87 944S 16V Loud Knocking, Oil Pressure Drop

SeanMcfly87 · 10:06 PM

Hey everyone! New member here! Okay, so my first post is definitely an important one for sure lol. I just finished a huge amount of work on the fuel rail/injectors, upgraded the vacuum lines to the larger Lindsey Racing ones, and re-sealed the oil separator because I had lost a ton of low-end torque over the last few months, and by doing all of this, I think I isolated a VERY large problem in my engine that I didn't know I had.

The engine began to rattle a tad, but nothing too crazy. The next day, I took it out and the oil pressure dropped to 0, and the engine began to rattle and knock like crazy, and I lost almost all power. I immediately pulled the car over and got it towed to my mechanic, who's going to do a diagnostic look tomorrow. Still, I was wondering if you guys had any insight as to what might be causing this? It could be good to give him some 16v-specific points of interest to look at. Here's an attached video with the most intense knocking it's had. Also about a year ago, the car was running a bit soft in the 2 cylinders closest to the firewall. Here's hoping it's not too serious.

https://www.youtube.com/watch?v=PmDj77m_8Mo

IdahoDoug · IdahoDoug's Garage

Shows "video unavailable" when I press on the link. Your mechanic should be able to quickly connect a mechanical oil pressure gauge to the engine, start it and confirm that you have no oil pressure. If that's a yes, its game over if you drove it long enough for the lack of lube to express itself as diminished power because that's massive mechanical damage happening.

JD159 · 09-20-2017, 11:05 AM

Hi,

With all S models, please change the two o-rings on the pressure reducing valve in the cylinder head. This will lower overall pressures and cause top end valve noise. Follow the advice in this thread:

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/954811-o-ring-sizing-needed.html

The video doesn't seem to play, but a loss in oil pressure and knocking sounds like a rod bearing.

SeanMcfly87 · 11:09 AM

Thank you for the advice so far! My mechanic says that what happened to the car wasn't fatal or drastic at all, but had I kept driving, I could have thrown a rod (I'm lucky I stopped when I did). The good news is, it seems to be caused by a spun bearing (there was also a tad bit of extra clearance), so a rebuild will fix this. I'm very lucky I didn't cause any damage to the block or head (or any essential bits, for that matter), so now it all comes down to a basic rebuild, and a bit of crank work may be in order. I will be giving updates in a topic as soon as the rebuild begins! I'm honestly on the fence about whether or not to restore to stock or enhance the NA 16v performance slightly, so any opinions on that matter would be much appreciated

(tis a numbers matching engine, so one idea was rebuild to stock for now, put it back in, and then find and create a non-numbers matching 16v powerplant and transmission down the road when more time and money can be utilized for it). Once I assess the cylinder wall damage (if any), I'll know whether keeping it at 2.5 or boring out to 3.0 is the way to go.
Here's the fixed video link again, btw:
https://www.youtube.com/watch?v=PmDj77m_8Mo

RedCarGuy · 09-22-2017, 04:35 AM

I think this is the first time i've ever seen someone say "the good news is, all I need is an engine rebuild"

It can be done, but if you're on the hunt for more power, ditch it and get something with more power. The 16v engine is not a great platform for making big numbers.

SeanMcfly87 · 09-22-2017, 08:51 PM

Quote:

Originally Posted by RedCarGuy

I think this is the first time i've ever seen someone say "the good news is, all I need is an engine rebuild"

It can be done, but if you're on the hunt for more power, ditch it and get something with more power. The 16v engine is not a great platform for making big numbers.

Lol very true, but it is good news for the sake of the block and head since they're numbers matching (so perhaps it's sentimental good news?). Had I thrown a rod, that'd be it for the original power plant for sure. And I agree with you about the 16v regarding power. It was more of a "hey if the block is worn and can't go back to 2.5 very easily, why not bore it out" sentiment, really