1997 850 GLT, No oil pressure

egoff · Post by **egoff** » 26 Aug 2015, 14:40

I just finished rebuilding the engine, however when I started it for the first time the oil pressure light came on. I put an external pressure gauge on and cranked the car over, and it never registered any pressure. While rebuilding the engine, I did remove and disassemble the oil pump, and did not lubricate it before putting it back in, so I feel confident that's the problem. How can I get oil to the pump without removing the pump itself? Or is it possible something is wrong with the pump itself? I'm a little stumped at the moment, so any help is appreciated. Thanks.

Post by **tryingbe** » 26 Aug 2015, 19:21

Did you replace the pump?

Post by **misha** » 27 Aug 2015, 09:08

Why would you disassemble working oil pump which,btw,never fails on these cars???

Post by **cn90** » 27 Aug 2015, 09:46

Did you fill the engine with oil before starting?

egoff · Post by **egoff** » 27 Aug 2015, 11:23

The pump was not replaced, everything looked in order when it was apart. The engine was rebuild because an oil line popped off, so I figured inspecting the oil pump would be a good idea. The engine was filled before it was started.

Post by **precopster** » 27 Aug 2015, 13:13

Did you disassemble and inspect all big end bearings (crankshaft) or conrod bearings?

egoff · Post by **egoff** » 27 Aug 2015, 14:54

Yes, all bearings were replaced, and new connecting rods were used

Rmind · Post by **Rmind** » 28 Aug 2015, 02:32

did you prime the oil pump before you try to start the engine?
when I rebuilt mine, with all the spark plugs removed, and the fuel injectors diconnected, you need to get the the starter to crank the engine for several periods of 20 seconds or so. you do this until the oil pressure light goes off . this procedure primes the oil pump and ensure proper lubrication and oil pressure, before you actually try to start e engine the first time.
the 20 second period is to avoid to overheat the starter.

egoff · Post by **egoff** » 28 Aug 2015, 08:37

No, I never primed the pump. I'll give that procedure a whirl though, thanks.

egoff · Post by **egoff** » 28 Aug 2015, 18:19

So I tried the method Rmind recommended, but still no pressure. I tested to see if oil was getting into the filter, and it was, but with hardly any pressure, more of a dribble. So I figured it had to be a fault with the oil pump. I just finished removing it, but everything looks fine. The spring for the relief valve is very tight, clearances are small between the gears, there was oil in the pump, and all appears to be in order. I understand there is an oil thermostat device immediately after the pump. If that were defective could it cause this problem? Once again, any help is appreciated.