The Dodge Challenger Message Board

Hey all, need your help I quess. This weekend I went out with the car to take a ride but then there was a guy in a hondy pushing me. Only for a sec, after the downshift he was long gone. But while reving the engine (not extremely) my oil pressure dropped down. From normally +/- 20psi above rpm x 1000 to about 5psi above rpm x 1000. Not good! so I stopped to check out a couple of things. Nothing strange found. After a while I ran the engine again and it was little bit higher. So I went home right away having my eye on the gauges and put it in the garage.

This is what I know so far:
- oil level OK
- oil quality OK, even changed it
- oil pressure hose is clean, no dirts
- oil pressure gauge OK, tested also with new one.
- oil filter OK

My first guess right now is a bad oil pump, but anybody else have any ideas I should check out?

(The oil pump bolts are tight otherwise I wouldn't have any pressure at all and the end plugs at the rocker gears are OK too as otherwise I wouldn't have pressure at all also.)

Hans, wouldn't suprise me if your rotors in the pump are scored and worn. Happened to me. My oil pump gauge was acting like a rev counter! On inspection I found the rotating pump internals were totally knackered. Feeler gauges? You could get sheet steel in the gaps!
It could also be the pressure relief valve in the pump sticking open. Swap out the pump for a new one anyway (cheap insurance) and go from there.
Good luck!

Are you saying the oil pressure has just started doing this or has it done this all the time?

I am not sure what the oil pressure should be. As long as it does not drop down as the rpm goes up I don't see the problem. Oil volume is more important than pressure. In fact high pressure can be an indication of a restriction somewhere.

If the small block oil pump is the same as the big block then there is a spring that regulates the pressure. A stiffer spring increases the pressure.

Also your oil may be too thin. Try using a thicker oil. Something around 20w-40w.

I use and always used 15w50 Valvoline HP without any problems with a good amount of pressure. The workshop says that a smallblock could idle with 8psi@1000rpm and @2000rpm it should be between 20-80psi. But although I'm just at the safe side the thing that worries me more is the difference between 'then and now'. But I will give it a shot this week to find out the truth.

If you are saying (I am still not clear) that it was better before and has got lower recently (with the same oil type) then I would lean towards Phils thinking and I would check the oil pump is not worn.

Jep, it was way better before Dave. So that's why I will open the oil pan this week to check out that stupid pump. My best guess was and still is a bad pump as this this is the about the only part I didn't replace last year...

So thx Phil & Dave

I remember many years ago I found that the oil pump on my 440 was not up to scratch. There is a set clearence between the rotor and the body/lid of the pump housing. It was a few thou out due to the sides of the rotor (or the housing?) wearing. All I did was take the housing and placed it on an engineers plate (flat surface) with a sheet of wet'n'dry. I just rubbed the housing on the paper to take off a few thou. This brought the pump back into spec. When I rebuilt the engine I replaced the pump but I still have the old one as it was still working fine when I replaced it.

One of the things I like about the big blocks over the LA engine is the external oil pump.

OK, problem solved. Yesterday we've removed the oil pan to check it all out. Found out the oil pump was worn to much. On a cold engine engine it was OK but with warm, thinner oil it didn't gave me enough pressure. Only problem is the time the oil pressure lost happened when driving 5000rpm.... So we've checked out the bearings also to be sure. Rods were still as good as new, but the main bearings were totally ruined. **** I was thinking. I still had a set of useable used ones laying around so they have to do work for the next month. Also installed a new oil pump off course. Started at 11:30am and it ran again 5:00pm with 80psi@3000rpm warmed up. Not to bad for only a noon of work.

Dave, what do you think of Milodon's hi-volume/ hi-pressure oil pump?

I don't have an opinion Joel. I have never seen one.

Nice work Hans, too bad of your new bearings. I would like to see your car one day. Maybe I'll drop by one day ok.

Hey robbert, long time no see on the board! To see the car you better go to the mopar meet next month or Drachten airstrip 14/15 June as my car isn't parked at my home but in a garage at tthe house where I used to live (near Rotterdam) before I moved over to where I'm now. So you won't see it when you come to my house. Still understand it?

It is sad but I have very similar problem – yesterday my 440 lost oil pressure completely. Red light on my non-rally dash pad is lighting like hell. When I pull out the oil sensor – sensor was dry like a desert, without one gram of oil. Engine was fully rebuild (except oil pump)– I finished the overhaul one month ago – new bearings, cam,......
Of course oil level was OK.
First I want to pull out the oil pump – how to do this without engine removal? How to checked if the pomp is OK or not?
Do you have any helpful tips?

The oil pump is driven by a shaft that extends down from the distrubutor drive. The pump end has a hex drive that can sometimes get rounded off and sometimes it can snap. That will stop all oil pressure dead.

Pull the distributor out and reach in and pull the drive shaft out to inspect it.

The workshop manual has specifications to check on the pump. If you need them mail me but if i were you I would get a new high volume pump and drive shaft.

You might have to un-bolt the engine mount(s) to lift the engine a little to get the pump off.

I have heard that high volume oil pumps can run out of oil unless you have a high volume oil pan. That is to say it will pump oil out of the pan faster than it can return to it while at high rpm

A bigger pan would just delay that process if it were true. And it is very far from true.

The only restriction in the 440 oiling system is the oil pick-up tube and inlet passage into the pump. NOT the return path.

The stock oil pick-up passage in the block is commomly drilled out to a half inch pipe thread and a hemi or Milodon pick-up used. But a high volume pump is a good idea even on a stock oiling system.

Yes Glen Dave's right, the first stage on up grading the oiling system is to drill out the stock 3/8th diameter pickup hole to take a 1/2" hemi pick-up. As for big oil pans , the more oil the better within reason, but you must make sure you have a correctly designed pan for you application, drag cars have different requiremnets to street driven ones.
The next stage after the uprated hemi pick-up is to go to an external oiling system, this uses an adaptor block that bolts between your block and oil pump and takes oil from a big pick-up inside the pan and routes it outside via a large diameter braided line. You can use a good quality stock style pump here, a 'Mopar' high volume , high pressure pump works good on engines up to 7500+ RPM. I had one on an engine making well over 750HP, that ran for many runs down the track and never agve a problem.
After this you would go to a swinging pick-up design which actually moves back in the pan to keep the pick-up in the oil as the car accellerates hard, generally at this point you would switch to a dual line setup on the inlet side of the pump and this is where the big after market oil pumps are used. The Miloden race pump is OK, but an old design, it's actually made for a Ford! And they suffer from a lack of self priming, which is a big problem if you need to get the car started in a hurry.
There are several companies now producing billet pumps, I use the RBRE on and that works fine on my stroker Hemi, Indy make them, a company in California called Titan also makes them.
You could also run a crank driven oil pump either single or multi stage , but this is all really race only.
Although my smallblock uses a single stage Moroso pump fed from a fixed pick-up in a modifed stock style pan. That makes 80PSI all the time and never drops below 55 unless you switch the engine off.
The biggest problem with keeping oil in the motor is generally the stock oil pan, unfortunately with the K memeber in the way there is only so much that you can do. A graphic demonstration of this is seen on the Superstock hemi A bodies that had the draglink going THROUGH the oil pan, now to say these things had very little steering lock is an understatement!
I had a custom ally on for my dart and it had to go back to the manufacturer to be modified so I could turn the steering wheel more than half a turn

Hi
Yesterday I removed distributor and oil pump and everything look good.
Before parts removal I changed oil and filter, I started the engine for few second and there were still no oil pressure, so I stopped the engine. When yesterday I pull out the oil filter, filter was dry – no oil inside so maybe the pick-up assembly is clogged? Today I will remove the oil pan......

The filter was dry?? I can't see the the pick-up being completely blocked. To my mind it would have to be not in the oil at all. You rebuilt the engine right? The pick-up tube was screwed into the block so that it would not move around? It sits about a quarter inch from the oil pan bottom?

I would have put money on the oil pump not being driven at all causing this. That would mean a snapped or stripped pump drive shaft.

Pop the dis out and pull the drive out, first thing I'd check?

Hi,
Yesterday I put all parts together and drove a pump by driller and oil run like hell. I can only suspect what caused the problem – or pick-up was cross-threaded or pump sucked the air.
Today I will do a test ride....

Jarek

a stock sb can't take 5000 rpms on a regular basis