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Discussion Starter #1
I'm wrapping up water pump replacement on my 2.7 engine (a fun job, to be sure), and when I try to start the engine, the 20 amp fuse for the coils and injectors blows. I did a cursory check of the wiring to the coils, which seems fine. Before I remove the plenum to look at the injector wiring, do any other suspects immediately come to mind?

I'm pretty sure that I reconnected everything properly while putting the plenum back on -- actually, it seems fairly hard to screw up (beyond forgetting a connection), since most of the connectors will only fit in one place.

Thanks for all help!
 

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Initial thoughts: Measure resistance from load side of fuse socket with fuse out. If reading not low, perhaps some PCM ign. coil or injector coils drivers are failed (shorted to ground) only when power is on. If low ohms, disconnect all loads from that wire. Measure resistance again. If still low, find out where wire is shorted to ground - did it get pinched to ground? If not still low, determine which load is shorted. One or two capacitors are between that wire and ground. Is a capacitor shorted, or is the wire connected directly to ground by mistake?
 

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quick glance at a wiring diagram, and that's all there is on that circuit.
6 coils, 6 injectors, and 2 capacitors.
all dark green/light green.
they come though the harness on the front of the engine.
 

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Discussion Starter #4
Checking on both possibilities. If I need to check the capacitors, are they in a computer somewhere, or ... ?

In my non-automotive experience, caps usually fail dead, not shorted.
 

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Checking on both possibilities. If I need to check the capacitors, are they in a computer somewhere, or ... ?
They're a little rectangular box about 3/4"x1"x3/8" IIRC - they clip onto a small bracket on the head (that grounds one side of the cap), a single wire of the coil bus plugs into it. They sometimes break loose from the bracket, but of course that wouldn't cause a short.

In my non-automotive experience, caps usually fail dead, not shorted.
Depends on the type. Aluminum electrolytics get leaky (conducting). Ceramics can go dead short, tantalums short out and explode. These are probably some type of plastic film - not known for shorting.

I mentioned the capacitors mainly to make sure the wire wasn't plugged into the capacitor bracket that is grounded. You're probably right - not likely the capacitor itself is shorted, but wouldn't rule anything out. The one thing you assume is not the problem just might be it. :)
 

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Discussion Starter #6
Well, more stupidity from my end ... my shadetree mechanic skills appear to be getting worse, not better.

Anyway, the capacitors on my car disappeared during the disassembly process. I know one was damaged, but I didn't realize they were capacitors. So when I started putting things back together, I grounded those leads to the valve covers. Presto: short circuit.

They're pricey little suckers, too: $11 each at Rock Auto, plus shipping. Anyway, I'll try to finish up next week ... and hope to God that I got the position of the timing chains and sprockets correct when putting in the new water pump. After assembly, I did turn over the engine by hand a few times and there were no ugly noises or unusual resistance. So we shall see.

One interesting discovery: Pulled the spark plugs and discovered the vertical electrode was almost nonexistent, with the gap at least four times what it's supposed to be. I'm replacing w/ Champion double platinum, which is what was in there, and evidently lasted 100k miles.

Got the sludge cleaned out, too. Man, what came out of the oil pan was REALLY ugly looking. Let it drain for a long time, then sprayed some mineral spirits up through the hole to get some more dregs out. When changing the oil filter, discovered there was an extra O-ring stuck to the engine. No wonder there was a constant drip. :)

Also took me more than an hour to get the alternator back in, which I'd removed to replace the thermostat, except that the new one (Stant) didn't fit, so the old one went back in. When it comes to engine compartment access, the most difficult car I've ever owned was a Saab 9000 turbo w/ transverse engine, but the Dodge is right up there.

Anyway, enough whining from me, and thanks to Peva and Yevrah for the help. Stay tuned!
 

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good thing you found the problem. should run without them as long as the wires are no longer grounded.
 

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You're welcome, and gad you got it figured out.

Were the spark plugs Bosch by chance? I ask because there is a particular model of Bosch plugs that have super thin center electrodes. Several people on this forum reported that they broke off, and, IIRC, in at least one case did engine damage.

On the double gasket, when replacing the oil filter, it's important to check that the gasket on the old oil filter comes off with the gasket instead of sticking to the oil filter bracket or engine block every time before putting the new filter on. Guaranteed if you replace your filters for a few years, you will have that happen at least once or twice. You're lucky it was a relatively slow drip - often it results in a steady stream, emptying the engine of oil within a block or two of driving, and of course damaging the engine.
 

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Discussion Starter #9
A new set of problems. Help, please!

Well, first the good news:Got everything put back together, including shiny new Mopar capacitors for ground wires to valve covers, turned the key, and ... the engine fired right up and ran smoothly.

However:
--got a p0344 code (intermittent cam sensor signal), which I'm thinking is probably some computer confusion as it has to relearn everything after being disconnected for so long. Cleared the code and it hasn't come back, yet. Cam sensor was replaced within the past year, so it should be OK (famous last words).
--oil pressure light goes on and off intermittently. I'm speculating the old sludge-laden oil gummed it up. If it keeps coming back, I'll replace the sensor. Have confirmed there's plenty of oil, and engine has idled long enough (approx 15 minutes) that if there really was no oil pressure, it would have ground to a halt.
--now the alarming part: There is a fair amount of what sounds like valve train noise (metallic ticking), which gets louder as engine warms up. Noisy lifters? If so, should I try a dose of Marvel Mystery Oil or such-like to help clean out? Also alarming: When I start the engine, there is about 5 seconds of what sounds like chain noise -- similar to the sound the first time I started after the water pump replacement. I had lubricated the timing chains before assembly, per various guides, and I expected to some initial noise the first time ... but every time?
--I did not replace the old chain tensioner (engine has approx 104k miles). It seemed to work properly -- lots of spring tension, no sticking -- and I made sure that all the old sludg-ey oil had been pumped out of it before re-using. After hearing repeated (likely) chain noise, I checked tensioner again from outside and confirmed there was plenty of tension when I pushed against it.
So, any guesses what's going on?
I had mildly screwed up during the chain-setting process before figuring it out, so I'm only 99 percent sure, not 100 percent sure, that everything is set properly. However, I assume that if the settings were seriously wrong, the engine wouldn't run smoothly, and/or there would be catastrophic valve damage -- neither of which seems to have occurred.
--Before starting the engine, I filled the radiator w/ antifreeze (to approx 80 percent) before connecting the top hose, and then topped off the water reservoir. After idling, the temp gauge warmed to normal level, the top hose warmed up, and opening the bleed valve resulted in air being expelled as the pressure rose -- like it's supposed to. However, I still felt that the lower radiator and heater hoses didn't warm up very much. The thermostat did open, however, as the water level dropped in the reservoir after the engine had warmed up. In previous experience with other vehicles, this usually sorts itself out after a while, and I'll continue to bleed and monitor coolant levels. Anything else I should think about?

So ... what to do about the chain and/or lifter noise? Cross my fingers, start driving and see what happens, hoping it's just lifter noise and will go away (which doesn't explain the apparent noisy chain at startup)? Or take everything apart again, double-check the chain settings and replace the tensioner? I've only revved the engine to about 1,800 rpm, being cautious, and there's no change in the sound at that speed.

As usual, all help appreciated..

PS: Regarding the previous question about whether the spark plugs that I replaced were Bosch: No -- they were the stock Champion "double platinum" plugs, which supposedly are more durable than Champion's "ordinary" platinum, and I replaced them with the same type (though a newer part number, per Rock Auto). The new plugs appeared to be identical to the old ones in terms of insulator length and depth, etc., and according to the Rock Auto guide, the Champions were OEM for this engine.
 

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Discussion Starter #10
One more thing: In looking at photos of new tensioners (see pic), there is a thin metal loop in one of the circular grooves (see photo). On my old tensioner, the loop had broken off, outside the engine, and was replaced without it. I'm pretty sure that the purpose of the loop is to hold the (new) tensioner compressed, until installation, when there's a procedure to release it ... so I'm pretty sure that it's supposed to break off ... and that I don't need it when re-installing the old one. Comments?
40619
 
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