New Dodge Owner... need help/advice

Happy to join the group here... I'm a new dodge owner and recently got a good deal on a 2001 ram 5.9 gasser about a week ago. I have put about 60 miles on it and the first time the check engine light went on was after 30 miles... showed I had misfires in cylinder 8 and 6... I did plugs a couple days ago and they all came out great except cylinder 6 was very hard to get out... I almost thought the plug was going to break but I got it out and new one went in just as hard. My check engine light came on again today but only cylinder 6 misfire. I'm wondering if anyone has had or heard of this problem... I'll do a compression test tomorrow and will also be doing plug wires as well. Note: all the plugs looked equally as bad but none looked stripped...and the wires looked to be origin. Truck has 143,***. Thanks in advance!

Joec5709 said:

Happy to join the group here... I'm a new dodge owner and recently got a good deal on a 2001 ram 5.9 gasser about a week ago. I have put about 60 miles on it and the first time the check engine light went on was after 30 miles... showed I had misfires in cylinder 8 and 6... I did plugs a couple days ago and they all came out great except cylinder 6 was very hard to get out... I almost thought the plug was going to break but I got it out and new one went in just as hard. My check engine light came on again today but only cylinder 6 misfire. I'm wondering if anyone has had or heard of this problem... I'll do a compression test tomorrow and will also be doing plug wires as well. Note: all the plugs looked equally as bad but none looked stripped...and the wires looked to be origin. Truck has 143,***. Thanks in advance!

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My first guess would be bad plenum gasket... Those seem to foul out plug #8 pretty quickly when they are shot. You can look down the throttle body and check for EXCESSIVE oil on the bottom of the intake manifold. A little oil is ok, but if its excessive, plenum is probably shot. CEL comes on for misfires, normal procedure there. I think it's programmed to come on if it detects multiple misfires on the same cylinder or something like that.

Could that seafoam spray into the intake clean that up? What does it Intail to replace one of those gaskets?

Joec5709 said:

Could that seafoam spray into the intake clean that up? What does it Intail to replace one of those gaskets?

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Seafoam would probably put the problem off for a very short time, but if the gasket is shot, it'll come back. As far as the actual repair goes, it's pretty intensive, but it's not hard to do. Guys do them here all the time.

The problem is caused by mismatched metals. The intake is aluminum, and the plenum plate is steel. When exposed to heat, the steel expands, busting the gasket.

The bright thing about it is the aftermarket has fixed Dodge's flaw and come out with a proper aluminum plenum plate so once you replace the gasket and the plate, you'll likely never have to do it again. It also gives you a chance to do some futureproofing stuff like switch to a 180 degree thermostat and you'll never get a better chance to do a full tuneup and switch to a new distributor cap and rotor. OEM components are the best way to go for those.

A full guide on replacing the plenum gasket can be found here. It's very informative.

http://www.ramforum.com/f61/plenum_gasket_what_where_what_should_i_do_about_*info*-37635/

Thanks, for that info. Helps a lot! I went out there tonight to look for any vacuum leaks after watching some more videos and learning more... found out the hose connecting from the air box to the valve cover to be disconnected... reconnected it and hopefully that helps.

Joec5709 said:

Thanks, for that info. Helps a lot! I went out there tonight to look for any vacuum leaks after watching some more videos and learning more... found out the hose connecting from the air box to the valve cover to be disconnected... reconnected it and hopefully that helps.

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First WELCOME to the group!
Glad you may have found the issue. Please update how it is going ! Thanks

The plenum is the subject of much debate. largely it comes down to one thing, a crappy oem gasket. That thing is way too thin even if both pieces were aluminum. The differential expansion is .0174 inches from 0*f to 160* which is about as cold and hot as the intake will ever get. To put that in perspective, thats about 6 widths of a human hair, and half the expansion differential the intake gasket sees, yet the intake gaskets rarely go out. All based on a 190*tstat. Simply putting a thicker felpro gasket on there will fix the problem for the remaining life of the truck. Sure, in the long run of another quarter million miles, switching to an aluminum plate would prevent further problems, but you really have to ask if you plan on owning it in 250,000 more miles.

As far as the 180*tstat goes, don't if you live anywhere the temps drop to or below freezing. I didn't even think it would make much of a difference, but going from the stock 190-195 to the slightly cooler 180 made a big difference in the winter, especially if you're heater core is gummed up and in need of replacement.

The repair is quite easy as long as you follow a couple very important steps. it'll give you a great change to change the cap and rotor. I have a full writeup somewhere around here on how to change the plenum with as little chance of snapping the intake bolts as possible.

One thing I would suggest along with plenum, if cyl 6 plug has a pretty hard time going in, chase it. Use a plug chaser and a little wd40 to chase the threads and clean them up. Just asking for trouble if your plug doesn't even want to go in, could definitely be cross threading.