2002 V70 No Start saga

[Roger_850T]

I found a deal on a "not running" 2002 V70 T5. The rest of the car seemed pretty nice, so I bought it. I've tried the easy things, and it's still not going, so I figured I'd start writing about it. Suggestions are welcome!

About the car:
154k miles, generally good condition. FWD. The car has VVT on the exhaust cam, but not the intake cam. No, I've never heard it run.

Issues:
1. Cranks over, but no start.
2. Check Engine lights, and generic scan tool gives P0340, "Cam Position Sensor" as the only code logged. If I clear it, it comes right back.
3. Can't talk to ECM with VIDA. It will communicate and give me the VIN, but nothing else.

Prior Owner spent a fair bit of time working on it with no success, so it's probably nothing simple.
I've done:
- Replaced Cam Sensor. PO had replaced it, and the housing was cracked and fixed with JBWeld, so I just replaced the sensor and the housing. No change, still sets the same code.
- Tested the wiring at the cam sensor. Sensor ground showed about 1 ohm to body ground, sensor +V was at 5.0V, and sensor signal was at 5.0V (plausible if ECM has a pullup resistor).
- Compression test shows low all around. 85-100 psi on all of them. I thought perhaps the lawnmower syndrome due to all the cranking, but added oil, cranked a LOT, and no success.
- Fuel pressure is good. It's about 55psig when cranking, and after 24 hours it's fallen to ~45psig.
- Spark plugs were wet and smelled of gas, confirming injectors are at least pulsing and discharging fuel.
- I thought the timing belt was off by one tooth, so I went through and meticulously set it on the marks. No change.
- Inspecting the back of the exhaust camshaft, and rolling it backwards to take up the slack in the cam VVT hub, it looked like possibly the cam gear was about 2 teeth off (advanced). I set the cam gear to the back end of it's travel, aligned the cam visually off the back, and put the belt on. When I turned the car over by hand, I felt interference, so I put it back to where it was. (It does look like PO has removed cam gears, as it looks like all cam oil seals have been replaced.)
- Verified ignition by pulling #1 spark plug and cranking with plug and coil resting on top of the head. Visually saw sparks. No idea if they are occurring at the right time or not.
- Tried disconnecting MAF (hoping for an easy fix), but no change - crank but no fire.

Other notes:
- Evidence suggests PO might have pulled ECU and sprayed with contact cleaner. I'll probably also pull the ECU, inspecting for corrosion and/or bad wiring.
- Evidence indicates the PO drove the car at least a bit after the timing belt was done. (Flap in fender was not secured, and tire has rubbed through fender liner.)

Next Steps:
- Get a cam locking tool, and re-do the cam timing from the beginning. Need to find a good procedure - all the ones I have found that talk about removing the cam gear say to mark it where it's at, but for me that's unreliable, so I need to figure out how to set it up on a new engine with no existing marks.
- Inspect CANbus wiring. Looking for any reason why I can get the VIN but nothing else via VIDA.
- Not sure, but I think I see JBWeld on the crank sensor, too. I'm going to pull it and inspect, replace the sensor and the mounting block if needed.


Questions:
- Any idea why I would get VIN but nothing else via VIDA?
- Do you have a good cam setup procedure?

Again, suggestions are welcome, so please speak up if you have an idea. At this point, I think it's all on the table.

Cheers!

Roger

[chrism]

Resetting the cam timing from square one probably isn't a bad idea at this stage of the game. When the previous owner attempted to realign the cam timing they may not have have been aware that besides the slots needing to both be horizontal, the intake slot needs to be above center and the exhaust needs to be below center. This would have put one of the cams 180 deg out. If the compression is low by the same amount across all 5 cylinders, that would make me think one or both cams are off.

When you reinstall the ECU make sure you get it locked back in properly with the pink locks slid all the way home. As they slide they also pull the ECU down snuggly, so you can't get a good connection if they're partially open - you'll see what I mean.

[jonesg]

I agree, the timing is way off.
2 teeth out shouldn't cause the valves to hit the pistons.

Follow the proceedure posted by F250 if you don't have the manual.
Cvvt hub change on p2 volvos

[Roger_850T]

So the cam timing was actually just about right. When I locked the cams with the tool, and rotated the exhaust VVT hub forward/clockwise, there was only a fraction of a tooth to the limit. I snugged it up tight to the limit by loosening the 3 adjustment screws between the hub and the gear, I'd say I moved it maybe 1° total in a forward / clockwise direction. Got pulled away, haven't had a chance to repeat the compression and start test yet. Hopefully this weekend.

Roger

[Roger_850T]

Compression is low across all five cylinders, at ~95psi. Nevermind the CANbus issue and the JBWeld on the crank sensor, I think I need to address the compression first.

Using a borescope, I can see on all 5 pistons where it looks like the exhaust valves have hit the pistons. I see two matching shiny divots in each piston. They all look about the same. Looking back at the valves, (tough to do,) I don't see any noticeable damage to the valves, but the piston faces tell the story.

Now I'm trying to decide between $600 for a rebuilt head, or $500 for a junkyard engine. Any thoughts?

Roger

[jonesg]

Personally I'd prefer the rebuilt head.
Interesting project you have.

[Roger_850T]

So I think I found the issue. I didn't want to pull the head (yet) because bent valves didn't seem to be the full issue. They would make sense for the low compression (maybe), but not the cam sensor issue. Also, when I read reports of people bending valves, they generally seem to get "no compression", not "low compression". I figured that the "low compression" and the cam sensor had to be related, I kept digging.

Since I meticulously set the cams with the crank sprocket dead on the mark, and I figured they pulled the crank sprocket when they did the oil seals, I thought "what if they managed to screw up getting the crank gear indexed correctly?"

I found the crank nut on at probably >400 ft-lbs. It took me standing on a 6' cheater bar to break it loose.

Sure enough, they had screwed up the crank gear. I think they didn't tighten it up, and it slopped around for a while. The splines inside the gear are worn almost flat. If it's half-way on, then the remaining splines grip properly, but once it's all the way on, I get ~10° or more of slop in the crank gear. Not good! Fortunately, the crankshaft _seems_ to be reasonably undamaged, and it's the gear that got worn.

If the crank gear was 10° off, that would explain both the low compression AND the continuously occurring "cam sensor" fault code. I am hopeful! Getting a new crank gear ordered, we'll see how it goes. Stay tuned...

Roger

[Georgeandkira]

Holding breath.
How does a gear which slips onto a spline shaft then turn and wear splines?
Wouldn't it just sit in the wrong position the PO put it in?

[abscate]

I would say those valves touched the Pistons , probably while not running, so I would not condemn the top end yet.

Without being too rude, is compression test being done with full battery, good cranking, al l plugs out, throttle body wide open?

[jonesg]

Holding breath.
How does a gear which slips onto a spline shaft then turn and wear splines?
Wouldn't it just sit in the wrong position the PO put it in?

Crank nut wasn't torqued, supposedly it should be replaced ...so I've read.
The crank gear walked halfway off and slipped on the splines.
The nut was tightened too late.
In that scenario the valve stems are bent.
Maybe they didn't use the crank holding tool.

I recall reading someone posting the same scenario not too long ago. Mechanic screwed up.