2004 s60 Won't start, low compression all 5 cylinders

JudgeRat · Post by **JudgeRat** » 23 Apr 2015, 16:29

Most times "Molly" would start right away every time, but every once in a while over the last 2-3 years she has had a problem starting where she would just crank but not catch. If I just held the key in the crank position for a while she would eventually start and run fine. My normal mechanic replaced the coils and plugs and checked the timing and everything was good, but I still had the problem every once in a while. 2 weeks ago she was running just fine, but when I went out to start her and drive home from a local run, she wouldn't start no matter what I tried.

I had her towed to the shop and the battery was low, the plugs were fouled and the cylinders were "washed" of course from all the starting attempts. She is not throwing any codes. I have had 3 different mechanics tell me that the compression on all 5 cylinders is only 70lbs. They also said the static timing was correct. Statistically, I know that there is a 15-16% chance that 1 of my cylinders is bad because of bad rings, but there is less than 1/100th% chance that all 5 of my cylinders are bad in exactly the same way and by the same amount.

Remember, she has not been running bad at all and no codes; I've just had an occasional problem with starting. I need my car to start; what could be causing this?

difflock54 · Post by **difflock54** » 23 Apr 2015, 17:58

Recheck your compressions for each cylinder with a teaspoon of oil in each.
See if there is a compression significant increase or not?
Could it be 'lawnmower syndrome' or alternatively an intermittent only, fuel pressure regulator/pump issue?

JudgeRat · Post by **JudgeRat** » 24 Apr 2015, 08:26

They did the "wet" compression test because of the ring "wash" and that's how they got the 70lbs readings. They also say the fuel pressure is good, but I also have noticed that I don't always hear the fuel pump pressure up during self-test when i first turn on the key (that could be that it has enough pressure left over). The fact that all cylinders read the same amount of low compression leads me to believe that its not rings at all, but that something is causing the variable timed valves not to close properly during the starting sequence. Am I thinking straight here?

JudgeRat · Post by **JudgeRat** » 24 Apr 2015, 12:11

I should probably also mention that the head gasket has been replaced twice in the last 3 years because it was leaking into number 1 cylinder and causing it to overheat. The first time a dealership did it but didn't recondition the head. The second time a machine shop reconditioned the head. I was told that head, cams, and valves all checked out at the time. There is no indication that the head gasket is leaking this time and there is no evidence of losing coolant or burning oil.

The reason I mention this at all is because I suspect that the overheating may have caused something to start failing intermittently but has now failed completely; perhaps the Crank Position Sensor or the Valve Actuators (or the fuel pressure regulator/pump as you mention) or something else along those lines? I'm thinking that the low compression is a red-herring and something else is wrong that is keeping the valves from closing properly.

draser · Post by **draser** » 24 Apr 2015, 12:49

How many miles on engine? Was the car in the shop when head work was done? If yes, did they gauge the bores? Far as I know VVT only kicks in after certain rpm, so it would not impact the test. Timing being okay, both intake/exhaust should close at some point, no codes either. How does it drive?

JudgeRat · Post by **JudgeRat** » 24 Apr 2015, 13:02

~120k miles. Car was in the shop when head work was done. As far as I know they gauged the bores and they checked out. She drives silky smooth; as a matter of fact, she was driving just beautifully before the no-start condition. No codes, no hesitation, no misfires, etc. Drove her one way for about a half an hour and was up close to operating temperature still when I came back out to try to start her.

draser · Post by **draser** » 24 Apr 2015, 13:19

Scratching my head...

JudgeRat · Post by **JudgeRat** » 24 Apr 2015, 14:12

So are the mechanics. I saw something on another post on a V70 that said something about the fuel level sensor...wondering if that could have something to do with it? I can't but think that there is something electronic that is malfunctioning and causing the valves to not close correctly. It just seems weird to me that the compression would be bad by the same exact amount on all 5 cylinders.

draser · Post by **draser** » 24 Apr 2015, 19:33

The only way to check camshaft timing is to line up marks on sprokets to 12, confirm crank sproket valley lines up to ridge on block. Then remove camshaft back caps to see the slots. Slots should be horizontal for non VVT side, and at slight angle for VVT side. Then remove timing belt. Then straighten VVT shaft to horizontal. Now holding shaft in that position with a locking tool rotate sproket all the way and its mark should line up to notch in cover (12 o'clock).

JudgeRat · Post by **JudgeRat** » 01 May 2015, 18:32

New mechanics say they have verified that the timing is correct, but still have the same low compression on all 5. They are going to try a leak-down test first thing next week. I can't help but think something is keeping the valves open. The only other thing might be if the head or block is cracked across all 5 (or the head-gasket has gone again...but it wasn't leaking anti-freeze, or blowing smoke, or overheating, or...). Getting fuel (too much?), getting spark, just won't start. Pretty stymied here.