Lab-mike

I just did a engine swap and installed a engine that has less then 1000 miles on in. Now I had to take all pulleys and sensors and oil cooling unit basically everything had to come off from the old engine and swapped over to the new engine. Basically it was just a short block that had heads on it. The car will turn over and starts right up and the oil pressure is at about 60-70 psi on the oil pressure gauge right at start up. But if I drive it for about 5 min and the car starts to warm up and I don't have my foot on the gas pedal the oil pressure gauge drops to 0 after it has been drove for only 5 min. But if I push on the gas pedal the pressure gauge will read around 40-50 psi. Also the first drive I took it for after the engine swap the red oil light came on for about 2-3 min and went off and has not come back on since then. Also I have just installed a new oil pressure sensor. I have Hks replica true dual cat back exhaust and resonated test pipes and Megan racing headers. Any help would be greatly appreciated.

suprasam

I will start.
1. did you check the oil level?

2.what weight oil are you using?

3.did you replace the oil pump?

4. Is the new a engine a revup engine and why was it taken out or its car at 1000 miles?

5.do you have a 350z or g35? The oil pressure sensors are different for each.

Lab-mike

It is for a Nissan 350z and is a VQ35DE engine . Yes I checked the oil level. And I just did a oil change on it. I used 5w30 mobile 1 and a brand new oil filter.
Now I didn't replace the oil pump because the engine was barely used.

Now the reason the engine was taken out at only 1000 miles is the first engine was hydro lock and this engine was bought. So my buddy installed the new engine and drove it for just a few weeks till a friend got behind the wheel after he had been drinking and slammed the passenger side rear end into a tree. So my buddy parted out the car and I took the engine. That's how I got a engine with less then 1000 miles on it.

Do you think it could be the oil pump.
Also I have noticed I have a oil leak somewhere because there is a good size amount of dripping on to the alternator and on to the floor.

The funny thing is I have oil pressure at a cold start up at around 60 psi until the car has warmed up and then the pressure slowly starts to drop and the car will start to over heat.

Can you tell me how would I know if the oil pump was going out or maybe it's just from the oil leak. Also when I hit the gas pedal the oil pressure will raise about to a 1/4 and the over heating temp will start to drop to half way on the temp gauge. I also don't let it run for to long because I don't want to damage anything really bad.

Maybe I should just take it to a automotive shop. I've just been trying to save as much money as I can.

suprasam

Can you pinpoint where the oil leak is? Valve cover, head upper oil pan?
I don't know of a good way to check the oil pump other that seeing if oil is circulating through the block maybe through the oil fill hole. Oily cams=good pump?

k6750gsxr

iTrader: (17)

I hope I am not right but when I had one of my motors built previously for the Z before I started doing everything my self I had the same issue. Start up would be good pressure but once car warmed up my oil pressure would go to zero at idle. 1500 miles later I spun a bearing. Turns out the clearances were not right on the main bearings causing no oil pressure at idle. I hope this is not the same for you but if it is you have a ticking time bomb for a motor as far as you bearings go.

dcains

iTrader: (15)

This is the part which bothers me. That's a very long time to see the warning light on. I can't say for sure, but if the Z is like all the other cars I've owned in 40 years, the oil light and oil gauge each have their own sensor, so when the oil light is on, it should be taken seriously.

It's normal for oil pressure to read lower when the oil is warmer, because it gets thinner, but if it's actually low all the time, and near zero at idle, you've got big problems. Good luck, and I hope you get it figured out.

Lab-mike

This might be a stupid question but do you think a oil leak could be the problem of why i have no oil pressure after the car warms up and the oil is thinner. But I can not locate the oil leak. I removed the alternator and it is covered in the new oil i just put in. so is most of the side of the engine bay near the power steering pump.

I've called to make appointment to take it to a automotive shop here in indianapolis indiana.

Hopefully they can fix it or I'll have to reinstall my old engine I guess.

I do appreciate all the help though, thank you.

djamps

iTrader: (1)

The motor is finished... start shopping, and in the mean time stop driving it so you don't have a window in your block (e.g. save it in one piece for the $1000-$1500 core charge)

rcdash

iTrader: (18)

Agreed. If you have 2 sensors showing zero oil pressure, the engine needs to be rebuilt.

Lab-mike

The oil gauge will be right above 60 psi on the gauge inside the car but after it runs for about 5-10 min it starts to drop and is usually right above the 0 marker on the oil pressure gauge inside the car. But if I hit the gas pedal the pressure will rise to about a 1/4 mark on the oil pressure gauge. I dropped it of at the automotive shop and there looking it over and are suppose to get back with me today with what they find out.

myfirstzcar

A piece of hydraulic hose with a 1/8 male npt fitting and a cheap mechanical gauge would tell you exactly what's going on. 2-3 minutes of 0 oil pressure would have that thing rattling and knocking like crazy. I highly doubt your engine is toast.

Lab-mike

Yeah it doesn't make any knocking sounds or any sounds at all. It just starts to over heat of it sits at idle. But once I hit the gas pedal the temp gauge will go down and the oil pressure gauge will rise but only to about 1/4 on the oil pressure gauge.

Lab-mike

I just got a call from the automotive shop and he said it does have oil pressure when it starts up. But thinks that it has a blown head gasket because after he had it run for a while to warm up it would let off a sulfur kind of smell. He said that usually is when coolant and oil have mixed together and is burning in one of the cylinders creating that sulfur smell.
Now I do have new Megan racing headers & resonated test pipes and a straight cat back exhaust system.

What do you all think?

06m90gt

bump i just purchase a z yesterday and everything was fine and today i drove 100 miles on interstate then came to an idle in town and no psi on gauge on red oil light came on, reved it a little to get off the road and the light went off and pressure rose up with the rpm, but at complete idle no pressure at all, let the car sit for two hours while waiting for tow truck and cranked it to move it and had full roughly 60 psi. so i have same issue apparently when its up to temp the pressure fall out. i checked identifix and found nothing but did find a thread on here of a gasket in the timing cover that apparently leaks and is a known problem for these cars. which makes since because previous owner told me it leaks oil and you say yours leaks but you can't find it, which is probably because it is inside the timing cover... Im going to research more tomorrow with a mechanic i know.

myfirstzcar

So your mechanic diagnosed a head gasket by smell?

Lab-mike

To 06m90gt , if you find out what gasket it is inside the timing cover that leaks oil or find out any other information I would greatly appreciate it. I've been trying to find what it could be and can't figure it out.

And to myfirstzcar, I took my car up to a automotive shop here in avon Indiana right outside of Indianapolis that told me he smelled sulfur smell coming from the car and that smell is usually made when coolant and oil mix and are burning in one of the cylinders. Now I don't know how much to believe that because I've done a compression test on the cylinders before I took it up to the shop and I was getting 130-135 psi on each cylinder. What else could I test for a blown head gasket before I rip all the way down into the engine to change a head gasket?

adrift_foolish1

Check your oil and radiator, if they're mixing a lot you'll get a milky mess in one or both. You said you did a compression check, did you look at the condition of the spark plugs? The timing cover is just sealed with rtv, it has a ton of oil and coolant passages. Any of that leaking could be big trouble.

myfirstzcar

Anything to do with oil pressure won't be held by RTV, but there may be a leaky o-ring or gasket behind the timing cover.

06m90gt

Okay so very long story short I found out my motor is toast I dropped the lower oil pan and it was full of brass,copper looking shavings, Rod and Main bearings most likely. I filled it with 15w40 diesel oil and lucas stabilizer to get me by and its holding pressure just knocking like hell, I do have a question though and i have searched through a few forums with no help. I found a low milage engine local But my car is a 2003 and the donor motor is out of an 05, I've noticed in searching for engines is seems there is a mid 04 model difference for compatability. Im wondering if I can use the 2005 motor without having to modify anything?

myfirstzcar

You should be able to use an '04 or '05 non rev-up with little or no issues. The differences would most likely be minor like a sensor plug or fitting etc.