Secondary tensioner cracks
 

Hi guys

I changed the secondary tensioners yesterday, the old plastic tensioners were both cracked all teh way along the front side and both had lost theit plastic chain guides. After I had taken the photos on of them fell apart in my hand, so changed not a moment too soon.

The service records had an invoice to fix an oil leak in the left hand bank cam cover ( $800 ) and when i opened it up there was blue RTV sealant everywhere - clearly the seals hadn't been changed and the 'technician' had just put as much RTV on as he could. That why I would rather do my own work ! Surely they must have seen the tensioners when they were in there.

Also installed a new water pump, though the old was turned out to be OK, new hoses, thermostat etc. I will replace the spark plugs this week, I had a look at them whilst in there and the electrodes are down to nothing.

Did you inspect the chains for wear? It sounds like they were running on the metal for a long time and may need to be replaced. If they are okay, you still need to drop the pan and remove the oil pickup to remove all the pieces of plastic from the screen.

Good idea. the chains looked ok, and the tensioners only had slight grooves worn on the metal ends, so may not have been running like that for long.

I will drop the pan next week.

Failure history
 

I was just wondering if there is any history regarding Tensioner failures. Is it the secondary tensioner which normally fails or is the primary tensioner also a salient concern. Additionally, is there any stats. on guide failures. Is it prudent to replace all 3 items? Any information on cost. I own a 1998 XK8 with 54K miles and would like to proceed in the near term by addressing these issues.

The secondary tensioners are definitely the larger concern. Even low mileage cars show cracks when they are checked. Recommend yours should be checked as soon as you are able and replaced if they are the plastic variety.

No consistency on when they let go, but it is an interference engine which means if they fail, you are looking at a very large repair bill.

My understanding is that the primary tensioners and lower guides are less of an issue. At 54k miles they should be OK. Mine are original at 104k.

I pulled the oil pan/sump off mine over the weekend and removed the plastic debris ln the bottom of the pan. From the amount of bits I removed, I would say that they are the sum of the two plastic skids missing from my original tensioners. There's not enough material to suggest that the primary tensioners have fallen apart yet, so for now I am happy to have just changed the secondary tensioners and am extremely glad that I did. The crack in each one goes from top to bottom, and I can't see how they could have been working as any oil in them would just have poured out of the side. No wonder I had a rattly engine.