The Chrysler Minivan Fan Club Forums banner

06 3.8 Broken Valve Spring

28K views 21 replies 14 participants last post by  Mopar madness2020 
#1 ·
Hey guys just wanted to post this incase anyone has questions or runs into this problem. Although extremely rare you can have a valve spring break. I had one go at 101K on a very well maintained 3.8. The springs are designed to never wear out but every once and a while you can get a weak one. This has nothing to do with driving style or lack of maintenence its just a bad spring. You can get one for 8 bucks and you will need a valve spring compression tool to remove/install. Just let me know if you need help on this topic.
 
#2 ·
I've been a member here for over seven years now and this is maybe the third broken valve spring I remember. Like you said, "Althought extremely rare, you can have a valve spring break."
 
#4 ·
I still wonder why it seems isolated to the 4th gens. Maybe their increased output per engine comes from a different cam profile that stresses the valve springs? Happens in race cars with mismatched parts, but these are factory engines and highly engineered.
 
#6 ·
OK, here is what happened... driving down the road to my house about 300ft or so before my garage the van started running insanely rough. I knew that something pretty bad had to have happened because there was no warnings and no engine light. Basically the engine will not throw a code if it is compression or fuel...I had a dead miss where one cylinder was not firing. Parked and popped the hood while it idled and you could hear the "fluttering" sound a valve can make when its not opening or closing properly. Shut it down right away and didnt dare to drive it anywhere for fear of more internal damage than had already happened.

Now here is how I fixed it... I wasnt sure if the messed up valve was in the front or the rear of the engine and I wanted to take a look under both valve covers anyway. I have found on these vans you need to take off the wiper assembly to really get to much of anything so it had to go. To do this you have to remove the wiper arms and some say they have been able to wiggle them off, I have done it twice now and needed a two jaw puller both occasions. Remove the top of the airbox, throttle body, and upper intake(unless your sure its under the front valve cover then you dont have to remove all that or the wiper cowl), there are several wire harnesses to unhook as well as hoses, im not gonna get into too much detail on that, this post is already long enough lol. OK, now you can get to your valve cover bolts (8mm, torque specs are 105in lbs and you can re-use the gaskets). I found that using 1/4in drive socket and 6in extension fit in the very tight space between the cast part of the upper intake and the valve cover the best. Boom there is was on the number two cylinder, it was the intake valve spring broken plain as day. Remove the rocker arm rail (10mm I think, torqued to 14 ft lbs) You will need a valve compression tool to remove the broken and replace the new spring. There are two small half-moon like clips that you must remove once the spring is compressed. Make sure you do not drop the valve into the head or its time to pull that too and thats not any fun. The valve is magnetic so you can use a magnet to hold it while you change the spring and clips. You can pull out the spark plug to check on the positon of the piston within the cylinder wall as well. I talked to several who know much more than I do about replacing all the springs and they advised not too. The valve springs are made to never wear out so if in the rare case you have one that does just fix the broken one and go on. I have been told that 99% of the time a spring breaks it will not bend the vale either. At any rate the van is running great now so my wife is super happy and that means I am too!
P.S. If your gonna change your pcv valve, do it when you have everything out... They are insanely hard to pull out of the van and almost impossible unless you remove the wiper assembly.
Hope this helps someone and thanks for the interest in the post.
 
#7 ·
As an alternative to using a magnet or using air pressure to hold the valve shut a trick I've used is to remove the spark plug for that cylinder then turn the engine until that piston is at the top, then turn it just a bit more until it has moved ~0.5-1" down the bore. You then feed in some cotton rope through the spark plug hole until the cylinder is full and turn the engine by hand back towards tdc until the rope is firmly holding the valves shut. It doesn't take much pressure to keep them from going anywhere. A bit of common sense does apply here - Only use a single piece of rope (don't try to feed one piece in after another, even if you tied them together... you'll never get the first one back) and make sure enough is sticking out the hole to grab to remove the rope later. Also, I suppose, don't turn it really hard towards TDC, you could damage a valve or damage the rope and end up removing the cylinder head any way.

This trick is great because you have full unrestricted access to the top of the valve, and you don't need a constant source of compressed air.
 
#11 ·
Never tried the rope method, altho I had heard of it. I used an air compressor when I did the valve seals on my '88 with the 3.0L. Of course, I used too much air and had to reposiiton the timing belt. :headbange
 
#12 ·
Ok sorry if i run on here. So van started running like crap. Changed plugs & coil. Nothing. Kept driving / was tolerable. Van died a couple times ( I thing jsut cuz running crappy). Then did not want to start a couple times ( I think this is unrelated has what I believe is original starter ...bought with 90,000 now has 165,000 miles) Has power, good battery, just hear a relay clicking under hood, nothing from starter. Started reading on here about melted harnesses / etc thought maybe something melted so bad that no I have this no start issue. Pulled intake & injector harness & looked under fuse box & around PCM / etc. NOTHING melted / etc. (only bad thing I found is the copper ground strap from eng mount to RT apron is pretty much green dust. Doubting that is the no start issue?? Anyway I have all this stuff off & figured I am gonna replace the frt valve cover gasket cuz it leaks & also cuz I want to see valve springs since that seems to be a reg prob with mysterious rough running, & guess what that is what it is. 2nd spring in from passenger side is broken. I have never replaced anything like that & am nervous about it. I like the sound of all 3 methods of keeping the valve from falling....not sure which I will use. What kind of spring compressor did you use. I see there is a chrysler specific one but it is over $100. any thoughts / advice well wishes would be appreciated by any who read this.

if you are in the western suburbs of chicago & like Jack Daniels & Steak there is that option as well LOL

2003 town & country limited 2wd 3.8L
 
#13 ·
As I said earlier, I've only used compressed air to hold the valves up, and that was when I changed the valve seals. I used a hose off an engine compression tester. It just happened to have the correct thread to mate up to the air hose. I used probably 90psi, which was overkill. You could get away with less air pressure, but I don't know how much less would be adequate. As for the spring compressor, I used one similar to this: Valve spring compressor. Of course, there are others that would work as well,
 
#14 ·
Regarding the starter issue: the Denso starter has contacts which have a tendency to get carboned up and will "click" when you turn the key, but nothing else will happen. A few extra turns of the key and suddenly the starter engages and the van starts right up like there was never an issue. In scenarios like this, you have two options, replace the starter, or pull the starter and replace the contacts (typically less than $20).

Regarding the broken valve spring: if you don't have a compressor, you can always use the old-school rope trick. Turn the crank so the piston on that cylinder is near the top of its travel, and feed a length of small diameter rope, cotton, nylon, whatever, into the spark plug hole until you cannot push any more into the cylinder. With the rope filling the void in the cylinder the valve may drop a bit, but not far enough for you to lose the ability to grasp the valve stem.
 
#18 ·
I don't think you need to stuff rope in the cylinder to keep the valve up. When I changed valve seals (rubber umbrellas) in my 1965 Dart 273 engine, I just raised the piston up, insuring I felt it up w/ a steel wire in the spark plug hole. I held the valve stem w/ a magnet and slowly lowered it until I was sure it bottomed on the top of the piston and had plenty of stem exposed. The problem with using air is what if you lose the air pressure? You might want to take a break for a day (need more parts, ...). Also, the air can spin the crankshaft unexpectedly and maybe send a wrench flying. I could just barely get the spring compressed enough to remove the keepers. That would be almost impossible if they were thicker, strong springs (for a high-lift camshaft). That is because the basic screw spring compressor has fingers which take up some of the space. On Mopars, you can compress the spring more using a special lever which slides under the rocker shaft. Never used one, but I understand you remove the shaft and all the rockers & washers, then temp install the bare shaft.

Wondering "what does an 1960's small-block engine have to do w/ our 'modern' 3.3/3.8L engines?". Other than the MPFI intake, nothing has really changed. Indeed, the stamped-steel rocker arms look almost identical to those in my 1965 383 engine (my 273 has neater adjustable rockers like the slant-six, since solid lifters). BTW, these V-6 engines are just as rugged, and indeed last longer since you don't have excess fuel from a carburetor washing the cylinder walls w/ gas.
 
#20 ·
I use rope.

I was cautioned / taught to NOT use magnet because if you magnetize the valve stem it will attract the particulate wear metal that circulates in the oil. Like a magnetic oil drain plug.

Becky and I were flying to North Carolina when a valve stuck in a Piper Cherokee. I had basic tools and hand proping the engine slowly found quickly that there was a no compression cylinder on our four cylinder lycoming. The next morning, we removed our shoelaces and fed them through the sparkplug hole. She couldn't believe it and I have to give her faith credits because after the impromptu repair, she got right back in and flew the rest of the way there and back home.:thumb:
 
  • Like
Reactions: kayaksue
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top