mikiman

Hello from Spain.
My 1990 firebird V6 has been stoped for 8 months. Today I started it and a lot of dirt came out of the exhaust pipes. Oil pressure has always been high, but today much more so. At idle almost at maximum, and at 3000 rpm it goes beyond maximum. Just before stopping it 8 months ago, I changed the oil and filter.




Thank you and happy new year.

OrangeBird

iTrader: (1)

If the pressure really is that high, perhaps your new oil filter is somehow defective (blocked, not allowing proper oil flow). What oil did you put in, was it the 5W20 or a thicker viscosity? If there really was such excessive pressure, that would indicate the oil flow is somehow being restricted, if this were the case I'd think the lifters would be ticking like Hell if they were being starved for oil. Were I in your situation, I'd first try another oil & filter change, using the specified oil (no thicker) and a filter from a different brand than the one you have now. If that don't reduce the reading, next I'd hook up a known good mechanical oil pressure gauge to see if the oil pressure actually is that high, the gauges in our cars are absolutely notorious for malfunctioning and giving false readings, both too low and too high.

PS, put some gas in that car!!!!!

mikiman

Hello. What is the correct pressure range for the V6?Where do I place the mechanical pressure gauge? in the PCV hole? Or in the place where the pressure sensor is threaded?

I will change the oil and if necessary the filter
Thanks

Vader

I believe the V-6 has a filter bypass valve built into the filter adapter, much like the V-8s. A plugged filter should cause the valve to open at about 15-18 PSI (100-130kPa). The blocked filter would only tend to reduce the measured oil pressure at the test/sensor port since the port is in the circuit downstream of the filter.

Getting an actual pressure measurement with a gauge is the most reliable indication.

What oil is in the engine? Viscosity makes a difference.

sofakingdom

iTrader: (1)

Always change the oil filter when you change the oil. In fact sometimes the right thing to do is to change the filter but not the oil. Never the other way around.

It is extremely likely that the gauge sending unit is bad. I would guess, better than 90% odds. Therefore I wouldn't bother with the mech gauge just yet; because, all you'll find out by going to all that trouble, is that the gauge sending unit is bad. A whole lot of work for nothing. Just skip all that and replace the sending unit. Then, if the gauge still reads wrong, use the mech gauge to troubleshoot further. You would remove the factory sending unit and put the mech gauge there, which is why you should just replace the SU first before messing with the gauge. No sense in spending all the money to get a gauge and then doing the same work twice, since it's almost certain that you will.

Correct oil pressure for the 6-cyl, when hot, is something around 200 - 240 kpa idle and 320 - 350 cruising.

AlkyIROC

Canada has been on the metric system since the 1970's and while working on vehicles, I still like my pressures in PSI. Oil, boost etc.

I have to laugh at the government on their "Canada is all metric" philosophy. I fill out an official government forms for annual safety inspections. They want tread depth and all brake measurements in millimeters however they still request tire pressure in PSI. Could be in kpa or even bar/millibar but nope, still in PSI. So much for being all metric.

As for the high oil pressure, pressure is a resistance to flow. A plugged filter may cause high pressure but normally the bypass valve would open before pressure got too high. The majority of oiling system operate ranges are between 30 and 60 PSI. I really don't like seeing a hot idle pressure below 10 psi and 15 psi at idle is considered normal. High oil pressure at driving rpms have many factors but really shouldn't go much above 70 psi. There's even a pressure relief valve built into the oil pump to prevent excess pressure.

Cold oil pressure doesn't really mean anything since all cold oil are hard to flow and will show high pressure. With hot oil, you would be more concerned with low pressure. If pressure is high like you are describing in the pictures, my first suggestion would be a new pressure sender. There's always a possibility that the dash gauge is defective but normally it ether works or it doesn't.

Get the oil hot and see what the dash gauge says at idle and at 3000 rpm. Shut off the engine and install a mechanical gauge where the sending unit is and repeat the test. If the mechanical gauge gives the same pressure as what the dash gauge said then the sending unit and dash gauge are fine and your problem is elsewhere however the mechanical gauge will probably show a lower reading. Looking at your idle and 3000 rpm pictures, I can also see the oil isn't hot. Coolant temp is only 70C/160F. Oil will be colder than that. The thermostat hasn't even opened yet. Based on those pressures, you may have a bad sending unit that will read constantly high an low and high readings.

If for any reason you decide to install a mechanical oil pressure gauge inside the car, DO NOT use the cheap plastic tubing supplied in a kit. Use copper tubing.

mikiman

Hello. I have changed the filter and oil for 5w30. After warming up the engine, the pressure is still high but it no longer reaches maximum. It has improved. And I have seen that the crankcase cover, the oil pan, is very dented, damaged, so it is smaller. Can that make the pressure higher? because there is more oil in less volume. And what I thought was oil coming out of the exhaust pipe is carbon along with water. I suppose that due to the cold, water condenses in the exhaust, which is new. Sorry for the mistake.

mikiman

I haven't changed it yet. They don't sell it in Europe and it has to arrive from the USA along with more spare parts.

TTOP350

iTrader: (8)

Cold/new oil is thicker and causes higher psi.
Welcome to winter.
In the summer the engine temps will be hotter than normal and oil psi will be lower.
Mess out of the exhaust is condensation, carbon and maybe rusty chunks of exhaust.
Having all these answers and suggestions from everyone here should get you fixed up.

Wife wants to drag me to Spain sometime soon