[Peter.]

Thank you so much for the time you have taken on this.

I would never have believed this but the issue is actually zero compression on cylinder 4. I managed to borrow a compression tester this morning or I would have checked it sooner. I guess it must have popped a valve or something for it to happen in an instant but at least now I know where the issue lies.

 

[Peter.]

Safe to say I've foud my fault

 

[Peter.]

You got that head off quickly based on the times on your posts!

I've only ever taken the heads off motorcycles but have never seen a deposit like that. Are those the intake valves that are covered in that gritty looking deposit?

Well I started stripping all off about 11am done about quarter to 5 just in time for roast beef dinner. It was a bit of a marathon but I got work tomorrow and I wanted to get bits ordered. The hidden bolt down the back of the head confounded me for a bit, as did the bottom support bracket bolt for the inlet manifold and the exhaust manifold studs are a sick joke for being so long. They'll be getting chopped down before it gets re-fitted.

The deposits are pretty normal. This cylinder is darker/wetter than the other three because it's not been firing just pumping fuel/air mix.

Plan now is new check the seat isn't damaged, new valve, lap all the others, new head gasket, cam chain kit and put it all back together.

 

[Peter.]

The valve seat looks damaged (as well as the valve). Are you going to repair or use donor head ?

No, the valve seat's good.

Head is all stripped, ports de-coked, valves de-coked. Just need the new valve now then lap them all in, lap the head flat and rebuild it.

 

[Peter.]

Well I'm in the workshop now but I did all this work in the street as I have no off-street parking.

Lapping the head is done with a cast iron plate which is charged with lapping compound. I have one that I know is flat to better than 1/100th of a mm I use it for reconditioning granite surface plates. It's a bit of a specialist thing that I do as part of my hobby but it's not difficult. If you do a search for cast iron lapping plate you'll find examples. They are just a flat cast iron face with grooves cut into them.

A typical 4-cyl ally cylinder head will probably be in tolerance if it's flat to within 2-3 thou (0.5-0.75mm). Skimming should comfortably achieve 1-2 thou overall flatness (the factory new finish will be much better) whereas lapping will achieve half a thou without trying and better than a couple of tenths (0.005mm) with care.

 

[Peter.]

Getting ready to rebuild this head today despite being full of flu

I could do with the tightening torque info for the head bolts, and the re-assembly sequence for the VVT unit, if anyone can help please.

 

[Peter.]

Yes that couldn't be more helpful thank you.

Pete.

 

[Peter.]

Valves lapped, head also lapped ready for re-assembly

 

[Peter.]

Had to make an adapter for my valve tool to reach deep into the head. This is the last valve getting installed. I used some cable ties to keep the hydraulic lifters in their proper places. There's 2 that you can't secure but they are at opposite ends of the head so if they fall out it's easy to see where they came from.

 

[Peter.]

I did it the hard way, mind you I hate working on cars and wouldn't even have done this on my own so I don't expect to be doing valves again anytime soon. But you know, it's my daughter's only transport and she relies on it for work besides she has our car right now so I have a good incentive to get it done

Head is rebuilt and ready to be re-fitted. The weather is very sour for the next few days so it's looking like a next weekend job.

I'd like to be introduced to the guy who invented that spring-loaded VVT system. I'd walk straight up and shake him

 

[Peter.]

Back at it tonight, I've cleaned up the block, changed out the cam chain & bottom pulley, guides, fitted new gasket and set the head in place with the bolts only lightly nipped up. Not going to torque it up in the dark so I'll wait for tomorrow after work to do that.

Question: I have my cam locking kit, fitted those onto the cams, put the pin in the flywheel and everything is nicely locked in place. Obviously I'll have to remove this to torque he head down and I have yet to fit the cam wheels and tensioner. What is the procedure here? The bottom cam sprocket is a friction drive, not keyed to the crank so presumably I can leave the bottom pulley bolt slack, fit the cam wheels, put in the tensioner then once the chain is all fully sprung torque up the bottom pulley to lock the cam chain drive sprocket in place and the timing is set?

 

[Peter.]

It this what you are after ?

Of course it is, thank you once again.

Pete.

 

[Peter.]

Well, today has been a marathon and no mistake.

I got the cams all timed and torqued yeterday afternoon after work, just leaving re-assembly of the manifolds and ancilliaries today which should have been an easy run.

Got it all put back together, cranked it over. I got a few half-hearted pops but nothing else just cranking.

I went through the various steps - check spark, check compression, pull the cover off and check cam timing. All three perfect. Pulled the injector rail and gave it a quick crank - all injectors firing as they should. Tried a few more times until the battery started running down a bit then put it on charge for a while.

Went back and same thing happened, just a few weak attempts to fire and nothing else. Decided to pull the injectors out again and check that they were continuing to fire as the cranking went on. Did this and the oddest thing happened. With the injectors firing into the free air behind the intake manifold, they engine was actually trying to run. Ok, so it's over-fuelling so much that it's running on the little vapour being drawn in the air intake/injector holes. I pulled off the throttle body to check the operation and it seemed to be working correctly. So then I thought, if it's overfuelling it should rev straight up with no throttle blade to restrict it so I put the injectors back in, left the throttle body off the intake but still plugged in. Cranked the engine and it started and idled (very roughly). Whilst it was running I grabbed the throttle body and held it onto the manifold and the idle settled right down.

I didn't understand any of this at all but I went ahead and fitted the throttle body, fixed the injectors into place, test-ran it and it fired up normally but idled rough (more on why below).

After this I re-assembled everything except the battery box and cold air intake. Ran the engine up again and it was a bit rough running. As it warmed up it was clear that it was not running on No1. Swapped out the coil for No2 and now No2 was not running, so we now have a dead coild.

So, I'm at a complete loss to explain the above shenanagans, the over-fuelling and why/how it righted itself, but I'm pleased to say that the engine is up and running and once I fit the new coil I'm sure it will be back to it's good old reliable self.

 

[Peter.]

To wrap this up, I fitted a new coil and the car is now up and running nicely again. Of course it's also had a good de-coke and a new camchain so here's hoping for many more happy motoring miles for my daughter.

Thanks for everyone who contributed and a special thanks to @RedSector for the time he's spent posting diagrams and service documentation for me. This was invaluable to me and I would have found it all quite difficult otherwise

Pete.

 

[Peter.]

Did you manage to reset adapations? Not sure if there's any regarding fueling though. If the engine was running hard maybe it needed more fuel before the rebuild? Cannot explain it any other way

No I didn't, I have no software for such things only basic ODB scanner. Certainly it did plenty of idling before I took the cylinder head off as I was trying to diagnose the misfire.

 

[Peter.]

Well, the story isn't finished yet. Today she was driving, got the message of doom back up and motor running rough. I suspected another coil going bad and not wanting to be changing another valve I ordered 3 more coils.
Error turned out to be P0011 which I gather is over-advanced intake cam. Now I checked the operation of the VVT motor and it homes itself and seemed to be operating properly. The rough running corrected itself when the engine was re-started and so far the MIL light hasn't returned since clearing the DTC's.

So, what's the most likely cause? The cam timing is 100% correct I checked it at least 3 times when it wouldn't start after the rebuild. The locking kit slipped onto the cams and settled into place perfectly.

 

[Peter.]

This engine is the 8FS version with the mechanical VVT actuator, I don't thnk it has that valve.

New symptom this evening is it's giving low oil pressure warning on idle, along with the above.

I am wondering if it is anything to do with the cam sprockets? They have an oil feed to them, though I don't have a clue why or what the sprocket gubbins actually does. Could the oil pressure warning and the P0011 be related?

EDIT: @CallMeFoxie It does have that valve. I thought that the worm-screw actuator was in lieu of the oil colnenoid but I've since found that they do different things. I have cleaned the valve which has a moderately gummed up filter screen.

 

[Peter.]

Okay, so I've put an oil pressure gauge on the engine and when it's cold I get 2 bar at idle but as the engine warms up the idle pressure drops away until it's at half a bar when the coolant temp gets to 80. after that I stopped the engine. I guess the oil pump is shot.

From cold:

After 5 mins of running

After 10 mins

After 15 mins I shut it off:

 

[Peter.]

I've removed the sump pan and oil pump. Having stripped the pump it has some wear but it doesn't seem excessive for a 70k miles engine. Thehousing is not gouged out save for a small patch right at the oil inlet port. the rotors are not badly scored and the gear faces are perfect. Rotors measure 25.92mm and 35.95mm. I have no clue what the wear specs are to check them.

Inside the housing

Rotors:

It's a lot of money to replace the oil pump if it's not the cause of the issue bearing in mind I'm already £400 in now