Sketchy! That's a ton of oil loss to cause op fluctuations in 1.5 hours of driving

Who knows how much the Magnums have to lose before the pump can't deliver adequate pressure??

 

Generally, when it gets to below three quarts, you start having trouble, unless your pickup tube is kinda gunked up, then it starts freaking out quicker.

 

So either my oil pressure gauge + pickup tube are both malfunctioning simultaneously (seems unlikely) or something else is going on. Re-doing the test again as I forgot to put my foot on the throttle the first time, and will do a wet test.

Appreciate all the help guys

So, I re-tested with the engine warmed up and the throttle pressed down and got 162 PSI on the first cylinder and at that point, I figured the rest will be within that range unless you guys think differently, I think its safe to say that the rings/guides are ok?

edit: i wanted to be thorough with the compression test so I removed all the spark plugs, kept the throttle wide open and hot

1: 170
2: 175
3:165
4:170
5:170
6:150
7:150
8:170

seems like #6 and #7 will need further investigation. I’m thinking either the head gasket (even though I think I would see coolant burning ) I’ll put some oil in those cylinders and see if the numbers go up

 

Actually, those numbers look pretty good. If you have the capability, a leakdown test on 6 and 7 will tell you wear compression is going. (my guess would be valves.) Still, do the wet test, see what the numbers do. If they jump significantly, (and I don't see that happening, except maybe on 6 and 7...) that means bad rings. If it doesn't change much, then the compression is leaking out somewhere else. These engines are know for cracking valve seats...... Leakdown test would show that.

 

Your PVC may be leaking also allowing oil into the intake. What kind of blow by does the engine have?

 

How do I check for blow by? And do you think that even if there was an issue #6 and #7 it would consume all that oil? I just don't see it smoking quarts.. Also noteworthy is Both valve cover gaskets are leaking, and when I took the spark plugs out, it had a lot of oil built up on the threads. Could it be a combination of the plenum, valve cover, and perhaps a small amount actually being burned by the engine via bad rings or the cracked valve seats as mentioned.


Since I am unfortunately committed to this rig (we were suppose to leave on a coast to coast trip last night) I ordered the hughes plenum kit, and will be replacing both pcvs, and valve cover gaskets.

 

Lots of places for oil to go. Thing is, even though mine had hellacious oil consumption, it really didn't smoke.... Might consider doing valve seals while you are doing the valve cover gaskets.... though, I would do the leakdown test before putting much into your current set of heads.

Also, get your PCV valve from the dealership, they actually have the correct flow rate. The same can't be said for the aftermarket parts. (last time I bought one, it was like 8 bucks.)

 

Can you confirm if an issue with the head on cylinders #6 and #7 would cause it to burn that much oil? Also what are your thoughts on a malfunctioning sending unit?

 

Almost sounds like that you have an oil leak that's under pressure with that kind of loss. Check the oil pressure sending unit at the back of the motor (to the left of the distributor)to ensure its not leaking. A leak there would certainly cause a big loss of oil. Also, check around the oil filter, too.

 

With the engine up to operating temp take off the pcv valve that goes into the valve cover. If you see/feel air pushing out that's blow by(air leaks past the rings into the crank case, When the pistons are coming down it "blows" the air out of the crank case).