Low Revs to Circulate Oil at Oil Change

I always thought that you could never get enough oil pressure by using the starter to make a difference. Oil is not going to get up to the heads until the engine is running.

 

Yes, flooring the gas while you crank the engine shuts off the injectors as they say. This opens up a can of worms though as some engines baseline with the ignition on before they startup.

The starter will bring oil pressure up, not as high as the engine running, but it will circulate the oil (including into the heads).

There's no point to prime it after an oil change. More oil bleeds down overnight than during the 20min or so you're changing oil. If you were hell bent on doing so, buy a $.50 switch from radio shack and some 12g wire and jump the starter as opposed to turning on the whole ignition system.

 

Bad idea on injected motors. The CIS variety will often backfire doing that and either displace or bend the air flow flap. Some electronic systems will do the same, others have a learning mode in operation during cranking and assumes idle stop throttle position and will learn incorrect info.

None of that takes into account that now the injection system is now dumping max fuel into the motor and is not being burned.

Then we still are not addressing another fact. The motor does have lubrication, everything is still coated with oil. Thats all it needs at that point. We no longer rebuild motors for worn out lubricated parts so all the paranoia is misplaced anyway.

 

It will, it just takes a while.

 

Your first sentence is wrong, the rest of your statement is spot on.

 

Any ideas on why it's such a common misconception?

http://autorepair.about.com/library/a/1b/bl203b.htm
"The best way to deal with a flooded engine is to not any more fuel to it. Some models have a "clear flood" mode. If you hold the gas pedal to the floor while cranking, it shuts off the fuel and allows the engine to clear itself and start. A check of your owners manual will tell you if your car has this feature."

http://www.tegger.com/hondafaq/startproblems.html
"Push the accelerator pedal to the floor and hold it there while cranking. The computer recognizes your action as an attempt at clearing a flooded condition, and shuts off the injectors. You might have to crank for a minute for it to work its magic. This method is listed in your Honda Owner's Manual."

 

To be honest I do not care how other cars operate. Here we are dealing with Ferrari. All but 2 cars (288 and F40) have Bosch. Those 2 cars have an MM system that is a clone of the Bosch D-Jetronic. Bosch systems do not do that. Bosch systems and their clone systems are so ubiquitous (most of Delco, Nippondenso and Lucas among others) I suspect the information is just wrong.

Besides carb or inj at cranking speed with WOT proportionally more air is going through than gas so it does have a clearing effect in a flooded motor. Does not make it a proper action, nor does it mean that the injectors are off. With a few acceptions on older systems if an injected motor flooded something is broken anyway.

 

On my air-cooled VWs (incl. Porsche) we simply remove the HT lead from the dizzy and let it touch ground. Crank engine until oil pressure builds. Push HT lead back into dizzy and zoom zoom! Pretty gosh-diddly-darn simple & easy IMO.

 

Not sure I agree with you on the no need to prime issue. At least on Mercedes, which mostly use hydraulic chain tensioners, if you start one up (especially the older V8s) after an oil change without first priming it for at least 15 seconds, you'll hear the dreaded chain slap at startup. Obviously, for a Ferrari equipped with timing belts, there isn't a hydraulic function for the tension of the belts so priming it may not be such an issue, but with the V12s on the other hand, I'd follow the rule for priming them.

Just my $0.02

Cheers,
Aaron
'82 GTSi
'83 400iA

 

Journal bearings retain oil by capillary action. Over many months it may thicken by evaporation and turn into a light grease. There is no worry there. The top end is what suffers as oil may take 30 - 45 seconds to lubricate the cam lobes.

Both the Maranello and the Enzo allow for pressures of 120 - 150 PSI at a start up temperature of 75 F. There may be more pressure at cooler start up temperatures but this is all I can test here in Florida. These pressures are with 20 wt. oil in the Maranello and 30 wt. oil in the Enzo. The cars normally call for 40 and 60 wt. oils.

I am not sure why but the Enzo starts up and revs to 1,500 - 2,000 RPM for 30 seconds or so, then settles down at 1,000 RPM idle. These Ferraris obviously do what is needed to get the oil up there fast. I have not seen other cars with pressures this high.

If you are that concerned about your engine, this is what counts the most:
Do not go above 3,000 RPM for the first 5 minutes. Do not go above 4,000 RPM until 10 minutes and do not floor it until the oil gets above 160 F at least. This usually takes 15 - 30 minutes of driving. The coolant may heat up in as little as 3 minutes but the oil takes up to 30 minutes. If you run with thinner oils as I do then you can floor it sooner.

Oil is too thick before it reaches at least 140 F in my mind. Cavitation is the main problem. This is the production of large bearing chunks torn out from your engine. This is the reason that some cars with almost no miles have ruined engines.

aehaas

 

None of the belt drive Ferrari's have hydraulic tensioners that are dependant on motor oil. The Benz's you speak of have a check valve arrangement in the tensioner and if the pressure bleeds down during the brief period that an oil change takes it is an indication the tensioner is bad and if the chain rattles badly it is time for one of those too.

 

Not necessarily. It's normal rule of thumb that on the M116/M117 V8s, you R&R the chain, tensioner and upper guide rails every 100K miles as precaution. However, I've seen this phenomenon of chain slap with cars that are either low mileage originals or have recently had the chain/tensioner, etc..R&R'd. Just the nature of the beast with MB/Febi-Bilstein/Laso chain tensioner design.

And yes, no hydraulic tensioners on belt driven F-cars, see my earlier post. But with the V12s, I would prime them...

Cheers,
Aaron
'82 GTSi
'83 400iA

 

It's actually true of the 12's too. They have mechanical tensioners except for the Enzo but it's hyd tensioner is designed to not back off..


The Benz tensioners must not be the same quality of the old ones I used to deal with in another life in the early days of 100/116/117 motors.

 

Probably so in the quality department, although on an M100, I'd sure want the best tensioner in there!! Don't want to blow up the mighty 6.3 or 6.9!!

The most trouble free chain and tensioner setup that MB ever used was/is on the M103 inline six. I've seen those engines with 300K+ on them on the original chain!

Cheers,
Aaron
'82 GTSi
'83 400iA

 

Interesting but what is the correct way to prime the engine of a 308 carb after oil change???

 

to help the large cats get up to temperature and burn off excess start up fuel sooner..

 

start as normal but keep load (rpm/throttle) as low as possible until pressure stabilises.

 

Seems to me that if you drive your car before you change the oil, you both warm it and circulate it through the engine. Both a good idea. Right after you change it, drive the car again to recheck the level. This is not rocket science; I can't imagine why startup afterwards is such a big deal.

Ken

 

It's not.

 

My God you guys worry about the most meanial stuff sometimes. Just start the freakin car, it wont break anything. I'm scraping to find the money to get my heads rebuilt. If I aint afraid to drain my oil and start the car after, no one else needs to be afraid. Trust me, the cars are overbuilt in the rotating areas, something else will have you pulling the motor out to repair long before you have a lubrication wear problem.

 

Artvonne,Rifledriver - Right On!!!

There's well over a quart of oil that's retained in the 3x8 engine AFTER you've completely drained the sump & removed the fillter.

If you don't believe me, just drain the sump & let the engine sit for a month & you'll be able to drain about a quart out of the sump. Let it sit another month & you'll drain at least another pint(been there several times).

Modern oils, especially the synthetics & blends have extremely high surface tension & film strength compared to the best oils of the '60s & '70s. As has been said earlier, you'll wear out a lot of other things before you see any sign of start-up wear on these engines.

BTW bergxu,
Rifledriver & ferrarifixer are both Ferrari factory trained technicians & if your profile is correct, I believe they were already servicing them about the time you were born. ;^)

 

Hey we're all on the same side here. I always changed oil and started the motor just like Ferrarifixer said but this thread suggested that there may be a safer way to prime the engine. I rather be safe than harm my toy's engine. Inquiring minds want to know. Happy Holiday.

 

Absloutely. No harm done.

Modern lubricants are great and a few seconds without oil pressure is no problem when there is no load. Happens all the time and our motors live a long happy life in spite of it.


The important thing to remember is , and I am sure Mr Haas has said it before, is that oil pressure does not protect your motor, oil does. The pressure just insures a constant and fresh supply.

 

Any ideas/comments about this company..they recommend NEVER changing their oil..well almost never!


http://www.synlube.com/