Little or NO power after bottoming out suspension- 1981 300SD - Page 14 - PeachParts Mercedes-Benz Forum

funola · #**196** 03-11-2013, 01:29 PM

Quote:

Originally Posted by Brian Carlton

Agreed.

But, what else do you have?

The engine ran almost "normal" when he advanced the timing with the IP.

May have what's in post #76 copied below. Actual experience from an ASE mechanic forum member automch.

" It is remotely possible that the crank and bearings were starved for oil when the pan was bent resulting a partial seizure and thus stalling after a mile. If the crank and bearings are galled it will have extreme friction and refuse to rev up to high rpm. This is rare as most times when this happens the engine seizes completely. Does the engine seem to be laboring, but smooth at idle? If so then pull the pan and look at the rod and main bearings. Like I said earlier it would be very rare but something I did see happen once with a Detroit 6V53 diesel. It would start and run after they ran it dry of oil. They added oil and drove it to my shop with very low power and a top RPM of 1400. It had oil pressure and did not knock. Upon tear down I found the rear main bearing had spun in the block and was seized to the crankshaft. Block was ruined. Just a thought."

Brian Carlton · #**197** 03-11-2013, 01:52 PM

Quote:

Originally Posted by funola

May have what's in post #76 copied below. Actual experience from an ASE mechanic forum member automch.

" It is remotely possible that the crank and bearings were starved for oil when the pan was bent resulting a partial seizure and thus stalling after a mile. If the crank and bearings are galled it will have extreme friction and refuse to rev up to high rpm. This is rare as most times when this happens the engine seizes completely. Does the engine seem to be laboring, but smooth at idle? If so then pull the pan and look at the rod and main bearings. Like I said earlier it would be very rare but something I did see happen once with a Detroit 6V53 diesel. It would start and run after they ran it dry of oil. They added oil and drove it to my shop with very low power and a top RPM of 1400. It had oil pressure and did not knock. Upon tear down I found the rear main bearing had spun in the block and was seized to the crankshaft. Block was ruined. Just a thought."

Yep, I saw that.

I still go not grasp how the bearing could consume so much horsepower at 1500 rpm to effectively prevent the engine from climbing any further but still allow rotation at idle without any additional fuel being applied.

funola · #**198** 03-11-2013, 01:55 PM

Quote:

Originally Posted by Brian Carlton

Yep, I saw that.

I still go not grasp how the bearing could consume so much horsepower at 1500 rpm to effectively prevent the engine from climbing any further but still allow rotation at idle without any additional fuel being applied.

Does friction increase exponentially (power of 3) with RPM?

vstech · #**199** 03-11-2013, 01:59 PM

Quote:

Originally Posted by funola

Does friction increase exponentially (power of 3) with RPM?

Hmm... not really, but airflow does via RPM, so load on the piston may increase, which would load a rod bearing if it's damaged... it's possible, but I just don't see it in this case.
I agree, if it was bearing, there would be shiny debris in the oil by now...
it's still gotta be fuel or timing.

funola · #**200** 03-11-2013, 02:08 PM

Quote:

Originally Posted by vstech

Hmm... not really, but airflow does via RPM, so load on the piston may increase, which would load a rod bearing if it's damaged... it's possible, but I just don't see it in this case.
I agree, if it was bearing, there would be shiny debris in the oil by now...
it's still gotta be fuel or timing.

We don't know if there is shiny debris in the oil or not since Rich has not looked for it. Starved of oil at 70 mph for a mile (around 3000 rpm in an SD?) would do some serious damage to all the bearings, would it not?

whunter · #**201** 03-11-2013, 02:19 PM

Give him a chance to remove the accessory belts, for the simple test.

I am hoping it is a rare multiple accessory bearing failure = massive load just short of belt slip.

Again: This is rare, but I have experienced it many times (often on crashed/repaired vehicles).

.

funola · #**202** 03-11-2013, 02:26 PM

How long should one run a motor safely without a water pump belt?

If the original oil filter has not been thrown out, it should be dissected to look for bearing material. If gone, the current oil filter should be dissected.

Brian Carlton · #**203** 03-11-2013, 02:44 PM

Quote:

Originally Posted by whunter

Give him a chance to remove the accessory belts, for the simple test.

I am hoping it is a rare multiple accessory bearing failure = massive load just short of belt slip.

Again: This is rare, but I have experienced it many times (often on crashed/repaired vehicles).

.

Again, the question begs on how the governor can maintain idle if the accessories are providing so much drag that the engine cannot climb above 1500 rpm?

To believe that it can idle with such an accessory drag without some additional fuel from the driver is unrealistic, IMHO.

funola · #**204** 03-11-2013, 02:58 PM

Quote:

Originally Posted by funola

Does friction increase exponentially (power of 3) with RPM?

This is in an engine with bearing damage, where the crank journals are no longer riding on an oil film, but with some spots that have metal to metal contact.

funola · #**205** 03-11-2013, 03:00 PM

Quote:

Originally Posted by Brian Carlton

Again, the question begs on how the governor can maintain idle if the accessories are providing so much drag that the engine cannot climb above 1500 rpm?

To believe that it can idle with such an accessory drag without some additional fuel from the driver is unrealistic, IMHO.

Maybe true in a SI engine? But a CI engine has more torque?

ROLLGUY · #**206** 03-11-2013, 08:40 PM

Quote:

Originally Posted by funola

Sorry, missed that. It's hard to keep track of chronology of events. Do you still have the oil pan and the crushed rubber piece on the bottom? Take a closer look at those parts and see if it could have caused oil starvation.

WHunter says the car was going 70 mph for a mile before it stalled. Is that true? Wouldn't running with low or no oil pressure for that long at high rpm cause more than one "spun bearing".

I don't suppose Brad looked at the oil pressure gauge after the impact? Maybe worth asking him.

Also ask him when the engine did not re-start after it stalled, whether the engine turned laboriously or did not turn at all. This may indicate the severity of the seizure at the time.

I am not sure exactly the speed he was driving, but it could have been as much as 70. He was traveling on a frontage road, and most cars travel around 60 when I drive on it. He thought he had a fuel filter problem, so he had a friend bring a set of filters, and he changed them on the side of the road. The primer pump was bad, so I imagine that is why they could not get it started, and towed it back home. Yes the dented oil pan crushed the rubber piece, and broke it at the seam where it attaches to the pickup. I did not bother to replace it, as it seemed to work without the piece on the bottom (I did not have a replacement anyway).

ROLLGUY · #**207** 03-11-2013, 08:46 PM

Quote:

Originally Posted by Brian Carlton

Agreed.

But, what else do you have?

The engine ran almost "normal" when he advanced the timing with the IP.

Not really. It had more RPM's, but no more power. Barely enough power to move the car, but not to shift (watching Brad test drive it, and seeing it go very slow).

ROLLGUY · #**208** 03-11-2013, 09:02 PM

Quote:

Originally Posted by funola

How long should one run a motor safely without a water pump belt?

If the original oil filter has not been thrown out, it should be dissected to look for bearing material. If gone, the current oil filter should be dissected.

I think that is a good idea, and easy to do. I will just drain the oil in a clean pan and remove the oil filter for inspection. Any particles are going to be on the outside, so dissection is not necessary.

Volker · #**209** 03-11-2013, 09:08 PM

Quote:

Originally Posted by funola

Maybe true in a SI engine? But a CI engine has more torque?

at idle an engine has zero net torque, otherwise it would keep speeding up... other words torque x speed from pushing piston equals torque x speed absorbed by accessories and friction drag...

JimSmith · #**210** 03-11-2013, 11:29 PM

Quote:

Originally Posted by Volker

at idle an engine has zero net torque, otherwise it would keep speeding up... other words torque x speed from pushing piston equals torque x speed absorbed by accessories and friction drag...

And any single or combination of belt driven loads that approaches 35hp at ~2000 rpm is going to make the source of the load glow in the dark in short order. That is a lot of heat for an alternator bearing or an air conditioning compressor bearing or the power steering pump bearing. Between the noise and the heat the problem would be very apparent very quickly.

Jim