I've heard conflicting opinions on the valvesprings installed int the 97-99 DOHC neons. some say theyre plenty strong (for the stock cams that is) and will stand up to 9000 rpm. (I do not plan on running that high by the way) I've also heard the PT Cruiser valvesprings are much stronger though, and the neon valvesprings are rather weak. consumerguide.com lists weak valvesprings as the contributing factor to the rough idle. my car does idle slightly rough and shudders slighly when its shut down. I'm just wondering which is true... Are the valvesprings too weak or not?
RadarLove
10-24-2005, 02:14 AM
It's not really a valvespring issue (with the DOHC's). The 2.0L engine in either form suffers from oil aeration issues, and the 2.0L OEM DOHC lifters trap this aerated oil and fail to pump up properly, reducing engine performance at high RPM. The 2.0L OEM rocker arms also tend to develop longitudinal cracks above 7400 RPM.
The 2.4L/2.7L DOHC valve train (rocker arms - p/n 04792295AB, and lash adjusters - p/n 04777976AA; total price should be under $250) uses bleed holes in the lifters for the aerated oil and also has a stronger rocker arm design, plus they're a direct swap into the 2.0L DOHC. These parts supercede previous versions (the 2.0L DOHC valvetrain is no longer available for purchase) making these upgrades 100% legal for stock class competition (like SCCA showroom stock club racing or Solo II).
To help with oil aeration, you can also install a crank scraper, like those available at www.crankscrapers.com, which have been proven very reliable on numerous neons. I made the mistake of trying to buy one second-hand on ebay... only time I've ever been ripped off... No biggie, I plan on going with their top-of-the-line setup with the Teflon scraper and windage tray...
Best of luck!
dodgeneonACR98
10-24-2005, 11:52 AM
Damn good info.
rice_eater
10-24-2005, 06:14 PM
So valvesprings are fine.. thanks for the info.
I have a question though... correct me if i'm wrong (i probably am), but i didnt think the DOHC had lifters? dont the cams directly operate the vavles? I'm not very well versed on the exact functions of a DOHC engine (or any engine for that matter, i'm only 16), i just vaugly understand their operation. if you could briefly explain the valvetrain to me i would really appreciate it.
RADAR, i gathered from your post that my valvesprings are fine, and that a crankscraper would be a worthwhile upgrade. but as you already know i'm on a tight budget was wondering if there is a large difference from the standard scraper to the teflon? I'm not racing my car, just the occasionaly "spirited" driving. Also, do you know what is causing my unruly idle and shuddering shutdowns? (it isnt a major vibration, but it is noticeable) Is it the oil aeration issues you mentioned? the reason i ask is because idle is hardly "high rpm", though i do notice the "flat spot" and the engine seems to act different between 6000 and 7000rpm. thanks for all the help.
RadarLove
10-26-2005, 01:33 AM
The cam lobe pushes up on the lifter. The lifter pivots and pushes the vlave down. The valvespring pushes the valve back up. And repeat... The Neon uses hydraulic lifters, which means there is a pocket that traps oil, which applies a preload to the valvetrain, so "valve jobs" (adjusting the lash adjusters) are not required.
For most people, the regular crank scraper is worth the $45 or whatever it is. It's an added layer of reliability, like spending the extra money on synthetic oil. For nuts like me, the extra money for the zero-clearance version and the windage tray is worth every penny - most people don't turn hard enough to cause the oil light to come on...
Idle and shuddering shutdowns are probably another issue altogether. My first bet would be carbon buildup in the combustion chamber. If you turn the car off, and the motor keeps going, that's the most likely cause. Mopar sells Combustion Chamber Cleaner that works great, and there's a product out now called Seafoam that's had some good success. I haven't used either in the Neon (used the Mopar CCC in the Jeep though...). Aside from that, the car could be running overly rich, sensors could be failing, IAC could be sticking, etc.
rice_eater
10-28-2005, 04:17 PM
Thanks for the advice. I'm gonna de-carbonize my engine and install a crank scraper on the next oil change. in the mean time i'll work on polishing the intake and retard the cams 2-4 degrees to try and get rid of the 6000-7000rpm flatspot. I've heard that helps the DOHC engines. as for the valvetrain.. i think i'll leave it alone. it should be able to support my list of upgrades i'm planning... its the trans i'm worried about LOL.
RadarLove
10-30-2005, 03:39 AM
If you're going to play with cam timings, be sure to do it on a dyno rather than relying on what other people have done. I thought the flat spot was more in the 4-5k range... have to look at a dyno though... and I'm pretty sure most people attribute it to the intake manifold.
Tranny should hold up fine. Upgrading to the PT Cruiser clutch wouldn't be a bad idea if your is in need of replacing anytime soon. And a good limited slip gets rid of the weak link...
rice_eater
10-30-2005, 03:22 PM
ok maybe i wont mess with the cam timing then, as i dont really have access to a dyno. Can you even change the timing with the stock cam sprokets? as for the clutch, it should hold up fine, as its a brand new sachs racing clutch.
I know if asked this a million times... but if i dont do any big smokey burnouts, will the stock differential hold up 200 bhp (175 whp, give or take)? The extent of punishment implied to the trans will be hard shifting (speed shift 3, 4) and a mild launch (3000rpm er so). I wont be racing this car or beating it daily by any means, so if i can save money by not installing a LSD great, but i dont want to go through trannies like socks. Thanks for the advice.
RadarLove
10-31-2005, 04:02 AM
It's the peg-leg burnouts that kill the differential. That and lifting the inside corner on a hard turn while accelerating...
200 Hp is asking a bit much of the stock clutch. I haven't heard enough about the Sachs clutch, but the few I've heard from don't rate it any better than stock. If it starts slipping within a few thousand miles, you'll know... As far as the differential, it's been known to hold 235 HP just fine (Steve K.'s 2.4L n/a monster), and I'm sure there are dozens of turboed neons out there using the stock diff making over 300 HP. At the same time, bone stock Neons launch the pins often enough to get a bad reputation. In an open differential, uneven wheel spin is what causes the failure, not torque/hp from the engine. A slip-in LSD like the Phantom Grip isn't all that expensive, easy enough to install, and works great. But it will eventually fail after enough abuse...
rice_eater
11-02-2005, 06:25 PM
thanks for the advice radar. the sachs clutch seems a lot grabbier than a stock clutch.. i dont know only time will tell.
I dont beat the car, nor do i plan to so i think the stock diff will be ok. if not, junkyard trannies are only like $250, and i can buy another tranny cheaper than i can install an LSD. I dont think the tranny will go out more than once, if at all, because i'm not that hard on it. the most abuse it will have to take is a mild spin on launch, slipping the clutch, not dumping it, and speedshifts. in fact, it will probably take more accidental abuse in the winter, when the tires accidentally spin on an icy corner. Thanks a bunch for the advice.
BTW... do lash adjusters make anydifference? summit claims they can restore lost hp on high mileage engines. my car has 109000 miles, and the valvetrain makes some noises, but thats normal on an overhead cam engine right? (soft clicking, humming, etc) they are cheap... but they still sound like more work than they are worth and a waste of money.
RadarLove
11-06-2005, 04:31 AM
The hydraulic lifters are designed to take up the slack, so lash adjusters on the stock valvetrain aren't going to make a difference. The valvetrain upgrade I mentioned includes new lash adjsuters because the clearances are a tad different. And SOHC folks using a cam with a reduced radius base circle usually get the right size lash adjusters. The ticking you hear is just the stock lifters taking their time to "pump up" with oil, more noticeable on colder mornings.
109k miles is nothing...
rice_eater
11-06-2005, 06:51 PM
Thanks again for sharing your wisdom RADAR. I was slightly worried about the clicking only because I'd never owned a neon before, and didnt know what a DOHC valvetrain was supposed to sound like. All I knew was it was clearly audible at start up (especially when cold, like you mentioned) and would die down as the engine warmed up, but you could still here it if you popped the hood. My uncle had a turbo talon (are those the same blocks as the 420A? I'm not sure) and he messed up his vavletrain bad. Of course he beat the snot out of it... my car was beat but only for a couple months by the previous owner before the tranny blew.
Just out of curiousity... How long do the lifters usually take to "pump up" with oil? Should the clicking go away completely or just get quieter? (I run synthetic oil, if that makes a difference).
RadarLove
11-07-2005, 05:45 AM
The Turbo Talon/Eclipse was a totally different engine. The '95-'9? had the 420A, which is the Neon block with a reverse flow Mitsubishi designed DOHC head (making 10 HP less than the Dodge designed DOHC head). The Dodge engine designations are D4RE (DOHC) and S4RE (SOHC).
How long it takes depends on the type and weight of oil being used, temperature, and aeration. I use Mobil1 5W-30 year round, have from about the 12k mile mark. usually a heavier oil will pump up quicker, but some people have better results going to a lighter oil. I only fill the oil to just over the "Fill" mark on the dipstick. If it's all the way to the top, the crank is going to make direct contact with the oil and whip it up like egg whites (well, not really..., just fling it all over the inside of the engine, gathering air along the way), which is where the crank scraper comes in handy. Even more so around corners where it moves from one side to the other (hence the desire for the baffle plates). Colder oil will usually pump up faster, but since all the oil drains out of the head within an hour or so, you have to get oil back in there, which takes a while when the oil is cold...
I live up in the desert (Albuquerque), and most of the tick goes away after 2 or 3 minutes. When I was living in CT and working in Mass, it would take a good 10-15 minutes on a really cold day. The tick never completely goes away on my car.
rice_eater
11-08-2005, 12:22 AM
Thanks RADAR, it has been quite cold here in WI recently, maybe that why i've been noticing it more. The clicks do go away in 10 - 20 minutes, or die down relitivley well. Like you said about yours, they never really go away completely. I'm glad to hear my car is "normal". I am running Castrol Syntec 10W30, BTW. How many quarts is the engine supposed to take? I just filled until the dipstick read full, I wasnt sure. I think I ended up putting 4.5 quarts in... I dont quite remember. does that sound right?
(LOL, sorry for switching subjects constantly... I guess I have a habit of causing never ending threads)
