The reality of dry starts on a vehicle.

[Hallmark]

Originally Posted By: AuthorEditor
I talked to a guy at a boat show once who was selling a gizmo that tapped into the engine someplace so you could run the engine and pump out all the old oil for an oil change. I can't remember the details, but I vividly remember him saying that at idle you could run the engine for quite a awhile (maybe minutes) until there was no oil whatsoever and there was very little danger of hurting anything. Seemed like a wacky way to me to get the oil out, but a lot of boat engines are very difficult to drain. Every boat show has someone selling some new device to accomplish the task. My current boat engine came with a handy pump that removes the oil from the sump, so I don't have the problem anymore.


The 'gizmo' you refer to sounds similar to a PreLuber that I have on a 1997 F-150. It is a pump installed between the sump and the oil filter and is activated by the ignition switch in the accessory position. It simply pulls dirty oil from the engine sump, routes it through the oil filter, and returns clean oil to the engine bearings/galleries for about 40 seconds prior to starting. In contrast to your description, it doesn't require running the engine to pump the oil.

The PreLuber is extremely handy for changing oil. Using a quick-disconnect in the hose behind the bumper, I just insert the hose in a jug and hit the ignition switch to empty the sump. With a change of filter and a refill of oil, I was finished in 7-8 minutes with no need to ever get under the truck.

 

[440Magnum]

Originally Posted By: rslifkin
Some old diesel trucks have a diverter valve to bleed some oil off to the fuel tanks, with an auto shutdown for when the oil pressure dropped. Then, change filter, fill it up with oil, and you're good to go.


Not to hijack the thread (well, too late probably)... but speaking of oddball valves and features relating to oil and fuel: P-38 aircraft had a provision to pump avgas(!) from the fuel tanks into the crankcases of the Allison engines under certain conditons... namely, to thin the oil for engine starting under arctic conditions. The fuel would then just evaporate back out of the oil as the engine came up to operating temperature.

 

[440Magnum]

Originally Posted By: Hallmark


The 'gizmo' you refer to sounds similar to a PreLuber that I have on a 1997 F-150. It is a pump installed between the sump and the oil filter and is activated by the ignition switch in the accessory position. It simply pulls dirty oil from the engine sump, routes it through the oil filter, and returns clean oil to the engine bearings/galleries for about 40 seconds prior to starting. In contrast to your description, it doesn't require running the engine to pump the oil.




There are also passive pre-lubers, which are just tapped into the oiling system at a single point- usually the pressure sender port. When the engine starts and runs, it pressurizes a canister with engine oil. A check valve prevents the canister from de-pressurizing when the engine is turned off. The next time you start the engine, you push a button and the check valve opens and shoots the pressurized oil back into the same port it came out of, distributing a slug of oil throughout the engine oil system. You then start the engine normally and the pre-luber re-pressurizes with oil, ready for the next start.

 

[Hallmark]

Originally Posted By: 440Magnum
There are also passive pre-lubers, which are just tapped into the oiling system at a single point- usually the pressure sender port. When the engine starts and runs, it pressurizes a canister with engine oil. A check valve prevents the canister from de-pressurizing when the engine is turned off. The next time you start the engine, you push a button and the check valve opens and shoots the pressurized oil back into the same port it came out of, distributing a slug of oil throughout the engine oil system. You then start the engine normally and the pre-luber re-pressurizes with oil, ready for the next start.


Interesting info. I assume those type of prelube systems don't have a provision for emptying oil from the engine to facilitate oil/filter changes.

 

[SteveSRT8]

We had two vehicles with home spun pre lubers as described above.

Worked very well at minimizing a dry start. One could reach 40 psi before the engine was cranked!

I have one very sweet custom made stroker small block with a Moroso oil accumulator that is less than 200 bucks and holds 1.5 quarts of oil under pressure.

Note that this device is not designed as a pre-luber, but can easily be used as such. It is designed to keep the oiling system pressure from dropping too low. It is just a simple spun aluminum canister with a separator in it to keep the oil under pressure.

 

[440Magnum]

Info on oil accumulators and how to use one as a pre-luber:
http://www.stockcarracing.com/techarticles/1594_oil_accumulators/index.html

 

[morris]

i posted this once before, but please dont get mad. back in the dark ages, my dad was changing oil in a 1977 chrysler new yorker, 440 ci, high miles. he jacked the car up, drained the oil removed the filter. mom called him to lunch, took 45 min. back to the 440, dad filled the oil, put filter on. started engine, no pressure. he called me, told him to take the dist out to and spin the oil pump. no pressure. he used a 600 rpm drill motor. called me back. i say use a faster drill. he used a 3200rpm drill, then he got oil pressure.

 

[Errtt]

All the stationary diesel engine generator plants I worked at had pre-lube pumps and pre-heat.
We would run the pre-lube before engine start if it wasn't an emergency. There was usually an automatic timed pre-lube for stand-by units, the engines can sit for weeks.

The smaller engines (GE Locomotive V-16 FDL series) held almost 400 gallons. The large diesels a couple thousand gallons.
Some engines don't have a oil sump/pan. They had a bed-plate to capture the oil and divert it to an underground oil tank. Some had 2-way valve for twin tanks underground and one at a time would be used. We can change oil in one tank, switch to that tank (while the engine was running, then do the other tank).
There were either a series of filters with a bypass to each or parallel configuration. We would change the filter elements also while the engines were running. Same with fuel filters.
If the engine wasn't running, we would use the pre-lube to fill and bleed the oil filters.

There are some interesting systems out there.

 

[Shannow]

While at Uni, I devoured all the SAE papers that I could find (Mech Engineers got access to the full SAE library on microfiche for $10/annum - a fair bit for a Uni student in 1988 - still we paid $300 for an HP15C, and $1.20 for a beer).

One that left me interested was one on an electrical pre-luber/filter, run against a standard oiling system.

Their assessment was that in OTR transport, they would seriously be worth installing.

For passenger vehicles, they estimated a 300-400% improvement in engine life, and stated that it was obvious why no OEMS offered them.

 

[aquariuscsm]

Originally Posted By: JHZR2
You are still reliant on whatever thin film plus additives exist.


If this is thrue,wouldn`t thicker oils mean less startup wear,since the leftover oil film will be thicker upon startup?

 

[Shannow]

Almost certainly.

my 25W-70 winter experiment, the engine cranked hugely slower than a straight 30...and when initially cranking, can only have been on the oil left in the clearances.

 

[JHZR2]

Originally Posted By: aquariuscsm
Originally Posted By: JHZR2
You are still reliant on whatever thin film plus additives exist.


If this is thrue,wouldn`t thicker oils mean less startup wear,since the leftover oil film will be thicker upon startup?


Not necessarily. "Thick versus thin" in the traditional sense has to do with viscosity, which has to do with flow (shear) characteristics. The remainder of oil when it is not pumped and under pressure from operation is just a film (after the engine is turned off, pressure relieved, oil drained out as much as gravity will reasonably do). It can be a few to many molecules thick, which means that it is in reality not many atoms thick. This means angstroms to nanometers perhaps, at best microns unless some capillary action keeps oil wicked in some gaps, etc.
Now a higher viscosity oil may remain in gaps if/when held by capillary action in small gaps, which could have an effect.

But a "thicker" (higher viscosity) oil will not necessarily leave a substantially thicker (depth) film at rest after gravity effected the oil drippage off the surface.

 

[Shannow]

Sorry, I read it differently.

There's definitely more drag when starting after a drained down thicker oil....not necessarily protection.

Although assembly lubes for first start are typically pretty thick...but diluted quickly by sump contents.

 

[JHZR2]

I agree. There will be more drag form a more viscous oil when it is sheared from initial movement.

My point is that a thicker (more viscous) oil isn't necessarily a molecularly deeper "thick" oil.