O2 sensor boss leak, engine vibration, oil & spark plug.. Love this forum - have learned a lot from earlier posts but wondering what you would make of this nice set of issues:
symptoms & observations:
1. "slurping" engine sound under load, with some loss of power.
2. O2 sensor boss is leaking (probably causing (1) unless these are just symptoms of a bigger issue)
3. heavy engine vibration @ idle and under load @ lower revs, and a noisier, growling engine than before. This issue started a year ago after getting bogged at the beach (wife driving..) and getting out at full power.
4. one spark plug head soaking in oil
with the good news being:
1. compression test looks good: 190/187/185/190 psi
2. no error codes
Any thoughts on:
- re O2 sensor boss - my car was part of for that recall and the dealer says it's been done (by previous owner). This recall has been closed in 2010. Before I'll have the O2 sensor boss welded which would void the case for Nissan having to fix it (and cat issues if so) - I guess my chances would be slim - or could I say it's Nissan's responsibility because a) apparently the recall fix wasn't done properly at the time or b) apparently their recall fix doesn't fix their design issue?
- re oil-fouled spark plug: probably not related the the other issue? The pcv valve seems to work fine (rattles, and sucks air when taken out of engine cover) I guess this sounds like a valve guide/seal issue?
- re engine vibration: I had a Nissan dealer take a quick look at the engine vibration but they didn't find anything obvious. Engine mounts are OK. I'm not a fan of leaving my car with them just to hear that they could replace part X at my risk - to find out that wasn't the issue..
Re: O2 sensor boss leak, engine vibration, oil on spark plug.. to add: I have now removed the exhaust manifold / cat.
Turns out the cat is broken too: looking up through the exhaust end of the cat you can see most channels of the (at least the lower part of) the cat are gone: I guess I'm lucky (judged by the good set of compression test data for all 4 cylinders) that the ceramic cat pieces haven't found their way back into the engine..
Would this broken cat and the cracked O2 sensor boss both be caused by Nissan's original design flaw behind the O2 sensor / cat recall.. ? Or would it rather have been the oil on one of the spark plugscausing unburnt fuel to heat up the cat.. I'm in limbo between taking this up with Nissan claiming the first - or buy a wreckers' manifold/cat and hope the oil at the spark plug won't cause the new cat to burn as well.. Replacing valve guides sounds like a lot of work for this car with its 192k km and its issues..
Date Registered: 02-2004 Location: SUTHERLAND, SYDNEY TOTAL POSTS:29094
Re: Yep, that's the cat converter gone for sure and by the looks of it, it has disintegrated from continues exposure to thermal heat load, which is exactly what the Nissan recall tried to address (in addition to the O2 sensor boss breakage). Here is what the recall stated:
Heat deterioration may occur inside of the Catalytic Converter when it is repeatedly attacked by excessively high thermal load. This could result in Breakage of the Catalytic Converter honeycomb. The weld zone of the O2 Sensor Boss (physically part of the exhaust manifold) may be damaged. If the vehicle is not repaired and driving continues, the O2 Sensor Boss may be broken.