Squeaking serpentine and valve or lifter noise

[Chris]

1994 Dakota 2WD 3.9L 141K miles
I have had the transmission rebuilt and done 25 or so miles on it and it runs and responds a lot better. Its not a rabbit but it isn’t a turtle anymore either.
The serpentine belt has started squeaking pretty much from the day after I had it in to get the motor checked so that I could isolate the transmission as the source of the problem I had then. I got worse lifter/valve noise right after that too.
It goes away with belt dressing but only for short periods. I theorise that if it goes away after spraying it that this means the belt is bad and not that the pulleys are out of line. Nothing is visibly out of line. Does anyone have any information of a more experienced nature? The belt is only $35 or so but I’d rather make sure I don’t need to change pulleys or retighten the crank pulley first. (I did the timing chain tensioner TSB last summer)

I also have the issue of lifter or valve noise that gets worse when accelerating. It feels like I am losing power to whatever is causing that noise. I say this because when the noise occasionally goes away or lessens I have more power to the wheels. It just occurred to me to check for codes. I will do so when the sun comes up but I don’t expect any.
I was just reading the plenum thread on another website and the “can of marbles” description of a blown plenum gasket symptom fits here. Thing is I did the Hughes Engines plenum kit last summer and along with the timing chain and tensioner it doubled the gas mileage I was getting and the can of marbles went away except on large hills and then it was only ticking like lifter noise!? I’m gonna pull the hat and take a look inside the plenum through the TB today but I do not expect to find any problem. Any ideas for diagnosing?

Topic

[college man]

If the belt dressing cures the belt noise then I would suggest a new belt.
Try and clean any dressing off the pulleys for the new belt. For the lifter
noise pick up a mechanics stethoscope at a auto part store and follow Dr
Eric in this video. 🙂

http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car#FindingNoisesVideo

[Chris]

I cleaned and wiped the pulleys &I replaced the belt. No squeaks at idle.
I got a stethoscope and I honestly do not hear much. There is a valve noise on the drivers side valve cover and the PCV which is only a few months old is very loud without the scope.
It wasn’t making that noise and losing power like I described either though.

Edit: I forgot to mention there are no codes and looking down the throttle body the intake is clean and dry.

[Chris]

I have driven it about 45 miles since replacing the belt and I noticed when I was going up the big hill while it was cold the noise was more of a ticking (which it has had since I owned it) and it didn’t feel like it was losing a lot of power (was some) and held the speed limit as I pressed the pedal down as it climbed instead of kicking down to go faster or slowing down anyway. .

That’s all good but I would still like to know how to discover the source of the ticking. The motor still feels a bit wrong and like it could be more responsive and tight if I fixed that tick. I think the tranny is fine now but we’ll see if it stays tight.

[Chris]

Drove this morning and the belt chirps when I first put it in gear and when going slow. Is this something I need to check?

The truck felt stuck or like it was struggling at 45mph going up hill and at 50mph on the hwy. I expect some of this is the computer learning how to handle the rebuilt tranny but I’m not sure.

[Jim Davis]

The 3.9’s are notorious for ticks and noise, areas known for it are timing chain, injectors and exhaust manifolds. I know that does not really help but maybe gives you a place to look and listen at closer too. Look for cracked exhaust manifold or missing bolts, Listen with your stethascope near the timing chain.

[Chris]

Thanks. I have already done the Timing chain and added tensioner that took care of the ticking coing from there. I also put in a hughes engines plenum. This is noise that I believe is mainly from the valve train that happens under load or on hills. The stethescope doesn’t show me much in park. I expect I might need to get that thing form Eric’s video so I can drive it around and listen to each head separately.
I’ve been focused on the heads since I owned it and as each repair or improvement was added the ticking keeps making think heads.

[Author]

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