Vehicle one morning started, RRRO RRROO, bang as if something snapped. Vehicle would just crank, bzbzzzzbzzzzzzbzzzzzzzzz, no start. Started it again. Heard a BIG BANGGGGGGGGGGGGGGGGGGGGG. Like a gun shot noise and smelt a burning smell in front of engine. Checked spark and fuel good. Check codes with scanner. Scanner couldn't pick up codes. Didn't know how to do flash codes. The day before, MIL was flashing. Checked timing and it was at 11 degrees, but should be at 5 degrees TDC. Adjusted throttle screw and got it to 9 degrees advanced the most. MIL stopped flashing. Did a compression test on all cylinders. READ 0. Rechecked with different gauge READ 0. Checked with a different gauge, READ 0 in all cylinders. Number 3 was wet with coolant. Cracked cylinder head in that cylinder or head gasket. Did a wet compression in all cylinders. Still read 0 in all cylinders. Took valve cover off and timing chain was tight. Cranked, crank by hand to watch valves to see if it was firing correctly or opening early or late. Any help would be appreciated. MILLION THANKS!
1st thought timing jumped a couple of teeth. Dave_island make sure the cam and the crank timing marks are in correct place. Then check compression again, if that motor is like a honda- the piston(s) might have holes or no skirts on the pistons. Always change the timing belt when its time or nightmares can happen. Good Luck. Please chime in and correct me if I'm wrong. -- fstf2v--
Timing was off. Marks weren't aligned. There was still no compression. I know that #3 cylinder had coolant leak somewhere. Pulled head off. BANG! All the exhaust valves were bent. Thinking of my options. Cylinder head looks good. No signs of cracks, but will put a new head gasket on. Replace exhaust valves and timing chain, guide, and tensioner. Also, all 4 pistons had dents on top. Not severe. Looks like 4 moon shapes. Also, I'll make sure the valve stem seats aren't cracked and head is true before I continue. Damn, just amazing how that 1 or 2 tooth on chain can make a big problem.
You might look around for a used motor. Sometimes that route is cheaper. Check the timing tensioner it could of failed then all that damage followed. Good luck- I've been there . fstf2v
Are you sure the marks in the pistons are dents and not simply the way they were manufactured? Most pistons have some sort of relief cut in them to allow the valves to open and close without interference - particularly higher compression engines. Of course, if the chain is off, even the indentations won't prevent them from slamming in to each other unless it is a non-interference design.
Don't write off those pistons just yet - I hope the new valves and gasket will do the trick for ya!
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90 Mazda b2600i pick up CRANK, but no Start
