I've done this timing belt once - it felt too tight, drove it for a while, definitely had a belt whine. The tensioner had no slack on it that time either, but I wasn't paying enough attention. Tore it down, frayed belt. Yep too tight. New belt ordered with timing (so far as I can tell) correctly set. Marks all match and tooth count is correct. There's still absolutely 0 slack in the belt on the tensioner side. I know I'm doing something wrong but what? I've had this belt on and off three times, with the marks all matched up from what I can see and still no tension on the left side......
In the pictures the tensioner is loose and that's after cranking it over a dozen times.
Also, I feel no slack on ANY side of the belt, between the cams or the non-tensioner side. It's been a complete PITA to get on/off. It's a brand new gates 145 tooth belt, so was the last one....
Bone stock engine? Or are you running a 0.120" head gasket? ;)
In reply to Keith Tanner :
So far as I know this is a bone stock engine. I did the water pump and timing belt when it was in the Exocet and I don't remember anything like this happening.... But the timing belt was frayed when I tore it down to put into this car so maybe it just didn't make as much noise while running or the exhaust was too loud in that car to hear it over... I'm stumped and frustrated
This was a "used JDM engine" that I picked up from ebay. Is there a difference? I was under the impression they were identical, it appeared to be 100% stock when I picked it up.
You can see the tear down of it @1:17 of this video:
No difference of which I am aware. Timing belts are usually fairly tight when you put them on, but there's usually just a little tiny bit of slack for the tensioner to pick up.
Does the tensioner move in when you have the engine at the tensioning position? That's not TDC, it's 60* before. That's the 1 5/6 turn position, and that's when you'll see the most slack at the tensioner.
I'll double check, but even with the last belt that frayed while on this car I ran the tensioner "maxed loose" (as far to the left as it would go when looking at the cam side) and it still sounded awful and clearly the car didn't like it as the belt frayed terribly. It's like I need a 146 tooth belt.....
No slack anywhere in the rotation. I guess I'll take it off another time.....?
I've got nothin'. Sorry. I can't imagine there's anything about the belt because Gates is good stuff, but my experience is all with OE or Continental.
Spit balling here. How does the lower timing belt pulley look.
I know that shouldn't cause the excessive tightness you're talking about, but it has to be something.
Take the idler and tension pulleys off and see if something's wrong? Measure them with a Micrometer? See if there's a tiny bit of slack in the idler?
Put wrenches on the camshafts and try to stretch the belt between the two a bit?
Is this why Flyin Miata makes those little cam lock tools?
Keep at it. Gotta be a solution.
Theoretically it could be a water pump where the mounting hole for the idler is mounted too far inboard.
Either a pulley is too large, the belt is too short, or the idler or tensioner is in the wrong spot. The pulleys appear stock, you could try a Continental belt, or do a careful measurement of the location of the mounting hole in the water pump. Make sure the tensioner is the correct diameter as well.
You need known good parts for comparison.
Edit:. Well, there you go.
So annoyed, I really didn't want to have to rip off the water pump too
Bad news, messed up water pump.
Good news, the spare engines water pump looks newer than the one that came off the other engine.
I'll take it
Thanks for the help as always CleverBoard! I don't know what I'd do without the hive.
Any idea what brand the incorrect water pump is? Could it be application related or manufacturing defect related?
That's a manufacturing defect. Nice catch codrus.
Wow! Nice catch! That's a weird one.
So, almost entirely off topic, did you know that if you slot the mounting holes in your Neon water pump, you can move your cam timing around a bit? Looks like that pump could be valuable to the right engine builder.
Streetwiseguy said:
So, almost entirely off topic, did you know that if you slot the mounting holes in your Neon water pump, you can move your cam timing around a bit? Looks like that pump could be valuable to the right engine builder.
Spec Miata cheater pump? :)
A very happy camper currently.
codrus (Forum Supporter) said:
Streetwiseguy said:
So, almost entirely off topic, did you know that if you slot the mounting holes in your Neon water pump, you can move your cam timing around a bit? Looks like that pump could be valuable to the right engine builder.
Spec Miata cheater pump? :)
Mmm. I wish I still had free access to a dyno. That might be worth investigating.
I think you could get to the level of tension I had on the bad water pump with a regular water pump fairly easily, with this one I suppose you could go past that - I'm not sure that's a great idea though. The belt was shredded with few miles on it.
If anything, I'd expect a SM engine builder to be running less tension and thus less drag on the belt. Same reason you run undersize bearings.
