High mileage 318

dapepper9

Senior Member
Joined
Feb 7, 2013
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Location
Iowa/Nebraska Border
Ram Year
2001
Engine
5.9L V8
My '99 318 is closing in on 290,000 but it's hurting bad... Developed a(n oil) drinking problem sometime in late 2019, early 2020... drains the pan in about 1,600 miles.

Put oil catchers in the PCV and breather lines and until recently, 10/11/2021, it wasn't catching tons of oil much less a significant difference between cylinder banks. After returning from a weekend long trip, the even cylinder bank was dumping oil 4 times faster than it ever had...

Odd cylinder bank (breather to air filter intake tube)
This is the typical amount I see after roughly 1 tank of gas on either side
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Even cylinder bank (PCV valve to intake manifold)
This is the amount upon return from my trip (return trip only) and it is 4 times the normal amount I would see and did see on the way down.
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In short, even though I don't drive a ton since 2020 even with it being my personal daily driver, as soon as I can get a new daily I'll be able to tear down and figure out what's going on. As it sits now, 300,000+ is a pipe dream.
Do a compression and leakdown test. That will tell you if it's ring wear or something else. My 360 at 230k had a fair amount of compression loss but not enough to explain the oil burn I was seeing, it was on the low end of acceptable. I actually switched to a high mileage engine oil and noticed a LOT of the oil burn died down. I suspected valve seals and when i swapped to the new block I tore the heads down to investigate. The valve seals were pretty brittle and it's my theory that the high mileage oil softened them up and allowed them to seal a bit better. It's not likely to solve the problem but it's a simple and cheap thing to try.
 

dodge862

Junior Member
Joined
Mar 29, 2015
Posts
12
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19
Ram Year
1999
Engine
5.2 V8 Magnum
Do a compression and leakdown test. That will tell you if it's ring wear or something else. My 360 at 230k had a fair amount of compression loss but not enough to explain the oil burn I was seeing, it was on the low end of acceptable. I actually switched to a high mileage engine oil and noticed a LOT of the oil burn died down. I suspected valve seals and when i swapped to the new block I tore the heads down to investigate. The valve seals were pretty brittle and it's my theory that the high mileage oil softened them up and allowed them to seal a bit better. It's not likely to solve the problem but it's a simple and cheap thing to try.
I actually have done a series of compression tests on it through last year and this year. 5 in total. No leak down test yet though I do have that in the works as soon as I can get ahold of a buddy who wants to help me out with that.

I wish I had bothered to put the date on these tests but they were spaced out by weeks to months. Test 5 happened today.

I've soaked the cylinders that had the worst compression in Seafoam just to see if I could free up any stuck rings.
I would pull the plug, dump a couple of ounces in the cylinder, let it sit for days, as long as I could, and crank it out of the cylinder before putting the plug back in and firing it up.

Today's test looked pretty good with the exception of cylinder 1. That spark plug was bathed in oil and absolutely fouled. I chiseled the thick carbon build up off of it before putting it back in. No other spark plugs had build up though cylinder 6 spark plug has been chronically coated in oil under the wire boot. No build up on the plug electrodes though so not sure what to think about that.

I have had my valve stem seals replaced once... let's guess and say that was around 157,000 miles? I could look up the exact mileage but this is pretty close. When I had that issue, I would get smoke from the exhaust on start up and it would regularly die after initial crank and fire until the oil burned off. The thought has crossed my mind that the valve stem seals could be bad again but it's not showing the same symptoms, not that it really needs to I guess.

What I am seeing though is high oil consumption, carbon blasting out of the exhaust and all over my garage shelves and everything on the shelves, and smells of oil burning due to high crankcase pressure forcing oil leaks around the block.

I appreciate the help too! I'm running short on ideas between bad rings, bad valves/heads, or some combo of both. Soon as I can land a new daily driver, I am hoping to tear down into this truck and see what's going on and get this oil consumption stopped.

Round 1
Cyl #1 - 145 PSI
Cyl #2 - 70 PSI (dry) 115 PSI (wet)
Cyl #3 - 165 PSI
Cyl #4 - 145 PSI
Cyl #5 - 60/75 PSI (dry) 120 PSI (wet)
Cyl #6 - 160 PSI
Cyl #7 - 150 PSI
Cyl #8 - 120 PSI

Cyl #2 - 155 (post Seafoam soak)
Cyl #5 - 150 (post Seafoam soak)

Cyl #8 - 145 (no action taken)

Round 2
Cyl #1 - 125
Cyl #2 - 155
Cyl #3 - 170
Cyl #4 - 155
Cyl #5 - 90
Cyl #6 - 160
Cyl #7 - 160
Cyl #8 - 145

Cyl #1 - 135 (post Seafoam soak)
Cyl #5 - 145 (post Seafoam soak)

Round 3
Cyl #1 - 130
Cyl #2 - 150
Cyl #3 - 150
Cyl #4 - 145
Cyl #5 - 125
Cyl #6 - 150
Cyl #7 - 150
Cyl #8 - 140

Round 4
Cyl #1 - 125
Cyl #2 - 160
Cyl #3 - 150
Cyl #4 - 160
Cyl #5 - 150
Cyl #6 - 165
Cyl #7 - 160
Cyl #8 - 140

Round 5
Cyl #1 - 135
Cyl #2 - 160
Cyl #3 - 160
Cyl #4 - 140
Cyl #5 - 150
Cyl #6 - 170
Cyl #7 - 165
Cyl #8 - 155
 
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