TLDR: 1990 (09/89) Miata on original timing belt. What are the chances of having keyway problems when doing a timing belt?
My middle son just got his learner’s permit. We were talking cars and he wants a Miata “the one with the pop-up headlights”. Well, I happen to have an NA stored that I barely use, so I am thinking of getting it ready for him.
I bought this Miata many years ago from a neighbor, it’s a short nose 1.6. I tracked it twice and never changed the timing belt, which probably has the 150k miles the odometer indicates and 35 years. I never cared because if it popped, iirc it’s a non-interference and I could just tow it home. But I'd like to do the timing belt if I pass it on.
What are the chances the keyway will be a problem? Is this an overblown problem or are the chances high? If it is opened up, look for a replacement engine or do the fix?
It's been many years since I've thought about them but I think most of the issues stem from issues when replacing the belt. If it doesn't currently have issues you should be fine replacing the belt and installing the crank bolt with loctite and the correct torque.
Yup, Loctite, the correct torque and assembly and put it out of your mind. They did sometimes fail, but they failed fastest when the bolt backed off. Even the long nose cars don't like that.
If the keyway does take damage, the Loctite fix (an actual recipe, not just using blue threadlocker) works.
Remember that if the belt breaks it may not damage the engine, but sure will ruin your day. I saw one belt break at a big Miata event in Moab with the owner hundreds of miles from home. Sure didn't make for a fun event. Do it now, do it right and you won't risk having to depend on a Jeep mechanic who's never seen a Miata before :)
I assume the front main seal is vomiting all over the front of the engine by now. Your water pump needs to be changed too.
