Forums
Forum Tools
|
 |
10:30:06 - 04/27/2024
V6 Dakotas
| From | Message |
Dr. Mike
Dodge Dakota
JOIN HERE
5/10/2004
11:38:12
|
 Subject: V6 broken cam?
IP: Logged
Message:
I think my 3.9L cam snapped... Has anyone else had this problem? How much of a job is it to replace??? The truck was running fine and just quit. we pulled the timing chain and gears, they were pretty worn, but turning the camshaft by hand does not turn the valve train.... Help!!!! what is a good replacement option for this part????
|
IntenseDak39
*GenIII*
5/10/2004
12:05:50
| RE: V6 broken cam?
IP: Logged
Message:
ummm.... unless you have the strength to twist a cam with your hand and open 12 valves, your valve train isnt gonna do anything.
What are the symptoms of your truck? does it even fire up, make noise?
before you go thinking your cam is broke (never heard of one snapping), do some more inspection.. rmeove valve covers and intake manifold check out your valve train.
btw, if there was some way that your cam could snap, your motor jsut wouldnt quit. It would provide a pretty good show for you as it died.
6.6 Lt. Big Block, 727 TF shift kit, 452 heads, edelbrock 750 cfm, .513/.513 284/300 crower cam, comp cams springs, comp cams pushrods, 1.5 roller rockers, dp intake, mopar ignition, mopar windage tray, dual exhaust w/ 40 series flowmasters, 4.10 gears, coilover drag suspension, approx, 3500 lbs
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/10/2004
12:37:22
|  RE: V6 broken cam?
IP: Logged
Message:
Basically what happened was, I was slowly down to turn into a driveway and my truck died, It was not running at high RPM just decelerating at a low rate of speed, as I reached the drivway, the truck stalled, so I coasted in, and tired to restart, the starter turned over and the motor actually sounded like there was no compression, it spun at a faster than normal rate. we did take off a valve cover and when the engine is cranked over (new timing chain and gears installed) the valve train does not move.... Crank turns, timing chain and gears turn, no valve movement??? We are pulling the intake tonight... How much work is it to install a new camshaft, what other parts should I replace if it is indeed broken? If its not broken what else could it be??? Also what is a good replacement cam, and the best place to purchase it? Thanks for the help/advice...
|
IntenseDak39
*GenIII*
5/10/2004
12:50:19
| RE: V6 broken cam?
IP: Logged
Message:
if you already have the valve covers and timing chaing cover off, you have already done the hard part. Next to get the camshaft out:
remove intake manifold
remove rockers
remove pushrods
remove lifters
remove timing set
pull cam out with a long bolt or cam tool
you have someone turn your motor over and not a single rocker moved?
6.6 Lt. Big Block, 727 TF shift kit, 452 heads, edelbrock 750 cfm, .513/.513 284/300 crower cam, comp cams springs, comp cams pushrods, 1.5 roller rockers, dp intake, mopar ignition, mopar windage tray, dual exhaust w/ 40 series flowmasters, 4.10 gears, coilover drag suspension, approx, 3500 lbs
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/10/2004
13:35:53
| RE: V6 broken cam?
IP: Logged
Message:
I'll be working on it tonight.. I'll let you know the prognosis after we get it out.. Can you suguest a good replacement cam and a place to purchase it? I know cams don't usually break but believe it or not, I had a cam break in an old Subi turbo before and the dakota engine sounded and acted the same way, at the time I broke the Subi cam, the shop that fixed it said it was the 1st one they had ever seen break.. My Dakota 3.9L has 200K on it and it still runs strong, or I should say it did before the cam thing....
Great motor, great little truck. I would buy another one in a heartbeat but I would like to nurse this one back to health...
|
JFH
GenII
5/10/2004
13:45:25
| RE: V6 broken cam?
IP: Logged
Message:
I got a great cam made, similar to the one of the ones sold by hughes engines.
www.hughesengines.com
http://www.cardomain.com/memberpage/546400
|
Mustang Man
Dodge Dakota
JOIN HERE
5/10/2004
14:12:26
| RE: V6 broken cam?
IP: Logged
Message:
I've never broken a camshaft, but I'd be cautious about what caused it to break. Here's a good way to test it:
First, take your distributor cap off and have a buddy turn the engine over. Since your timing chain is in the front of the cam (driving it), if the cam is broken, it won't spin your distributor rotor (rear of the cam). If the rotor spins, your cam is fine. If is doesn't, there should be a shear pin in the distributor cam (drive) gear that could also cause the rotor not to spin. Since you have to pull the dist anyway to replace the cam, this would be the easiest thing to check first.
Unless you have seriously high pressure valve springs wearing out the cam lobes/putting metal fragments in your oil, I'd suspect oil starvation would've broken your cam.
You can probably test your oil pump by removing the cam gear off of your distributor and rigging the top of your distributor to an electric drill to spin it fast. I'm not sure which way a 3.9 distributor spins, but someone else here could tell you. Once you have it spinning the right direction, oil will generously flow out of your pushrods, so you can rule out the oil pump...
I'm tapped after that. I have no idea what else could cause a cam failure in a "responsibly" driven engine...
Keep us posted so we can all learn from your unfortunate experience!
|
IntenseDak39
*GenIII*
5/10/2004
18:19:17
| RE: V6 broken cam?
IP: Logged
Message:
did you notice anything about your oil pressure before the truck quit running?
6.6 Lt. Big Block, 727 TF shift kit, 452 heads, edelbrock 750 cfm, .513/.513 284/300 crower cam, comp cams springs, comp cams pushrods, 1.5 roller rockers, dp intake, mopar ignition, mopar windage tray, dual exhaust w/ 40 series flowmasters, 4.10 gears, coilover drag suspension, approx, 3500 lbs
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/10/2004
20:30:09
| RE: V6 broken cam?
IP: Logged
Message:
OK, here is the story so far....My friend and I went over to where the dakota is located and his dad who is working on it had the front off of the motor again, the right (facing the motor looking front-to-back) valve cover off, and the motor was half jacked out on an engine hoist. We put a bolt in the crank and turned the crank with a breaker bar, low and behold, the valve train moved just fine, showing us the crank is intact.
My friend (who is helping me) does a lot of constuction work for Borg-Warner Automotive, in Ithaca where we live, today he talked with the technicans at Borg and they told him it sounded like a plastic gear that drives the distributor broke. They say that when this plastic gear fails the motor will turn over funky and actually act like the cam has broken...
After hearing this, we proceeded to pull the oil pan (what a pain in the ass that was) and found that tons of metal shavings (from the worn out timing gears I hope) were littering the bottom of the oil pan near under the area below the timing gear. The crank turns the oil pump shaft just fine, but the oil filter was plugged badly. As far as the oil pressure before it stopped running, it was doing some weird stuff, The pressure would be good but every once in a while it would drop to zero, then repressurize again. Also pressure was vey low at idle, and came up at around 2000 rpm. After seeing the plugged oil filter, I'm sure that was the problem. We ran out of steam before we could pull the distributor cap to check and see if it was turning with the crank but that is our next step.... Good news is the cam is working even though my buddie's dad said is wasn't.. Bad news is lots of metal in the pan... I brought the pan and one gear back, I'll take a photo and post it so everyone can see how badly this puppy was worn! Currently my guess is the timing gears and chain wee so badly worn that the chain was just spinning on the gears.... I'll post photos soon to see if anyone here confirms... Has anyone ever heard about the plastic distributor/oil pump gear story going bad before????
Thanks for everyones input...
M
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/10/2004
21:19:53
| RE: V6 broken cam?
IP: Logged
Message:
Photo links for damage to timing gears, oil filter, and the metal sludge:
http://images.andale.com/f2/115/106/3849332/1082441000410_DSC05440.JPG
http://images.andale.com/f2/115/106/3849332/1084804446685_DSC05444.JPG
http://images.andale.com/f2/115/106/3849332/1084810998955_DSC05439.JPG
|
IntenseDak39
*GenIII*
5/10/2004
22:09:30
| RE: V6 broken cam?
IP: Logged
Message:
wow that is one wore out timing chaing!
you didnt pull the distributor out or anything did you?
looks like right now you can get a new timing gear set and just set the cam at TDC and the crank at TDC (make sure you have the correct stroke!). Then just put your chain on and you are set!
really, not bad at all for 200K miles!
6.6 Lt. Big Block, 727 TF shift kit, 452 heads, edelbrock 750 cfm, .513/.513 284/300 crower cam, comp cams springs, comp cams pushrods, 1.5 roller rockers, dp intake, mopar ignition, mopar windage tray, dual exhaust w/ 40 series flowmasters, 4.10 gears, coilover drag suspension, approx, 3500 lbs
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/11/2004
07:23:54
| RE: V6 broken cam?
IP: Logged
Message:
The distributor is still in, we are just going to pull the cap and if the rotor turns with the cam, leave it alone... OK, someone set me straight on setting the new timing chain and gears up correctly at TDC. What is the proper proceedure? are there marks I can just line up or do I have to set TDC? also what cylinder should I set at TDC? Sorry for all the questions, I'm a newbie to working on timing issues.
|
dodgeboy
Dodge Dakota
JOIN HERE
5/11/2004
09:53:27
| RE: V6 broken cam?
IP: Logged
Message:
wow, that timing chain is beyond words.... Even on a 200k motor there is something seriously wrong to wear the gears out like that. Thats definitly the culprit though. The oil pump is driven by the camshaft, if the gears are that worn the chain is going to slide across them rather than turn them. Thus no oil pressure and no valve train movement. Luckly with the stock cam its supposed to be a non interference motor so you probably didnt bend any valves. Setting the new chain up is simple. There will be a mark on the cam and crank sprockets, these need to be facing each other. Cam mark pointing straight down, and crank pointing straight up. Put the two sprockets on without the chain and rotate the cam and crank by hand untill the marks line up. Now remove the sprockets, hang the chain on them and slide the two sprockets and chain on as an assebley.
Make sure you clean all of the metal out of the oilpan and off of the oil pump pickup. Once you get the chain on do a compression test on all of the cylinders to check for bent valves. Do this before you put the timing cover and such back on.
If you have compression in all cylinders button it back up, add oil and coolant and fire her up.
The oil pump drive gears are metal not plastic, they dont just break. The Borg-Warner guy didnt know what he was talk1ng about.
|
xmr
GenIII
5/11/2004
13:52:45
| RE: V6 broken cam?
IP: Logged
Message:
With that kind of wear on the timing gear and chain there has to be a blockage keeping the oil from getting to the chain. I would look for stopped up oil passages.
'98 cc auto /Home brew cold air with K&N,Dynomax, Superchip Tuner, 1.7 RR,, F&B tb. NAPA cap and rotor, 3923 plugs,tps mod,relocated iat, 180 t'stat, Crankshaft sensor mod.,PVI
|
IntenseDak39
*GenIII*
5/11/2004
14:19:19
| RE: V6 broken cam?
IP: Logged
Message:
there really isnt a passage for oil. I think there is an oil slinger on the crank and some of it drains from the valley area.
6.6 Lt. Big Block, 727 TF shift kit, 452 heads, edelbrock 750 cfm, .513/.513 284/300 crower cam, comp cams springs, comp cams pushrods, 1.5 roller rockers, dp intake, mopar ignition, mopar windage tray, dual exhaust w/ 40 series flowmasters, 4.10 gears, coilover drag suspension, approx, 3500 lbs
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/13/2004
21:58:23
|  RE: V6 broken cam?
IP: Logged
Message:
OK… Here is the update… At this point we are starting to get pretty frustrated. Any and All help would be great appreciated. Here is the stasis. We have the oil pan off; the oil screen as most of you may have seen from the photo was very plugged. I bought a new oil pump and cleaned the pan, siphon screen and have yet to re-install it even though the old pump worked. We have not been able to pull the rotor cap it’s a pretty tight fit for our hands and the nuts are badly rusted nut we are still working on removing it to check and see if its turning ok with the cam. The shaft that turns the oil pump is turning just fine with the cam when the timing chain and gears are installed.
The big trouble is this… and please correct us if we are doing something wrong… Oil pan off, timing gears and chain on correctly (cam mark at 6 o’clock, and crank gear mark at 12 o’clock) we have absolutely no compression!!! We even tried messing around with the timing by advancing and retarding (by hand to be sure we had valve clearance first of course) it to the point where the cam would hit the pistons… No compression anywhere with normal timing or by advancing or retarding… Remember when this quit running is was not a catastrophic event, I was traveling about 40mph and let off the throttle to slow and enter a driveway, the engine idled down normally and it just stalled… Trying to restart after the stall produced no compression, as if the all the spark plugs were removed. We put a compression gauge on #1 and #2 cylinders and turning the motor over with the starter won’t even move the needle on the compression gauge. What are possible causes??? Pistons, cylinder sleeves, crank, rods, block, and valve train all looks intact? Valves seem to operate in sequence all valves moving normally. We are at a complete loss for answers? I have floated valves in big blocks and done massive damage and had more compression... Is it possible that somehow the cam lobes are so warn that it could cause the engine to stop making compression? If so, why were there no symptoms before it just stalled and quit running? No popping, backfiring, no smoke, didn’t burn oil, temp and oil pressure was good. The only sign of anything being wrong was the annoying diesel sounding timing noise from the badly warn timing chain and gears and it was running slightly rougher than normal but nothing major. It started fine, ran strong, and did not burn excessive oil, gas, or anything? I hope someone here has an answer to our problem… I’m at the point where I’m ready to turn the truck into a v-8 project…. HELP!!!!
|
dodgeboy
Dodge Dakota
JOIN HERE
5/13/2004
22:13:08
| RE: V6 broken cam?
IP: Logged
Message:
Check every cylinder for compression. If the cam, lifters, pushrods, rockers and timing chain are all in. and you are still getting 0 compression you have bent valves. The valves only need to be barely cracked open to give you a 0 comp reading. You arent allways going to hear them being hit.
Time to yank the heads...
|
Mustang Man
Dodge Dakota
JOIN HERE
5/14/2004
09:56:14
| RE: V6 broken cam?
IP: Logged
Message:
Check your compression gauge on any engine that runs just to make sure that it works. My old K-Mart gauge gave me fits before it quit working totally.
To ensure you have the correct cam timing, try this on Cyl #1. Do this only if you're unsure about the 12 o'clock crank/6 o'clock cam markings.
1. Starting at top dead center (place long screwdriver in sparkplug hole to verify or crank 12 o'clock/Cam 6 o'clock) both intake and exhaust should be closed.
2. Turn crank slowly until piston is at Bottom Dead Center (Screwdriver will go down and intake valve should open to let fuel/air charge in and then close to prepare for the compression stroke).
3. Turn crank slowly until piston is at Top Dead center again (full compression is achieved here and both valves should be closed). Continue turning the crank until it is at bottom dead center again.
4. The exhaust valve (the one that lines up with the exhaust port) will begin to open while you continue to turn the crank. When you're at Top Dead Center again, you're back at step 1.
The only reason I posted this is because I don't know the proper timing for a Dodge, I'm still learning, though.
|
dodgeboy
Dodge Dakota
JOIN HERE
5/14/2004
10:14:11
| RE: V6 broken cam?
IP: Logged
Message:
Make sure you have the correct orientation for the crank sprocket. There is usually two marks on the chain if its an aftermarket piece. The mark that orients with the crank key is not the one that you line up with the cam mark to get to tdc. the actual mark is counterclock wise from the crank key.
Even if it is slighlty off on timing you should still be getting some compression
|
Dr. Mike
Dodge Dakota
JOIN HERE
5/14/2004
11:16:44
| RE: V6 broken cam?
IP: Logged
Message:
First off, thanks to all of you for sharing your knowledge and advice! I'm pretty sure we have tried all cam and crank orientation options, I'll try that one last time, but even thought I did not hear any funny engine noises when this all first happened, my instinct tells me bent intake valves... We have tried virually ever combination possible in degrees with cam and crank and not even a slight flutter of the compression gauge needle. We thought it might be the gauge, so we did try it on another engine, and it worked just fine... The only sign of any hint of compression was after turning the engine over at one timing change setting we got a very leak not even close to normal popping (pressure) release from the #2 cylinder. ????? Comments??? Questions? Advice?
|
dodgeboy
Dodge Dakota
JOIN HERE
5/14/2004
11:20:07
| RE: V6 broken cam?
IP: Logged
Message:
The valves are bent. Time to pull the heads and have a look. Hopefully the valves didnt crack or dent the pistons. If they did its time for a whole new long block....
I broke a 20k mile edelbrock chain in my motor a month ago. No noise at all,, just died. bent 5 out of 12 valves and cracked 3 pistons....
|
| | P 1 Next Page>> |
|
