Oil pressure relief valve

[redfisher]

I believe my oil pressure relief valve may be sticking. Has anyone ever cleaned or replaced this valve?

It's located in the oil cooler center bolt on top of the oil filter. Can it be serviced without taking the oil filter base from the motor?

Also, when purchasing the center bolt assembly, do the spring and relief valve come with it? They are listed separately in the service manual, but in the parts manual only the center bolt assy is listed.

Thanks,
John McD

 

[Larry Bastanza]

John,

The bolt on top of the oil cooler pedastel is not the pressure relief valve. The pressure relief valve is located in the oil pump housing. See page 8-6 of the service manual. You will have to remove the oil pan to get to it. The steps are on page 8-7 of the service manual.

Go here: http://www.nsxprime.com/FAQ/Reference/1991-1992_parts_catalog/1-c9.jpg

You will see the relief valve and it's components in the parts catalog on line. It is hard to see, but these parts are individual part numbers.

Question: Why do you suspect this to be a problem??

HTH,
LarryB



[This message has been edited by Larry Bastanza (edited 23 October 2002).]

 

[redfisher]

Larry,

Thanks for your reply. Now that the weekend is here I can get back to focusing on my car.

I see the oil pressure relief valve on the oil pump in the diagram you provided the link to. But there is also a relief valve and spring located in the oil cooler center bolt shown on page 8-10 of the '92 service manual. Do you know the purpose of this valve?
The oil pressure readings while driving my car lead me to believe it may be sticking. Sometimes, the oil press would take a 1-2 increment shift across the board. The min/max during normal driving, (shifting @ 4k), would one time be 2-6, then might shift to 1-4. This would be independant of operating temperature. It seemed to me I had read somewhere that this could be something to watch for with this motor. And the note in the service manual next to the relief valve in the oil cooler indicates this part may need periodic service. What do you think?

On another note, I had my car aligned the other day, and I was wondering, wouldn't the tires last a lot longer without all the neg toe in the front and all the pos toe in the rear? It would seem the neg camber in the front and rear is the reason the tires on all corners tend to wear the insides hard. Has anyone you know of ever tried to set the car up with neutral numbers? How do people that race set their cars up?

Thanks for your help,
John McD

 

[Larry Bastanza]

John,

I reviewed page 8-10. You are correct this is a relief valve also. I suspect this relief valve is not for main oil pressure, but it is a safety relief valve in the case that the oil filter gets clogged. In the description of the lubrication system in the manual (1991)this relief valve is not mentioned. The 1992 manual may have more on this, or even later service manuals. (The 1991 manual is lacking in some areas based on the first year print IMO.)

I would recommend you send an e-mail the MarkB or Barney to confirm this, I am not 100% sure. I will try to do the same.

There have been many cases on the forums about wacky oil pressure readings, and the causes can be mechanical, electrical, etc. The first thing you really have to do is install an alternate gauge (mechanical) to see what the actual oil pressure really is, to rule out any gauge/electrical issue. We can discuss that in a little more detail if you like.

In regard to alignment, especially about "toe" you should talk to Karl Zimmerman. He is an advocate of "0" toe front and rear. It is my understanding the Toe "out" in the front is there to help preload the front bushings (rubber) to give the car a crisper turn in characteristic. Toe "in" in the rear is to stabilize the rear end.

I have my car set to 1994 specs, and you are correct the wear is evident. This is also true of the camber (negative). If you are running OEM tires, I see no problem with trying a less agressive alignment and see if you like it. I use my car about 5K miles per year, so I am less concerned about the wear then someone who uses their car 15K miles. I have decided a new set of rubber once a year or so I will live with.

I personally have not driven a car with the toe and camber reduced, so I cannot comment about the characteristics, but I would say give it a try.

I have full four wheel alignments done for $65, so I consider this experiment a small investment. The bottom line is you can always put it back

Oh, a major question in regard to this is what is your setup? Are you completely stock, or have you lowered the car, changed shocks, etc?? OEM Tires??

HTH,
LarryB

 

[redfisher]

Larry,

Thanks for the reply and all the information. Regarding the oil pressure, I'd be interested in any addition info you may gain from consulting with the others you mentioned. I would also like to tie-in a mechanical gauge to compare readings. Where would you suggest connecting the hose? Any additional details you may have would be appreciated.

Now on to alignment. I have just purchased a new set of wheels and tires. On front 17x7 37 neg offset, rear 18x8 45 neg offset. Prior to that I was running OEM wheels and tires. The inside edges on all tires had worn unevenly, especially on the right side. I figured an alignment was in order. I had never paid much attention to the alignment specs until I reviewed the print out from the shop. I assumed there was a reason for the unique setup, but wondered what the sacifice in performance would be with more neutral settings. I too drive my car sparingly during the year, but would like to get as much wear from my tires as possible. If you can put me in touch with the guy you mentioned who has tried the neutral alignment settings I'd be much obliged.

Thanks again for your help,
John McD

 

[DanO]

I’ve heard of people replacing their oil pressure sending valve located on the driver’s side of the front head (in front of the spool valve). I’m not sure if there’s a TSB on this or not but I think this erratic oil pressure reading is somewhat common. Check out page 8-3 of the ’92 manual (upper left hand corner) to see the device.

DanO

 

[Larry Bastanza]

redfisher,

To test the oil pressure go to page 8-5 of the service manual. It shows how to install a mechanical gauge. I would rig up a longer hose so you can tape the gauge to the back window and go on a drive, and read the gauge when your symptom appears.

The pressure sender you will remove to install the gauge is the sending unit for the oil pressure light, so your oil pressure gauge should still function. Also based on DanO's comment the oil pressure gauge sender is indeed a different one up on the head.

DanO makes a good point about the senders. I am leaning towards a guage/sender problem too.

The test described will certainly decide if its a gauge/sender or a real pressure problem.

Considering the cost and time to perform all this, DanO's advice may better serve you, since I am sure the sending unit he is refering to is probably not too expensive, and pretty easy to change.

Keep us posted.

HTH,
LarryB

 

[Larry Bastanza]

redfisher,

In another thread here we have been discussing oil pressure. It does not specifically relate to your problem, but it seems to be going in the direction of a bad sender unit, so it could be related.

The cost of the sender looks like about $143 with the discounts available. Just an FYI.

The thread is here:
http://www.nsxprime.com/ubb/Forum10/HTML/000861.html

My theory is slowly loosing ground based on data I have been getting (this is why I guess it's a theory

, however it is a good discussion about strange oil pressure readings at the track. Make sure you review the thread that Hrant points us to also.

HTH,
LarryB

 

[redfisher]

Larry & all,

I have reviewed the two oil pressure related threads forwarded to me. This forum sure is a great reference for people needing information on these cars.

One thing that came through clearly to me, the stock oil pressure gauge has known and documented problems. Based on this, I will no longer trust this gauge to report such vital real-time information to me in the cockpit. I will be installing a mechanical oil pressure gauge this weekend. I plan to tee into the pressure switch line at the oil filter as mentioned in one of the referenced posts.

IMO, the two most important engine monitors to have while driving are oil pressure and coolant temp. The information should be accurate and repeatable. It is very surprising to me that a car of this caliber is equipped with a system that obviously doesn't report reliable/repeatable oil pressure info to the driver. I'll let you know how my install turns out.

Thanks again,
John McD