K20A2/K20Z1 Low Oil Pressure
Thread Starter
Honda-Tech Member
Joined: Sep 2011
Posts: 118
Likes: 0
K20A2/K20Z1 Low Oil Pressure
Long story short - I have a 2006 type S that I bought from an owner who decided to continue to drive the car with an overheating motor, resulting in both the head and the block warping. To sum things up, I kept some of the bolt ons from the motor and went ahead and found a good deal on a K20A2 bottom end and a K20Z1 head. I freshened up both the head and block with all OEM parts including rings, bearings, valve seals, head gasket, etc, etc.
So once the car warms up, the oil light will start to flash, then shortly after it will stay lit. If I tap the gas or rev the car up, the light goes away, but as soon as it falls back to idle, the light illuminated again. I also get what seems to be whether a timing chain slap noise or a VTC actuator noise both of startup and at certain RPMs while driving. The VTC actuator is brand new OEM.
The oil pump, oil pump guides, oil pump chain, oil pump chain tensioner, timing chain, timing chain guides and timing chain tensioner are all brand new OEM.
I thought at first that maybe it was just an oil pressure switch problem, so I bought a new switch, but that didn’t do it, so I hooked up the oil pressure gauge in place of the switch and read the oil pressure.
According to the FSM, the oil pressure at idle should be 10 psi at minimum and 40 psi at 3,000 RPMs at minimum. Well, my idle pressure was around 4 psi and my 3,000 RPM pressure was around 25 psi, so my oil pressure is definitely lower than allowed.
As dumb as it may sound, I thought about just trying to shim the pump to bump up the oil pressure, but maybe I should just find the real issue it’s having.
Also, I changed the oil and put 10w40 in it to see if that would help, and it did not.
I’m not exactly sure where to continue going about this, so any help or advice is appreciated.
Thanks in advance!
- DJ
So once the car warms up, the oil light will start to flash, then shortly after it will stay lit. If I tap the gas or rev the car up, the light goes away, but as soon as it falls back to idle, the light illuminated again. I also get what seems to be whether a timing chain slap noise or a VTC actuator noise both of startup and at certain RPMs while driving. The VTC actuator is brand new OEM.
The oil pump, oil pump guides, oil pump chain, oil pump chain tensioner, timing chain, timing chain guides and timing chain tensioner are all brand new OEM.
I thought at first that maybe it was just an oil pressure switch problem, so I bought a new switch, but that didn’t do it, so I hooked up the oil pressure gauge in place of the switch and read the oil pressure.
According to the FSM, the oil pressure at idle should be 10 psi at minimum and 40 psi at 3,000 RPMs at minimum. Well, my idle pressure was around 4 psi and my 3,000 RPM pressure was around 25 psi, so my oil pressure is definitely lower than allowed.
As dumb as it may sound, I thought about just trying to shim the pump to bump up the oil pressure, but maybe I should just find the real issue it’s having.
Also, I changed the oil and put 10w40 in it to see if that would help, and it did not.
I’m not exactly sure where to continue going about this, so any help or advice is appreciated.
Thanks in advance!
- DJ
Thread Starter
Honda-Tech Member
Joined: Sep 2011
Posts: 118
Likes: 0
Honda-Tech Member
Joined: Jan 2013
Posts: 9,998
Likes: 1,230
From: The South - Roll Tide !!!
Re: K20A2/K20Z1 Low Oil Pressure
Your answer is the obvious answer IF the block main journals and the crankshaft are totally virgin. However, if the crank has been micro-polished and/or the block main journals have been line honed/bored... then using the stock colors from the block and crank markings would set the oil clearances too big unfortunately. It only takes ONE bearing clearance to be too big and you can lose enough oil pressure to cause problems. If you think your bearings are good on clearances... what about an oil galley plug or O-ring being missing or loose ???
Trending Topics
Thread Starter
Honda-Tech Member
Joined: Sep 2011
Posts: 118
Likes: 0
Re: K20A2/K20Z1 Low Oil Pressure
Your answer is the obvious answer IF the block main journals and the crankshaft are totally virgin. However, if the crank has been micro-polished and/or the block main journals have been line honed/bored... then using the stock colors from the block and crank markings would set the oil clearances too big unfortunately. It only takes ONE bearing clearance to be too big and you can lose enough oil pressure to cause problems. If you think your bearings are good on clearances... what about an oil galley plug or O-ring being missing or loose ???
Anyways, unfortunately I did not mic the main journals on the crank, I did not mic the bearings, I did not check the main journals in the block with tri-mics or a bore gauge, and I did not plastigage when I put the bearing in. As a CNC machinist who is always very meticulous with everything he does, and has a great deal of finesse, I’m very ashamed to say that, but unfortunately, just like everybody else in the world, I get to be in a great hurry sometimes too. This time, it just may have cost me some time and money that I didn’t want to spend.
Though I did not check any clearances, being a machinist - nothing stuck out to me on the crank or the journals in the block as far as machining marks go. In other words, it did not look like the crank was polished in any way, nor did it look like the main journals were align honed. Everything looked pretty ‘stock’ to me.
In hopes that my oil pressure issue is NOT coming from the main bearings (or maybe even the rod bearings), what else could I check? Does anybody have maybe a diagram on the whole oil pressure system, or a checklist of what all I can check? Maybe I am just missing an o-ring or a bolt of some sort may be loose. I’m trying to stay positive and have wishful thinking, as I won’t be a very happy camper if I have to pull that motor out again... Could my ($40) cheap oil pressure gauge be faulty by chance?
Anyways, here’s an update to what I did over the past few days - I shimmed the oil pump relief spring with a .070” shim and resealed the spring sealing bolt, I resealed the sealing bolt that goes into the main cap cover, I tried blowing compressed air through the port to the oil switch incase something was clogged up, but it seemed like the air moved through freely, and I changed the oil yet again and put a Honda OEM oil filter on it. The oil pressure is worse now than it was before. I get maybe 1-2 psi at idle now and about 15 psi at 3,000 RPMs.
I’m lost. Any suggestions?
Honda-Tech Member
Joined: Jan 2013
Posts: 9,998
Likes: 1,230
From: The South - Roll Tide !!!
Re: K20A2/K20Z1 Low Oil Pressure
No apology necessary... many of us here have experienced your level of frustration at some point I assure you. I suggest you examine the bearings again and see if there is any damage to them. Does the oil have "glitter" in it when drained ??? With the engine still in the engine bay, it is difficult to properly check the oil clearance of the main bearings unless you can create a way to support both ends of the crankshaft and remove the weight of the crankshaft from increasing the "smear" of the plasti-gauge that you are measuring with. Let us know what you find and we will try to help. Pictures will help us help you.
Thread Starter
Honda-Tech Member
Joined: Sep 2011
Posts: 118
Likes: 0
Re: K20A2/K20Z1 Low Oil Pressure
No apology necessary... many of us here have experienced your level of frustration at some point I assure you. I suggest you examine the bearings again and see if there is any damage to them. Does the oil have "glitter" in it when drained ??? With the engine still in the engine bay, it is difficult to properly check the oil clearance of the main bearings unless you can create a way to support both ends of the crankshaft and remove the weight of the crankshaft from increasing the "smear" of the plasti-gauge that you are measuring with. Let us know what you find and we will try to help. Pictures will help us help you.
If no luck from any of the above, I suppose I will start looking into bearings.
Trial User
Joined: Dec 2023
Posts: 1
Likes: 0
Re: K20A2/K20Z1 Low Oil Pressure
I think at some point later today or tomorrow, I’m going to check the VTC solenoid and screen, along with the VTEC solenoid screen (even though they are both brand new), and probably run a bottle of some kind of detergent or maybe auto tranny fluid in the motor to free up a (hopefully) clogged oil passage.
If no luck from any of the above, I suppose I will start looking into bearings.
Honda-Tech Member
Joined: Mar 2025
Posts: 3
Likes: 0
Re: K20A2/K20Z1 Low Oil Pressure
Long story short - I have a 2006 type S that I bought from an owner who decided to continue to drive the car with an overheating motor, resulting in both the head and the block warping. To sum things up, I kept some of the bolt ons from the motor and went ahead and found a good deal on a K20A2 bottom end and a K20Z1 head. I freshened up both the head and block with all OEM parts including rings, bearings, valve seals, head gasket, etc, etc.
So once the car warms up, the oil light will start to flash, then shortly after it will stay lit. If I tap the gas or rev the car up, the light goes away, but as soon as it falls back to idle, the light illuminated again. I also get what seems to be whether a timing chain slap noise or a VTC actuator noise both of startup and at certain RPMs while driving. The VTC actuator is brand new OEM.
The oil pump, oil pump guides, oil pump chain, oil pump chain tensioner, timing chain, timing chain guides and timing chain tensioner are all brand new OEM.
I thought at first that maybe it was just an oil pressure switch problem, so I bought a new switch, but that didn’t do it, so I hooked up the oil pressure gauge in place of the switch and read the oil pressure.
According to the FSM, the oil pressure at idle should be 10 psi at minimum and 40 psi at 3,000 RPMs at minimum. Well, my idle pressure was around 4 psi and my 3,000 RPM pressure was around 25 psi, so my oil pressure is definitely lower than allowed.
As dumb as it may sound, I thought about just trying to shim the pump to bump up the oil pressure, but maybe I should just find the real issue it’s having.
Also, I changed the oil and put 10w40 in it to see if that would help, and it did not.
I’m not exactly sure where to continue going about this, so any help or advice is appreciated.
Thanks in advance!
- DJ
So once the car warms up, the oil light will start to flash, then shortly after it will stay lit. If I tap the gas or rev the car up, the light goes away, but as soon as it falls back to idle, the light illuminated again. I also get what seems to be whether a timing chain slap noise or a VTC actuator noise both of startup and at certain RPMs while driving. The VTC actuator is brand new OEM.
The oil pump, oil pump guides, oil pump chain, oil pump chain tensioner, timing chain, timing chain guides and timing chain tensioner are all brand new OEM.
I thought at first that maybe it was just an oil pressure switch problem, so I bought a new switch, but that didn’t do it, so I hooked up the oil pressure gauge in place of the switch and read the oil pressure.
According to the FSM, the oil pressure at idle should be 10 psi at minimum and 40 psi at 3,000 RPMs at minimum. Well, my idle pressure was around 4 psi and my 3,000 RPM pressure was around 25 psi, so my oil pressure is definitely lower than allowed.
As dumb as it may sound, I thought about just trying to shim the pump to bump up the oil pressure, but maybe I should just find the real issue it’s having.
Also, I changed the oil and put 10w40 in it to see if that would help, and it did not.
I’m not exactly sure where to continue going about this, so any help or advice is appreciated.
Thanks in advance!
- DJ
There’s a sealing bolt and out of all the web searches I’ve done trying to figure out why I’m having the exact problems as you with the same scenario, I couldn’t find anything about why I wasn’t getting pressure. Until my girlfriend found this looking at my manual one day. And to think all I had to do was drop the oil pan and windage tray to fix instead of two more tear downs trying to figure it out. This sealing bolt is where the oil squirters and Mains oil path exit from so without this bolt
Thread
Thread Starter
Forum
Replies
Last Post
Shinny
Honda Civic / Del Sol (1992 - 2000)
14
Jan 16, 2017 10:43 AM
spiffy_civic
Honda CRX / EF Civic (1988 - 1991)
14
May 1, 2011 12:59 AM
lilxvtecxpwr
Forced Induction
10
Dec 7, 2004 07:57 AM