the fact that the sensor is putting out the data mean that it (coolant temperature sensor, which is brand new) is operating properly? So you're saying that operating temperature is the only thing that flips the Renix system into closed loop operation? How would you proceed? Swap the ECU with another one to test ?

Not exactly, as I understand it. If I'm flooding the fuel bowl with too much pressure, it could run rich and then the 02 sensor reads that and doesn't flip it into closed loop. Right? :dunno: