The 75 and ZT Owners Club Forums - View Single Post

drjonts · 2nd February 2020, 16:56

Hi folks,

Update: I didn't have much time before the rain came the other day and I thought while the engine was cold and the belt 'slack' I would see what I could do as a test tweak to the cambelt tension. As it looked like the tensioner piston really hadn't shifted in 23k miles, I thought...why not see if anything can move in there.

So I got my little 3/8" ratchet and a flat screwdriver bit together, a mirror lodged beneath the area of interest at an angle and a torch on a magnet, I set about attempting to get the flat of the screwdriver bit into the small gap between tensioner piston body and the pulley carrier. After a lot of tries (mainly of course due to moving backwards with the mirror image) the bit was in place and I gingerly pulled on the ratchet handle.

Didn't feel like very much had happened to be honest, but on checking, the belt must have tightened very slightly as I didn't have the same slip back and forth on the cam sprocket. I took another look down at the mirror and tried to convince myself that a tiny shift had taken place and perhaps I couldn't now see alignment of the pin holes in piston and tensioner body. Perhaps this had moved a mm or 2?

Had forgotten to snap a before picture but managed to get a set up to snap what I could see now.

These show the position after things moved a tiny bit - there was less of the piston showing before I tweaked things when the locking pin holes looked to be still aligned.

Bit the bullet today and started the car up. No obvious flapping from cold on the run between cam sprocket and waterpump and no obvious 'tight belt' noises. Left it running for a bit and things seem OK. Will repeat a few cold starts and see if the piston stays where it is rather than being pushed back on cooling. When happy I'll put the cover back on and try o keep an eye and an ear on it.

Fingers crossed I may have saved the belt from running slack and doing any potential damage. I can keep an eye on things for a bit and hopefully extend the lifetime of everything until the time is better for a belt change. Obviously I can't check the pulley wheels and I still have a feeling that something is 'jammed' enough to not move under the piston action - either the piston itself is stuck or weak or the pulley carrier is stiff (having also found Gary's (Lovel) post about a binding pivot).

Cheers for now.

Jonty

2nd February 2020, 16:56	#74
drjonts Loves to post MG ZT-T 160 Join Date: Dec 2015 Location: Devon Posts: 288 Thanks: 179 Thanked 70 Times in 53 Posts	Pictures Hi folks, Update: I didn't have much time before the rain came the other day and I thought while the engine was cold and the belt 'slack' I would see what I could do as a test tweak to the cambelt tension. As it looked like the tensioner piston really hadn't shifted in 23k miles, I thought...why not see if anything can move in there. So I got my little 3/8" ratchet and a flat screwdriver bit together, a mirror lodged beneath the area of interest at an angle and a torch on a magnet, I set about attempting to get the flat of the screwdriver bit into the small gap between tensioner piston body and the pulley carrier. After a lot of tries (mainly of course due to moving backwards with the mirror image) the bit was in place and I gingerly pulled on the ratchet handle. Didn't feel like very much had happened to be honest, but on checking, the belt must have tightened very slightly as I didn't have the same slip back and forth on the cam sprocket. I took another look down at the mirror and tried to convince myself that a tiny shift had taken place and perhaps I couldn't now see alignment of the pin holes in piston and tensioner body. Perhaps this had moved a mm or 2? Had forgotten to snap a before picture but managed to get a set up to snap what I could see now. These show the position after things moved a tiny bit - there was less of the piston showing before I tweaked things when the locking pin holes looked to be still aligned. Bit the bullet today and started the car up. No obvious flapping from cold on the run between cam sprocket and waterpump and no obvious 'tight belt' noises. Left it running for a bit and things seem OK. Will repeat a few cold starts and see if the piston stays where it is rather than being pushed back on cooling. When happy I'll put the cover back on and try o keep an eye and an ear on it. Fingers crossed I may have saved the belt from running slack and doing any potential damage. I can keep an eye on things for a bit and hopefully extend the lifetime of everything until the time is better for a belt change. Obviously I can't check the pulley wheels and I still have a feeling that something is 'jammed' enough to not move under the piston action - either the piston itself is stuck or weak or the pulley carrier is stiff (having also found Gary's (Lovel) post about a binding pivot). Cheers for now. Jonty Last edited by drjonts; 2nd February 2020 at 23:27..