cranks, no start – low compression all cylinders

[crypkilla]

2005 Ford Focus ZX4 SE 2.0L Duratec (I think) 220,000 miles

Had a few hard starts over the past couple weeks. Then suddenly wouldn’t start. Cranks fine, and almost fires barely.

Compression ranges from 40-80 psi (up to 100 with wet compression test). Compression was 210-215 four years ago with same gauge and same testing method (engine cold, all plugs removed, wide open throttle, fully charged battery)

For what it’s worth, spark and fuel are good. Each coil-on-plug/spark plug combo produced strong blue spark when removed and laid on engine ground. Fuel pump and assembly were replaced a month ago (check valve had failed). There is fuel at the rail (no shrader valve available to test pressure, but I disconnected the line to verify fuel). Noid light confirms that each injector are receiving signal. And plugs smelled like gas when first removed. There do not appear to be any air intake or exhaust restrictions.

Only other detail that is probably not related: for the past month there was an exhaust smell in the cabin when running the heater. When pulling the plugs I discovered that one plug was loose and it was clear that combustion gas and crud had been escaping around it.

So it would seem that my mechanical timing is off. Chain jumped a tooth? But why? Stretched chain? Failed tensioner? Maybe the crank sprocket rotated on the shaft or something (I guess they’re not keyed to the shaft so this is possible?). I do not hear any chain slap.

What else could it be? Does this vehicle have some sort of variable cam timing system that could be screwed up?

And what should I do? Pull it all apart (not the worst job ever) and look for misaligned timing marks? What if I skipped timing and bent a valve?

Topic

[Billy]

Checking the timing is a good idea. After that, you’re probably looking at ringlands. 220K miles is a good life for a Ford engine.

[Its me]

Sounds like the timing is off or a blown head gasket. If all cylinders are equally low then that is a good clue it may be timing. Possibly timing belt/chain jumped some way. May want to look at that.

If you suspect a bent valve, you can do a leak down test.

Good luck

-Karl

[crypkilla]

So the timing chain is good.

I set piston #1 at TDC on the compression stroke. I was able to insert a straight edge in the notches in the ends of the cam shafts indicating indicating that the timing chain hasn’t skipped a tooth or anything. Then I hand turned the crankshaft in reverse to check for excess slack in the chain. The cams gears began to rotate immediately suggesting no slack. Anyhow, slack alone shouldn’t cause a no start.

[quote=”relative4″ post=185689] you’re probably looking at ringlands. 220K miles is a good life for a Ford engine.[/quote]

Remember that the car ran perfectly before it suddenly wouldn’t start. I doubt that ringlands are the problem.

[quote=”ToyotaKarl” post=185740]Sounds like the timing is off or a blown head gasket.[/quote]

It’s virtually impossible that a blown head gasket would cause low compression in all cylinders. I also have no other symptoms of blown head gasket.

I’m at a loss.

[Its me]

If you are confident the timing is proper, then it sounds like time for a leak down test. That should pinpoint it.

Good luck

Karl

[crypkilla]

So the leak-down test shows major leaking on cylinders 1 through 3. (Turns out cylinder 4 is good. A new compression gauge and leak-down test show it’s good.)

Cyl 1 is leaking out the throttle body. Cyl 2 and 3 are leaking primarily out the tailpipe. So I’m thinking the valves are bent slightly.

Inspection camera does not reveal broken/burnt valves. When I plop my long screwdriver into the cylinder while finding TDC it leaves shiny marks in the carbon on the center of the piston. Well, on at least piston #1 I can see a single crescent shaped shiny mark off to the side of the piston below one of the intake valves. (I don’t see any shiny marks on the other two beside those from my screwdriver which are less pronounces on those pistons.) So I’m thinking this was from the valve making contact. But they really appear to be seating so i don’t know.

Remember though that the valves are not contacting the piston right now. When I had the valve cover off, everything appeared to be in time. So what happened? All I can think is:

1) Could a chain have enough slack (from say a weak/failed tensioner) to cause valve interference without actually skipping teeth?
2) could it be something with the springs? But I can’t imagine how multiple springs would have suddenly broke or weakened.

I’m stumped.

[Its me]

Going over the redine rpms can cause bent valves. The pistons and valves are moving too fast and collide. On a manual vehicle it can happen by missing a shift under heavy throttle (some cars have a Rev limit to protect this) or a missed downshift 5 to 2 instead of 5 to 4 and the engine can’t help but to go over redline.

Karl

[Bluesnut]

If engine compression gets too low an engine simply will not start and run. That sounds like what is happening here because 40-80 is beyond horribly sucking. I’ve seen engine with 90-100 on every cylinder that would not even cough.

In one case for giggles and grins I shot a healthy shot of oil into each cylinder, reinstalled the spark plugs, and fired it right up. After sitting for a while after shutdown it was right back to a no-start again. The oil would bump the pressure up enough to where it would run.

Your engine is toast.

[Wyr Twister]

No matter what , it sounds like the head will have to come off .

A – How much is the car worth ?

B – At that mileage I would try to calculate the cost of a full overhaul , or

C – What price would be a good used engine – or a crate engine .

For me , it comes down to dollars and cents .

God bless
Wyr

[crypkilla]

So I learned how to do a proper leak-down test…

Cylinders 1 through 3 are all leaking out the intake valves. (Nothing is leaking out the exhaust as stated earlier.)

I pulled the head, and I can see light from a flashlight coming through one of the intake valves on cylinder number 1. No light on the others.

Timing was dead on. No sign of bent valves, and no reason for it either.

How should I proceed? Why would intake valves go from seating perfectly 4 years ago, to only holding 40-80 psi on only three cylinders? Why was the car running basically fine just before it died?

[Billy]

[quote=”ToyotaKarl” post=186269]Going over the redine rpms can cause bent valves. The pistons and valves are moving too fast and collide. On a manual vehicle it can happen by missing a shift under heavy throttle (some cars have a Rev limit to protect this) or a missed downshift 5 to 2 instead of 5 to 4 and the engine can’t help but to go over redline.

Karl[/quote]
^ This

[James P Grosso]

Old weak valve springs will have way less pressure, and you can float the valves at a lower RPM, but I think that engine is a dual overhead cam design, and I would still suspect the cam timing is off?
Did a quick search, and you can pick up a used engine really cheap for those cars.
Found this one for $350, and less than 40,000 miles:

http://www.weberbrothersauto.com/product.aspx?t=3468249&gclid=CMfr8r6O2NMCFQGqaQodydMNow

[Its me]

You say you the valves dont look bent….

Let’s define Bent valves… Bent valves don’t have to look like what some people percieve as bent valves (like pistons crushed them or bent them and They are at a weird angle.

Bent valves very often appear straight but are bent slightly enough to keep the valve from fully seating…

Karl

[Andrew Phillips]

[quote=”ToyotaKarl” post=187531]You say you the valves dont look bent….

Let’s define Bent valves… Bent valves don’t have to look like what some people percieve as bent valves (like pistons crushed them or bent them and They are at a weird angle.

Bent valves very often appear straight but are bent slightly enough to keep the valve from fully seating…

Karl[/quote]
+1. It only takes a few thousandths of an inch.

[crypkilla]

The valves aren’t bent. I spun them (by hand) in a drill press and checked them with a dial gauge.

To be clear again, the cam timing was not off and there is no indication that the valves made contact with the pistons.

The valves aren’t seating fully. With the head AND cams removed, I can not pull vacuum at the intake port on cylinders 1 through 3. There does not appear to be any deposits on the seat or valve. The car did not overheat.

Synthetic blend oil had 30k miles on it and was 1 quart low. No other problems.

What happened? I am going to spend $100 on gasket set and bolts, and $260 at the machine shop to regrind the valves or whatever. Am I throwing my money away?

[Its me]

I am not sure why you keep looking for a supernatural explanation on why your valves are not seating.

Several posts ago you mentioned you saw a half moon shaped shiny spot on a piston. That is a good indicator a valve came in contact.

Since you dont like my (or anyone elses possible explanation) try taking your head with valves to a machine shop and ask their opinion…

I’m out…

[Author]

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