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j1b1e1
Dodge Dakota
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10/15/2006
22:55:11
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 Subject: 3.9L won't start after timing install
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Let me give you the history, I was sitting at a traffic light and the truck went dead. No prequil, it was as if someone turned the key off. It had (for about 10,000) miles been losing power though I figured it was about time for that. It's got 200,000 miles on it. It has been gone through a few years ago, but I'm not sure to what extent. It's a 1993 3.9L dakota. Now for the good stuff, as soon as it quit I tried to restart it and it spun over extremly fast as if it had no compression. The first thing I think is the timeing chain so I towed it home and tore into it. Sure enough the chain had eaten the cam gear (well half of it) and it was lacking teeth on one side. I actually pulled the chain off without removing anything. Sounded like a simple fix. I got a new chain and put it on then I looked online to see how the marks on the gears went and found them to both be at 12 o'clock. I put it togther and it sounded the same, like a loss of compression. I talked to a friend of mine who has "mitchell on demand" and saw that the gears actually point towards one another, making mine 180 out. I tore it all down again and turned the cam 180 degrees and reinstalled the cam gear. This seemed like the most logical answer. The trouble is that it's still the same. It spins over quickly and won't start. I checked for spark and found that it has spark on #1 and I put a timing light on it while it was starting up and everytime it hit the crank was at TDC. I disconnected the battery and left it overnight to reset the PCM and nothing changed there either. It will spin freely and then a backfire out the carb once or twice. The rocker arms are all rocking back and forth. I can't seem to figure this one out, any advice would be appreciated. Thanks, Billy
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ES
Dodge Dakota
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10/15/2006
23:17:45
|  RE: 3.9L won't start after timing install
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I read of a few people on here bending valves from breaking a timing chain. Do a compression check and see what u find.
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J and J Auto
GenII
10/16/2006
01:19:17
| RE: 3.9L won't start after timing install
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You can install the chain either way
12, 12
cam 6, crank 12
its a 2 to 1 ratio turn the crank 1 revolution and
the mark on the cam will change from 12 to 6 or 6
to 12
What you need to do is watch the valves on #1
drivers side after intake opens and closes
bring to TDC 0 now pull the cap and the rotor
should aim towards #1 wire marked on cap also
rotor button centered over cyl line on dist
pickup plate
the rotor will aim towards pass side fender and
#1 on cap
If you were 1 tooth off it may noy start because
of the injector sync being off
check this and see where your at
Larry
J&J Auto
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j1b1e1
Dodge Dakota
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10/16/2006
09:27:42
| RE: 3.9L won't start after timing install
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Wouldn't I have felt a resistance (if it were bent valves) when I turned the motor over manually by turning the crank with a socket? Also, wouldn't the rockers be stuck or restricted? I was under the impression this was not a zero tollerance motor and that wouldn't be an issue. That makes sense about the chain being either way, I wish I'd have asked before tearing into it. I'll try checking the distributer, but how would it be off if I'm firing at TDC on the timing light when I try to start it? However I'm grasping at straws and will check it as soon as I get home!! Thanks for the info. Billy
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Chris
Dodge Dakota
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10/16/2006
10:37:16
| RE: 3.9L won't start after timing install
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I've noticed on my 93 3.9 that there are actually 6 timing marks on the damper, I guess because there are 6 bolts holding it on, so you don't have to worry about the orientation when you bolt it up. That's all fine and dandy except that your timing could be 180 out and a strobe light will indicate correct ignition timing.
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Joe M.
Dodge Dakota
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10/16/2006
16:06:07
|  RE: 3.9L won't start after timing install
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easier way
pull the #1 plug out
hold a finger over the hole (for air seal)
have someone "click" the key over
once you hear or the compression starts to push your finger off the hole
pull the dist. cap
the rotor should be sitting on the #1 plug wire
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fotodak
Dodge Dakota
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10/16/2006
16:16:01
| RE: 3.9L won't start after timing install
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If cam timing is correct look for bent pushrods.
The 3.9 is the same as a 318 and I've bent a few pushrods from slinging timing chains.
I think as the others your cam timing is off.
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Huggins
Dodge Dakota
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10/17/2006
08:40:13
| RE: 3.9L won't start after timing install
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I know when I built the engine in my truck, I had to install the cam and crank gears both with marks at 12. 6 and 12 wouldn't work and this is the only engine I have ever seen this on. 6 and 12 threw the cam timing way off, when I spun the engine over by hand and watched everything in relation to one another.
Remember in order to have compression, you have to have the full amount of air coming into the cylinder "not neccessarily going out of" and something to compress that air...
It's not that hard to pull a valve cover, rocker and check for pushrod straightness. Takes about 15 minutes "tops" per valve cover if you've got the tools laid out and know how to go about it...
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j1b1e1
Dodge Dakota
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10/17/2006
22:19:46
| RE: 3.9L won't start after timing install
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Well, I figured it out today, I pulled the #1 spark plug to check for compresson and found none. I pulled the # 5 rockers and checked for pushrod straightness and they were good to go. I then was stumped again and didn't really want to tear it down again. I decided to go to the #1 and start there. I pulled the rockers and when I did they poured water out of them as I raised them. I knew before I saw the severly bent up pushrods that they were going to be that way. Apparently one/both head gaskets leaked water into the cyl. and hydralocked. Looks like I've got my weekend planed out for me. Thanks for all the input from everyone! It's forums like this that help us shadetrees keep the little bit of money we've got and gain knowledge we don't.
Billy
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Mike Stager
Dodge Dakota
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10/17/2006
23:35:35
| RE: 3.9L won't start after timing install
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I feel your pain. I just got done replacing the engine in my wifes Grand Am after finally figuring out what was wrong with it after 4 months of head scratching ( off and on...yer head gets a little raw from all that scratchin'...y'know? )
Ended up being a broken camshaft of all things. We had an intake gasket leak which froze the rear cam bearing, ate up the 2nd bearing and torque from the timing chain ( now stretched ) twisted the cam off giving me 2 1/2 cylinders to fire. Bent a valve and a pushrod. I would have never guessed that the cam had broken in half for the life of me until after I had replaced the timing chain, oilpump and a piston, had the heads repaired and bolted it all together only to have it run just as bad as before. Pulled a valve cover off and had the wife turn it over. Bingo. And that was also the cause for my lack of oil pressure ( you think? ). I just spent 3 days swapping out the old motor, swapping over the new parts I bought, and putting the replacement motor in. The new motor fired up after literally 2 revolutions. You've never seen a happier guy than me that night.
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J and J Auto
GenII
10/18/2006
01:53:03
| RE: 3.9L won't start after timing install
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Message:
humm when you pulled the plugs so it would turn
over easy for the chain install you did not see
antifreze on the plugs
Ya they will not run with water in the cyls
you may have also washed the rings off squirt
some oil in the cyls and comp check if it goes
up good if not its the valve
a simple test that has been done for years
Larry
J&J Auto
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Cassidy
Dodge Dakota
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12/14/2006
19:28:52
| RE: 3.9L won't start after timing install
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i have a 92 dak with a 3.9 and the timing chain broke, bent all the valves, i pulled the heads and went through them. i have the engine back together now and it wont start. think the cam might have wiped out when all the vavles bent?
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pcdarks
Dodge Dakota
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12/14/2006
20:55:07
| RE: 3.9L won't start after timing install
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I experienced exactly the same thing when my chain went. It would turn over very quickly because the valves were out of sync with the compression stroke. Unfortunately I also found out that a 3.9 is an interference engine which means you have most likely bent valves. Sorry.
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kathy
Dodge Dakota
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3/04/2007
14:46:34
| RE: 3.9L
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i need to know how to put the making for the cam crank shaft
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j1b1e1
Dodge Dakota
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3/04/2007
17:31:21
| RE: 3.9L won't start after timing install
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Message:
Either Way, it'll go 12 to 6 or 12 and 12. It's a two to one ratio (meaning it'll ture two on the cam and once on the crank). I just hope you didn't break the chain like I did. BENT VALVES :-(
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