Camshaft starving for oil...

[sreams]

Hello all,

I have a recently acquired '71 300SEL 3.5. After a few days, I noticed a squeaking sound at the top of the engine on the driver's side. Opened up the valve cover, and noticed that most of the cam lobes were basically dry, and that most of the cam oiler fittings were partly melted. I've cleaned things up, put in all new fittings, and cleaned out the cam oiler tube completely. The tube is clear as are all of the holes along it. Trouble is... I'm still only getting oil at the ends of the camshaft. The center lobes are still dry for the most part. What can I look into next as a possible cause?

BTW... the engine runs otherwise perfectly.

Thanks ahead.

-Scott

[kbflorida]

I've wondered the same. They made the oiler tube diameter bigger by about 25% in the late 70's, I think, on 117 engines. So I wonder if there was a design weakness with the earlier system.
But it seems like it would be more a pressure issue, doesn't it?
With good pressure, a smaller tube should deliver oil, too.

[sreams]

According to my oil pressure guage... I have great oil pressure, so I'm not sure it's that...

-S

[leenart]

Whats the compression, temp? I am wondering if you might have a blown head gasket. Is it on one bank of cylinders or both? My first guess is a bad oil pump but your saying the oil pressure is good. Are you getting 30psi at idle when warmed up. If the car sits in traffic on a hot day or is driven hard the pressure should not drop below 15psi at idle.
Another point is your oil filter.
If this is on one bank then I would pull the head on that side and rebuild it as its probably shot if its running dry. At the very least change the seals and guides and have the head cleaned.
I wouldn't drive or even start it, until the problem is solved. If you oil starve the crank that engine will be toast
leonard

[kbflorida]

my oil pressure is good, too, yet the right cams were worn badly and my car clearly had oil delivery issues up top.
can there be blockages farther down in the feed that comes up to the oiler tubes? I'm not clear how the whole system is laid out.

[sreams]

My oil pressure guage is pegged at all times except when the car is warmed up and idling. At that point it reads about 2 bar (about 30psi). The problem exists with just one bank of cylinders. It is starting to sound like I might have a couple of clogged oil passages, so pulling the head looks like the next step. Thanks, guys.

-S

for a colleague, in which the oil passage through the head from the block had become blocked, probably because they were using one of those Teflon additives in their oil regularly. It ruined the cam bearing areas in the front, causing the cam to seize and break the timing belt, and also two of the cam lobes.

[kbflorida]

[QUOTE=Fimum Fit]for a colleague, in which the oil passage through the head from the block had become blocked"

Dumb question maybe, but can those passages really be cleaned without removing the heads? A blast of compressed air, plus some carb cleaner?
thanks

[300SDog]

For what it's worth if you wanna first try compressed air, oil passages can be found underneath the camshaft towers fore and aft..... that's my .02 cents.

(edit: meanwhile ask yourself what melted the plastic fittings...... probably been not enough oil going through the camshaft oiler for long, long time.

[leenart]

melted fittings Wonder what the valve seals look like....
As for me I'd do a compression test and then if all looks good pull the head and send it out.
You know whats funny about a Mercedes, its a lot like a horse, no matter how minor the problem the solution is usually pull the engine!
Leonard

to have the cam bearing saddles line bored for an oversize journal cam, so access to clean the oil passages was no problem.

[sreams]

It looks like the camshaft oiler is fed from the rear cam bearing only. The passage through the bearing was plugged up with carbon deposits. I've cleaned it out and things look good now.

-S