Another case of 'I've tried everything'

Blondie · 10-12-2006, 06:09 PM

Gapped reference sensors.
Checked for spark. Twice.
Tested voltage at injectors and watched injectors fire as well as scoped out the rest of the fuel rail. Twice.
Adjusted, readjusted and adjusted the timing again. Three times.
Rechecked the timing. 1000 times.
Checked cap, rotor, ignition coil. Twice.
Battery is new.

I can crank the starter till the cows come home but I cant get the car to fire. I'd be satisfied with a backfire at this point.
It feels like the starter isnt cranking anything. Ie no compression.

I whipped out the compression tester this morning. Remember my question from a while back about the really high compression numbers I got? Well explain this one to me: ALL my cylinders now read 0 compression. I can feel the air shooting out the cylinders when i crank it, so, (among other reasons,) Im pretty sure my compression tester has given up the ghost and there is in fact more than 0 psi down there.

I havent gotten the car on the road yet or gotten the engine to sustain an idle so I havent been running her NEARLY enuff to blow a head gasket or destroy my rings. (I tracked the lack of an idle down to vacuum leaks. But unfortunately I havent been able to test my work out yet cuz i've been caught up with timing and reference sensors since then.)

Gas is definately there, spark is definately there. Timing is DEFINATELY there.

Like I said, I use to be able to get her to fire...never ran well but I replaced the engine and have been tweaking everything since.

Zero10 · 10-12-2006, 07:16 PM

You say you adjusted the timing 3 times. How far out was it the first time?
If the answer is 2 teeth or more you could have bent valves on all 4 cylinders causing no compression and no start.
Given that your compression tester is reading 0, I would check it with another to verify. If there is no compression.......
You say you replaced the engine. I don't know the whole story, but do you know that the engine you replaced it with doesn't have bent valves?
Tell me you at least changed the timing belt and rollers on the replacement engine.

Slam · 10-12-2006, 07:22 PM

Second that.

If your compression checks out okay, a faulty ignition switch can ruin your whole day. You can crank the car but not start it. Mine actually kills the power to the DME and I can watch it happen on the tach. I've learned a key-wiggle trick but I'll be changing that switch really, really soon.

Razorback1980 · Razorback1980's Garage

I'm with Zero...if it's whirling over like there is no compression, you have some bent valves. When my timing belt stripped the teeth, that's what it did after it bent only one valve. Get a new compression tester, but I'm betting the valves need some work.

SoCal Driver · SoCal Driver's Garage

Bent valves.

drift a 944 · 10-12-2006, 11:24 PM

Quote:

Originally posted by Razorback1980
I'm with Zero...if it's whirling over like there is no compression, you have some bent valves. When my timing belt stripped the teeth, that's what it did after it bent only one valve. Get a new compression tester, but I'm betting the valves need some work.

I am a second casualty of this.

Blondie · 10-13-2006, 04:31 AM

I did a top end rebuild, belts and rollers.

Bent valves on all cylinders?

The ONLY time I'd crank the motor was with belts tensioned and the timing set. The timing has been out 1 1/2 teeth retarded and advanced, to see what would give me the best results. No more than 1 1/2...

Thought I was safe up to 2 teeth, correct?

Razorback1980 · Razorback1980's Garage

I'm not sure what the tolerance is, but I know what the starter sounds like with bent valve(s). It whirls like you have no compression. Either test your gauge on another engine or get a second compression gauge, that will tell you the story. I am guessing it will probably measure the same as the first. The compression was probably so low that it never measured on the scale. If you pulled the cam tower back off, you could look at the height of the valve springs and that should tell the story for sure without pulling the head. Not sure of any other way to confirm it. Compression has to be good for the engine to run.

Zero10 · 10-13-2006, 08:48 AM

You _should_ be safe for up to 2 teeth, but I have no idea how you could possibly go in 1/2 tooth increments.....
I'll give you some highly classified information, for best results, align everything with the timing marks. Advancing/retarding by 1 tooth or more is going to make things worse, not better.
There are adjustable cam gears out there, but for the most part they are there to restore timing when the head is milled a large amount.

Go test your compression tester on another engine, or try a leakdown test on your engine.
If it is cranking at 400-600RPM and sounds like a sewing machine then you have bent valves, but even then you should eventually get a backfire of some sort.