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[zealious]

Hi guys.
Lately my oil pressure light comes on after heavy driving. I still have plenty of pressure according to the gauge so Im thinking that either the sensor is going or that the oil gets so hot and thin that a slight amount of pressure is lost. can some one confirm my logic?

I swapped my engine oil cooler for an external mount to the radiator type. And I dont think that will be enough for when summer time comes around in florida. I want to order an electric cooling fan to attach to the cooler. My question is if anyone knows a way that i could wire the fan to the original auto on/off fan thats standard on my car.

[Kevin Wood]

Do you notice a reduction in oil pressure on the gauge? If it's the original oil pressure switch my experience is that they only need a couple of psi to extinguish the light so if it's coming on and the switch is OK you have a problem. Some oil pressure gauges are heavily damped and don't show quick fluctuations well. Worth changing the pressure switch just to make sure I guess.

Could it be oil surge? Does the problem coincide with heavy braking, cornering or acceleration? Is it dependant on oil level?

Regarding the fan, I would say you're better off running it from a separate temperature sensor in the oil circuit. High oil temperature is likely to coincide with good airflow through the main rad. and therefore the main fans won't be running.

Out of interest, why did you change from the original oil cooler?

Have you considered something like a Laminova?

Kevin

[zealious]

thanks kevin.
Actually I use the car to deliver pizza with. And its been getting pretty hard driving. but im positive its just the switch since i do have some psi that goes up on acceleration.

Is the switch hard to find? Expensive?

I changed it because my gm dealer wanted to charge me 450 USD for a replacement cooler. AND because I figured I would get more consistent performance out of it.. Never having to worry about the in engine cooler failure again seeing how it was an amazingly huge pain in the arse.

IM not familiar with laminova.

[Markjay]

The oil pressure switch is at the lower front of the engine, easily accessible and requires two minutes and a 24mm ring spanner.
The part costs here under £5 (~$10 USD).
I suggest replacing it only to confirm it it is faulty or not, though the chances are it isn't...

In you case it is possible that the long route the oil takes to the external oil cooler reduced the oil pressure at idle.

Also, oil pressure light coming on at idle on hot engine is normal for high-mileage engines, no need to worry if it goes of when the rev go up.

If it is neither of the above, then you should also consider the oil viscosity... you should ideally be using 5W or 10W / 40, but you can also try 5W or 10W / 30 which is thicker and might solve the oil pressure at low rev problem.

[Marks DTM Calib]

What is the gauge reading at idel and 3000rpm.

I guess the pressure sender will be considerably more expensive as it has not only a pressure switch but also a sensor for the gauge (Caterra's have an oil pressure gauge instead of the TID/MID/GID/CID display) but, they are pretty standard across GM engines so should be easy to source.....

5W30 oil should help things to....I suspect this might well be as a result of teh external cooler, does it have a stat on it...?

[Auto Addict]

Would a simple oil and filter change help?

[Marks DTM Calib]

I suspect its a standard mineral oil ans the oil cooler isnt!

As a result at high temps the oils getting excessively thin....

The great thing about the oil to water heat exchanger is the pretty constant oil temp it maintains...

[zealious]

Yes mark i belive ur right. At about 3k rpm i get 15psi when the lights on or off.
I was having this a few times after VERY long drives before the oil cooler. But it stoped until i started deliverying pizza again.
I have been using full synthetic 10w30.

[Kevin Wood]

15PSI at 3K doesn't sound like a lot. I don't know this engine that well, but I'd expect most engines to be up at 40-60 PSI at that speed.

Either the oil filter / plumbing is too restrictive, the oil is getting very hot or there's another problem like a sticking oil pressure relief valve. This is assuming the gauge is reading correctly, of course.

Can you temporarily remove the oil cooler from the circuit and just bridge the oil cooler connections on the block to see if that improves matters?

As Marks DTM Calib said, the beauty of oil to water coolers is that they can't overcool the oil because the oil can never get cooler than the water. In some cases they help get the oil temperature up after a cold start too, by working in reverse. Sounds like geography might be on your side in this case, but in the UK an oil to air cooler would result in overcooling of the oil most of the time unless a thermostatic valve is fitted in the circuit, which results in more oil pressure drop.

As it sounds like you don't need anything better than the standard oil to water cooler in the application you have it might be a good idea to source a replacement standard cooler and see if that solves the problem.

Kevin

[zealious]

im sorry kevin. its most likely at 30psi. there are no numbers. just notches and at 3k rpm it goes to the 3rd notch. im going to try replacing the switch and see if that fixes it.
I can not simply send the oil to the block because the oil light only comes on after very hard driving. or on a hot day.

So back to adding a fan. Would it be a good idea?

[Kevin Wood]

OK. Appologies. I forgot you said it was after hard driving. That brings us back to the oil getting a bit hot.

It might be worth trying a 40 viscosity synthetic oil. Although in some respects it'll just be masking the symptoms, a 30 weight oil is the minimum recommended for the V6 and in a hot environment I would have thought it'd benefit from a thicker oil. This will also retain better viscosity at high temperatures and might stop the light coming on.

The fact remains that if it's got worse since the oil cooler change then the new cooler is either a bit restrictive flow wise or not providing enough cooling.

I'd be inclined to fit a fan of some kind temporarily, wire it up to switch on the dash and see if it helps.


Kevin