Plastic Chain Tensioners

[19shaun79]

Hey Folks,

When is the right time to change the chain tensioners?
I have to replace the impulse sending wheel on the exhaust cam (long story) and when I was removing the VANOS, I was looking at the plastic chain tensioners and and there was a plastic square that popped off one. You can see in the diagram on #2 the square where the plastic piece popped off. It almost went down to the oil pan.

Should I change the tensioners now that that piece has come off? The rest look fine.

TIA.

Shaun

[sapote]

It’s not a plastic tensioner which is #5. It’s the #3 upper guide that has its lower tip broken off.

[19shaun79]

"It’s not a plastic tensioner which is #5. It’s the #3 upper guide that has its lower tip broken off." - thank you.

Here are some pics... is this a long DIY?

[nahvkolaj]

When you're in far enough you can see it, it's a quick job to replace #3. I replaced mine with a Beisan part while fixing my VANOS.

https://beisansystems.com/product/s54-exhaust-upper-chain-guide/

[sapote]

"It’s not a plastic tensioner which is #5. It’s the #3 upper guide that has its lower tip broken off." - thank you.

Here are some pics... is this a long DIY?

No hard, but the EX cam sprocket must be removed, and also the vanos hub. This means the vanos must be retimed, so search and learn how to set the timing. Also remove the cam sleeve bolts -- 12 total -- and clean the threads then add medium Loctite to avoid they backing out leading to bent valves.

[bigjae46]

The tensioner shouldn't need to be replaced. The guide is what breaks.

If you're talking about parts #1 and #2...#1 is aluminum with a plastic wear surface. I'm sure the plastic will fail at some point. To properly replace those parts - you have to remove the head due to the timing chain overhang. The head gasket may not seal back up where it meets the head, block, and timing cover.

So what I'm saying is replace the upper guide and send it.