Help! Oil choice on a Mack 300 that eats cams

[crashz]

Hopefully Molecule and the oil gurus can step in here and recommend something here.

A little history: This Mack only has about 10K miles on the current cam. An expert mechanic mentioned that its exhibiting the properties of a bad cam already (popping sound in the air intake). This truck has be owned and operated by my father's company for all it life, with marginal maintenance. The cams are lubed by windage off of the crank and rods. Our trucks have always run a commercial grade name brand(what ever is cheapest in 55 gallon drums) 15w-40 diesel. The truck is a 10 wheel dump truck that sees equal amount of on road and off road work. I'm sure that the off camber operation plays havoc with the splash lubed cam (ie oil not always getting to the cam evenly).

In a last ditch attempt to keep it running (this is after a winter of repairs) we dumped a gallon of Lucas into the oil to see if it would help keep the cam lubed. We will also have to adjust the valves and hopefully that popping will go away.

Even if it needs another cam, this will be the fourth that the truck has seen with a maximum of 200K miles. My question is, is there a product that we can use that will help keep that splash lubed cam from grinding to a nub? I was thinking a super EP suppliment or something? The engine is very clean inside, however I was thinking of adding ARX to the crankcase for the positive effects of the esters (cleaning and EP).

 

[Chris142]

I was thinking of using the newer Delo 15-40 with Moly or that Valvoline 15w-40 (blue?) that also has Moly.

Maybe add an oz or 2 per qt of Synpower too? Whats the thing hold 10 gallons or so? That would be 40 ounces of Synpower!

 

[dri]

crashz,
A company across the street from me has many mack trucks,different kinds, RD's, MR', and granites, scattered across three locations. I think they all have the same mack engine. I don't know which one, but some say Renault on the block. Two branches use Castrol Tection 15W40 and have cam problems, while the third location didn't have any problems and used Mystik 15W40. I don't know if it's the oil, or the maintenance practices or what. But the foreman was worried they he'll start having cam problems since they're changing his branch over to Castrol. But it does make a pretty cool popcorn popping sound when running, doesn't it! Part of the engines are still under warranty, and all Mack does is adjust it, noting the condition and send it on it's way, replacing the cam if there is enough to adjust!

 

[Kestas]

From my days involved with cam design I remember that ZDDP, an anti-scuffing agent, is very important for cam wear. You want as much ZDDP in the oil formulation as practical.

 

[crashz]

Chris - Thanks for the recommendation. These hold 11 gallons of oil. Since the oil in it is fresh, I was hoping just to add a product to it. Synpower may work pretty well to beef up the moly. I wish I thought of it before dumpinga gallon of Lucas in there.

dri - Thanks for the comments. I'm not to familiar with the Renault engines as ours are all pretty old. AKA - back when Macks were made in Allentown! But I guess this has been common on most of their inline six engines (237, 285, 285/300, 300, and 350)

You should hear this thing pop at idle! Sounds like a hollow tube being hit with a baseball bat. Funny thing is that it goes away as soon as you rev it up. That why I think the cam is OK but valves need adjusting. Especially since we just pulled the heads and replaced the valve springs.

 

[crashz]

quote:

---

Originally posted by Chris142:

quote:

---

Originally posted by crashz:


You should hear this thing pop at idle! Sounds like a hollow tube being hit with a baseball bat. Funny thing is that it goes away as soon as you rev it up. That why I think the cam is OK but valves need adjusting. Especially since we just pulled the heads and replaced the valve springs.

---

Once the boost comes up the pop goes away because it's being forced into the cyl.

---

I just got a sinking feeling in my stomach... you're completly correct.

 

[Chris142]

quote:

---

Originally posted by crashz:


You should hear this thing pop at idle! Sounds like a hollow tube being hit with a baseball bat. Funny thing is that it goes away as soon as you rev it up. That why I think the cam is OK but valves need adjusting. Especially since we just pulled the heads and replaced the valve springs.

---

Once the boost comes up the pop goes away because it's being forced into the cyl.

 

[Ken2]

My first choice in an oil would be Schaeffer's #151 Moly Bond 15W-40. It'll give you the most protection possible. You might also ask Schaeffer about the advisability of adding #132 Moly E.P. Oil Treatment because of the bad design of this engine and the cam problems...but I wouldn't add it without Schaeffer's OK. After the #151 conventional oil has cleaned up the engine, I'd consider switching to #700 synthetic blend 15W-40 for longer oil life and even more oil film strength. #700 from the get-go is very good, but about one out of 20 older engines has high consumption for one or two oil changes with the syn-blend until things get cleaned up.

http://www.schaefferoil.com/datapdf/151.pdf
http://www.schaefferoil.com/datapdf/132.pdf
http://www.schaefferoil.com/datapdf/700.pdf

Nothing can correct a mechanical design defect, but these oil will give you the longest cam life possible.


Ken

 

[kenneth neeley]

What rpm is being used for low idle on the engine?