I'm new to this forum, so I hope someone can help with my problem. I have a 2005 Civic (D17A1 engine) that needed a replacement engine. After a long and painful dealings with an engine manufacturer (long story), I've ended up with a 2001 engine to rebuild. Per Carfax's, the engine only had 79,000 miles on it when the car was scraped for an accident. The looks of the engine makes me believe that's about right. So, since we had the engine on the bench, we replaced the rings and main and rod bearings. The crank was clean and measured with in specs, so we didn't grind the crank. The bearings we used were Honda bearings. We also replaced the oil pump with a Mellings oil pump. The rods and mains plastigage between 0.001" and 0.0015" clearance.We also replaced the orifice in the head. We also added an electric oil pressure gauge which we have checked against 3 other mechanical gauges. When we start the engine (10W30 oil) cold (room temp) we get near 100psi oil pressure at 2000rpm and over 50psi at idle . However, after driving the car for 20minutes or so, the idle oil pressure will drop to less than 5psi. We've checked the oil pressure with different oil weights up to 50 weight just to see the effects and we get about the same results. This is driving me nuts.

One other strange occurrence, we've had two Fel-Pro oil pan gaskets fail since we've rebuild the engine. Hope someone can help with this problem. I miss my Honda.

 

Hello,

Is the oil pump new or used?
If used than have you checked the clearances in the pump?

Best regards

 

Well i am also in the same boat. I am at 80 psi cold idle and around 15 psi hot idle. After driving for a while the pressure drops. at 7k rpm i have around 40 psi pressure. I am taking engine apart. My plastigauge results were good. the only place that can lead to low oil pressure is clearance unless you have some crack somewhere. I am going to mic the crank and see what clearances i have.

 

Well oil pressure specification as per Alldata is a minimum of 10psi with and oil temperature of 176 degrees. That helps one of you. A couple thoughts on this, you may have and internal engine oil leak at the pick up, the oring to the main oil gallery, or the back plate for the oil pump gears. I have seen similar issues with oil pressure caused by leaks such as this with the VQ35DE nissan engine. Good luck.

 

At first we installed a new Melling pump and later we re-installed the original Honda oil pump. The Honda pump did a little better than the new Melling pump.

 

What oil filter are you using?

 

Using a Honda OEM filter

 

The only other thing I can say is get a new OEM oil pump.

 

Check the gasket between the oil pickup and oil pump. Maybe pump is sucking air instead of oil.

 

well, i opened everything and ground the crank mains down to .25 and put matching bearings. now pressure is up to 20 psi hot idle. I wouldn't blame the pump. Get the crank checked out.

 

I'm trying to understand your engine's conditions compare to my engine, so I have a few questions. You stated earlier that s plastigauge results were fine. What clearance did the plastigauge show? What were the clearances after you had the crank ground? Were the final clearances checked by plastigauge or did the machinist measure them? What instruction did you give the machinist grinding your crank? Thanks

 

Rule no 1 . Never use plastigauge first. I did that and believed that all clearances were right. But when I used a micrometer, the clearance was more than 3 times factory limit. My plastigague results were in .0015. I ground the crank to .010 over and put .25 (in mm) oversized bearings. Didn't even use the plastigague. Just put everything together and got oil pressure right back.
I have D16A6 with Y8 head, Y8 crank running 20psi boost. I have a ported stock pump. Just hogged out from the oil sump gasket till the end where the pump meets the bock. All sharp edges inside the pump rounded off.