oil pressure problem

[r34 gtr]

quite often when i start my car i hear a knocking from what appear to be the bottom of the engine. not a bad knocking per say, as in nothing that would really harm the engine ( i know what this baby can handle rod knock wise, believe me) but its kind of nerve racking. my oil pressure has been all over the place lately, pegs the gauge when cold, takes a really long time to stabilize to its usual "hot" pressure... it also doesnt register any oil pressure for about 30 seconds after the car starts, but often it sounds just fine. it could well be my crappy autometer gauge is on the fritz, but i was thinking it might be the oil pressure regulator on the pump? or maybe the pump itself is getting tired. it looked to be in perfect shape, only 40k on the pump (last time i checked on it - 8k ago). my gauge is less than a year old, which is why ive been hesitant to blame it on that.

anyway, let me know what you guys think. my friend (who knows nothing about cars) said "it sounds like your car is chopping wood." to give you an idea.... the knocking isnt much louder than my (incredibly noisy) injectors.

- Tim

[NismoBgt]

My guess is its the pump going.. and you are hearing valve clatter from the lifters not having oil on the. Just my take..

[knightrider]

i had the same issue, sometimes my car would not register oil presure for a couple seconds, then at the track, the oil pump went and my engine siezed.

[Swedish Mike]

If you got bad bearings you loose oil pressure, only seen this in CA18 engines but you often loose oil pressure and hear lifter noise before the crank knocking start.

/Mike

[r34 gtr]

ill check tomorrow when its cold and try and figure out where the sound is coming from.

Mike, the engine was rebuilt very recently so it wont be bearings. timing is dead on, and its got great compression.

- tim

[Nowhere]

what weight of oil and are you running an electronic gauge or a mechanical gauge?

[boost_boy]

quite often when i start my car i hear a knocking from what appear to be the bottom of the engine. not a bad knocking per say, as in nothing that would really harm the engine ( i know what this baby can handle rod knock wise, believe me) but its kind of nerve racking. my oil pressure has been all over the place lately, pegs the gauge when cold, takes a really long time to stabilize to its usual "hot" pressure... it also doesnt register any oil pressure for about 30 seconds after the car starts, but often it sounds just fine. it could well be my crappy autometer gauge is on the fritz, but i was thinking it might be the oil pressure regulator on the pump? or maybe the pump itself is getting tired. it looked to be in perfect shape, only 40k on the pump (last time i checked on it - 8k ago). my gauge is less than a year old, which is why ive been hesitant to blame it on that.

anyway, let me know what you guys think. my friend (who knows nothing about cars) said "it sounds like your car is chopping wood." to give you an idea.... the knocking isnt much louder than my (incredibly noisy) injectors.

- Tim

I've experienced the same problem on well built, meticulously mic'd and plastigauged engines. The only thing I can say if the bearings are new, clearances are well within tolerances, camshaft bearing cradles are not worn, and there are no leaks, start looking at the stupid pump. I've had pumps that are not that good at regulating was the engine is warmed-up and that seems to be the case for you. If you've re-used your old, then you're crazy. But then again, I've put in new pumps and I've gotten the exact same problem you have. Changed pumps until the problem went away. It's just soemthing about remanufactured pumps that spooks me nowadays because it causes me to do repetitious work which is not beneficial to me at all.

Dee

[Swedish Mike]

Mr Dee, how much does a CA pump cost in USA?

/Mike

[boost_boy]

Mr Dee, how much does a CA pump cost in USA?

/Mike

The ones I get are $200 U.S. Some folks say they pay a little over $100 U.S. for theirs.

Dee

[Swedish Mike]

The ones I get are $200 U.S. Some folks say they pay a little over $100 U.S. for theirs.

Dee

The 200 USD is OEM right? That´s a really good price, we pay 400 USD here.

/Mike

[boost_boy]

The 200 USD is OEM right? That´s a really good price, we pay 400 USD here.

/Mike

Have you personally experienced fresh builds with oil pressure dramas? This high temperature when cold and tapering to low temperatures when hot seems to be common with a lot of engines. I've personally experience these situations and have been forced to eat labor charges due to such a situation. Experts will be quick to point out possible excessive clearances, but what happens when those clearances aren't excessive? This oil pressure crap is a touchy subject and with it, I am not too proud to the point that I can't take anyone's advice on the subject.

Dee

[Swedish Mike]

Have you personally experienced fresh builds with oil pressure dramas? This high temperature when cold and tapering to low temperatures when hot seems to be common with a lot of engines. I've personally experience these situations and have been forced to eat labor charges due to such a situation. Experts will be quick to point out possible excessive clearances, but what happens when those clearances aren't excessive? This oil pressure crap is a touchy subject and with it, I am not too proud to the point that I can't take anyone's advice on the subject.

Dee

I´ve only changed oil pump in the expensive engines, not CA with bearing swap and grinded crank. On these engines I normally just open up the stock pump and clean it.People never want to pay 400 USD extra without hp gains unfortunatly.

In the forged internal CA´s I always change it. Pretty easy to talk people in to this if they spend $5000 on the set up.

The common thing with all my customer CA´s are this, never any noise after the rebuild.Only the lifters for a day or so until the oil fills them 100%.

These engines seem very oil sensitive and maybe I´m just lucky but fully synt Mobil oil and cleaned internally (all oil holes) helped me.

My last CA (a few years ago) started making noise in the lifters after a while, one week later the bearings started to hammer. Oil pressure got lower every day.After the rebuild I fitted a Mitsu turbo and other stuff to make more hp´s and I also removed the crappy turbo oil feed.When I started it up I had low oil pressure and lifter noise, strange...After a few days of thinking I tested to mount a restrictor on the oil feed.Everything just worked perfect! The hose I used was to damn big and the oil pressure just went out that way.

/Mike

[r34 gtr]

im worried about it. the oil pressure didnt register until about a minute and a half after i started it this morning. yes i let it run. it just has to make it 250 miles tomorrow and then i can rebuild it a third time if need be.

what really gets me is how smooth the car is when the pressure finally registers. it had really high pressure all day today too. i was pulling ~75psi at a steady 3200rpm after the car had been driven for 20 minutes.

dee, i didnt bother replacing the pump out of principle. the engine only had 36/7k miles on it when i rebuilt it completely and so it shouldnt have needed a new pump at all. i mean, those things were designed to last quite a while right? i cleaned mine and everything, and it looked brand new. not even the slightest wear on any gears or anything.

ive never had this "creeping death" thing happen to me before. usually my car will just have a sudden catastrophic engine failure causing me much pain and forcing me to pay for 200 miles worth of towing.

do you know i havnt revved my engine past 5500rpm in the past year and a half because im afraid it will break?! it sucks! im dead serious too. last time i got on it it broke, and i only revved it to 4500. heres to having the single most unreliable ca18det in the universe. cheers!

- Tim

[boost_boy]

Tim my boy, Swedish Mike dear lad,

My issues with the oil pressure has been solved. After wondering if the engine has problems and wondering if I had gotten another skanky oil pump, I got desperate and took the 240 I'm building for yet another ride. Since it was the 2nd time I had opened-up the engine, I made sure before I reassembled that all tolerances were in spec, though this car is running a machined, balanced and polished crank.

So I took the car up the Florida turnpike enroute to the junkyard to pick-up a radiator for my turbocharged hyundai elantra and noticed the oil pressure only moving slightly higher than 25psi after 4000rpm. Now I'm saying, I built this engine right not only because of the amount of money involved, but the mere fact that I'm tired of pulling this motor in and out. I figured if the oil pump is really bad or the engine is out of spec, the low oil pressure will destroy the engine.

I drove the car back home with the same results. I left the car running and removed the oil pressure cap and "voila" oil was spraying out of the cap onto the turbo (No oil pressure problem there). Removed the turbo's incoming oil line and a powerful stream of oil was present. So frustrated with this crap, I pulled the oil pressure sending unit (autometer) off my sentra, connected it to the 240 and this thing now has a gang of oil pressure being displayed via the gauge. Took it for a ride, 2-stepped it, scared people, got the car sideways, and just down right dogged it, and that oil pressure is at 80psi by 7500rpm.

So in short, go after the sending unit; it worked for me.

Dee

[Swedish Mike]

Tim my boy, Swedish Mike dear lad,

My issues with the oil pressure has been solved. After wondering if the engine has problem an wondering if I had gotten another skanky oil pump, I got desperate and took the 240 I'm building for yet another ride. Since it was the 2nd time I had opened-up the engine, I made sure before I reassembled that all tolerances were in spec, though this car is running a machined, balanced and polished crank.

So I took the car up the Florida turnpike enroute to the junkyard to pick-up a radiator for my turbocharged hyundai elantra and noticed the oil pressure only moving slightly higher than 25psi after 4000rpm. Now I'm saying, I built this engine right not only because of the amount of money involved, but the mere fact that I'm tired of pulling this motor in and out. I figured if the oil pump is really bad or the engine is out of spec, the low oil pressure will destroy the engine.

I drove the car back home with the same results. I left the car running and removed the oil pressure cap and "voila" oil was spraying out of the cap onto the turbo (No oil pressure problem there). Removed the turbo's incoming oil line and a powerful stream of oil was present. So frustrated with this crap, I pulled the oil pressure sending unit (autometer) off my sentra, connected it to the 240 and this thing now has a gang of oil pressure being displayed via the gauge. Took it for a ride, 2-stepped it, scared people, got the car sideways, and just down right dogged it, and that oil pressure is at 80psi by 7500rpm.

So in short, go after the sending unit; it worked for me.

Dee

Haha, good! Really nice reading, not often problems like this can be solved for free!

/Mike