On this week’s show, a call came in from Julia. Something Ray said confused me.
“Juliette’s car (1993 Geo Prizm) has 233,498 miles on it, and as far as she knows, still has the original timing belt and clutch. She’s a poor student–should she change them preventatively? Tom and Ray think the clutch is probably okay because the car has driven mostly highway miles. But the timing belt is likely hanging on by its last thread. If it breaks, it won’t wreck the engine, but the car will stop running, and that could be dangerous if she’s crossing railroad tracks.”
My Corolla is of this same vintage, and has an interference engine. Since the Geo Prizm and Corolla are essentially the same vehicle, wouldn’t Juliette’s car probably sport an interference engine too?
I believe that both engine options in those cars are interference engines and T & R are wrong.
A friend of my youngest son had a belt snap on his Prizm while in college and it suffered cylinder head valve damage.
years ago, my brother paid money for a shop to replace the timing belt. They cheated him and didn’t replace the belt
When it eventually broke, there was absolutely no damage to valves or pistons. I know this 100% because I am the one who diagnosed the no start and replaced the belt, water pump, tensioner, seals, etc.
I suppose it’s possible this Geo has the 4A-FE 1.6, which I believe is also freewheeler
I can’t attest to the accuracy of the listing but for what it’s worth and I certainly don’t remember the example owned by a college friend of my son as that was over 10 years ago.
Good info @ok4450 . From what I can tell, the 1993 Prizm sported two engines, both DOHC, either a 1.6 or a 1.8. According to your list, both are interference designs.
If @db4690 says the 4afe and 7afe are freewheelers then they are freewheelers. No doubt about that. db4690 has provided me a lot of info on my 4afe, and he has (or maybe had) a 4afe equipped vehicle as I recall, so who would know better than a pro-mechanic who has owned that particular engine? We don’t know for certain that the 93 Geo in questions sported one of these engines, but it seems likely, so Ray was correct when he said no need to worry about bent valves if he timing belt breaks.
It seems there remain folks, experts among them, out in internet-land who continue to claim the 4afe is an interference engine. See below. I’m wondering if the reason for this is that when the 4afe timing belt breaks, there may be a mechanism for severe engine damage that isn’t related to interference vs freewheeler, but something else. And the mechanics prefer just to tell the customer it is an interference engine rather than explaining the actual problem that happened when the timing belt broke.
Is the 4afa a interference engine?
"You are about to go through a dilemna with mechanics when you discuss this engine. Most books claim that the 4A-FE is an interference engine, and most mechanicswill agree. I went throught the same issue with my 1994 Mazda MPV V6. Luckily, your 4A-FE is a non-interference engine- like my MPV is. The clearance is close but it still is non-interference. "
“… the 4AFE engine and has busted his timing belt @ 82K… His mechanic is telling him this has caused his valves to be bent. I have gone to Gates and Napa site and each seems to indicate this is a non-interference engine. However, a quick call to the local Toyota dealer ship, the parts guy said it was in fact an interference engine. I have searched till I cannot search no more and cannot find a definitive answer to this question on this site…”
