4.6 DOHC Oil Change Interval

[03cvpi]

I believe the 4.6 was back spec'd to 1997-98 for 5w20. I have a chart from ford I'll have to dig out. I tried running 5w20 in a 94 and it did not like it at all. Noisy and massive oil consumption. I have been using amsoil 0-20 in an 03 4.6 SOHC and I'll have a used oil analysis on it in August, that's the 1 year mark and it should have 10k on it by then. The motorcraft filter will go 10k, I have done it on a 4.6 and a 2.0 escort. How clean the pcv valve stays is in relation to how much oil is burned by the engine. I just replaced one on a 4.6 with 106k on the unit and it looks as good as new,but that car used less than a pint of oil every 7500 miles. One of my older 4.6 motors used a quart every 6k miles and the pcv looked like junk at 55k miles.
The catch can is good for motors that use oil to keep the cat from getting plugged, but if the motor does not burn oil or very minimal amounts, you don't need to bother with a catch can and the available room under the hood of a marauder will make it a little hard to run the plumbing, On the SOHC 4.6 the factory recommended replacement interval for the pcv is 100k, but I check them every oil change and replace as necessary. Also there is no good aftermarket pcv for the 2002 and up that I have found yet. If I remember right Ford get 17.00 for the pcv.

 

[Ben99GT]

4.6s, when driven hard (i.e., high rpm), are known for sucking oil through the PCV into the intake manifold.

4.6s force a ton of oil into the heads at high rpm, the cams and followers then whip it up pretty nice and finally some oil makes it past the PCV baffles and into the PCV valve itself. The engine doesn't need to burn oil or experience any significant blow-by for this to occur. It just happens when you have a heavy right foot. It's more of an an issue with the 4Vs because they tend to turn higher RPM and tend to be driven harder.

The solution to this problem is either a catch can, oil separator, PCV pre-filter or a crankcase vacuum pump.

 

[c3po]

Originally Posted By: Ben99GT
4.6s, when driven hard (i.e., high rpm), are known for sucking oil through the PCV into the intake manifold.

4.6s force a ton of oil into the heads at high rpm, the cams and followers then whip it up pretty nice and finally some oil makes it past the PCV baffles and into the PCV valve itself. The engine doesn't need to burn oil or experience any significant blow-by for this to occur. It just happens when you have a heavy right foot. It's more of an an issue with the 4Vs because they tend to turn higher RPM and tend to be driven harder.

The solution to this problem is either a catch can, oil separator, PCV pre-filter or a crankcase vacuum pump.





Ben99GT, I just ordered a JLT PCV Valve Pre Filter, it mounts on the drivers side breather tube which goes to the cold air induction hose and right into the throttle body.

On light acceleration there is some oil mist that can travel into the throttle body, even worse on hard acceleration. Marauder owner's that have Catch Cans have reported that when they installed this JLT PCV Valve Pre Filter that they hardly had anything in there Catch Can. It seems under hard acceleration the PCV Valve either closes off or cannot handle the pressure so it goes out the breather tube.

My small block chevy was designed right in that there is a foam type filter in the breather tube. I do not know if it is made out of cotton or some other material.

I do not want to deal with cleaning out the throttle body and my thinking is that the oil mist over time could cause some problems.

 

[03cvpi]

At high throttle angles (ie: at or near wot) the pcv valve is normally closed due to lack of sufficient vacuum to open the valve. If the valve is open at or near wot, the valve is defective or the engine has excessive blow-by to force the valve open. There has to be enough vacuum at the throttle body to defeat the spring in the pcv to open it. I have used catch cans in the past, but only on vehicles that use higher amounts of oil between changes. The one I remember the most is a 94 cv I bought new and drove to 265k before selling it. I was too lazy to change the valve seals and it had a blow-by problem from the exhaust valves. After about 140k, it used a quart every 3500-4000 miles and from about 1998 until I sold it, every year I would have to pull the egr valve and clean off the backed on oil residue and reset the computer. I fixed that problem with a catch can and would drain 4-6 oz out of the can every week. The pcv on this car was so crudded up after 35k miles I would just replace it.On the 03 and 04 cvpi I currently drive neither use much oil at all and I beat the heck out of the 03 every day and both the pcv where replaced after 100k and neither really looked bad. I also stick with the kiss principle when making mods to the daily driver, before I would add a catch can, I would build a inline drip filter. With the new style PCV on the modular engine, you simply cut the old one in half, discard the top, remove the plug and spring, fill lightly with #6 stainless steel wool and either glue or heat shrink it to the bottom of a new pcv and stick it back in the manifold. I have done this on several 4.6 and 5.4 that use about a quart of oil per change interval and it works in lieu of a catch can. But like they say, there are many ways to skin a cat.

 

[Gary Allan]

The PCV valve is a regulated manifold leak. It is, in effect, its own WOT port. That is, within the restriction of the length and diameter of the hose, it should parallel CFM sucked through the horn. The valve itself should have no spring to prevent it from opening. It should be there to compress in the event of a back fire in the intake and prevent ignited gases from reaching the crankcase.

 

[Fordiesel69]

Getting back to the original posters questions, being the 4V engine is a twin cam design, the potential for more metal in the oil (chrome & aluminum), I would error on the safe side of using a good filter, WIX, Motorcraft, or amsoil for 5k changes until you get a feel for the wear levels. The oil can be the best ever and can withstand 25k, but if the oil is getting loaded with metal, and other stuff, you will just be grinding it into your bearings. Oil and a filter is what $35-40? Cheap insurance in my opinion. A marauder has the capabilty of lasting 20+ years. It's best to keep it in tip top shape.

Oil consumpion issues seem to plague many OHC and DOHC designs, both 4.6L's included. If consuption is more than 0.5qts (synthetic) in 3k miles then look into some aftermarket accessories to correct the problem. All my P71 based crown vics I have ever owned used 0.25 to 0.5 qts in 3k miles depending on what oil is used. 4V engines I hear can use a little more. The good new is despite the oil consumption, NYC taxi cabs still reach 300k and possibly more.

 

[UNC038]

I run Motorcraft 5w20 in my DOHC 4.6 changed out at about 5k. I do have a used oil analysis posted.

 

[c3po]

Fordiesel69, makes some very good points here.

I would think that a good quality oil filter like the Amsoil EaO and a Filtermag should help, as well as a Maintenance Dose of auto-rx.

When I have been doing 5000 mile oil changes there has been no oil loss, but I drive this car very conservatively.

Once I am done with the Clean and Rinse Phase of auto-rx it might be a good idea for me to take a sample of oil out at 5000 miles and get an oil analysis done. I can then get the numbers back and see if it is safe to run the oil out to 10,000 miles.

Without a used oil analysis it is just a guessing game, at least with a used oil analysis I can post it on here and get recommendations.

 

[Ben99GT]

Originally Posted By: 03cvpi
At high throttle angles (ie: at or near wot) the pcv valve is normally closed due to lack of sufficient vacuum to open the valve. If the valve is open at or near wot, the valve is defective or the engine has excessive blow-by to force the valve open. There has to be enough vacuum at the throttle body to defeat the spring in the pcv to open it. I have used catch cans in the past, but only on vehicles that use higher amounts of oil between changes. The one I remember the most is a 94 cv I bought new and drove to 265k before selling it. I was too lazy to change the valve seals and it had a blow-by problem from the exhaust valves. After about 140k, it used a quart every 3500-4000 miles and from about 1998 until I sold it, every year I would have to pull the egr valve and clean off the backed on oil residue and reset the computer. I fixed that problem with a catch can and would drain 4-6 oz out of the can every week. The pcv on this car was so crudded up after 35k miles I would just replace it.On the 03 and 04 cvpi I currently drive neither use much oil at all and I beat the heck out of the 03 every day and both the pcv where replaced after 100k and neither really looked bad. I also stick with the kiss principle when making mods to the daily driver, before I would add a catch can, I would build a inline drip filter. With the new style PCV on the modular engine, you simply cut the old one in half, discard the top, remove the plug and spring, fill lightly with #6 stainless steel wool and either glue or heat shrink it to the bottom of a new pcv and stick it back in the manifold. I have done this on several 4.6 and 5.4 that use about a quart of oil per change interval and it works in lieu of a catch can. But like they say, there are many ways to skin a cat.


Get a crankcase vacuum pump, and you'll never see oil in your manifold again. Oil being sucked through the PCV is not an indication of excessive blow-by on these engines. Brand new ones will do it with the factory PCV setup when driven hard.

 

[Ben99GT]

Originally Posted By: c3po
Ben99GT, I just ordered a JLT PCV Valve Pre Filter, it mounts on the drivers side breather tube which goes to the cold air induction hose and right into the throttle body.


I have one of those as well...

 

[c3po]

Originally Posted By: Ben99GT
Originally Posted By: c3po
Ben99GT, I just ordered a JLT PCV Valve Pre Filter, it mounts on the drivers side breather tube which goes to the cold air induction hose and right into the throttle body.


I have one of those as well...

How do you like yours and how often do you clean it. Mine should be arriving tommorow or Thursday.

 

[Ben99GT]

I clean it every few months, it really does catch quite a bit of oil.

 

[c3po]

Originally Posted By: Ben99GT
I clean it every few months, it really does catch quite a bit of oil.


It looks like yours is mounted on the PCV side and not the breather side.

JLT told me that for a Marauder you could only mount it on the breather side and not on the PCV Valve side.

Does that seem strange.

 

[Ben99GT]

Yea, mine is mounted on the PCV side.

Are there clearance issues with the Marauder or something?

 

[c3po]

Originally Posted By: Ben99GT
Yea, mine is mounted on the PCV side.

Are there clearance issues with the Marauder or something?


I will have to call JLT, but maybe there is. The guy from JLT told me that more oil mist would be coming out the breather side.

I guess you do not have anything on your breather, does your breather have a tube that goes to your cold air intake hose.

 

[Ben99GT]

Well, I can tell you I get zero oil in my TB or inlet tract, the oil definitely comes through the PCV side.

I've seen JLT recommend a filter for both sides though.

 

[c3po]

I will also ask this question later today on the mercurymarauder.net board

I went out and looked at my car and I think I maybe able to use this on the PCV side, but I will get the info 1st too make sure.

 

[Steve S]

cool car, With your driving and filters 10,000 miles with PP and Amsoils recommendations [25,000 miles].The Amsoil filter is the filter to use for the longest oil changes that is what it is made for. Why would you need to change the pcv valve at your chosen intervals ? syn oil should keep the deposits if any minimal if none. An italian tuneup does good. Don't forget the trans and differential maybe the powersteering and brake fluid.

 

[c3po]

Originally Posted By: Steve S
cool car, With your driving and filters 10,000 miles with PP and Amsoils recommendations [25,000 miles].The Amsoil filter is the filter to use for the longest oil changes that is what it is made for. Why would you need to change the pcv valve at your chosen intervals ? syn oil should keep the deposits if any minimal if none. An italian tuneup does good. Don't forget the trans and differential maybe the powersteering and brake fluid.


I changed the Differential Fluid at 18,000 miles.

I plan on changing the Transmission Fluid at 30,000 miles, at that time I will also be changing the powersteering fluid.

My owner's manual says to change the coolant at 100,000 miles, but this car is now 5 years old and I plan on changing it sooner.

I might also change the Brake Fluid at 30,000 miles too.

 

[Ben99GT]

That's one well maintained Marauder!

Let me know when you want to sell it...