2005 E320 CDI lifters

[Bigdaddybenz]

Hi guys, so from a previous post I have a lifter that is tapping pretty well and at the advice of multiple forum members I switched from Mobil 1 to Lubro Moly engine oil. The end result is that it did quiet down a bit but the lifter noise is still present, the noise appears to go and come at variable times or more accurately is less pronounced.

I still find it annoying as my CDI now sounds like an older 300D. With 199,500 miles I guess that I can’t complain but I want the engine to sound silky like it did when I first purchased the car.

Anything else that I can try?

Has anyone here ever replaced the lifters on a CDI themselves?... Is it very difficult?

Thank you guys in advance

[97 SL320]

Lifters have either a disc or check ball for a check valve. This prevents oil from escaping while the engine valve is being opened by the camshaft. This valve wears out and allows oil to leak out. Thicker oil " helps " but the only real fix is to replace the lifter.

. . .But what lifter to change? .. . . I've read that someone used audio recording software with one channel on a trigger referenced to #1 TDC compression and another a mic that the swept around the engine. They then looked at the time between TDC and the noise to determine where on the cycle this was occurring.

I'd try to reference to the camshaft signal then plot out the intake / exhaust valve operations.

[Bigdaddybenz]

Wouldn’t you just replace them all?

[97 SL320]

Originally Posted by Bigdaddybenz

Wouldn’t you just replace them all?

It depends on cost. If they are $ 5 each , then replace all but if $ 25 * 24 =
$ 600 and the car won't go another 200 K then replace the one that is leaking + any that have rapid bleed down when pressure is applied.

Given this is an overhead cam inline 6, lifting a cam isn't that much work. ( This engine is based on the gas M104 from the 90's correct? )

[Bigdaddybenz]

I can only assume it is based odd the M104, Looking at the price of materials I tend to agree with your assessment. Better to simply replace the defective one.

What is entailed to replace the lifter, does the timing chain and camshaft require removal?

[97 SL320]

I've removed cams from the M104 to scavenge parts but have not reinstalled. A read through the shop manual will fill in details. I have rebuilt / repaired countless engines of many brands so the repair will generally follow:

Remove valve cover

Turn engine so camshaft timing marks line up per the manual. Clean the sprockets / chain and match mark the chain to sprocket location with paint. I've used a small grinder / scribe to put a small mark it if looks lime paint will be rubbed off.

Loosen / remove tensioner unit. This should be what looks like a large bolt on one side of the timing cover. The tensioner might have a ratchet that needs reset before reinstalling it. See manual for details, generally screw in tensioners can be removed without parts / chain guides falling out.

Devise some way to bungee a singe cam sprocket to the hood ( install a prop so the hood won't close ) or wood laid across the inner fenders ( look at a front drive transmission removal tool to get the general idea ) Unbolt the cam sprocket, pull it off the cam and install the bungee. The goal is to keep the chain engaged into all sprockets. The cam might rotate once the sprocket is removed so it will need reset for installation.

Remove the upper portion of the timing cover.

Unbolt and remove every other cam bearing cap, keep them in order and they are not interchangeable nor can they be reversed. Usually they are numbered. Evenly loosen the remaining ones until the cam is free. At some point in the cams rotation, valves will be at least partly open trying to cock the cam in the head. The goal is not to have one bearing cap holding the cam down, this can lead to damage of the cam / thrust faces of the head.

After the cam has been removed, any lifters you want to change will slide out of the bore when grabbed with pliers. Lube the new lifter on all sides ( oil is fine ) and drop the lifter in.

Cam reassembly consists of reinstalling the cam and caps, be sure to locate the one that takes up cam thrust / end play, this needs to be installed first and monitored so the cam isn't bound up.

After this is complete, move to the other cam if needed. The M104 has variable cam timing on the intake so taking that apart consists of removing a 8mm headed bolt, removing the slug attached by this bolt, removing a large nut then pulling the assembly apart. This will be somewhat fiddly. Everything is keyed to prevent a timing issue doe to miss-assembly.

<<<<< CRITICAL >>>> Once the cams and tensioner are back in place, turn the engine by hand ( Clockwise from the front ) by using the front pulley a minimum of 2 revolutions then recheck the timing marks. ( Remember, 2 rotations of the crankshaft = 1 rev of the camshaft. ) If you feel something solid hit, stop, a valve is hitting a piston due to timing being off. You will feel compression, this will be a springy increase in force but if you wait a few seconds you can freely turn again.

If timing is good, put the other parts back. Start the engine, let idle <<< MORE INFO >>> With new lifters you will have a valve tap until they pump up, this is normal.

This is a very straightforward repair for an engine guy or someone that has removed a cylinder head from this type of engine. It is pretty advanced for a person that has never done this kind of thing.