Diagnosis

[chris.richard]

As part of the house moving process I had to move the Stratos to a friend's garage until I get the new one ready. Engine makes a loud knocking from the bottom end, about crankshaft rev frequency. Not apparent when cold, or above 2000 rpm. Any ideas ( cheaper the better! :rolleyes: )

[strat6v]

Rods,Mains or big ends. Easy to get the sump off.

[Arthur]

Chris,

I had the same. Fretted over bearings; chewed fingernails over fouled injectors; panicked over money, and especially having to work.........talked to a very knowledgable man, who said - if you've got those awful plugs with the rim electrode, chuck them away. Sure enough, I had just one duff plug in the 6 - fitted new (at huge expense) with real centre electrode and standard bent-over tab; all problems gone away, plus much easier to drive at traffic speeds.
Can't remember the plug designation, but it's the type quoted in the CD manual for the "S" engine.

Worth a look-at, for sure. I was convinced I was losing a bearing.

Arthur.

[chris.richard]

Eee, Arthur, you had my hopes up for a minute there! I've pulled all the plugs, and they're all fine. Iridium ones I put in, I can't remember the number. Front bank been running a bit rich, which fits with the MOT finding of one bank running richer than the other. Now why would that be? :confused: All three injectors would have to be equally out, so points more to the power unit or ECU.
The middle plug had had some water ingress down the hole, so I'll change the coil pack for a spare in case there was a poor contact with the plug.

[CorseChris]

A rich-looking bank could be a slight cam timing error on one bank perhaps?

First reaction to your description of the noise does suggest a problem with a big-end bearing though :( Pretty common problem with these motors it seems.

The 155 V6 has had a hot oil knock at idle for a very long time, as long as I've owned it in fact, so well over 50k miles. I replaced the shells last year as it was getting really bad, which helped for a while, but the noise is back and it's showing a reduction in oil pressure at most engine speeds. On inspection of the shells I removed, it was obvious what's making the noise! #1 big end was looking decidedly worn. I sometimes wonder just what happened to this car before I got it.

Off with the sump and have a quick look........