congratulations on the pass, another years motoring, and extra congrats for the emissions too, something which terrifies us all

congratulations on the pass, another years motoring, and extra congrats for the emissions too, something which terrifies us all

So just when I was congratulating myself on getting a MOT for the V6, and thinking I could move on to the BG ...

... I was on a trip a few days ago, and just as I arrived at my destination the car started running poorly and the oil light came on. In a few minutes, the entire 5 litres of new oil I'd put in for the MOT two weeks before, had all peed out the bottom of the car

I thought I'd left the oil filter loose, or the drain plug. But no. Then I thought the new rear rocker gasket had leaked. But it seemed dry. The sump gasket was also fine.

Then I thought the PCV valve might be blocked, and the extra pressure in the engine caused a leak through the gaskets. But even with a new valve, the oil still leaked out.

Then I noticed this:



A core plug had fallen out of the engine block, and when I did a test and filled up with some new oil and turned the engine on, the oil started pouring out the hole!

It should look like this (photo from Andy Bowen):



There are two of these on the V6, apparently they cover holes that were made when the engine was manufactured. Mazda still supply these plugs, and for only £8, but it would take a week to get it from Europe, and I didn't have that long. Fortunately with Hughie's help I located a correctly sized core plug for £2 on eBay, and paid to get it delivered the next day:



After filling the hole with a silicon-based sealant, I banged in the plug. It took a while because there is limited room in a V6 engine bay to swing a mallet, but after about 20 minutes of tapping with a small lump hammer it was finally flush against the block all round:



Test drive today ... no leak from the new bung! (the white stuff is sealant I smared around the edge, just as an extra precaution):



However, the car was STILL leaking oil, though only very very slowly. After some investigation I realised that it WAS also leaking from the rear corner of the rear rocker gasket, which I replaced in February ... evidently I didn't do up a nut tight enough. When I looked at the gasket the other day it was dry, but obviously because there was no oil in the engine at that time, I couldn't turn it on to check the gasket when it was under pressure. After the main problem was fixed and the oil was replaced, and I did a test drive, I was able to see the oil dribbling out.

At least it's manageable / sortable, and I don't seem to have a leak from anywhere worse. Fingers crossed ...

S

Wow, you were lucky if you stopped the engine before it ruined the bearings,
Swing a mallet? under there you can't even swing a cat ...
And there was me thinking that core plugs only did the coolant circuit!
Learn something every day.