Last post on Mar 20, 2011 at 7:01 AM
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#73 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [shipo]
Sep 29, 2010 (1:32 pm)
Oh, well, that explains everything. My parents owned a couple of those, and other family members owned a couple more. I can't think of any engine that was more durable and rugged in its day. I'll vet the Mopar slant-six would give a Mercedes diesel of the '60s and '70s a run for its money.
#74 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [hpmctorque]
by MrShift@Edmunds HOST
Sep 29, 2010 (4:44 pm)
They have a lot in common actually. Both long-lived, noisy, like to burn oil, agricultural in personality, and they go shakey-shakey if neglected.
The Slant 6 was simpler of course. That thing has about 4 moving parts. I've seen wood stoves more complicated than a Slant 6 engine.
I've seen Slant 6s wheeze and cough and throw out a smoke screen and wobble and sputter and refuse to start, but I never actually saw one that had thrown a rod.
Benz diesels liked to crack cylinder heads. You'll often find that the claim of "this engine has XXXXXXXXX miles on it" doesn't include the cylinder head.
#75 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [Mr_Shiftright]
Sep 30, 2010 (12:03 pm)
I had a "Slant-6" in a 74 Plymouth Valiant. The engine developed an oil leak and needed a quart every 500-800 miles. Being the kid that I was, (18 and should have know better), tried drag racing a friend and didn't check the oil. Needless to say, it threw a rod, (Rod Knocking) Check the oil and there was no oil on the stick. Took three quarts to bring it back to full. But would you believe, I drove that thing another six months with it knocking before it finally quit. Put another one in it from the junk yard for $150 and drove it another year.
#76 of 82 light tapping motor
Sep 30, 2010 (12:43 pm)
new head,oil,and cover pan gasket new oil pump and new connecting rod bearing and new lifter and its still has a light tap to it i know what else to do help.....
#77 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [mo_shade_tree]
Sep 30, 2010 (1:09 pm)
"Needless to say, it threw a rod, (Rod Knocking)..."
You got it right the second time.
Typically a "thrown rod" implies that a rod has broken somewhere between the crank throw and the wrist pin. In many cases, given that the rest of the engine still has a few revolutions left in it, the remainder of the rod still attached to the crank manages to punch a hole in the side of the block.
In the case of your 1974, the usual term is "spun a bearing".
#78 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [shipo]
Oct 08, 2010 (1:29 pm)
I saw a guy throw a rod on an old Chevy one time. It somehow missed hitting a water jacket and the guy drove it home about 20 miles afterwards.
Can't imagine the noise it must have made!
#79 of 82 Re: Engine oil leaks and transmission (gear) oil leaks - longevity and failure [isellhondas]
Oct 08, 2010 (1:41 pm)
Yeah I've seen holed skirts as well (the engine block kind that is); not usually too many water passages in the skirt.
Mar 20, 2011 (6:46 am)
Since I haven't been in here for a while I'd thought I'd post an update. My consumption issue has slowly gotten worse. It now uses a qt about every 800-1000 miles. However, I did replace the spark plugs and wires a couple of months ago and none of the plugs looked to be oil fouled. In fact, they all appeard to have the nice hazy look you typically see with a properly running engine. The engine also doesn't smoke (at least not that I can see anyway), it still runs fine, doesn't seem to have lost any power, and it still seems to do just as good fuel economy wise as it ever did. So I just keep a few extra qts of oil in the trunk and keep driving it...why not?
#82 of 82 Re: Update [bottgers]
by MrShift@Edmunds HOST
Mar 20, 2011 (7:01 am)
Indeed, why not? You might try an experiment, which requires a friend to follow you in their car.
Accelerate on some empty road, maybe say in a lower gear so that the engine revs up pretty high---then let your foot OFF the gas until the car slows way down, and then PUNCH it.
Then ask your friend if he saw a momentary puff of blue smoke as you punched it.
If he did, this would verify worn valve guides or valve stem seals.
By driving the way you did, you created high engine vacuum when you let off the gas, and then LOW vacuum when you punched it---this would suck any oil from the upper cylinder head past the worn guides or seals and into the combustion chamber.
If you are just idling, or revving the engine while standing still, you don't create the conditions necessary to suck oil past the worn guides and seals. So you won't see smoke. And seeing it as you drive is difficult, as the smoke would be temporary.
If you want a definitive answer, get a Cylinder Leakdown Test performed and post the results here.