Oil pressure on 454

[jc55]

Hi All
Just a little concerned with the oil pressure reading when the engine is hot. At start up, the oil pressure gauge shows well over 40 psi, once the engine is up to operating temp. the oil pressure drops to slightly less than 20psi. Under load, as in going up a hill, the oil pressure will come up to about 30psi. The oil pressure gauge is the original in dash unit. The 40 psi line on the gauge is the middle of the gauge and there are no other numbers on the gauge, only divisions. Accuracy is probably not all that great. The engine does not use any oil and the oil on the dipstick is as clean as new. A friend who has very good hearing thought he could hear a slight bottom end knock when the engine was under load. I personally can not hear any knock, but then again my hearing is not the best. Is 20psi too low at operating temp? would replacing the oil pump be the answer. The mileage is approx 34000 miles. Maybe I'm just being paranoid,but we are planning a 2000 mile tour within the next week.
Jim

 

[Raypc800]

Just out of curiosity what type of oil do you use?? Also watch your oil pressure gauge when you shut the engine off does it go to zero or while driving does the needle bounce around a lot?

 

[DonTom]

Hi All
Just a little concerned with the oil pressure reading when the engine is hot. At start up, the oil pressure gauge shows well over 40 psi, once the engine is up to operating temp. the oil pressure drops to slightly less than 20psi.

Sounds normal enough to me. Oil pressure is supposed to drop as the engine gets warmer.  But if it went much lower, I would be more concerned. Then you would use a test oil pressure gauge (much more accurate) direct on the engine and then find what the spec is for the engine when warm.

Most idiot lights (IIRC) come on at less than 10 psi of oil pressure.

The reason most new cars now have oil pressure meters that show dead center under all normal conditions is because too many people ask the question you just asked - - -even on new cars! Most new cars these days use a digital sensor to a meter that only looks analog. Many people still like meters better than idiot lights, but the new meters are the same as an idiot light but that's all that's needed, IMO.

-Don-​

 

[jc55]

Thanks guys.
I'm not sure what oil is in it, as it was serviced at the dealer just before we bought it. We have put about 1000 miles on it since then. Its going back to the dealer for some other minor issues tomorrow, so I'll have them check it out, and let you know what they say.
Thanks again
Jim

 

[Mark R.]

Sounds OK but a bit on low side to me with that mileage, the only way to know what is going on is to put a independent oil pressure gauge on engine, this is extremely simple so even a slightly handy guy can do it (yes I am a sexist). The dash gauge is most likely electric, sending units for these are a known week spot and are easily replaced,  if you want to know what the oil pressure is for sure just unscrew the sender and install a mechanical gauge. The mechanical gauge (typically) consist of a fitting to screw into the engine block, a long very small poly hose and the gauge its self, they can be had at any auto parts store, buy the cheapest you can find, this will be used for testing one time, then sit is your box of junk that your children will inherit!

Test procedure, find electric oil sender on engine ,the oil pressure switch and oil sender for older 454's are mounted on the lower left (driver side) front of the engine block just above the oil pan, unplug sensor and start engine for just a second or two, if gauge does not read any pressure, you have the correct sender to remove. Simply unscrew sender and screw in new fitting that comes with new mechanical gauge, attach hose at this fitting and  to gauge as per instructions, do not add thread sealer at this time, this is a test not a installation, a tiny drip will not affect your pressure reading, and you do not want to take the chance of introducing sealant into oil for no reason. Start engine and you should have you answer in a second or two!

Replacing the oil pump on a 34K motor is probably not going to fix any thing, pumps go bad but its a long shot, high volume and high pressure pumps are available but you are not there yet. :

If this was my rig I would not do this test unless oil pressure went lower ten what you are getting now..

 

[Bob.n.Sue]

At 34,000 miles, as long as the oil is clean and not below the add line on the dipstick, my guess is that the oil is not quite heavy enough for the driving conditions.  This is a typical cause of oil pressure that starts out OK and then falls off as the engine warms up.  Even though a drop from 40 to 20 is not excessive, specially for a big block Chevy, it will probably improve if you change the oil to a heavier weight at your next oil change.  I wouldn't go crazy with the heavy viscosity oil, however, specially if you're going to operate in colder winter weather.  Usually your manual will recommend which oil to use under varying weather conditions.

 

[jc55]

Thanx to all for the input, I spoke with a mechanic at the dealership today.. he was not concerned with the readings on the gauge.. suggested that they were normal and not to be concerned. He did suggest an oil additive or a heavier oil. It presently is 10w30 so perhaps 15w40 would do it, He did go on to say that  34k on a MH engine is like 80-90k on a regular vehicle. the MH engine is basically operating under full load most of the time, due to the size and weight etc. Makes sense to me.
Jim

 

[Mark R.]

I spoke with a mechanic at the dealership today.. he was not concerned with the readings on the gauge.. suggested that they were normal

If they were normal why is he suggesting oil additives and a change of oil viscosity?

If I went to the doctor and the doctor said my blood pressure was normal and then said so lets put you on blood pressure medication for it, and you will need to change your diet, it would not make sense to me.

You may want to check your owners manual's for the MH and any car you own, I would only add the oil additives they suggest, typically  NONE, but what do all those professional automotive engineers know! Same goes for the correct oil to use, 10-30 is heavy oil by today's standard, most vehicles call for 5-30, my Mercedes calls for 0-5, most likely the only thing that will change going to a heavier oil is you gas mileage, it will go down!

 

[Bob.n.Sue]

I agree with your mechanic.  10w 30 is OK for cars and light trucks, but it's a little light for the kind of use your engine gets, particularly in summer months.  I wouldn't be surprised to find that your manufacturer recommends 15w 40. Mine does.

 

[boatbuilder]

Shell's Rotella 15W-40 has been the heavy duty oil of choice for many years.  Unless you are in real cold temps that is what I would put in a big block.  Mobil's Delvac is also a good choice.

 

[jc55]

Thanx again guys... just to clarify the mechanics suggestion for a heavier oil or additive... that was just a suggestion of what I could do if I wanted a little more oil pressure, not necessarily what he would do.
Jim

 

[DonTom]

I agree with your mechanic.  10w 30 is OK for cars and light trucks, but it's a little light for the kind of use your engine gets, particularly in summer months.  I wouldn't be surprised to find that your manufacturer recommends 15w 40. Mine does.

What year engine?

My year 2000 RV (also 7.4L or 454 CI) uses 5W30 all year as recommended, has a little more than 107,000 miles on the engine and I have normal oil pressure and it eats almost no oil at all in a couple of thousand miles.

-Don-

 

[dogwalker]

That oild pressure sounds normal to me. I have owned allot of 454's, my last one was a 97, and also made a slight lower end knock sound (mostly could hear it at idle) I ran straight 40wt from then on. Always ran quiet after running 40wt.

 

[DonTom]

That oild pressure sounds normal to me. I have owned allot of 454's, my last one was a 97, and also made a slight lower end knock sound (mostly could hear it at idle) I ran straight 40wt from then on. Always ran quiet after running 40wt.

Do you know which year they redesigned the 454? What grade oil was yours designed for (what did the owner's manual say?). When did they go to MPFI? When I purchased mine, I was expecting it to be throttle body injection and was pleasantly surprised to discover it was MPFI. I was also surprised it was designed for 5W30.

-Don-​

 

[dogwalker]

Mine was designed for 5-30wt as well, but once the milage gets racked up, and depending on climate that all changes. Mine was vortec multiport injected as well. I thought 96 was the first year multiport injected vortecs. But you never know with RV's.

 

[Bob.n.Sue]

I'm pretty sure that '96 was the first year for the Vortec engines. 

 

[DonTom]

I was never clear on what "Vortec" meant. But are all the Vortec MPFI? If so, then I should not have been surprised when I took off the engine cover for the first time. Under the hood, there's no way to miss the word "Vortec". I don't know what the word means or stands for (if anything) but it seems GM is proud of that word.

-Don- SSF, CA​

 

[DonTom]

Mine was designed for 5-30wt as well, but once the milage gets racked up, and depending on climate that all changes.

Going from 5W30 to straight 40W sounds like too big of a jump, IMO, especially when engine is not fully warmed up. They say most wear is when the engine is cold and then started.

-Don- SSF, CA​

 

[Bob.n.Sue]

Take a look here, Don.  Even though this site reports that the Vortec engine was first introduced in '86, I'm pretty sure it didn't arrive in big blocks and MH chassis until around 1996, or so.  I was working at an RV dealership that year, and remember when they first started appearing.  They were all direct port FI engines at that point, but I'm not sure if any where made with throttle body FI or carbs before that.  GM had direct port injection in production in '86 (Corvettes, etc.)

http://www.vortecengine.com/

 

[DonTom]

Take a look here, Don.http://www.vortecengine.com/

Thanks for the info. I see now that "Vortec" is from the word "vortex".

-Don- SSF, CA​