oil pressure ups and downs

[70Barracuda]

Somethings not right. My OP goes right up to 60 at start up. Goes up 4 more as I give it gas. Then as I drive in first gear it goes down to 30 or so then right back up to 60. Hit second, down to 30, quick back to 60.
As it warms up it does this less and less. Today I put on a new Auto Meter gauge. Starts up to 60-65, start driving down to 20\30. Shut off, start up back to 60. WTF!!
I'm thinking the oil pump is going bad. Melling HV What do you think?

Thanks

[cudabob496]

What weight and type of oil. The higher pressure at startup sounds normal, and after the oil warms up it will go down 20 or so psi. I've got a yellow 72 Cuda. Used to live in Aloha.

[70Barracuda]

Think it has 10-40. Its a 340. When were you in Aloha? I went there, 79 grad.

[dwc43]

What size line are you running from the engine to the gauge. If it's too large you will see lots of fluctuations. There was an article in a Mopar mag not long ago where they put a #4 stainless an line on there gauge and had the same problem.

[bjoehandley]

Somehitng else to look at is what kind of filter are you using, Dad found that made a huge difference in his high mileage (currently 281k) 4.0l Cherokee. He had a big drop with Fram, but hasn't had issues with Motorcraft, NAPA/Wix, and Puroilator. I've only used NAPA/Wix and Puroilator Pure 1 in my 4.0l '98 Cherokee

[70Barracuda]

Thanks DWC it is an AN braided line, what size, not sure.. The fitting takes a 9/16 wrench. How to tell if that is the problem? I supose I could put the plastic line on for a test..

The oil filter is a WIX racing.

Thanks

[pcrmike]

Also the viscosity of the oil has to be considered. The oil is thicker when cold, and the pump will push it thru, but it will not flow as easily until warmed up. If the engine is a tight-clearance motor, you would not notice this, but on one that has a bit of wear in teh bottom end, especially mains, it will be more noticeable. Let it warm up a little before romping too hard on it, or go to a thinner oil. :-)PCRMike

[70Barracuda]

The engine is only 2 years old and I hardly drive it. Especially since I fried the 5oo hp Hays clutch last July. I just drive it around now for fun. That POS clutch wont hold much now.

[pcrmike]

If it hardly has any miles on it, then you need to be with a thinner oil. Just my .02, but all the motors I build, I recommend no heavier than 10W30 in a good oil like a Royal Purple for the first 20-30K, (conventional for the first 1000) before stepping up to the 10W40. As soon as you swap, you will see a difference. It becomes a thing of volume, not pressure. Give it a shot, and you will see. :-)PCRMike

[cudabob496]

On my 496, after breaking in the rings for 1500 miles, I switched to 10-30 synthetic. The beast likes it!

[dwc43]

Originally Posted by 70Barracuda

Thanks DWC it is an AN braided line, what size, not sure.. The fitting takes a 9/16 wrench. How to tell if that is the problem? I supose I could put the plastic line on for a test..

The oil filter is a WIX racing.

Thanks

Welcome, anytime. I'll see if I can find the mag I read that in so you can look it up too. I bought 4 at one time. 2 Mopar mags a Muscle car mag and I think a hot rod cause it had some Mopar stuff in it.
The filter should not effect this problem. Not sure what size braided hose you have either. You could test the plastic line, but a better idea would be to get the copper line. Most parts stores sell them too. I think you'll find this will cure the problem.

[wilks3]

Did you use teflon tape on any of the fittings going to your gauge? If so there might be a piece of it stuck in the little hole at the gauge port. Happened to me once, oil psi would not go above 35 psi or below 5psi when shut off.
You should rethink the racing filter for street use. Wix says racing only because of micron rating. Put a NAPA Gold (WIX) on it, 1085(1/2 qt) ,1068(3/4 qt) or 1515(1 qt) your engine will thank you. The racing filter could also be cause of your oil pressure gauge problems.

[70Barracuda]

No teflon tape. The OP stayed the same with the NAPA gold as the WIX racing.
Thanks

[pcrmike]

LOL! The Napa Gold IS the premium Wix racing filter! That is who supplies them for NAPA. :-)PCRMike

[crisser]

I had one do this to me also. Sounds like the pump relief is opening. Might want to check the pump spring or for trash in the pump or the ball seat.

[wilks3]

Wix makes filters for NAPA, thats true. The NAPA # is 1515, while the Wix # is 51515. The racing # would be 1515R. There is a difference between the racing and the premium NAPA filters, they aren't the samething. Ask for a NAPA filter book, it explains the differences.

[dwc43]

Originally Posted by 70Barracuda

Thanks DWC it is an AN braided line, what size, not sure.. The fitting takes a 9/16 wrench. How to tell if that is the problem? I supose I could put the plastic line on for a test..

Thanks

Welcome anytime. And the article about the gauge line was in Car Craft Aug. 2007 pg. 79.

It reads like this.

"Want to freak yourself out? Install a -4 braided-steel line bewteen your engine and the mechanical oil pressure gague and watch the needle go crazy. A larger oil line reduces the damping effect on the gauge and you see more of the pulsation that occurs with an oil pump. Nothing has changed except that the larger line allows you to see more of the pulsations that have always existed:you just never saw them before using the larger line."


Hot Rod Aug 2007 has a list for AN to Tube sizes that someone should copy and sticky for future use here.


1/4 = -4
5/16 = -5 Note: -5 is uncommon use fittings to upsize to a -6
1/2 = -6
3/8 = -8
5/8 = -10
3/4 = -12



What's the plastic or copper line size for an oil pressure gauge? 1/8"?

[oldguyalso]

Yep. 1/8 it is. I think you have a typo in the chart. -6 is 3/8 and -8 is 1/2. Of course I could be wrong! LOL

[pcrmike]

Thanks for the clarification, wilks. Good info. :-)PCRMike

[dwc43]

Originally Posted by oldguyalso

Yep. 1/8 it is. I think you have a typo in the chart. -6 is 3/8 and -8 is 1/2. Of course I could be wrong! LOL

Not my typo, but I think you are right. See where I made that side note about -5? I just put that part in my words to save room. I'll type it out for you. Note:-5 is uncommon, but trans cooler fittings are often 5/16, so you can use adapters in the transmission and the radiator or cooler to upsize to 3/8 or -6.

Some where along the way they messed up there list in the mag. Do you have a correct list?? IF so please post it or tell me what i need to change on mine. Now I'm confused ... lol!!

[pishta]

Originally Posted by dwc43

Not my typo, but I think you are right. See where I made that side note about -5? I just put that part in my words to save room. I'll type it out for you. Note:-5 is uncommon, but trans cooler fittings are often 5/16, so you can use adapters in the transmission and the radiator or cooler to upsize to 3/8 or -6.

Some where along the way they messed up there list in the mag. Do you have a correct list?? IF so please post it or tell me what i need to change on mine. Now I'm confused ... lol!!

AN uses 16ths as its reference. like a #8 is an 8/16 or 1/2 inch. I believe this is correct. Do you guys ever bleed the plastic capillary oil pressure line? I always get a bubble in mine right at the guage no matter how often I bleed it. Sure wakes up the guage when there is no air in it!

[dwc43]

Originally Posted by pishta

Do you guys ever bleed the plastic capillary oil pressure line? I always get a bubble in mine right at the guage no matter how often I bleed it. Sure wakes up the guage when there is no air in it!

Yes, on every car every built with a gauge.

[djswwg]

a bit off topic; when you do change your clutch, use a Centerforce unit-light years better............djs

[65TerrorCuda]

Bleed the gauge? I've never heard of this. How do you do it without spraying oil all over your car's interior, and what effect does it have on the gauge?

[cudabob496]

I thought a racing oil filter meant it could take a higher pressure before bursting?

[dwc43]

YEs, racing oil filters are designed with thicker cans to prevent burts or deformations with high oil pressures some are above 100 psi.

[pishta]

Originally Posted by 65TerrorCuda

Bleed the gauge? I've never heard of this. How do you do it without spraying oil all over your car's interior, and what effect does it have on the gauge?

I just crack the brass fitting behind the guage with a napkin handy when its running and watch the air bubble travel to the guage and escape, tighten the fitting and your bled. The action in the guage is very hyper, it shows all the little wiggles that the pump produces. The air bubbles really dampen the needle amd affect the pressure reading on the low side. I usually get an air bubble after an extended sitting.

[aarracer]

Hi

It sounds first off like somehow your oil pump may be going south.

Or you have some of the same problems as in the post quoted above.

Or you may have a faulty gauge or maybe a kink in the op line.

I would check all the above starting with the easiest first.

If you still have your last oil filter, cut it open at the flange end and cut and peel out the filter element paper like an accordion and see if your oil pump or other engine parts are now residing in your filter element! Shiny is steel, dull is bearing!

Good luck

AARRACER

[cudabob496]

I've always seen air bubbles in my guage oil lines, but they never seem to affect the guage performance. But I have limited experience.

[70Barracuda]

Well guys,
I put the plastic tube that came with the gauge on. No better. Guess its time to take off the pan. crap.. Must be the relief spring.