Thanks Snowfan, I suspect of bad valve stem seals because when I start it in the morning I can see a good amount of smoke blowing out the exhaust but just when it starts for the 1st time. The low compression test on cylinder 7 (120 PSI) compared to the others (150 PSI) also concerns me so I did a pressure leak test blowing air in the cylinder and turning the engine to chech if the valves were good and what I think is that the intake valve on cylinder 7 is leaking a bit (I can hear air passing to the TB), did it with other cylinders as well and they seem to be well sealed.
Is there any additive to use in the gas to clean the valves? I really don't want to take it apart, not driving her much now..

 

Thanks, I might do that because I really think the PCV valve allows intake to suck a large amount of vapors from the valve cover, a lot more than necessary based on the blowby rates that I could measure.

 

Smoke on first start is often stem seals and can add up to an amazing amount of oil. 1-2 qts in 3000 miles.

I have never used an additive that helped with something like this but at 60K miles, might try it. If the intake valve on 7 is carboned up from oil you might get a good result. Try Techron in your gas for several tankfuls before you do something like Seafoam that is more aggressive.

A compression check every 1000 miles to see the rate of gain or loss, if any, could be a good idea. I found a wallered out valve seat on one of my heads that caused compression to hit 100. Again, that was at major miles.

Is there any chance your engine has severe wear from lack of oil changes or low oil?

 

I bought this truck 3 years ago after a 3 year search for a decent truck and have not put a lot of miles on it but I bought it because it was in great condition and I missed so much my previous 3.9 dakota.
I don't believe it had lack of oil changes, but on the records a previous owner replaced the radiator for some reason (overheating? not sure). The cylinders compression is pretty much around 150 LB except for cylinder 7 (120) and I could find out the intake valve on 7 leaks a bit so I figured that would be the reason for the lower compression. Wet compression test shows increase of 25 LB on all cylinders.
I think next step would be valve stem seals but down here in Brazil parts are expensive and rare, need to import and they end up costing 5x the original price in the US.
I am running 100% syntetic motor oil 10W40.
On all my old cars that are over 50,000 miles I use 20W50 semi-syntetic and change every 4,000 miles or one year...
Never heard of Techron will look up and try it but monitoring the compression is a good measure. Fact is that this Dakota is now a low miles/month ride. Thanks for your input!

 

Techron is a Chevron product for cleaning fuel systems.

 

I found 10 new stem seals in my shop I can send you no charge if you want them. Shipping on you.

 

Hey thanks! I would really appreciate if I had someone who could send a few parts to me direct, but I want to pay for, paypal or some like that... Right now I'd need the whole set of valve stem seals and perhaps VC gaskets and the tool to compress the springs..? (besides a bunch other things...) Is there anyone who owns a shop that I could buy direct, do you?

 

I'll message you. I have the spring tool and will check on parts prices and shipping. I don't want to clog up this thread since its the plenum sticky.

 

I did the plenum swap a little over a year ago and I was wondering something today.

What are the chances that any of the excess oil would get in your vacuum lines and gum up other components on the truck, ex. The t-case or other 4x4 components, or even the lines themselves? I read this article in its entirety Jan of 2015 in my spare time, (took forever!), but didn't see anyone even ask or address this issue. If it even is an issue. Just curious.

 

The rest of the vacuum lines have flow going TOWARD the intake, so, it shouldn't be an issue.