Oil Pump Failure Warning Signs?

[robeats91t]

I've read many threads lately regarding low oil pressure and have seen a bunch more on rod knock, and am wondering what the prerequisites are for oil pump replacement.

It should go without saying that it's cheap insurance to replace the oil pump on a built motor, but how about on a bpu? My engine has approximately 150k miles and shows great oil pressure--about 40psi @ idle cold, and about 20-ish psi @ idle warm. Cruising at about 3000rpm once warm, my pressure is just above 40psi. So, everything seems ok...for now.

When the oil pump fails, does it tend to go in a catastrophic fashion? Or is it typically a gradual deterioration in pressure?

Thanks in advance guys!

 

[IJ.]

Our pumps rarely fail.

I've read a LOT of reports on old pumps being pulled down and being within spec but I figure for what a new pumps costs it's cheap insurance to buy a new one and check it's clearances before installation.

 

[rakkasan]

Our pumps rarely fail.

I've read a LOT of reports on old pumps being pulled down and being within spec but I figure for what a new pumps costs it's cheap insurance to buy a new one and check it's clearances before installation.

werd. Mine old one was well within specs when it was checked at 122k miles.

 

[robeats91t]

If it weren't such a pain, I'd pull the engine, drop the pan and pull the pump and check the tolerances...but if I were to do that, I may as well do a lot more than just check tolerances. I could just get a new pump, oil pan gasket, front seals, etc etc etc, but I may as well just save up for a more thorough rebuild of the bottom end if I'm going to pull the engine.

Would a good aftermarket oil pressure gauge provide any type of insight into the health of the oiling system, or will the stocker be just as good?

Or am I just as good rolling with it and not worrying about it?

 

[IJ.]

The stock gauge while slow and not terribly accurate is good for showing "trends"

By this I mean you get used to where it sits under certain conditions and will notice if there's a change ie: Cold start Hot idle and so on.

Has there been a change that makes you suspect the pump?

 

[robeats91t]

Everything's been a-ok so far, IJ--Mileage is getting up there and I just want to make sure I don't have any unwelcome surprises!

 

[IJ.]

Apart from the horrible joke that is the GTE Cooler circuit our Oil system is pretty reliable

 

[Bishop92t]

It's pretty rare for the oil pump to fail. Usually what I see is someone runs their 7m low on oil or runs with dirty oil and it spins a bearing. The bearing material enters the oil pump and eats it up. If the motor is out it's definitely a good idea to replace the oil pump, but I wouldn't make a special trip into the motor just for that. At the modification level that requires a new oil pump, you're already at the mod level that requires a fresh motor in the first place IMO. I've been running 350+rwhp for the past 3.5 years on my original shortblock untouched (166k miles now). Oil pressure is a bit low but far from out of spec or even a level to be worried about.

I've run both the stock gauge and aftermarket for the better part of the past 5 years on my N/A and turbo. I've noticed the stock oil pressure gauge very gradually over time displays less pressure then there actually is. The fault seems to lie in the oil pressure sending unit, perhaps it gets dirty or just plain old but replacing it seems to restore the "lost" pressure. This is a very gradual process, not even noticeable in a year or two's time. Worth buying an aftermarket gauge? I did, but the money could be better spent elsewhere. The stock water temp gauge is horrible and I'd definitely spend the money on a upgrade there first.

 

[robeats91t]

Thanks for the info, guys; I figured that most failures were due to neglect, but I figured I'd see if there was something more to some of these new oil system-related threads. Based on Bishop's info re: gauges, I may skip the nice oil gauge and start saving for a new oil cooler/filter relocation setup. :naughty:

 

[jetjock]

The stock coolant temp issue must be the sensor because the gage movement itself is very responsive and can be made even more so. Plenty fast as it comes though. It has to be the thermistor in the sensor or the thermal mass of the sensor itself. I wonder if a better one is out there.

 

[robeats91t]

jetjock, even if the sensor's nonlinear response could be made more accurate, the gauge still needs accurate markings to really mean anything, correct? One thing I really enjoy about my GReddy water temp gauge is that I now have numbers to attach to temperatures, instead of just "the gauge is just under halfway up," or "the gauge is between 2/3 and 3/4 of the way up."

I would be interested in a sensor with a more narrow range than the stock sensor, because it's rather annoying that the temperature gauge reaches operating temperature once the thermostat opens, and stays at the "just under the halfway mark" until at least 105*C.

Does anyone know of a resource where I could search for temperature sensors that may allow us to at least improve the accuracy of the stock gauge?

 

[3p141592654]

JJ, when you say the gauge is responsive, is that by applying a variable resistance dummy signal at the sensor connector? I am wondering where the dead response comes from. You know the gauge barely moves from 80 - 105 C, I'm sure that is done mainly to keep warranty claims down like the now famous Ford oil pressure gauge that is actually connected to a pressure switch.

 

[3p141592654]

Three terminals at the gauge, one terminal at the sensor. Is there a signal conditioning box somewhere between the two?

 

[robeats91t]

Now I see your point, jetjock. The lack of numerical data is rather insignificant when you have the ability to see trends in your temperature fluctuation. I just checked the TSRM for the resistance values of the stock thermistor; I may have to shop around and see if there are any aftermarket (AutoMeter, among others, came to mind) sensors that will fit the stock location (*and fall within the specified resistance values*) that will be more sensitive to temperature changes.

Great idea about checking thickness; there may be a market for modified temp sensors (I know I'd like a more sensitive thermistor). At the very least, I'd love to know how much material can come off...

Hah, nice addition there to keep it on topic!

 

[IHI-RHC7]

Ooh, Interesting read here.
What I can say is that when replacing the fan shroud, our temp guage reads consistanly lower temps now. That must mean that there was over a 20* differance if the guage doesn't read a change from 80to 105* normally...
That said, it would be great to know what made the guage "slow"...

 

[supra90turbo]

Plant an autometer in the factory location, and using the factory needle, print a face that looks factory as well, but has numbers.
voila!

 

[Boss302]

didn't ron already do this with a boost guage? oh and attempting to keep this on track how do you check tolerances on the pump?

 

[3p141592654]

I remember the mkII Supra repair manual had a plot of resistance versus temperature for the coolant temp sensor. It was not exactly linear but pretty close.

My volvo's temp gauge always reads exactly half way even though if you track the engine coolant temp using the OBDII port its going all over the place from 190 to 220F in a typical drive. I think this is deliberate to make you feel good!

But, getting back to the topic... the oil pump clearance is measured using a feeler gauge. Its pretty straight forward once the pump is out of the car. http://www.cygnusx1.net/supra/library/TSRM/lu/LU_10.html

 

[3p141592654]

I wonder if a line amp off of the ECU temperature sensor could be used instead of the stock sensor.