Hey guys, new here and looking for some ideas.

Long story short, my durango (2003, 4.7)developed a miss. I was getting a p0300 random misfire code. I found that cylinders 6 and 8 weren't firing right. I was getting spark and fuel, but the plugs kept fouling. New plugs and coils and still fouling. I finally broke down and took it in to a mechanic. He thought at first it was blockage in the injector rail, but said he saw mositure in the cylinders so it must be a head gasket. I drove it home and as I got almost home I heard a clatter and it died. I got it pushed into the garage and started dismanteling it. Got the passengers side valve cover off and found a broken camshaft.
I'll have the head off this evening so I can assess the rest of the damage but I'm hoping beyond hope that I didn't ruin my pistons. The clatter I heard was the front half of the cam breaking the bolts for the retainers and the rocker arms flying all over the place. A bearing seized on the back half and all the valves are in the closed position.

My biggest question is where can I get a replacement camshaft/bearings etc? I have been searching the entire interwebs from top to bottom and although I have found many things, a place to purchase a camshaft for a dodge 4.7 isn't one of them. (I'm not really interested in a set of performance cams, but if that is my only option. . .)
Also, what are my chances that the machine shop will be able to extract the broken bolts from my head?

I'll keep you all posted with what I find tonight when I get the head off.
Thanks

Lombard

 

You're better off getting a rebuilt head that comes with the camshaft, lifters, & everything else. There isn't any cam bearings to replace, the cam sets directly into the carrier that's machined into the head itself. Each carrier surface has an oil hole in it that allows oil to flow through the hollow camshaft.

If you broke the cam then most likely one of these oil holes (or more) is blocked up with sludge which prevented the cam from getting adequate oil.

The 4.7 is also a zero clearance engine, meaning that if a valve is not seated fully and the piston comes up it's going to hit something. You'll know better once you pull the head, but since you had two cylinders misfiring before I would suspect that there's more damage. You can't really assess it fully until it's torn down though.

If you find that one side is blocked up with sludge, I would suggest that you go ahead and pull the other side and examine it closely as it may not be far behind.

Bob

 

Thanks Bob. I was kind of afraid of that. New heads will come with a cam? When I still thought it was a head gasket issue I was planning on taking the heads in to get a valve job etc anyway, but since there are no bearings I am definitely looking at a new head. One of the carriers is black where it seized up. Getting the timing apart took longer than I expected last night so I didnt' get the head off, but all I have left is unbolting the exhaust and pulling it. If it's 0 clearance then I'm afraid of what I am going to see. I'll update this weekend once the head is off. Thanks for the reply.

Lombard

 

You can buy them as a set already set up with cam on.


You might be able to take it to a head shop and have them fix it up for you including a new cam. If it can be done, they can do it or point you in the right direction.

 

Yes, when I searched for my replacement head everything I saw came with cams. FWIW, be careful if you buy a junkyard one. I picked up one locally that was from the "cash for clunkers" craze and found it to be no good. While the head / cam looked great, I found that the oil passages were completely sealed up with whatever plastic goo they poured into the motors to seize them up. Returned it without a problem, but it would have been a disaster if I hadn't checked the oil holes first.

You might be surprised that there's no damage to the pistons if the cam broke and the valves closed before the piston came up. It's different when a timing chain breaks as at least two of the valves are guaranteed to be open while the engine stops. You should be able to easily see where water was leaking in, the piston tops will be cleaner than the others. Check the block / cylinder bores for cracks as well.

Timing is fun to get apart, isn't it?! Just wait until you put it back together! Depending on how far you tear it down (if you end up taking off the primary timing chain / sprockets) you may find it much easier to reassemble if you pull the radiator as well. It gives you a straight shot to the chains & tensioners for finding timing marks. Also, if you didn't mark which timing cover / water pump bolts came from where, get in there and figure it out now. There's a few that will bottom out in threads if they're in the wrong place.

I've dealt with these guys in the past http://www.headsonly.com/ and have had good service, but check around locally as well, any good machine / engine shop can help you out. There also may be some site sponsers that can help you out?

Bob

 

Thanks for the info. I got home from work a little early today so I decided to finish getting the head off. As far as I can tell there is no damage to the cylinders/block at all. I'm pretty excited. I can tell that it spent the first 80k miles of its life in NY though as there is a ton of surface rust on the block/exhaust etc, but nothing bad. Now I can rest easy this weekend knowing I'm not being forced into a complete rebuild. I'll pop the other head off sometime this weekend so I can take it in for a valve job since I'm in this far, and get it cleaned up as well.

I haven't pulled the timing sprockets out, is there any reason i have to? Is there a crank seal behind them? If so I'll pull them out so I can replace that. I marked all my chains/sprokets, as well as the bolts for the cover. And thanks for the tip on pulling the radiator, that will make putting it together again MUCH easier.

Lombard

 

I would ensure that the crank is a TDC and on #1 cylinder for tear down if possible!!!!!

 

Since you need to buy a new cam, and you will have to install both upon reassembly why not drop in some HO cams instead of the standard ones? It'll never be easier to do...

 

No real reason to pull the primary chain unless it's worn or you feel like replacing it. Inspect the tensioners carefully, I believe the Haynes manual lists the service life on them with a thickness measurement.

+ 1 Hydra with the TDC comment, it's a must. I know you marked all of the chains beforehand, but it's REAL EASY to install them one tooth off as the tensioers will be slack (holding pins inserted into them) and the cam position marks are "well, that looks like it's pretty much straight up" when they're first installed, plus the damned valve springs will keep the drivers side cam from lining up easily. You'll see what I mean when you put it back together!

There are some "plated" links on the chains, you're better off cleaning them up good and identifying them, then follow the timing procedure in the book. It involves rotating the engine by hand a few times and the links ending up in the proper places. Sure would have been easier with a couple of "real" timing marks!

Oh yeah, one more tip.... stuff some rags in the lower timing case when you install timing parts, it'll prevent you from dropping parts into the oil pan.

Keep us posted.

Bob

 

Thanks for the replies guys. I did make sure to have #1 @ TDC before I took things apart, so hopefully that will make things easier. When the cam broke it took out one of the guides on the right (passengers) side so I'll be replacing the guides at least.
On that note, how do you get the guide out that is attached to the head?

@modaine

I have read about being easy to add the HO cams/intake. What kind of performance increase/gas mileage hit am I looking at? Suggestions where to look for parts? Money is tight so I might not be able to swing it, but if I can I am definitely intrigued by the possibility.

Also, any reason to stay away from a reman head from a place like autozone? I put some on my grand am a couple years ago and didn't have any issues. Just wondering what your thoughts are on the subject.

I took the good head in to the machine shop this morning, block looks great so I am glad for that. I'll be ordering the rest of my parts tonight or tomorrow (payday ) Thanks again for all the advice!

-Lombard