Mercedes 450SEL 6.9 engine ticking/noise

[daantjie]

Maybe we have veered off a bit from the initial post, ha-ha, but there is a question which has been bugging me with regards to how a worn out valve guide manifests in the audible ticking/clicking of the compensator/lifter?  The noise is intermittent and cycles "on" and "off", so I can only assume that this is when the lifter pumps up, then loses pressure, and repeats this vicious cycle?
I can only postulate that the lateral movement of the valve stem inside the guide causes a disturbance in the movement of the rocker arm, which in turn transfers to the lifter and thus somehow by vibration (?) causes the on and off cycling in the lifter ?

[robertd]

before getting stuck into more serious stuff check the SUSPENSION HYDRAULIC PUMP

simply remove the 4 retaining bolts pull pump out from front casing then remove the small drive piece at the back with you fingers,

reinstall without the drive piece and try the engine again,

worth a try and may save you a lot of grief

[TJ 450]

I agree, If it was the pump, that would explain the cycling... you could even just check it with a screwdriver as a stethoscope. Definitely no harm in checking and at least crossing it off the list.

Tim

[Randys01]

Let's recap on a few points. As I have reasoned earlier in all of this, the spring is there to ensure the lifter remains as near as full as is possible on start up. Other wise the clatter would be awful.
By the way..it is not the oil pressure holding the valve lifter "up"... that is a misconception!  The oil supply is there to merely keep the reservoir full. It is the internal design of the ball valve  [and the spring] to ensure the working chamber hydraulically locks up. If you think about it 30 psi oil press could not lock a valve lifter when 180 psi is  trying thru leverage to squash the daylights out of it.

Daniel...when  valve guides are stuffed, they have their own distinctive crack crack crack and it is the valve stem hitting the guide wall. maybe a bit of cranky valve seat noise too. When guide wear noise is present it is difficult to isolate the lifter noise. As I mentioned earlier, you can get a great static reading for the lifter clearances but as soon as you start it, ouch.!  Unless it's out by a country mile, lifter clearance issues are a more benign clic clic clik..not crack crack crack.  IMHO, it would be a rarity for a guide to be so worn that the lifter could never compensate.

If u think about it, just say some lifters were nearly always  in lash. Up to  about 6 thou would still sound like a solid lifter motor..tap.. tap tap.
This engine of HC's sounds like it's gargling 3 inch ball bearings.

Nearly for sure our case study here is shagged guides [putting aside the pump possibility ] but we need to eliminate the lifters.
So until such time as Harry C gets on with it, we are all spinning our wheels.
btw when you get a random tik tik tik  passing in and out of the oh valve gear, it will generally be the same little annoying little rogue beastie lifter.  Isolating it is a curse but why is it so?  Assuming all things being equal...solid guide clearances...clean gallery..newish lifter..compatible rocker arm socket..correct setting, the only explanation is......I reckon dodgey ball valve in the lifter...

[daantjie]

well, now that we have successfully hijacked this post

Randy, not sure if you recall our back and forth on the M100 site (RIP for now), but here is a pic of what I found on one of my compensators when I pulled it:

As you can see the LHS one in the pic had popped out of it's collar completely once I took the rocker arm off.

I have researched this topic a lot, and apparently only 2 things can cause this:

1)  Valve float  - highly unlikely in my case - also valve springs are top notch.
2)  Negative clearance - hmmm..?

Also, I am still perplexed by the fact that my tapping is intermittent.  Surely with worn out guides on the inside of the guide, and valve hitting laterally the side of the guide, the noise will be constant and quite the racket, no?  My noise comes and goes every 3 - 5 seconds, cycling faster as you pick up revs, but it is definitely not constant, but "on" and "off".

All 16 lifters are new, and I have also replaced the rocker arm on this suspect lifter.  Cams are also new (30k miles and look great), and gallery has been surgically cleaned.

Man would I like to solve this riddle...

[UTn_boy]

Randy, that's not entirely correct.  I already touched on why the spring is there, so repeating what was said wasn't necessary. The spring, whether it's present or not, is not strong enough to hold things together when the camshaft lobe comes around to open the valve.  The ones in the 6.9 engines I have here have no springs in them, nor is there a "ball" valve.  They're nothing but an inner and outer part.....just like the later M-117 engines.  I have to wonder if someone put the wrong hydraulic elements in both of these engines....but both ran very well and quiet before they were removed.  Go figure.  Furthermore, the oil pressure at high RPM is much higher than 30psi.  The system runs at 45-60 psi.  Remember that the numbers on the oil pressure gauge, 1, 2, and 3, refer to 1 Bar, 2 Bar, 3 Bar, etc.  One bar equals 14.7 psi, and 3 bar equals 44.1 psi.  Suffice to say, oil pressures have much more to do with the hydraulic elements than you give credit for. 

Daantjie, since you have new camshafts, hydraulic elements, and good valve springs we can rule out a lot.  This only leaves sloppy guides and/or incorrectly set lash clearances caused by a wrong thickness shim or bad hydraulic element.  Wrong valve lash clearances can cause intermittent ticking, and while worn guides are usually a constant tick, that won't always be the case.  But do rule out your hydraulic pump first.  They also cause intermittent ticking when internal problems arise or when a leveling valve has a massive internal leak. 

[TJ 450]

The M116/7 engines use the same elements though, right up to the 420/560 and they have the springs... I've built up quite a collection of them.

I also have a set off a 380 M116 that are the same. You'd think if anything it would be the first M100s that would have a different version (maybe the first run of the revised M116/7 from 76 too).

Tim

[TJ 450]

Utn_boy, did you take any photos of those lifters when you had them out?

Tim

[daantjie]

Randy, that's not entirely correct.  I already touched on why the spring is there, so repeating what was said wasn't necessary. The spring, whether it's present or not, is not strong enough to hold things together when the camshaft lobe comes around to open the valve.  The ones in the 6.9 engines I have here have no springs in them, nor is there a "ball" valve.  They're nothing but an inner and outer part.....just like the later M-117 engines.  I have to wonder if someone put the wrong hydraulic elements in both of these engines....but both ran very well and quiet before they were removed.  Go figure.  Furthermore, the oil pressure at high RPM is much higher than 30psi.  The system runs at 45-60 psi.  Remember that the numbers on the oil pressure gauge, 1, 2, and 3, refer to 1 Bar, 2 Bar, 3 Bar, etc.  One bar equals 14.7 psi, and 3 bar equals 44.1 psi.  Suffice to say, oil pressures have much more to do with the hydraulic elements than you give credit for. 

Daantjie, since you have new camshafts, hydraulic elements, and good valve springs we can rule out a lot.  This only leaves sloppy guides and/or incorrectly set lash clearances caused by a wrong thickness shim or bad hydraulic element.  Wrong valve lash clearances can cause intermittent ticking, and while worn guides are usually a constant tick, that won't always be the case.  But do rule out your hydraulic pump first.  They also cause intermittent ticking when internal problems arise or when a leveling valve has a massive internal leak.

Thanks Aaron.  My pump has been overhauled and I am sure it is not the pump.  Also, there is no way a leaking leveling valve will cause the pump to make a noise, as the pump feeds the pressure regulator, which in turn feeds the "5th sphere" (main accumulator), which in turn supports the leveling valves via the height control switch, so there are multiple check valves and system buffers between the pump and the valve.
Also, I really do not see that the pump could cause such a  sort cycling noise.  Once the cut over pressure has been reached (you will actually feel a knock on top of the main bolt on the pressure regulator when this happens), the pump does very little work, unless needed to pump up the 5th sphere again. Excess fluid is now being returned to the tank via return/leak lines and duct in the pressure regulator, and this is the very slow dribble you can see through the filter in the tank with the car running. This is all very clearly laid out in the service manual.  Again there is  no way that the pump should cycle on and off every 5 seconds.
For a test of the cut over, and it's pretty cool to watch too, have someone actuate the "H" setting with you watching the fluid in the tank with a strong flashlight, while keeping your hand on the large bolt.  You will see the fluid rapidly dropping as the fluid is now pumped into the struts to raise the car.  Once the pressure has been equalized again, you will clearly feel the knock as cut over is reached.  Then again you will see the fluid rush back into the tank as the lever is pushed back in to "N" setting.

[TJ 450]

Hi Daniel,

My car was also doing the cycling... I became very familiar with it too. I put it down to some kind of weird harmonics as it was at highway cruising speeds. Unfortunately I haven't road tested the car yet to confirm if it's actually quiet now, but that will be happening very soon (some time over the next couple of weeks). Initial running of the engine suggests that all is good now though.

Tim

[Randys01]

yes Daniel I recall we touched on your specific issue on the M1oo Board.  In fact a lot of this thread has already been covered in that forum.

If you read the bottom of my last post, I advanced the theory that your symptom is likely due to  a rogue lifter that has intermittent locking issues. Whilst you have concentrated on one dodgey element in the past and replaced the lifter/rocker etc, there is nothing to suggest that is the ongoing culprit.

EM me separately and I will explain to you how I would proceed..it's a long rigamaorle that we won't clog this Board with.

Cheers

[daantjie]

yes Daniel I recall we touched on your specific issue on the M1oo Board.  In fact a lot of this thread has already been covered in that forum.

If you read the bottom of my last post, I advanced the theory that your symptom is likely due to  a rogue lifter that has intermittent locking issues. Whilst you have concentrated on one dodgey element in the past and replaced the lifter/rocker etc, there is nothing to suggest that is the ongoing culprit.

EM me separately and I will explain to you how I would proceed..it's a long rigamaorle that we won't clog this Board with.

Cheers

Will do boss

[UTn_boy]

The M116/7 engines use the same elements though, right up to the 420/560 and they have the springs... I've built up quite a collection of them.

I also have a set off a 380 M116 that are the same. You'd think if anything it would be the first M100s that would have a different version (maybe the first run of the revised M116/7 from 76 too).

Tim

Are you sure about the M-116/M-117 hydraulic elements?  Again, none of the ones I have, have replaced, or current used ones have springs in them.  This is all too strange.

And no, I didn't take pictures, but I can certainly take some.  What exactly would you like a picture of? 

Daantjie, The pump can make ticking noises on a cyclic basis if one of the leveling valves, lines, or regulator is blocked.  It'll also make noises when it's worn out.  They'll only make noises from being worn out if they've been starved of lubrication. 

[harrycarry250]

Hello all, thank you to everyone who posted their insight over the years!

The saga continues on this vehicle. I took a long (LONG) hiatus from looking at the car. I put stabil in the tank and started up the car periodically over the years to the keep the suspension happy. Shockingly the vehicle has remained in a relative state of quality as the years have gone by.

Since we last spoke:

I did the full valve shim procedure and while I did make many adjustments, the sound of the engine did not change whatsoever. I also inspected inside the cylinders and did not notice any scouring.

The motor still makes the exact same noise but it does not seem to be getting worse.

Here is the link again. Any thoughts? The only thing I have not done from the thread is to remove the hydraulic pump and run the engine without it. I feel like the next step after that is to inspect the rod bearings. Does anyone have a video of their engine with a bad pump? I would be shocked if a pump could make such a noise.

https://youtu.be/TFkaaZfeUj4?si=bRRY-xCOS7dTWmYQ

As an update to newcomers: Strange intermittent ticking noise from engine. Valves adjusted, chain and guides replaced, all hydraulic lifters replaced.

[tcj]

Have you already ruled out the rotocaps?
Crack in the manifold?