I have a Volvo S40 1.9T 2002, which my daughter uses and I do too occasionally. Have the following issues:

Part-1
1a) About a month ago as my daughter was driving on the highway the car stopped accelerating, the battery light and the check engine light came on, and she had to pull over to the shoulder and get the car towed.The car is now sitting on my driveway.
1b) When I try starting the car, there seems to be no compression.
1c) I checked the ODI codes and read P0335 (Crankshaft Position Sensor). Also there were two other codes P0341, and P0336 that were "Pending Codes" which my OBD code reader (Actron OBDII CP9125) manual explains as errors that have not appeared manytimes to register in the car's computer.
1d) About 2 months prior to the above incident, the car would hesitate to start (needing a few cranks before it started), and also once it started it would rattle for a minute and then it would be normal.

Part-2
2a) Also earlier (for over 2 yrs.) I had "Check Engine" light on, and occasionally (once about every 10 mins. of driving) the car would hesitate to speed up (for just 1-2 Secs.) when I pressed the gas pedal, but picked up speed immediately after. I got it fixed only last year.
MyVolvo Specialist Mechanic read the error codes as P0237 and P0171and replaced the Boost Pressure Sensor and after that it was working fine.
2b) Again about a month ago (which is about 10 months after theBoost Pressure Sensor was replaced), the car started doing the same thing - notspeeding up (for 2-3 secs) when the gas pedal was pressed. But this washappening much less frequently about 2 times a day, as opposed to once every 10mins. earlier.
2c) About a month ago I took it to my Volvo mechanic again, to see ifthe Boost Pressure Sensor had gone bad again. This time he came back withcode P0420 and said I needed to replace Catalytic converter. Which I did notdo, and kept running the car (after which Part-1 trouble happened).
2d) Also for over 2 years the engine would rattle immediately after starting. That would last for about 1-2 mins. and then it would be normal. As I have an engine oil leak, I guessed it was due to low oil level; after I re-filled the oil the engine rattle that happened each time, reduced to once in 10 times or so. Since the leak is minor (requiring me to top-up every 6-8 weeks, I have not bothered to fix it.

3)So my questions are:
3a) Will it be OK if I just replaced the Crankshaft PositionSensor?
or
3b) Are codes P0420 and P0335 interlinked, and do I need toreplace both Catalytic Converter and Crankshaft Position Sensor?
or
3c) Is it something else?

Some more Info:
The car has 170K miles, timing belt and water pump were replaced at 140K, but has been leaking oil from top gasket onto the timing belt. But
the timing belt is not broken.

Thanks in advance for your help & guidance!

 

theory #1: When the battery light came on, it suggested a problem with the charging system - alternator, voltage regulator where the system voltage fell below 12V or so - which can set off odd OBD codes. Did you have the battery replaced or have the alternator checked out? What I'd do is clear all the codes first off (anything bad will just get set again) then check battery voltage and try starting with a jump. The P0420 code is saying your two O2 sensors disagree beyond a preset range - so that could be a bad cat, a bad sensor or two, an exhaust leak or your voltage issue set off the odd codes.

theory #2: The crank position sensor went bad impacting spark/timing etc and you ran rich for a bit until the engine stalled setting off the battery light - meaning the car was at speed, died & lost power setting off both the battery light and a check engine code or two...

 

mt6127: Thanks for the response. I will check it out. Also, I added "1d)" & '2d) that I had forgotten earlier.

 

oil leak/low level would not influence a rattle at start up tough to say what it is without hearing it. I'd start by replacing the sensor.

 

I will replace the sensor and let the forum know if it fixed the problem. Thanks mt6127!

 

Is the Crankshaft Position replacement a DIY job, for someone with very average skills? It will be nice to hear some experiences, with links to videos/Instructions/Posts if it can easily be done. Thanks!

 

can say about the S40 - mine's at college so I can't give a look. If its similar to the 850 - it should be a half hour job. Take a look for a sensor plugged in the transmission housing - down from the right side of the cylinder head. The replace on the 850 is pretty straight forward so I'm hoping the s40 is as well.

 

Guys:
In response to the P0335 code I had, I bought a Crankshaft Position Sensor and yesterday I called a mobile mechanic over to install it. The guy came, opened the hood and showed me what had really happened.
a) The serpentine belt (to the alternator) and the tensioner pulley had broken.
b) The oil leak (probably from the head gasket) was all over and most likely caused the belt to deteriorate.
c) Result of belt breakage - the alternator was not running to charge the battery, the car died displaying the battery light.
Now I have both parts (Belt & Pulley), 2 cans of brake cleaner to clean the oil and am waiting for my mechanic to come back & fix it.
So, it's likely it was never an issue with the Crankshaft Position Sensor in the first place.

 

I'd suggest looking more closely at the source of the oil leak especially if it got on the belt. The CAM seals and the VVT itself are common leaks on this car and will spew oil on the timing belt...not sure about auxiliary belt though. I've not read a single post ever about a head gasket leak on this car causing belt issues...

 

Here's the update:
a) My mobile mechanic installed both the serpentine belt and the tensioner
b) Tried starting the car, and as before (b4 installing the belt & tensioner) the engine would simply run with no compression.
c) Tried jumping it, just in case the battery was not strong enough. But again no compression.
d) Then he installed a new Crankshaft Position Sensor, due to the P0335 code.
e) Tried starting, and again no compression.
f) Finally he said there was nothing else he could do, as he thought due to the oil leak and the serpentine belt breakage, the car's timing had messed up, and there was most likely engine damage.
g) So the car is essentially dead and ready for the junk yard!
h) He said I may get a second opinion if I had any doubts about his diagnosis before junking the car!
And I agree with Pierre that the oil leak was not from the head gasket but from the cam seals, which should have been taken care of when the timing belt work was done.
Any Suggestions please? Or should I just trash the car? Thx!

 

I would not give up just yet. I would consider getting the mobile mechanic back for a cylinder compression and leak down test. This would confirm whether engine is toast or not. I'd go from there.

 

Guys, this is the classic symptoms of the slipped and/or broken timing belt. No compression? You got 8 bent exhaust valves.

 

The timing belt is neither slipped nor broken.
How to do the compression test? The mechanic said it can't be done.

 

compression test is done with all the spark plugs out of the head and you put the compression gauge in the first cylinder. you should also pull the full pump relay or injector fuse/ relay to not feed in any fuel. Crank the engine 5-10 seconds and record the top pressure. do for all cylinders. for a turbo engine 150 PSI is norm, for an NA its closer to 180. That's the dry test. Now drop a couple tablespoons of oil in the spark plug hole and repeat. that's a wet test where the oil helps the rings seal better. Note that on a cold engine you will get lower than correct numbers but you're not looking for 150 vs 120, you're looking for 120+ (which should be enough to start the car). Bad signs are zero (bent valves) 60 or so in two adjecent cylinders (bad head gasket between), low number dry/high number wet shows worn rings, same low number low and high could mean a burnt valve (ie not seating fully) or a valve timing issue. Obviously if you can't crank the engine over, you can't properly do a compression test - so next would be to rent/buy an inspection camera

 

Thx for the detailed resp. mt6127, appreciate that very much!
I am checking with my mobile mech.
But, I have been having these doubts in my mind.
a) Is it even possible for the engine to get damaged, just because the serpentine belt & tensioner are broken, while the timing belt is fine?
b) My mechanic said that the "timing" is messed up, because of serpentine belt ripping off, and that has damaged the engine. Is he right? Finally
c) Assuming the car passes the compression test, now with the Serpentine belt, tensioner, and crankshaft position sensor replaced, what could still be the problem?
Thx for the clarification! I am sure it will be helpful to others in the forum who have faced similar issues, and will serve as a ready reference for them going forward.
Thanks Again!

 

Having a serpentine belt come off in itself would not damage the engine. But I suppose that if the serpentine belt got caught up in the timing belt when it broke it's possible that this might alter the timing temporarily without breaking the timing belt such that valves came in contact with piston...but I'm really just guessing here.

I certainly wouldn't be giving up without confirming what the heck is wrong and honestly, I might be tempted to go to a reputable mechanic to make sure that I got the goods....heck I might even go to the dealer for piece of mind!


The other thing you could try is to turn the crank manually to confirm that the crank itself is in good working order. I say this because you mentioned an oil leak along the way. If I were you I'd eliminate the possibility that the engine was run without sufficient oil seizing the motor altogether. it's an extreme case, of course but easy enough to troubleshoot.


Pop the wheel off on passenger side, access the crank bolt via the small flap in the wheel well cover and use a 32mm (I think) socket, extension and breaker bar to see if crank can be rotated manually. If it does not move at all...that's an issue. To crank it more easily you could take the spark plugs out but I don't think that is necessary - it should turn with some force exerted.

 

Pierre: Thanks for the advice. I will check with my original Volvo mechanic. He's a reputed and knowledgeable guy. Only a bit expensive, which I guess is understandable!
And, No, the oil was never low. Even though the engine bay (near the timing belt, serpentine belt & tensioner) had a lot of oil all over due to leak from camshaft seals, the car would not lose a lot of oil. I would always check the oil level and keep adding to it. So, it was never low on oil.
And, even though we have not tried turning the crankshaft manually, I am almost certain that it's cranking; only that there's no compression.
May be as you suspected, the debris from the serpentine belt may have temporarily got stuck in the timing belt and thrown the timing off. And, if that indeed is the case, my questions are:
a) How simple/difficult is it to set right the timing?
b) Can my mobile mechanic do it? I guess, he's good, but may not have all the necessary tools, or,
c) Does it need special tools that may be available at Volvo service centers only?
Will provide feedback on my next steps. Thx Again!

 

Here's the challenge: if the engine (cams/crank) were permitted to continue turning when timing was more than slightly off the chances are very high that the pistons hit the valves which means an engine rebuild is in order. This is because the x40 runs an interference engine where there is overlap in the movement of the valves and pistons. As long as everything is in time all is good. But the minute things go out of synch wammo! If there is in fact "no compression" - which can be confirmed with a simple compression test, you have a decision to make around a) replacing engine b) rebuilding engine or c) selling as is.

 

Thanks, Will keep the forum informed!