Hello everyone, I'm here with a dilemma.

I have 2004 Volvo S60 with 2.4 NA engine and 5 speed manual transmission.

There's a TL;DR; at the end.

A little over a month ago, the engine stalled while driving. I couldn't get it to start, but was able to coast into the first parking lot on the side of the road, which was a church. I cranked the engine over, but couldn't get it to start.. I had an OBDII scanner in the trunk, which returned the following codes:

• P0420 (Stored) - Catalyst System Efficiency Below Threshold

• P0339 (Pending) - Crankshaft Position Sensor A Circuit Intermittent

When I continued to crank the engine, I noticed that the tachometer did not move from 0 RPMs. That night, my roommate gave me a ride home and I ended up leaving the car in the church parking.

The next morning, I returned with some tools and removed/reseated the sensor and its connector with no success. After work that day, I was able to locate a replacement crank sensor from a dealer and installed it - no change.


The original and the new crankshaft position sensors.

With no luck, I had the car towed home.



The following morning, I resumed diagnosing the issue. I swapped the sensors, check for a broken/frayed wire, but did not find anything. I also removed the ECU and confirmed continuity from the sensor side to the ECU pins. Afterwards, when I was testing/cranking, the engine wasn't consistent... As if, the timing belt had slipped!!! (There is oil leaking on the belt side of the engine, which is quite possible)

The diagnostics took a different turn. I got my old compression gauge, and tested with the first two cylinders - it tested at 60 PSI on one cylinder and 90 PSI on the second...

I then took the accessory belt, and timing belt cover off. When it was time to turn the engine to align the cams, I noticed it was missing the 30 mm crank bolt. Found a new one and installed it. Aligned the camshaft, and confirmed that both cams and the crank was still in time.

Removed the timing belt, wiped the oil off anything I can, and washed the oily timing belt with dish soap. I then realigned the cams and crank and re-installed the timing belt to continue testing. This time, I tested all cylinders, which yielded very low compression.

#1 - 34 psi
#2 - 38 psi
#3 - 20 psi
#4 - 10 psi
#5 - 30 psi

It seems like there are bent valves, but it doesn't make any sense, since the cam/crank are all lined up. Just as a precaution, I also took pictures of the timing marks.


Crankshaft, Exhaust Cam, and Intake Cam timing marks

For my next step, I have purchased a borescope to check for bent valves. It should arrive by end of day tomorrow.

TL;DR;

1. I was driving and engine stalled.
   1. OBDII scanner returned codes P0420 (existing) and P0339 (new).
2. The ECU does not seem to be not reading the RPMs from the crank sensor.
   1. Reseated crank sensor and connector.
   2. Replaced crank sensor with new one.
   3. Tested connection to ECU pins - confirmed connectivity
3. Cylinders now have very low compression.
   1. Front side of the engine has oil leak - not sure whether it's crank or cam seal.
   2. The 30 mm crank nut was missing, it has been since replaced.
   3. Timing marks were not off.
   4. Removed and reinstalled timing belt - no change.

Does anyone have any idea as to what may have happened?

 

Your clue is the missing bolt that was intended to keep the crank pulley/timing gear tight against the crankshaft - I'd bet if you remove that gear you will find it stripped on the inside and not aligned with the crankshaft any longer. All three gears are still aligned - yes - just not with the real crankshaft position. BTW the crank sensor code occurred because the cam and crank sensors did not agree -

More than likely you have bent valves. It's a DIY job, just takes a lot of time and patience. Be sure to use new torque to yield head bolts. Sorry for your troubles

 

Update:

hoonk, you were correct; the crankshaft timing gear was stripped. The day I visited the Pull-A-Part in and pulled another one. to replace it with.


The old and the replacement timing gear


My concern is with the splines on my crankshaft; some of the splines are worn. What do you guys think? Is it safe to use, maybe with some red thread locker?




Here's the crank from the car I pulled the timing gear from:


The crank at Pull-A-Part