Quote:
Originally Posted by Laird Scooby
Denso make good plugs too, they are always my secod choice after NGKs - if they were the same price or cheaper than NGKs they'd be first, it's only the cost that puts me off Densos.
I've only ever known one set of NGKs do what you describe and by sheer coincidence, was in my 760 with the later B280E under the bonnet.
I wonder if your timing cover has gone porous? After hearing your diagnostic efforts, it suggests that may be the case.
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Here is a brief summery of the running rich issues which we are still trying to get to the bottom off. The Haynes manual isn't much help either.
Slowly but surely we are making some very slow progress forward, without going two steps backwards, I guess this is a good thing. In the past it has been running so rich it is filling the sump with fuel. Flooding and destroying the spark plugs. We started off with the sender unit thing in the tank, cleaned out all the lines, removed the pump from under the car, blew this out and the lines to the engine bay filter, along with what looked like tiny spider corpse's and tiny bits of debri. So I knew this part was good now and working, plenty of fuel pressure at the fuel distributor, though nothing coming out of the injectors. New injectors and spark plugs, car still wouldn't start. So we ordered a new fuel distributor kit, and on stripping the unit down found a washer had fallen off the spring which had punctured the thin tin gasket. Replaced, the rubber seals, resurfaced the 2 parts and reassembled everything, fitted this back on the the car. Now it finally started after minutes of cranking and blew black/blue/white smoke out the exhaust, not a great deal but enough to think there is something not quite right. Then it was decided to look at the distributor cap and leads, which isn't an easy task on these as the injection system is in the way of the cap coming off. Everything stripped off and access to the cap was better. We found that the dissy was missing one of the retaining clips. So out came the dissy to try and match a new one. While this was being sorted, the core plug leak water from under the exhaust manifold. This was duly replaced, new gaskets also fitted there. With all the additional new parts everything was refitted, and hey presto, a runner, well, a 4 cylinder runner and more black smoke than a poorly running diesel truck! No amount of fiddling with the mixture control would work, although the car would rev very well indeed, then it just flooded itself out. The spark plugs were soaking wet and 12 litres of fuel had disappeared very quickly. A quick check of the oil level revealed where it had gone. We drained out 8 litres of black fuel from the sump. I poured new oil in, dried off the plugs and restarted the car, only to be shocked by the amount of white/blue/black smoke from the exhaust. This was so bad it resembled a blown turbo. Then the car stopped again, now the only way we could gat the car running was to keep the throttle well open and keep feathering it. Took out a few plugs again to find them swimming in fuel. This killed the spark plugs now had totally destroyed the plugs, so a new set was ordered. The new Volvo HT leads we bought are rubbish, 3 of the ends that plus over the plugs spilt and were shorting out, so we slipped these off and fitted the original ones. Still the engine ran far too rich and flooded these new plugs. So we made the decision to remove the entire housing that holds the butterfly thing. On doing this we found the adjuster screw wasn't attached to the butterfly clip, the plunger too was a little sticky so we were guessing this may be causing the over fueling issues. Once we had fixed what was obviously someones bodge we refitted everything and got the car running on cold start idle which was such a relief. However as soon as the car started to warm up and the revs dropped slightly it stalled. Timing out, mixture out, I don't know but at least we are starting to make headway now, and no smoke out the exhaust, just a hint of over richness. I did remove a couple of the plugs and believe it of not, the tip was not black soot, of wet, just a sign of rich running. However the thin tin gasket is leak so now that has to be removed and separated...again!! I remember when I first fitted the new gasket there was a grease pack with the kit. This time I reused the old gasket and used no grease, I wonder if this has caused it to leak?
Oh, the oil has stopped leaking from the hole, but good call Laird. I guess when we replace the water pump, we will see things a bit better.