1977 Canadian Newport--engine oil consumption

[Pclancy]

You guys have steered me through countless issues since I purchased this beast. I call her the world's luckiest Newport as I have doggedly fixed every issue that has arisen (and there have been many). I now am invested far more than the car is worth. Such is life. I am obessive complusive, and now turn to ask for advice on the last major current issue.

Oil consumption on the orginal 400 engine ranges between 6-700 miles a quart. I know it is burning the oil, as every seal and gasket has either been replaced or adjusted to the point where any seepage is not the problem.

The engine does not smoke noticeably when driving. A bit on start up (lighter color). The engine has about 60,000 miles on it (not flipped). It sounds and runs great.

I have very good mechanics. Their advice is to test compression, and from there maybe do a leak down test. And then take it from there. The suspicion is that this a top end problem, most likely to do with the valves or valve guide seals. Much muttering about how the original lean burn system (recently removed after it quit working and after much hassle replacing all the ignition components (some more than once--cheap parts) and then tinkering with the TQ carb to get it to run less lean) may have contributed to this problem over the years.

Before I pull the trigger, what advice do you have? How much am I looking at, worst-best case scenario? If the engine needs an overhaul, do I rebuild or remanufacture? I assume there are no crate 400s, right?

With many thanks

 

[cantflip]

Runs good? Then you're fine... 20-30 years ago the rule was still to check the oil every fill up and that oil consumption you have is still with some factory tolerance today... even though many cars don't even have a dipstick (except behind the wheel maybe).

I appreciate your pursuit of perfection, but to open a good running engine for that consumption is perhaps a fools errand. I see late model specs allowing for 1 quart per 600-1000 miles.

If you feel that you must do something, here are a couple things to consider. If you foul plugs (oil fouling would be thick carbon deposits and perhaps a gooey or oily residue), try flushing the engine with ATF. Drain one quart, add one quart cheap ATF, run for a little while (20 minutes ish)... it is important to let it sit overnight and run again for at least 5-10 minutes before changing the oil and filter. This may help a stuck oil control ring... but wont do much for a valve seal.

If you have reoccurring leaks, or lots of them... change the PCV valve... if you like to fiddle, there are adjustable ones (pricey, but reusable). The PCV meters the crankcase gasses drawn by the engine into the intake for incineration. Too little PCV flow can cause crankcase gasses to build pressure and push oil past seals, rings or gaskets. A sign of this would be increased consumption on longer highway trips and less on short in town driving.

I wouldn't try either unless I had a compelling reason to. Well, maybe I would toss a cheap PCV valve in just to see what happens. Change the PCV breather with the valve too.

 

[traintech55]

Chrysler's valve seals were not that great back in the 70's and 40 years later are probably rock hard and worthless. They can be replaced without removing the head from the engine.

 

[saylor]

+3

suckky answer, but my trusted mechanic told me the same thing - i said it still drips oil - he said quit looking at it.

bah hell lol

 

[75LandYacht]

Runs good? Then you're fine... 20-30 years ago the rule was still to check the oil every fill up and that oil consumption you have is still with some factory tolerance today... even though many cars don't even have a dipstick (except behind the wheel maybe).

I appreciate your pursuit of perfection, but to open a good running engine for that consumption is perhaps a fools errand. I see late model specs allowing for 1 quart per 600-1000 miles.

If you feel that you must do something, here are a couple things to consider. If you foul plugs (oil fouling would be thick carbon deposits and perhaps a gooey or oily residue), try flushing the engine with ATF. Drain one quart, add one quart cheap ATF, run for a little while (20 minutes ish)... it is important to let it sit overnight and run again for at least 5-10 minutes before changing the oil and filter. This may help a stuck oil control ring... but wont do much for a valve seal.

If you have reoccurring leaks, or lots of them... change the PCV valve... if you like to fiddle, there are adjustable ones (pricey, but reusable). The PCV meters the crankcase gasses drawn by the engine into the intake for incineration. Too little PCV flow can cause crankcase gasses to build pressure and push oil past seals, rings or gaskets. A sign of this would be increased consumption on longer highway trips and less on short in town driving.

I wouldn't try either unless I had a compelling reason to. Well, maybe I would toss a cheap PCV valve in just to see what happens. Change the PCV breather with the valve too.

That's good stuff Jeff, thanks. I'll change my PCV Just as a precaution before the Carlisle trip. Maybe I should start a thread and get everyone's input on what's needs to be checked/ changed before long road trips. Hmmmmm.

 

[rags]

the truely o.c. CHANGE their oil precisely every 500 miles. PRECISELY! oh, just forget it, you're good.

 

[Pclancy]

Runs good? Then you're fine... 20-30 years ago the rule was still to check the oil every fill up and that oil consumption you have is still with some factory tolerance today... even though many cars don't even have a dipstick (except behind the wheel maybe).

I appreciate your pursuit of perfection, but to open a good running engine for that consumption is perhaps a fools errand. I see late model specs allowing for 1 quart per 600-1000 miles.

If you feel that you must do something, here are a couple things to consider. If you foul plugs (oil fouling would be thick carbon deposits and perhaps a gooey or oily residue), try flushing the engine with ATF. Drain one quart, add one quart cheap ATF, run for a little while (20 minutes ish)... it is important to let it sit overnight and run again for at least 5-10 minutes before changing the oil and filter. This may help a stuck oil control ring... but wont do much for a valve seal.

If you have reoccurring leaks, or lots of them... change the PCV valve... if you like to fiddle, there are adjustable ones (pricey, but reusable). The PCV meters the crankcase gasses drawn by the engine into the intake for incineration. Too little PCV flow can cause crankcase gasses to build pressure and push oil past seals, rings or gaskets. A sign of this would be increased consumption on longer highway trips and less on short in town driving.

I wouldn't try either unless I had a compelling reason to. Well, maybe I would toss a cheap PCV valve in just to see what happens. Change the PCV breather with the valve too.

 

[Pclancy]

I forgot to mention that my mechanics have told me the same thing...stop worrying about it they say. Enjoy it as it is. Fix something else on it. Alas.

Let me replace the pcv valve and breather. I honestly haven't noticed if the oil consumption is higher on the road than in town. (Note, I use this car as a DD and drive it both long and short distances at the drop of a hat). She has never stranded me).

Question: Traintech55's comment about the valve seals is interesting....What exactly is involved in replacing them? How much labor is involved? If you don't need to replace the head from the engine to change them, what exactly do you need to do?
What is a likely sign--beyond excessive oil consumtion--that they are toast?

Thanks

 

[traintech55]

You will need a valve spring compressor and a very good magnet on top of the regular hand tools. If you have an air compressor then you will also need the adapter to screw in the spark plug hole, though you can fill the cylinder with rope and rotate the engine to T.D.C.
1. Remove the valve cover and rocker arm.
2. Remove spark plug.
3. Fill cylinder with rope or air so valve will not fall into cylinder.
4. Compress valve spring and remove keepers.
5. Remove seal.
The seal just slides on over the valve, be careful not to push the valve in if using air.
Reverse procedure to install.
NOTE; the intake and exhaust seals air different.

 

[cantflip]

I forgot to mention that my mechanics have told me the same thing...stop worrying about it they say. Enjoy it as it is. Fix something else on it. Alas.

Let me replace the pcv valve and breather. I honestly haven't noticed if the oil consumption is higher on the road than in town. (Note, I use this car as a DD and drive it both long and short distances at the drop of a hat). She has never stranded me).

Question: Traintech55's comment about the valve seals is interesting....What exactly is involved in replacing them? How much labor is involved? If you don't need to replace the head from the engine to change them, what exactly do you need to do?
What is a likely sign--beyond excessive oil consumtion--that they are toast?

Thanks

I'm with your mechanic's here... I gave a little symptom info in my post... Don't jump into needless repairs without establishing a cause first.

 

[traintech55]

I'm with your mechanic's here... I gave a little symptom info in my post... Don't jump into needless repairs without establishing a cause first.

X2

 

[mr. fix it]

ditto on all above responses...

 

[70bigblockdodge]

If compression test and leak down are reasonable I would just run it. The seals will help but as long as it is not a mosquito killer, oil is still cheap.

 

[300rag]

... The seals will help but as long as it is not a mosquito killer, oil is still cheap.

I remember my 76 400 had to have #6 and #8 plugs cleaned every second fill-up, they were so oil-fouled, and that was at about 25k miles. Unfortunately well out of warranty, at 5 years old.

 

[70bigblockdodge]

I remember my 76 400 had to have #6 and #8 plugs cleaned every second fill-up, they were so oil-fouled, and that was at about 25k miles. Unfortunately well out of warranty, at 5 years old.

My 383 would foul 5/7 till I changed valley pan.

 

[GregG48203]

What is a likely sign that they are toast?

If you see blue or black smoke from the tailpipe for a minute or two when you first start it up cold, this is a sign of bad valve seals.

 

[Pclancy]

Chrysler's valve seals were not that great back in the 70's and 40 years later are probably rock hard and worthless. They can be replaced without removing the head from the engine.

Bonus to this gentleman. I had a compression and leak down test done; both showed "normal" to very good readings. So we replaced the valve seals. My mechanic used the same words almost--the old ones were "hard as a rock." Will report later on as to how my oil consumption changes. Thanks to all for the great insights. My 40 year old 400 seems to be in great shape!