Pressure relief valve
Pressure relief valve
My S2 1600 engine was completly rebuilt and I recall when I first started, cold oil pressure was over halfway. When I took the car on its first test run last weekend, pressure was very low (just above minimum) and not really reacting to higher RPM. Have not done another cold start yet but thought I would check the pressure relief valve first. I assume it can be stuck in the open position so that pressure does not build? How do I know it is stuck open? I checked the parts book against my oil filter base and it seems to have more parts than I have on the car! I noticed item 14 is incated as discontinued - i made the corrections as shown on the page attached (Item 6 on my car seems to contain item 5,8,15?). Note part 9 is also missing the "stalk" - it only has the threaded part to screw on the filter. Hope someone can help me out here!
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Re: Pressure relief valve
The series 1 relief valve consists of many parts.
The part you show is the series 2 relief valve. This one is known to very very occasionally not close. On the picture it is closed and looks properly cleaned. I doubt that valve caused the problem but it is not 100% ruled out. If you can find a series 1 valve I would replace the S2 valve.
Much more likely is a bad contact inside the pressure sender. Originally the range of the sender was 0 - 6 bar. The ranged is stamped at the bottom. They are no longer available new. Replacements are 0 - 8 bar. I always repair the 6 bar ones.
You can test the sender with compressed air, a pressure regulator and a manometer. At full range (either 6 or 8 bar) the resistance should be 0 Ohm. At 0 bar the resistance should be 300 Ohm. The change as a function of pressure is linear.
The wiring and instrument inside is easy to test. Pull the wire from the sender and hold the contact against a metal part of the engine. The needle should jump to full scale.
The part you show is the series 2 relief valve. This one is known to very very occasionally not close. On the picture it is closed and looks properly cleaned. I doubt that valve caused the problem but it is not 100% ruled out. If you can find a series 1 valve I would replace the S2 valve.
Much more likely is a bad contact inside the pressure sender. Originally the range of the sender was 0 - 6 bar. The ranged is stamped at the bottom. They are no longer available new. Replacements are 0 - 8 bar. I always repair the 6 bar ones.
You can test the sender with compressed air, a pressure regulator and a manometer. At full range (either 6 or 8 bar) the resistance should be 0 Ohm. At 0 bar the resistance should be 300 Ohm. The change as a function of pressure is linear.
The wiring and instrument inside is easy to test. Pull the wire from the sender and hold the contact against a metal part of the engine. The needle should jump to full scale.
Re: Pressure relief valve
As always, thanks for your help Huib. The sender unit is a new one so should function correctly. WIll test it. And if OK, I will check with a proper oil pressure tester. I recall on my beta montecarlo, I had the dash instrument calibrated to the sender unit.
Re: Pressure relief valve
Sounds like the right approach.
If it is a new sender, it is most likely an 8 bar unit. The dash instrument will never go to full scale as the pressure relief valve opens at 6 bar. If you managed to buy a new 6 bar unit let me please know where.
If it is a new sender, it is most likely an 8 bar unit. The dash instrument will never go to full scale as the pressure relief valve opens at 6 bar. If you managed to buy a new 6 bar unit let me please know where.
Re: Pressure relief valve
Hi Huib - I parked the car up since my last post as I had other priorities. Now slowly zooming in again on the issue. Have fitted a new spring in the relief valve (was a few mm longer than the original) and may do a test start after fitting. I do not supect this will be the solution though as the pressure would need to be high in the first place to open the valve...So....It must be the pump (cannot think of anything else). I recall measuring the pump tolerance but admit I forgot to add the thickness of the gasket, dumb! As the technical manual does not mention it...still dumb, I know. So will remove the pump and measure again - I assume this can be done by simply lifting the engine sufficiently (10cm?) to get clearance between pump and subframe? Plan on shaving a sliver of the pump housing to get it back into tolerance...
Re: Pressure relief valve
Forgot toask - just to make sure - the series 2 oil filter housing does not have the insert with the pipe (number 9 in the pic in the post above) - just the threaded base, correct (as shown in the photo)
Re: Pressure relief valve
Yes. It is possible to lift the engine enough to replace the oil pump. You have to remove the hoses to radiator and some other stuff.
I can't remember seeing any Fulvia oil filter base without the nr 9 pipe.
I can't remember seeing any Fulvia oil filter base without the nr 9 pipe.
Re: Pressure relief valve
Ok will check if I can get someone to send me a pic of the series 2 oil filter base - if the extension (number 9) is missing, maybe that also can contribute to the problem!
Re: Pressure relief valve
Ok will check if I can get someone to send me a pic of the series 2 oil filter base - if the extension (number 9) is missing, maybe that also can contribute to the problem!
Re: Pressure relief valve
Why not check the parts catalog?