XUD Oil Pump Drive Chain Tension.

David W · Unread post by **David W** » 24 Mar 2007, 18:58

Guys,

Been years since I've been inside a 1.9TD sump.... so reliable these engines! Anyway I'm changing the sump on my newly bought Xantia Estate as the old one is damaged.

While it's off I've been tweaking the oil pump drive chain and pondering if it feels a bit slack. It probably isn't but, as far as you can describe a tension in words, how slack/tight should they be?

Thanks,

David

Stewart(oily) · Unread post by **Stewart(oily)** » 24 Mar 2007, 19:48

It just sort of lies there, theres no tensioner is there? and from memory one of the sprockets is plastic

Stewart

AndersDK · Unread post by **AndersDK** » 24 Mar 2007, 19:49

Hi David -

Last time I was in that place on an XU I also noticed the chain was pretty slack - approx 15mm movement both sides - but by no means able to touch itself on the run between the cogs. Its normal as there are no means of taking up or adjusting the slack - except shim the entire oil pump base with the characteristic L-shaped steel spacer.

If you do a simple calculation on a circle - and then add just 1/4 a mm to the radius - think about the resulting increase in perimeter lenght : 2*pi/4 = 1.57mm.
No wonder the chain will be slack after a run-in period

David W · Unread post by **David W** » 24 Mar 2007, 20:55

Thanks. That's what I'd hoped to hear. With no tensioner or "slippper" guides (like an older type engine timing chain for example) I guess it will flop about a bit at rest. I'll not worry about it.

As a matter of interest the reason my sump is damaged is because it appears my car (at less than 70K) has suffered the classic engine failure at no.4 conrod. They have replaced the engine but used the old sump with alloy welded repairs front/rear where the various engine parts had tried to escape. It was a DHX code.

The things you find when getting that shiny new purchase home!!

David