Got a 1968 M72 Jeep (Military) Truck. Has A 231 Overhead Cam 6 Cylinder Tornado engine. Most folks never saw or heard of this engine for good reasons. It is a low powered, poorly designed Lemon that the US Gov bought. It has 2 major faults, along with a 1000 minor ones. Fault 1, the cam lobes and valve wear out quickly due to poor luberciation. 2. The distributor shaft that drives the oil pump has a fiber gear on it that can fail and as far as I have read there are no replacement fiber gears available. The FIX I have a new cam and valve lifters. So Am I on the Right Track: The Army / Kizer co says use Gov 30 wt non detergent oil. That results in the quick Cam Wear. (This engine has 35,000 miles on it and 4 cam lobes are worn flat/ Zero compression on those 2 cylinders). I plan on using 00-20 wt Penz Full Synthetic in it. The much thinner oil plus the much greater Lube of synthetic should allow more oil to get to the Cam and reduce the wear. 2nd advantage the thinner oil should be much easier on the fiber gear that drives the oil pump. NOTE: I have ran synthetic in several old Old engines, 235 chevt 6, 300 ford 6, chevy 283 ....... No issues noted. Sooo Wish me luck or tell me some good reasons not to proceed. Your thoughts please. 1 addition, The rings seem to be fine, it quit smoking after I replaced the valve seals.
A unique ? for almost 1 of a kind situation. Need some old pro advice on an old engine. 231 Jeep Tornado
- Thread starter aray
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No arguments from me assuming you have adequate oil pressure with 20w!
if you’re worried that a 30-grade oil causes too much wear and you’re considering using a 20-grade?
The amount of misunderstanding about what causes wear and what does not is sometimes baffling. Thinner oil will not reduce wear.
The amount of misunderstanding about what causes wear and what does not is sometimes baffling. Thinner oil will not reduce wear.
HDEO 10W-30, like Rotella T5; would be great for that engine. Would not run 0W-20 in something that old that probably has problems with oil pressure.
Probably is not used in the cold, so 10W would flow to top of engine just fine in moderate temperatures.
Probably is not used in the cold, so 10W would flow to top of engine just fine in moderate temperatures.
The cam lobes (not journals) are splash lubed? or lubed from oil slinging off from around the rods? If so, I do wonder if a thinner oil would get oil flung onto that area faster... but I do wonder if just simply using 0W30 is the better thing to do here. 30 for operating temp, while still being "thin" at cold start. [But I'm assuming that "thin" oil is easier to fling at lower engine speeds, like cranking. And I'm assuming how the lobes are lubricated, maybe there's a gallery run to them somehow? hole in the lifter that gets pressurized oil to them?]
But I do wonder if any modern oil is going to avoid this wear issue altogether, I mean, comparing ND30 to anything on the shelves today... is it a fair comparsion?
But I do wonder if any modern oil is going to avoid this wear issue altogether, I mean, comparing ND30 to anything on the shelves today... is it a fair comparsion?
AZjeff
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Photos of truck needed.
This will not be the answer you want to hear.
When I had a 4wd junkyard back in the 90's I saw a bunch of these. I had an employee who was bound and determined to make a good one out of 5-6, with flat cams too, that I had in inventory.
In the end, nothing can help this motor. A small block Chevy or a 350 Buick takes less time to install than changing the cam on those hunks. He got 2 of them working, both blew up in one form or another, and after wasting a year of his life, he ran the Buick and lived happily ever after.
When I had a 4wd junkyard back in the 90's I saw a bunch of these. I had an employee who was bound and determined to make a good one out of 5-6, with flat cams too, that I had in inventory.
In the end, nothing can help this motor. A small block Chevy or a 350 Buick takes less time to install than changing the cam on those hunks. He got 2 of them working, both blew up in one form or another, and after wasting a year of his life, he ran the Buick and lived happily ever after.
My answer to reputed cam lobe eaters, and I've had a few (non Jeep), is always Redline 10w40, but recognizing the gear concern, I'd consider their full additive 10w-30.
It may be putting a Band-Aid on a much larger issue, but have you looked into any of the new DLC coating options for cams and lifters?
Nice rig and kudos for you trying to keep old iron still rolling. As others (and you) have described, there is a reason you don't see these motors much anymore. Unless you want to do a restore to put in a museum and drive it only in the local 4th of July parade, consider a different motor swap. I imagine you are on Jeep forums already, what engine do other put in this beast? If your intended use is for 'wheeling. You'd be much happier with a more common and modern engine. Pics would be great.
I'd use a good synthetic HDEO 5W30 or even something like TDT 5W40 in it. Why they'd spec a non-detergent 30 grade is beyond me. An XW20 is not the answer, that's for sure.
Euro 5w-40 is what I would use...
Wait, is the WiKi right and this is a 6 lobe cam operating 2 valves per lobe? I'd love to hear about how that works.
Seems like an opportunity to have a small run of gears made.
I agree if you have a suitable cam DLC coating it and the followers might be a good option, it wont be cheap.
Seems like an opportunity to have a small run of gears made.
I agree if you have a suitable cam DLC coating it and the followers might be a good option, it wont be cheap.
Yea Nate This engine has a history of very little oil getting to the valve train. It has 2 valves worked off each cam lobe. # 2 cam cam lobe wears flat and 3 does almost as bad. the cam and rockers are spray lubercated. I am going to install a line off the oil pressure gauge to spray oil onto these 2 cam lobes. My thinking is the 00-20 wt synthetic squirted on #2 and #3 will provide enough lube to reduce the wear. I can send you a picture of the cam and valves if that would help. I cannot believe this engine has been around 60 years and I cannot find where anybody has tried this before???? My understanding is Synthetic provides 20 x more wear protection.
Not so sure about that, conventional has come a long ways too. I wouldn’t use synthetic just because “its better”, in this app, anything is better than ND30. Although it sounds like it’s got little to do with the oil and everything to do with the engine design—which is unlikely to be helped by oil selection.
Now if you start plumbing in oil sprayers, maybe you can change all that. But if you do that, I bet you could go back to 10W30 or 15W40 and be fine—the problem is inadequate oiling of the cam lobe, nothing else, right?
Mobil 1 0w-40. Just don’t put a 20 wt. in there.
note: the cam lobes on my vintage Fords and Shelby’s also rely on splash lubrication. On one of the Shelby’s I put over 100,000 miles on it in 12 years using Mobil 1 0w-40 and Mobil 1 15w-50. Zero wear on the cams and all bearing surfaces.
There is no science to substantiate the premise that a 20 wt will “sling farther or faster”.
note: the cam lobes on my vintage Fords and Shelby’s also rely on splash lubrication. On one of the Shelby’s I put over 100,000 miles on it in 12 years using Mobil 1 0w-40 and Mobil 1 15w-50. Zero wear on the cams and all bearing surfaces.
There is no science to substantiate the premise that a 20 wt will “sling farther or faster”.
If you're gonna make a spray bar, might as well spray then all...
No that’s not anywhere near true. Again more misunderstanding about how lubrication systems work and what actually prevents wear.
Once again a thinner oil does not protect better. Film thickness prevents wear not the other way around.
Oh and synthetic oil does not provide wear protection. That “20 x” is beyond ridiculous.
Keep in mind that adding another branch in the oiling system will reduce oil pressure. The 0W-20 will decrease oil pressure even more. A secondary electric oil pump to feed the cam sprayer would allow you to feed a high volume of oil to the cams without the engine oil pressure dropping.
A thinner grade of oil will only increase oil flow when the oil pump is in pressure relief, which will normally only happen when the oil is cold. If the wear issue is happening when the engine is at operating temperature, a thinner grade won't help.
Your oil sprayer idea might work, but it sounds like the engine will still inevitably fail when the oil pump gear wears out. I'd look for a solution to the oil pump issue. Maybe take the drive gear to a machine shop to see if you can get better one made, or better yet, try to find a solution that involves installing a higher-flow oil pump.
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