I rebuilt my 99 ram 5.9L engine in December. After 1000 miles it was 3qts of oil low. No oil leaks were present. I used the Hughes engine aluminum plate replacement on the plenum but suspected something was up. Vacuum test from the local mechanic shop says there is a vacuum leak on the intake. So that would mean plenum correct? Any ideas why it would have been leaking even with the new replacement? I torqued it down to the 84 in-lb spec and pattern. Also, now after another 500 miles, my passenger cylinder head has started to seep oil at the back of cylinder 8. Are oil vapors getting sucked in and during compression pushed out passed the gasket? Is that now comprised and will need to be replaced as well? Thoughts very much appreciated as I am debating on what to do going forward.

 

Created a separate thread for you.

 

Try a new Mopar PCV valve first.

 

Two very simple tests...
1) Remove your oil filler cap, is there a giant sucking sound from within the engine? Not sure, put a tissue, towel or piece o paper over the oil filler hole, does it get sucked down or blown off the hole?, and
2) Remove the air filter housing, open the throttle body valves n look down to the floor of the intake, is it a swimming pool of oil?
If neither a sucking sound, sucked down oil hole cover or swimming pool in the intake, then likely nort the plenum.

 

I do have a new PCV valve. Not mopar though. Bottom of plenum looked pretty clean when I looked down it a couple weeks ago. I'll check again this weekend. As for the sucking and paper towel trick have not tried or looked into that. What would have caused the vacuum test failure at the shop if not the plenum?

 

Do you have an engine scanner, one that has capability of reading live data? Not necessarily plenum. A vacuum leak is kinda like saying, life's unfair...okay, compared to what? Be more specific! Oil leak at rear of cylinder head could be the valve cover gasket or intake manifold to block leak, or...pictures n/or specifics are needed here

 

Appreciate the help so far. I won't have time to look at it for a few days. But next post I'll have some pictures and take a look down the intake again and do that paper towel test along with listening for any sucking sounds. As for an engine scanner that reads live data, I don't have one. Is that a must to figure this out? Would this scanner work http://www.obdreaders.com/OBD+Reader...r+Live+Data/8/ ?? It seems a little too cheap from what I have seen at other places but if it will work i will definitely buy it to help.

 

Aftermarket PCV valves flow to much air, so they are a vacuum leak. Not sure if it's all brands or just some of them. If the shop told you it was leaking, why didn't they locate the leak? Spray the oil leak with brake cleaner, tighten the valve covers and see if it still leaks.

 

Got some pictures of that cylinder head leak. The first one is pretty good as you can see a drop of oil hanging there. above the cylinder head gasket it is perfectly clean so not coming from the valve cover. I did the paper towel test on the intake, definitely sucking it in. I looked down the intake again and yeah there was some good oil streaks in there this time. I'm thinking that I had a defective gasket. If you are familiar with felpro gaskets they often come with blue lines in the black material. I do not know what it is but I remember my plenum gasket in my rebuild kit had raised blue ridges rather than the flat ones (also felpro) that came with the hughes engine aluminum plate. I didn't think much of it at the time but pretty sure those raised blue parts are not getting compressed enough to make a good seal. Going forward I am going to get the hughes engine air-gap intake with no plenum. As for the cylinder head gasket, probably should just replace that right or do you think it will stop if the cylinder isn't getting oil in it anymore?

 

It looks like it's blowing back from the front or leaking down the back side of the head. I would retorque the heads and try to see if the back of the intake is leaking. Spray them with brake cleaner and see what happens. The leaking plenum has nothing to do with the external leak. Pull the PCV valve out of the valve cover and try the paper towel again.