Loud Tapping, Rough Idle, Had to Tow - Page 3 - PeachParts Mercedes-Benz Forum

Maxbumpo · #31 05-14-2015, 12:45 PM

Quote:

Originally Posted by kalikar85

I started it up again (before the tow) and it was apparently fine: no tap and no rough idle. Second time it was tapping again and shaking.

Hmmm, how long did you let it run when it was not tapping and the idle was smooth? Did you do anything different in the starting procedure, like push on the priming pump to prime the injection pump?

That metal may have been in there for years from some earlier malfunction, now corrected.

Give your experience level, I'd say button it all up and see how she runs. If you've still got the tap and rough idle, try ruling out a fuel issue (injectors or delivery valves). Send an oil sample to a lab for analysis - this will definitely tell you if the damage is recent or old news.

If you decide the engine has internal damage, I'd shop for a used engine that you can verify is in good running condition.

charmalu · #32 05-14-2015, 01:44 PM

You mention in post #1.

quote:
I was also chasing an oil leak yesterday and drained some of the oil because I found it was over-filled.

First you have an oil leak, how bad and from where?

When was your last oil change?

How often did you have to add oil?

How often do you check the oil level?

About two weeks ago I checked the oil level in the 240, it was about 2 inches over full. Wiped off the stick and checked it again, Right at the full mark. HMMM that`s weard. next day the same, and since it has been at the full mark. This morning checked it for my Wife, and was right at the full mark.

My 85 300D did this too several times, really don`t know what causes this. and it doesn`t do it all the time.

Now maybe yours was doing this too, and then you drained the 2 or so qts?
I think with even 4 qts in the pan, the engine will still run w/o much trouble. though we or you don`t really know the amount of oil that was in there.
When you drained the pan, how much came out?

As Maxbumpo said, the debris in the pan may have been from a prior problem, and the pan was not cleaned out.

You did mention you heard some clanking and banging around in the engine, that isn`t a good indicator.

Charlie

leathermang · #33 05-14-2015, 01:54 PM

When I first pull the dipstick out on my 240 it shows NO OIL ON IT...
my heart almost stopped the first time I saw that...
but if you put it back in you should get the true reading... it showed just right..'
and many have recommended that these cars be run with the engine oil showing half way between High and Low on the dipstick...... over that can cause oil burning for some reason... does with mine..
AND something to check.... the COLOR of your dipstick has to be correct for YOUR engine.... we have had people find it was the wrong color... and thus length...

Maxbumpo · #34 05-14-2015, 02:32 PM

Quote:

Originally Posted by kalikar85

doesnt the crank case expose the crank? Im actually unclear, after removing the crank case during valve adjustment and removing the oil pan as to where the rod bearings are. Aside from Valve Adjustment procedure, Ive never had any other experience with working inside the engine.

Valve cover is on top of the engine, that is what you removed to get to the valves and the timing chain.

If you consider the engine as layers of sandwich:
Valve cover
Valve cover gasket
Head (contains valves, camshaft)
Head gasket
Block (contains pistons, rods, crankshaft, oil pump)
Oil pan gasket
Upper oil pan
Lower oil pan gasket
Lower oil pan.

You would need to remove the upper oil pan to get to the crankshaft and rod bearings.

barry12345 · #35 05-14-2015, 02:47 PM

Not a dog with a bone syndrome. I am wide open to others thoughts. My thought is rather than differant amounts of fuel fill and that is probably occuring. The principal suspicion is the sequential timing is changed as any element with getting less fuel.The injector will open later than by design.

The lift pump is a constant pressure type but at the same time only recharges once per injection pump revolution. Filling the later elements in a a really low fuel pressure initial setup may mean they are almost scavaging from the decreasing low pressure profile.

Since the relief valve is no longer functional. There is nothing to provide a constant fuel pressure through the remaining fills until the lift pump recycles again.fuel most likely is not able to flow through the filters quick enough to make up the deficiency even if the constant pressure is still available at the lift pump.

As I have said I feel this is a long term deficiency problem that wears the first cylinders rod bearing faster. Why I know something is going on is the engine sounds different with different fuel pressures to the base of the injection pump. The power balance of the engine sounds better with good pressure as well. . Anything you can actually hear has got to be signifigant.

Plus in corrected situations there seems a little more power available in the seat of your pants. With that relief valve closed because of not enough pressure to keep it open. The pulses that are generated inside the base of the injection pump are fierce. How and if they contribute to the issue is another unknown to me.

Now back to your oil viscosity issue.I am no rocket scientist. Say you have a car on 10-30. The car is burning a quart of base oil every 300 miles. You change to a straight 30 weight. Your consumption on average will drop to 5-600 per quart usually..

The only change that seems reasonable to me is the viscosity in effect must remain better. The multi grades state they protect to the same. Still it almost cannot be on a true overall viscosity basis.

The 10-30 has a polymer type component that changes with temperature. The molecule size of it might be much larger in any temperature state than oil. Or only at higher temperatures.

We all realise that a 240d on 15-40 will usually consume more oil than normal on the highway. I attribute this to the higher rpms on average it must run at in comparison to the 617 for a usable speed. I do wonder if the same engine was on straight 40 if the consumption pattern would be less or more on the highway. I suspect it might be less. Just not certain of that either.

Another thought along this line.If you are burning multi grade oil. Is the polymer being burnt up at the same rate? If not by continually adding oil you would have an increase overall of the polymer component. That may be good or bad. I just do not know.

The producers of the multigrade oils have not been particularily open about the whole picture. My wifes car for example takes a 0-20 synthetic oil. To keep the warrranty valid they want only certain oils used. This has led my to wondering why the synthetic oil must be special. Plus what is in it that is different than the normal run of synthetics.

The best yardstick I have been using to determine the probable life left in my engines is the oil consumption rate for a long time now.There is a serious problem with wear. Once it reaches a point it almost exponentially increases.

BillGrissom · #36 05-14-2015, 03:00 PM

I would at least take off the lower oil pan, since fairly easy. One often must do that to replace a leaky gasket anyway. That might give enough view to tell what is wrong. As I recall, all you can see thru that hole is the oil pump, lower timing chain, and #1 cylinder, but perhaps a mirror would let you see all the rods. You can rotate the engine with the crank bolt, with exactly the right socket to fit the narrow gap to the fan shroud. The bolt on the p.s. pump is tempting. People say not to rotate the engine using it, but I have.

I agree that if the metal shards are from a bearing, then the crank is probably marred, but doesn't hurt to inspect if you can.

leathermang · #37 05-14-2015, 03:06 PM

Quote:

Originally Posted by BillGrissom

.... The bolt on the p.s. pump is tempting. People say not to rotate the engine using it, but I have.....

NOT PEOPLE...

The Mercedes Benz Factory Shop Manual specifically forbids using that nut to turn the engine.

That is a tapered shaft and pulley inside and you can ruin the shaft over torquing it... which by definition turning the engine will do. But it is YOUR car and you are free to mess it up as you please by not following what the factory says is correct procedure... they make these rules just to harass owners.. not because they know that much about the cars....

barry12345 · #38 05-14-2015, 03:08 PM

Not a dog with a bone syndrome. I am wide open to others thoughts. My thought is rather than differant amounts of element fuel fill and that is probably occuring. The principal suspicion is the sequential timing is changed as with any element getting less fuel than another.The injector will open later than another one. The effect being a timing reduction more likely than a fuel amount. Any element overloads in a good fuel pressure situation.

The lift pump is a constant pressure type but at the same time only recharges once per injection pump revolution. Filling the later elements in a a really low fuel pressure initial setup may mean they are almost scavaging from the decreasing low pressure profile available down the line of sequential loading.

Since the relief valve is no longer functional. There is nothing to provide a constant fuel pressure through the remaining fills until the lift pump recycles again.Fuel most likely is not able to flow through the filters quick enough to make up the deficiency even if the constant pressure is still available at the lift pump. Any filter acts as a restrictor to some extent.

As I have said I feel this is a long term deficiency problem that wears the first cylinders rod bearing faster. Why I know something is going on is the engine sounds different with different fuel pressures to the base of the injection pump. The power balance of the engine just sounds better with good pressure as well. . Anything you can actually hear has got to be signifigant.

Plus in corrected situations there seems a little more power available in the seat of your pants. With that relief valve closed because of not enough pressure to keep it open. The pulses that are generated inside the base of the injection pump are fierce. How and if they contribute to the issue is another unknown to me.

Now back to your oil viscosity issue.I am no rocket scientist. Say you have a car on 10-30. The car is burning a quart of base oil every 300 miles. You change to a straight 30 weight. Your consumption on average will drop to 5-600 per quart usually..

The only change that seems reasonable to me is the overall viscosity in effect must remain better. The multi grades state they protect to the same. Still it almost cannot be on a true overall viscosity basis.

The 10-30 has a polymer type component that changes with temperature. The molecule size of it might be much larger in any temperature state than oil. Or only at higher temperatures.

We all realise that a 240d on 15-40 will usually consume more oil than normal on the highway. I attribute this to the higher rpms on average it must run at in comparison to the 617 for a usable speed. I do wonder if the same engine was on straight 40 if the consumption pattern would be less or more on the highway. I suspect it might be less. Just not certain of that either.

Another thought along this line.If you are burning multi grade oil. Is the polymer being burnt up at the same rate? If not by continually adding oil you would have an increase overall of the polymer component. That may be good or bad. I just do not know.

The producers of the multigrade oils have not been particularily open about the whole picture. My wifes car for example takes a 0-20 synthetic oil. To keep the warrranty valid they want only certain oils used. This has led my to wondering why the synthetic oil must be special. Plus what is in it that is different than the normal run of synthetics.

The best yardstick I have been using to determine the probable life left in my engines is the oil consumption rate for a long time now.There is a serious problem with wear. Once it reaches a point it almost exponentially increases.

As for air cooled engines. I do not care if the manufacturere specifies 10-30. They are more prone to metal to metal contact. I only cut grass in warmer weather. So all our lawn tractors get straight 30 or 40 weight detergent oil.

We never have worn engine problems. The overall lawn tractors eventually all fall apart around engines that are still running as new. Although if the tractor had an internal 100 percent aluminium oil pump except the shaft. I might not do this.

My brother in law has said he has run into a few problems with modern oil pumps. The owners had been using a heavier oil than specified is what he thinks the issues may be.

kalikar85 · #39 05-14-2015, 03:15 PM

wow thanks, a lot of good stuff on here.

i dont think im going to go down a fuel delivery pressure rabbit hole right now.

Quote:

Originally Posted by Maxbumpo

Hmmm, how long did you let it run when it was not tapping and the idle was smooth? Did you do anything different in the starting procedure, like push on the priming pump to prime the injection pump?

It ran about a min normally. I didnt prime anything. Just started it back up with the hood up to confirm/ deny wth was going on. No shake, nothing.

But it did sound like someone dropped a marble in it (exaggeration) prior to pulling over which is why I unquestionably pulled off.

Quote:

Originally Posted by charmalu

You mention in post #1.

quote:
I was also chasing an oil leak yesterday and drained some of the oil because I found it was over-filled.

First you have an oil leak, how bad and from where?

When was your last oil change?

How often did you have to add oil?

How often do you check the oil level?

About two weeks ago I checked the oil level in the 240, it was about 2 inches over full. Wiped off the stick and checked it again, Right at the full mark. HMMM that`s weard. next day the same, and since it has been at the full mark. This morning checked it for my Wife, and was right at the full mark.

My 85 300D did this too several times, really don`t know what causes this. and it doesn`t do it all the time.

Now maybe yours was doing this too, and then you drained the 2 or so qts?
I think with even 4 qts in the pan, the engine will still run w/o much trouble. though we or you don`t really know the amount of oil that was in there.
When you drained the pan, how much came out?

As Maxbumpo said, the debris in the pan may have been from a prior problem, and the pan was not cleaned out.

You did mention you heard some clanking and banging around in the engine, that isn`t a good indicator.

Charlie

I had changed the oil about 5 months ago.

I checked it and it was very low about 2 months ago. I added a gallon (and may have overfilled it at this point). The drip started shortly after: a slight drip from where the engine meets the transmission on the bottom seam.
Chasing the drip, I checked the oil and it was about two inches over. I drained a couple quarts to where it was about a half inch over.

I always use Delo 400 LE SAE 15W-40. I check the oil when its warm (not hot/ not cold).

Upon draining the oil to scope out the pan for shrapnel yesterday It drained about 2.75 gal. total.

__

Debating at this point whether to button her up and give it a shot. Or plan on pulling the upper pan this weekend with a buddy. I think Ill do both and just take a hit on 2 gals of oil but its raining now.

leathermang · #40 05-14-2015, 03:16 PM

Quote:

Originally Posted by barry12345

Not a dog with a bone syndrome. ....

The evidence is looking otherwise...

first.... the setting of the fuel is done with the drip method ON THAT NUMBER one cylinder.... so if anything IT WILL BE CORRECT and the others 'overfueling' according to your visualization.

second.... even if that first one was getting less fuel no physics rule suggests that would cause more pressure on that piston... in fact it suggests less .

third.... the pop pressures are within a range ...none are perfect... and do effect the timing.. but there is NO evidence that what you suggest about number one.... and refer to ' first' ..... would cause it to be out of sync with the piston movement....

leathermang · #41 05-14-2015, 03:19 PM

Two point Seventy Five ..... GALLONS .....?????
is that correct for what you drained out ??????
How much is your car supposed to hold ?

kalikar85 · #42 05-14-2015, 03:28 PM

Quote:

Originally Posted by leathermang

Two point Seventy Five ..... GALLONS .....?????
is that correct for what you drained out ??????
How much is your car supposed to hold ?

sorry, it was about 2.5 gal. total that came out, yes. (plus what I pulled the night before chasing the leak pre-problem)
it filled up a 2.5 gal Topsider Oil Extractor Can when drained to check the pan.

So it was about 2-3 qt over-filled still. is this a serious factor?

leathermang · #43 05-14-2015, 03:31 PM

OK...
here is a potential reason for the failure..
Overfilling is WAY BAD because it can put the oil level so high that it is whipped by the crankshaft .. or the air around the crankshaft... so it oxidizes it......
that VERY QUICKLY takes away its lubrication properties..

Maxbumpo · #44 05-14-2015, 03:41 PM

So it sounds like you added a gallon when you thought it was low, two months ago, and it immediately began to drip oil from between engine and transmission, which may mean the oil level was overfilled by 1 gallon (4 qts) or more, and was lapping at the rear main crank seal, which is not designed to have fluid pressure against it and promptly began leaking.

leathermang's comment on the crankshaft whipping the oil is right on, all that splashing would add air bubbles into the oil, which could then get sucked up by the oil pump and from there reduce the lubricating and cooling ability of the oil, so then bearings may have suffered.

What is really curious to me is that you say it ran with no noise and smooth idle for a minute right before the tow. Maybe when you let it sit, the air came out of the oil, and there was enough oil pressure / lubrication to temporarily prevent the knocking?

leathermang · #45 05-14-2015, 04:12 PM

Quote:

Originally Posted by Maxbumpo

=....leathermang's comment on the crankshaft whipping the oil is right on, all that splashing would add air bubbles into the oil, which could then get sucked up by the oil pump and from there reduce the lubricating and cooling ability of the oil, so then bearings may have suffered.....

OH... I did not visualize it past the oxidation... that is a very likely scenario....once you have significant actual bubbles in the oil then the oil pump immediately has pressure problems just the way a brake system with air in it does... the air compresses.... so your whole ability to push oil under sufficient pressure to those bearings is compromised FAST....
Good Catch....