Sometimes doesn't crank, pressure in intake manifold

[Eric B]

This has happened to me three times in a row:

The car will try to crank but it sounds like the starter is groaning. Sounds like the starter is not engaging or not able to turn the engine. It starts fine the second time I turn the key. Battery voltage is 12.6V. It just doesn't sound like a battery issue to me but I need to do more checking.

This is what makes me think it something more serious. When the engine is shut off I can hear pressure being relieved through the air cleaner for several seconds. Could this be related.

Has anyone experienced this. Maybe a timing issue, timing belt tensioner, cam chain tensioner, stuck valve, valves out of adjustment..??? I would like to provide more info but it's hard to tell what's happening when you are inside the car and the windows are closed. Now that it's in my garage and I can listen while someone else turns the key I can't reproduce the problem. But I can hear the pressure relieving from the air cleaner when the engine is shut off.

Car is a 1993 SHO 3.0L MTX 151,000 miles. Maintenance is up to date. Last valve adjustment was 100,000 miles and all tappets were withing spec.. Timing belt was replaced 5000 miles ago and tensioner is fairly new.

Thanks for looking.

 

[HotRodKid]

If your starter doesnt want to crank properly the first time, but works properly the second time, its a battery / wiring / starter issue. If the starter is not properly engaging with the flywheel it would either spin at insane rpm or sound like a spoon in a blender.

The pressure being relieved through the intake is normal. The engine stopped at a point where there was either some pressure or some vacuum in one of the cylinders and the intake valve for that cylinder is open just a crack. All cars do it.

 

[Eric B]

Thanks, I'll do some more checking on the electrical then.

 

[Eric B]

So I have 12.5 V with the engine off and 14.0 V with the engine running. Does that make sense. Should I measure voltage while cranking. I have had batteries that show good voltage but run down during cranking.

 

[TwistedMunky]

You need to load test the battery. Most places that sell batteries will test them for free.

 

[Eric B]

I agree. I had a battery that acted fine most of the time and voltage was good. Sears load tested it and said it was bad.

I think I found the problem. This started after I changed the oil a week ago. I may have bumped the positive terminal on the starter solenoid when I was wiping oil off the starter. It's still the original spade type terminal, it's not attached with a nut like the service units. It was loose, it's on tight now we'll see what happens over the next couple days.