Alfa Romeo Forums banner

164 Q Oil Pressure Question w/photos

2K views 5 replies 4 participants last post by  velocedoc 
#1 ·
I have been getting lower and lower oil pressure readings on my '94 Q and it is bothering me probably more than I should be concerned about. Having a background in 4 cylinder Alfa's, when the pressure is dropping you begin to think the bottom end is going out. I want to drive this Q to the Chicago convention but fear the bottom end is going to give way before I get there or on the way back. Its a long walk on some of those roads in Nevada!

I installed the mechanical guage and started the car. The engine has 20-50 Valvoline Synthetic with about 500 miles on the oil change. This is what I got at full read before even moving the car.


As I drove down the street watching the guage it went all the way up to 80 psi. That is great cold oil pressure. As I came up to the stop sign the oil pressure dropped to 60 psi with the temp about 150. I pulled out on to the road for a short test drive. The pressure rose to 68 psi and held steady. I went about a mile and turned around. The pressure dropped to 48 psi at idle...normal, with full temperature on guage.

I drove down the road back towards the street but decided to go for another 3 miles and turn around. The pressure was holding around 52 psi steady. When I pulled up to turn around the pressure dropped at idle to...

This is good idle oil pressure in my book.

I drove back to the house watching the pressure. The pressure dropped again to 46-48 psi at 3000 rpm. The idle in the drive way after a 6 mile drive was...


Revving the engine to 3000 rpm steady...this is what I have for oil pressure with a full hot engine...

42 psi.

I am not happy with this oil pressure. Why is there a drop in oil pressure every time the car comes to an idle position? (drive-idle-drive-idle)

Honestly I am not that familiar with the 164 oil pump to know what is happening. The idle pressure seems perfect...hence the bottom end must be in good condition. The relief piston spring might be getting weak and not pushing the relief piston back to keep the pressure up. Does this sound logical?

Anyone have a picture of a late 164 oil pump from a Q/LS?

I checked with Alfa parts and they have a late model oil pump in stock.

How hard is it to change out the pump? Do I have to remove a cam shaft to do that? :(
 
See less See more
4
#2 ·
I don't see a problem am I missing something in the translation?
 
#3 ·
I think the oil pressure should be up around 55+...There was a picture of a 164 at road speed posted just the other day and the guage was showing 55+. That is what I am thinking the pressure should be. What does the factory say the pressure should be? When I got the car the pressure was 55+ at road speed..now this is what I am getting.
 
#4 ·
When warm my gtv6 has always had quite a drop in oil pressure, except when the engine was very young, your 164 doesn't seem that bad ... how many miles are on it?

Not to insult but - it does have the correct amount of oil in it right?

G
 
#5 ·
Your Mechanical Gauge is Certainly Showing More Pressure Than Any Dash Guage on a 164

As you probably noticed, the dash gage is horribly inaccurate, especially as the miles pile up. Most show almost 0 at idle, although the red light does not go on. From what you are showing, it certainly seems better than the 10 psi per 1000 rpm that most Nord engine people, including me, are used to, especially at idle. At higher RPM's the pressure relief spring affects the maximum pressure that can be produced. When cold, however, the maximum pressure can be higher than the relief spring can handle, so you get higher pressures when the engine is cold. If you have good oil pressure at idle, I wouldn't worry about the maximum pressure that can be obtained at high revs. I don't think you have anything to worry about.
 
#6 ·
This is what got me all started was when the guage was showing a very low reading of 0 at idle and only about 40 psi at road speed. Having worked on 4 cyl. for many a year, good oil pressure is a good thing for me. When I see the pressure dropping, it is either the guage or the bottom end dropping out. that is why I put in the mechanical guage and went for drive. The pictures tell the story.
What gets me is this, how come the pressure drops after I come to an idle and then back up to speed with out the pressure returning to what it was before I came to an idle? It would seem to me that if things were working correctly, the oil pressure would come back up to what it was before I went down to idle. (ie. if it was 60 psi and at idle it was 25 psi, then the pressure should have gone back up to around 60 psi when I got back up to speed). Each time I came to idle the max psi dropped.

This has me wondering about the inner workings of a 164 oil pump and similiarities to the 4 cyl. engine. I hear everyone telling me the pressure is ok, I just don't want to lose the bottom end of a good engine while driving somewhere. My GMC 6 cyl. has higher oil pressure than the Q and they have about the same mileage- 180,000 miles. (of course it doesn't rev the same :) )
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top