Hello, I am "new" to this forum. I have been a member here before but not for a while, I think my old account got deleted. Regardless, it's nice to be a part of such a great forum again. Looks like this site has grown quite a bit!

I have tried searching for the following information before posting, but I could not find exactly the same scenario.

Anyway, I have a timing belt issue that I would really appreciate some help with. I own a '91 Civic Si w/ original D16A6 w/ 175k, I purchased the car from my roommate who had the timing belt/water pump replaced late last year. The car has not been driven much between then and now but I have been doing some much-needed maintenance on it. Most recently, I did a valve adjustment which it needed pretty badly, to the point that I did not notice that the new timing belt was whining until I adjusted the valves.

I have tried to re-adjust the belt (with the engine cold) like 3 times now, following the shop manual. Every time the manual tensioner seems to give the belt a slightly different amount of slack, which I understand because it's just a spring-loaded adjustment and how accurate can that be? Regardless, I followed the shop manual each time and the belt still seems to whine when the engine is fully warmed up. When cold, there is almost no whine although it may have a slight one.

I don't think I have the belt too tight, although I really don't know for sure because I was just letting the tensioner adjust itself where it's supposed to. I did not apply any extra force or anything. I've felt belts on d-series before that were tighter than this without making too much noise. It kinda bothers me, but I can't seem to get it to go away. I'm afraid to make the belt too loose, and I have also re-adjusted the alternator belt and currently it is the only other belt.

Vehicle drives perfectly, timing has not jumped or anything, and otherwise this engine is actually in great shape. I am assuming thermal expansion is causing the belt to whine when the engine is warmed up, but why?

Any help with this would be much appreciated.

 

I've seen timing belts on D series engines that get pushed a little farther back of forward when they are put on, that might be causing it to rub on the lower gear down on the crank shaft, theres not much room down there. I would check to make sure the timing belt isn't pushed in too far on the various gears its attached to & rubbing. Not sure if that helps but thats the first thing i would check

 

wouldn't it do it all the time if that were the case?

 

Yea but like you said it expands some when it heats up, which could be why it only makes the noise then, anyway thats just one thing to check that doesn't cost money... Also, even though the belt tensioner should have been replaced with the timing belt, check it anyway and make sure its not going out, just to be sure. Again, it doesn't cost money to check out stuff like that, always a good idea before you spend any on new parts or a mechanic

 

Well earlier today I did a few things to the car, and while I was at it I re-checked the timing belt area. Tension seems okay, belt is on track correctly, tensioner is (as far as I can tell)) in good working order. I'm starting to think this noise may be mostly the alternator. Come to think of it, I had '96 EX that made almost exactly the same noise until I replaced the alternator after it failed, so maybe that's what's happening. Tomorrow I'm going to check around with my stethascope. Will report back.