1991 q45 spark plugs

[BHurvitz]

I have used stock plugs in the past, but I am thinking of trying NGK Iridium IX spark plugs, part # BKR5EIX11. Has anyone tried these? Also I was thinking of the Bosch platium 4s. Appreciate feed backBob

[DAEDALUS]

One of the cardinal rules here is to use only the factory NGK plugs. Anything else just doesn't work as well or for as long, and some (Bosch) are reported to have electrodes break off inside the combustion chamber, damaging the engine.

[Q45tech]

There is nothing to be gained with iridium as the plugs need to be replaced every 60-75k [4-5 years] to clean the leaking oil out of the spark plug well and to keep the threads from galling.

With individual coil on plug designs the plugs will almost always fire even after they should be changed for other reasons.

The NGK oem come is multiple heat ranges to select for your location and driving style most aftermarket [Bosch] are one style fits all [UGH].

[maxnix]

Another Q45tech post of relevance:

http://210.101.116.115/fisita/pdf/A144.pdf

Understand the technology of these alloys. What advantages each hasand if they are for you especially note the 900C-1200C tiptemperatures and oxidation problems under severe service.

[DrewQ45]

There is nothing to be gained with iridium as the plugs need to be replaced every 60-75k [4-5 years] to clean the leaking oil out of the spark plug well and to keep the threads from galling.

With individual coil on plug designs the plugs will almost always fire even after they should be changed for other reasons.

The NGK oem come is multiple heat ranges to select for your location and driving style most aftermarket [Bosch] are one style fits all [UGH].

Jeez... I cringe when I see this as I have brand new set of OEM plugs sitting in the trunk. Current plugs have 80K (she's still running like a champ) on them but I don't want to change them until I get the under-plenum hose set... a job I won't do till 70 degree temps are standard again! Is there a way to seal the seating so the oil won't leak into the spark plug well? My last set had one or two submerged.

...Drew....

[Q451990]

Is there a way to seal the seating so the oil won't leak into the spark plug well? My last set had one or two submerged.

Some members have had success smearing some RTV at the seam near the top of the spark plug well, but the real solution is resealing the rocker covers. The problem is that once you're far enough to smear the RTV, you're right there at the plugs and might as well replace them!

Heath

[maxnix]

And except for a couple of breather hoses, doesn't have that much to do with plenum removal.