NS_Carguy

I just watched this this morning . I love this guys 944 vids they are super helpful .
I don't know if it will help but he gives a few tips on an oil pressure problem he is having .

MattyRoose

what hoses is he blocking off in that video?

Martin's928

I, uh, I mean a guy I knew did his water pump/belts, forgot to tighten the crank bolt, had it back out and stop driving the oil pump. Within moments, the valve clatter was shockingly loud. I, uh, he torqued the bolt and no problem 3 years later. No oil pressure pretty obvious. I hear...

ealoken

my engine had the QPR failure, did read pressure, but no..

MattyRoose

vetter59

My car is that '88 on post #16, I had did a total engine rebuild, and could not get oil pressure, on initial start, had Brent on video take a look at it for me. He did get oil pressure, but if I let car sit for more than 24 hrs, oil pump seemed to loose its prime, no oil pressure again. This happened several times over a couple weeks so I could not use the car. The priming procedure that seemed to work best for me was to plug off hose to crankcase vent, and idle air valve, and using a air hose with a rubber tip blow gun, blow about 30psi regulated shop air into oil dipstick hole, with DME relay removed to prevent starting, cranking at least 5-8 revolutions. Sometimes you would have to repeat this sequence several times to get oil gauge to register pressure, but it worked every time.
I had used a 84 block, for the rebuild [original '88 had a scored cylinder], so it required i use the updated OPRV , but ultimately the problem was that this used OPRV. I then tried a original 3 piece OPRV, and I had never had a problem since!

MattyRoose

brooklyn944

Reviving this thread from the dead since it's relevant to my situation. I'm pretty sure I know what the issue is, but I'd like to check with you all first.

Background: A few weeks ago I did the front seals, water pump, belts, and rollers on my '87 NA for the first time. Oh, and I replaced the radiator because I'm an idiot an punctured it getting a pulley off. A bit after wrapping up that service, the oil pressure gauge started fluctuating downwards and I got the idiot light. Thing is, I knew the sender was bad since it had been pegged at 5+ for a long time. So after pulling over immediately and inspecting the area for anything catastrophic, I figured the sender truly kicked the bucket and all was well, then drove the ~35mi drive home. Obviously a dumb assumption in hindsight, but the gauge went back to being normal (aka pegged over 5 bar). About a mile from home the gauge issue came up again and a loud ticking/knocking sound from the engine started. The sound is coming from up high around the back end of the motor - about cylinder #3 and the cylinder head. Video here: https://streamable.com/k0cugb

Actions: Apparently I didn't torque the crank bolt correctly - realized that after seeing the power steering pulley wobble while running. So I've torqued the bolt correctly this time and I did a compression test, which came out seemingly fine. Results were (#1) 171, (#2) 160, (#3) 160, (#4) 160 dry and 190, 180, 175, 175 wet. Spark plug #4 was noticeably oily when it came out though.

I'm thinking potentially lifters lost oil or something with the rod bearings at this point. Does that sound right? I've been hesitant to let it run and fully warm up, being afraid of damaging something more. Are there any other tests I should try out on the street before having to get to a garage and open up the engine to know for sure? Thanks yall!

T&T Racing

Contact Blackstone Labs, Ft. Wayne, IN, believe you request oil sample analysis kit online. Drain oil while taking a sample in a large container. Send the oil sample in a cardboard box, not their black plastic exterior container. Decline that there is any hazardous liquids, etc. Why use the cardboard container because some postal employees do not know the rules and the black package in a slot for further inspection, delaying the sample delivery time. The Blackstone analysis tests for bearing babbit material, indicating a failed or going to fail bearing

Martin's928

Did exactly the same thing. Actually spun out my crank bolt and had to get another one. Wife was about 2 blocks from home when it started rattling and she pulled back into the garage. Replaced the crank bolt and fired it up. Stopped rattling after a few minutes of oil pressure normal and is running great 2 years later. If, like mine, you didn't run it for very long making the noise, it seems there is no damage.

T&T Racing

If very low oil pressure, then the hydraulic lifters are not receiving oil, thus large clunking noise.

brooklyn944

Thanks all for the replies!

Sure enough, the sound went away once I got brave enough to let it fully warm up. Must have been the lifters. I'll be replacing that oil pressure sender with a nice VDO one so I can better track whats happening in there.

T&T, I'll definitely be sending a sample over to that lab. Sound like it would be great info to know even if the engine seems to be running fine.

T&T Racing

For my race car, I do an oil analysis every oil change. My oil changes are about every 10-15 hrs engine time

Breakaway944

If you have the two wires for the oil pressure sensor on the wrong terminals the gauge will peg for pressure and will only come down with no pressure. Check your wires before ordering a new one.