Question about busted timing belts and pistons

If your interference engine pukes a timing belt while driving around town, say, at <3,000 RPM, generally speaking, do the pistons usually survive? Pistons in question reside in a 325iX M20.

I dunno about the porcupine cars and any quirks they may have, but generally, the pistons will USUALLY survive, if with a scar or two (or 5). Valves: toast. Head: $salvageable.

I have seen a couple punch holes in pistons and/or bend rods. 95% of the time it just needs some valves. I guess that's one advantage of a 5 valve engine (1.8T), the valve stems are the diameter of toothpicks.

I've seen 50/50 results. One showed no signs of damage just the valve imprint in the carbon on the dome the other started and ran fine a few times then started smoking bad. Pulled it apart to find the top rings pinched in the ring lands.

44

I've seen THIS!!!

Long story short, I tried to sell customer timing belt on a Talon due to mileage. He told me I was a crook and his timing belt was fine. I tried to warn him about how ugly it can be when the belt breakes. He, again called me a crook and went on his way. Less than 3 months later his car came back on the hood with a "crank no-start".

Warranty does NOT cover this!!!! He couldn't look me in the eye when I showed him the carnage and explained how much more money the job will now cost.

DrBoost wrote: I've seen THIS!!! Long story short, I tried to sell customer timing belt on a Talon due to mileage. He told me I was a crook and his timing belt was fine. I tried to warn him about how ugly it can be when the belt breakes. He, again called me a crook and went on his way. Less than 3 months later his car came back on the hood with a "crank no-start". Warranty does NOT cover this!!!! He couldn't look me in the eye when I showed him the carnage and explained how much more money the job will now cost.

did he try to blame you for the failed belt- as in "you must have damaged the belt on purpose to make me come back"?

My step-son drove his Talon 500 miles from Houston and it died 4 miles from my house. I towed it home on the rope and dug into it. It cranked, had compression, but no spark. Eventually I found it was the timing belt tensioner that grenaded. I put a new timing belt kit on it and he drove it home. He was lucky.

You crook! You tried to sell him a timing belt more than TWO MONTHS before he needed it! lol

Seriously, though, those pictures are amazing!

fast_eddie_72 wrote: You crook! You tried to sell him a timing belt more than TWO MONTHS before he needed it! lol Seriously, though, those pictures are amazing!

Pfff. That's nothing...

After dropping a valve in my 11.5:1 Turbo D16A6.

Depends on how soon you got the clutch pushed on. One rotation = bent valves, coasting with the clutch engaged = much more carnage.

2.5 DOHC Subarus are interference engines, recently did one which fired up perfectly. 1.3 Fiats are interference, did one many years ago and it busted right off. 1.8 VWs are allegedly freewheel, I saw many with bent valves.

So it depends on how the stars were aligned, how many chickens you sacrificed to the valvetrain gods, your hat size and sock color. In short: the only way to tell is to time it, stick a belt on it and see what happens.

See my related post on this same board.

http://grassrootsmotorsports.com/forum/grm/interference-or-not/29016/page1/

Jensenman wrote: 2.5 DOHC Subarus are interference engines, recently did one which fired up perfectly. 1.3 Fiats are interference, did one many years ago and it busted right off. 1.8 VWs are allegedly freewheel, I saw many with bent valves. So it depends on how the stars were aligned, how many chickens you sacrificed to the valvetrain gods, your hat size and sock color. In short: the only way to tell is to time it, stick a belt on it and see what happens.

Which VW 1.8's? older 8v (CIS era) were, 1.8 16v and 1.8T's yeah right. I make sure mine's done every 30K mi. Odd quirk of the 2.0 8v's given the right circumstances they can survive a belt break with no other damage despite being interference.

I think the timing belt in my 90 CRX lunched it's self. It is the D15B2. (I think) I of course was driving it and it just quit running while MODERATELY accelerating. When I try to crank it it pops thru the exhaust and occasionally the intake. Of course it is the busiest time of year for me at work so I had it towed to a locaI shop. Wonder how many valves it ate?

http://grassrootsmotorsports.com/forum/grm/interference-or-not/29016/page1/

In reply to neckromacer: the later 1.8's and all 2.0's were, according to VW, freewheels. I damn sure saw a bunch with low compression after timing belt failures.

porksboy, the earlier 15 series in our last LeMons car ('86 Civic Si) bent a bunch of valves, that's why I got it cheap. The good thing is that through Rock Auto, valves etc are dirt cheap. Like $2 each intakes, $4 each exhausts.