Hey guys... greetings from the U.S. Hope all is well. I am posting here because I got no answers on the US Z boards I frequent. Before I post this, understand I been messing with Z32's for about 8 years, have done numerous timing belt jobs, engine rebuilds, etc, so I am not a noob to the process. Now having said that, I have a problem I have never seen before. I recently got rid of my big cam heads and went back to stockers cause I got tired of my cam gears rattling non stop, and one of my JWT cams snapped, so I got a set of stock heads and had them gone through and put them back on the car. I set the timing belt/tensioner using the FSM procedure TO THE LETTER. I can set it, get it right, and when I get to step 18, everything seems perfect, until I turn the motor over. As soon as the motor turns over clockwise, the gap immediately expands to about 7mm. I have taken it off and reset it like 8 ****ing times now, and it still will not hold the gap right. It is a new tensioner, a new belt, all new pulleys. I replaced it all because it was doing the same thing with my old tensioner and belt. I thought maybe the belt had stretched, so I replaced it. I also considered something wrong with the tensioner, so I replaced it. The FSM doesnt say anything about turning the motor over there at step 18 before re-installing the timing covers, it just says check the gap after it has set for five minutes, I left it for an hour and had just under a five gap every time, until I turn the motor over. If I walk away from it and let it set for a bit, it will settle back to about a 6mm gap after it has expanded from turning the motor over. I don't get it. HEEEELLLLPPPPP!!! Thanks guys. P.S. the tensioner body is almost all the way to the stops to the right (facing the front of the motor) to get the gap right with both tensioners. Any help is greatly appreciated.
Yeah... I thought so too. It doesn't matter if it is all the way to the stops in the body of the tensioner, it does the same thing. Before I changed the tensioner, the body of the tensioner WAS all the way to the stops. Like I said, never seen this before, ever, in about 20 times of doing this. Never.
sounds like one of your cams is seizing... if you have 0mm gap them turn the engine over and end up with 6-7 something is holding the timing belt.. pull your cams off, then pull your lifters out, put the cams back in, they should all rotate freely
When you put the belt on at TDC, turn the motor backwards (anti clock wise) for a few teeth to take up the slack. Then turn the motor clockwise to pull all the slack to the tensioner. Adjust the tensioner (block bolts) into the belt to take up the slack. Lock the block bolts and release the 10mm retaining bolt in the tensioner. Turn the motor anticlockwise a few teeth and the clockwise a few teeth to check the tensioner gap. If the tensioner is too far open and the tensioner is at its max adjustment on the block then the belt is either stretched or wrong. Normally when you apply this method the first time the gap is usually 2mm and the tensioner need to be backed off slightly to get the 4mm gap. Oh yeah, and sometime the USA forum can be "real helpful: lol
Hey brother... thanks for the input. This is a complete fresh build. I had to replace the block because when I pulled it apart after the camshaft snapped, I found that my cometic head gaskets had been, evidently, slightly leaking coolant into the cylinders and three of them had some pits that couldn't be honed out. So i bought another block, had it bored, decked, line bored, tanked, and honed. All new seals, new rings, gaskets, fresh heads, the whole deal. So, I put it back together and started it, warmed it up, burped the cooling system, and watched the tensioner. It stayed around 6mm or so, and the belt was really tight when I shut it off, so I took it for a drive to try to get some pressure on the rings to get them seated. I put about 15 miles on it, accelerating, lugging the motor, compression braking, shifting up and down a lot. When I got back, I checked the tensioner with the engine running and it looked to be right at 4 mm. Now after shutting it down and letting it cool for awhile, the tensioner is at about 3.5mm. So, I will watch it and see how it goes.
This normally happens when the heads have been skimmed too much. How much did they take off them? I would grind out the adjustment hole in the tensioner a little so you can set it properly. The other option is expensive.
The heads were shaved about ten thousandths, the block was too. A total of twetny thousandths wouldn't make that much difference I wouldn't think. I just went and checked it again and it is still sitting at about 3.5 to 4mm. I think it'll be ok. It just freaked me out cause I couldn't make it set right. I have done the timing belt probably 20 times with the number of times I have had motors apart over the years, and this is the first one that ever gave me that much trouble getting it to set right. I really appreciate all the input guys. Like someone said, often times on the boards over here, people just want to be smartasses about everything.
Yep 20 thou isn't much, But they may have been done before. Good luck with it. That's the exact reason I don't post on TT.Net anymore. Too many adversarial bastards.
Hehe. I wasn't going to be so blunt re the USA forums, but I do agree. Your most welcome to hang around here as we are a helpful bunch. Twenty thou on each side of a triangle shape (timing belt pattern) would add to quite a bit at the tensioner. The tip on grinding out the adjuster hole in the tensioner base plate can help as Tektrader has said We had a belt on the weekend we were transferring from a spun bearing motor (while being run in) 1,000km so the belt was still new. When we put it on the replacement motor could not get the adjustment below 6mm. So toss that belt and put another new one on. All good.
