Weird crank but no start (long)

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rbtconsultants

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We've been working on the 2002 liberty 3.7l for a bit now, since it dropped a valve seat. In summary, engine was pulled, a couple pistons replaced, new timing set installed, heads were replaced with remanned heads. The engine is now back in.

When we first put the engine back in, we fired it. Basically ran it off battery for a few seconds. Had no alternator or belt on it, no cats or o2 sensors, bare bones. Exhaust was loud but It ran, but the fuel rail was leaking. After a few seconds of running I tried to rev it, it backfired through the intake, and wouldn't start after that. I chalked that up to going lean from low fuel pressure from the leaking fuel rail.

A few days later installed the new fuel rail. It behaved exactly the same way. It fired up, ran for probably 10 seconds. Turned it off, restarted it for another 10 seconds. Then tried to rev it, big backfire through the intake, wouldn't start anymore.

Started to think it was electrical. Battery was low and we were starting off of a power booster. Decided to charge the battery. That was Wednesday.

Today, Saturday, tried again with charged battery, no booster. Fired immediately, idled ok, revved it fine. Seemed all good, turned it off. Spent the rest of the day reassembling everything, alternator, belt, cats, everything plugged in and back together, except air cleaner assembly.

Then, tried to fire it again. Immediate single big backfire through intake, then no start. Tried a bunch. Sounded like it wanted to fire a few times, but no joy. Left it with the battery disconnected and charging. Trying to figure out what is next. I would not be surprised to get back to it tomorrow and fire immediately, or not at all. Confusing.

There are no codes. I actually disconnected the cam sensor at one point just to see if would code. It did. Tried the same with the crank sensor but it did not throw a code. I don't know if that is because it wasn't running, or if it should tell me something

So, timing? Intake backfire would point that way, but the timing was set dead on when the new chains/tensioners were put in. Plus, would it start sometimes and not others if timing? Could a cam sprocket be off just a tooth and cause all this? I guess I can pull the valve covers and see if something looks off.

Compression? Didn't do a compression test with a gauge but pulled plugs and did confirm compression. Plus it did start/run several times. Maybe need to test with a gauge, was going to but have misplaced my gauge somewhere. Have to buy a new one I guess.

Electrical? I did pull one coil/plug today and there was spark, didn't seem particularly bright. Thinking about a new battery. Low voltage could make the computer act weird I suppose, cause backfires, no start, weak spark, whatever.

Fuel? I can hear the pump priming. Popped the quick connect on the fuel rail and fuel coming out when the motor is turning over. Maybe I need to get a fuel pressure tester. Maybe an injector problem? Old fuel? Fuel was very low and probably 6 months old. Added a couple gallons of fresh but no change. I didn't pull the plugs to see if they were wet.

Anybody have any thoughts? What would you check first? The weird part to me is three times now it has run, then backfired and wouldn't start anymore until I let it sit for a day or two. Just odd.

Thanks

Bob
 

Logan Savage

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Just guessing but when you get the backfire & no start , I'd pull the plugs & see if they were all wet . Since it starts after sitting a day or two , sounds like it's flooding the plugs out .
 

rbtconsultants

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For closure, it turned out to be timing, but not exactly the "off by one tooth" issue. I said it was weird, and weird it turned out to be. I got a new compression gauge and did compression test, and passenger side was fine but the whole drivers side bank was very low, like 20-40. So that said timing to me, since the head gasket was new and the head was rebuilt, so what would make all three cylinders on that side low? Had to be timing.

The timing chains and sprockets were set correctly. I stared at them for awhile and tried to convince myself that somehow something was off, but I just couldn't see it.

So, I took the sprocket off the cam, and it turns out the little nub on the end of the cam was not in the sprocket keyhole, and the cam was about 40 degrees off, which is like three teeth. So I guess when I tightened the sprocket onto the cam I didn't get that lined up exactly. It was tightened to 90 foot pounds but with that nub not in the keyhole it looks like it allowed the cam to move independently of the sprocket and get misaligned. So I believe timing actually changed from startup as we tested, which helps explain weird behavior.

I recall the fit of the sprocket on the end of the cam was tight and I used the bolt to to draw it in, and the washer covers the keyhole so it wasn't obvious.

So, this time, I tightened it all up, then loosened and removed the bolt and washer and checked to see that the nub/keyhole was aligned and the sprocket was flush on the end of the cam. Then I put the bolt and washer back on and tightened to spec.

I guess I got lucky because this doesn't appear to have resulted in any interference damage, and now I have 150-180 compression in all cylinders.

So, have to reassemble, put the valve covers back on, reconnect everything, etc. And I didn't have time tonight, but since compression is good all around and it has run already (somewhat) I am confident it will run. We'll get time on Saturday and expect it to be back on the road. I'll report back.

Thanks for thoughts and help.

Bob
 

TwoBobsKJ

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Good diagnosis! :waytogo:

Definitely give us the final scoop on how it runs when you get everything buttoned up.


Bob
 

rbtconsultants

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So, got the jeep running today, but still not good news. My saga continues. The engine ran but it was blowing white smoke. I let it warm up to operating temp in case it was just burning things off but it got no better. I began to fear a problem with my head gasket installation.

I decided to run another compression test to see if something had changed. Compression on all cylinders was fine except #1 which was very high, like 230. Turns out it was taking on coolant, which became apparent when it sprayed coolant out while I was checking another cylinder. I ran a pressure test on the cooling system, and coolant literally bubbled out of that cylinder.

So, I blame my installation of the MLS gasket. The heads were both remanufactured so I'm not concerned about the head sealing surface (I hope). I likely did not do a good enough job of surface prep on the block. I used gasket remover and plastic razor blades, but apparently that wasn't good enough for MLS. Plus I guess I shouldn't have gone with the Ebay gasket set. I didn't really realize the tolerances of the MLS and figured if MLS came off, MLS would go back on no problem, and that MLS was MLS. Wrong.

I have now researched and realized a couple things. I should have used Felpro gaskets, which are engineered for rebuild situations and are more tolerant of surface preparation. Maybe even use a little Mopar spray gasket sealant. And I should have used Roloc bristle discs to do the surface prep as specified in the FSM.

So, my next step is to run a leakdown test on all cylinders and see if the problem is just on the left head or on both. If it's just cylinder #1 I'm tempted to throw in a bottle of liquid head gasket like K seal and see if that helps. Worst that can happen is the head is coming off anyway.

With all my experience under this hood now, I believe I could have the heads off and on with a couple days of work. So, not the worst thing I ever did wrong, but crap.

Hope this helps others learn from my mistakes. I'll keep updating.

Bob
 

ltd02

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I used the Felpros without trouble. This was my first time changing headgaskets. Plastic scraper my fingernails and alot of rubbing alcohol. Saw that disc recommendation too, but didn't use them since all the old stuff came off. I did use Bar's Headgasket fix when HG initially went and it lasted for two years. Not an endorsement but at the time I was desperate so just sayin'.
 

mx3_ryder

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Your situation is the exact reason I opted for entire new engine when my #2 intake seat dropped. I just didn't feel confident in getting the heads sealed properly and the troubles I may have following the rebuild like you are experiencing. Did you reuse your head bolts or buy new? Also did you follow the correct torque to angle sequence per FSM? Sometimes graphite head gaskets are more forgiving then MLS when doing a rebuild and tend to seal better when sealing surfaces are not to spec.
 

rbtconsultants

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Well, I don't mean to make this sound like this is awful for me. I mean, I hate doing things twice, but I enjoy working on cars, I have the tools and garage and it's a spare car so I'd much rather spend the time than the money. And I'm always willing to learn, and mistakes are a good way to learn.

Anyway, we used new head bolts angle torqued as specified in the FSM. As far as Graphite rather than MLS, are there graphite gaskets for the 3.7l? Googling shows some listings on EBAY but I'm not confident those aren't just generic descriptions. There are no references that I can find searching in any forums or anything indicating people have installed graphite gaskets on this engine.

Bob
 

rbtconsultants

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It's been a little bit, but the jeep is back on the road. Turns out the rebuilt head I bought on the Internet was bad.

I removed the driver side head and cleaned the block surface with a Roloc bristle disk and used a new Felpro head gallery and reinstalled. Ran a leakdown test and was still getting leak from cylinder #1 into the cooling system. God hated my jeep.

Removed the head again and took it to the local machine shop, which is where I should have gone from day 1. They pointed out that the head was cracked, had previously been welded and the weld failed. Head is garbage. Now I have to try and get my money back from these Internet jokers. "Machine Shop Pros". Avoid.

So my local guys got their hands on a core for me and rebuilt it. So both heads have been rebuilt, including all valve seats having been replaced/upgraded.

Got the new driver side head on this weekend. Got everything reassembled. Jeep starts right up, blows smoke for quite a while, I guess burning lef t over coolant out of the cats/exhaust. Now it Purrs. I can barely tell it's running when idling. I drive it for about half an hour, smoking from exhaust and under hood smoke from oil burning off the outside of the engine seems to be gone. So, I need a bit more seat time just to be confident all is well. It did sit for many months.

But boy it is nice to be driving it again. The work to make it live again was fun and frustrating. I would absolutely do it again if I had it to do over.

Bob
 

Birdman330

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For closure, it turned out to be timing, but not exactly the "off by one tooth" issue. I said it was weird, and weird it turned out to be. I got a new compression gauge and did compression test, and passenger side was fine but the whole drivers side bank was very low, like 20-40. So that said timing to me, since the head gasket was new and the head was rebuilt, so what would make all three cylinders on that side low? Had to be timing.

The timing chains and sprockets were set correctly. I stared at them for awhile and tried to convince myself that somehow something was off, but I just couldn't see it.

So, I took the sprocket off the cam, and it turns out the little nub on the end of the cam was not in the sprocket keyhole, and the cam was about 40 degrees off, which is like three teeth. So I guess when I tightened the sprocket onto the cam I didn't get that lined up exactly. It was tightened to 90 foot pounds but with that nub not in the keyhole it looks like it allowed the cam to move independently of the sprocket and get misaligned. So I believe timing actually changed from startup as we tested, which helps explain weird behavior.

I recall the fit of the sprocket on the end of the cam was tight and I used the bolt to to draw it in, and the washer covers the keyhole so it wasn't obvious.

So, this time, I tightened it all up, then loosened and removed the bolt and washer and checked to see that the nub/keyhole was aligned and the sprocket was flush on the end of the cam. Then I put the bolt and washer back on and tightened to spec.

I guess I got lucky because this doesn't appear to have resulted in any interference damage, and now I have 150-180 compression in all cylinders.

So, have to reassemble, put the valve covers back on, reconnect everything, etc. And I didn't have time tonight, but since compression is good all around and it has run already (somewhat) I am confident it will run. We'll get time on Saturday and expect it to be back on the road. I'll report back.

Thanks for thoughts and help.

Bob

Had the same issue happen when I redid the intake manifold and lifters on my F350, the teeth were out of line for the distributor. Put everything back together for the life of me couldn't figure out why the damn thing would crank and crank with no fire. Pulled the distributor out, saw it wasn't lining properly adjusted and solved. Felt like an idiot for not checking alignment when I put it back in.
 

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