I have a 1995 Nissan Pathfinder 4x4 V6 with 118K miles, that is giving me some minor trouble.
Upon starting, I sometimes hear valve tapping sounds coming from the engine, which would mean to me that the oil is not circulating properly. This quickly goes away after 3-5 seconds. I just changed the oil to 20w50, and I added some Lucas heavy duty oil stabilizer. The problem went away only for a few days.
I get a slight exceleration knock using 87 octane fuel. I added Marvelous Mystery Oil, but the problem quickly return a few days later.
I would think 20w50 would make it worse if the problem is lack of circulation at startup. Use 5w-30 per the manufacturer's recommendation and make sure the oil filters you are using have anti-drainback valves. How often do you change the oil?
Try a different brand of gas, or fill it up at the 89 pump and see if the pinging stops.
Wouldn't that be "piston slap" ? There is a piston slap problem on some 95-96 VG30 engines. I don't rememer the details but a google search will gibe you more details on this.
Could be. My '96 Honda developed that problem at about 50,000 miles. The oil filter is a cheaper test to do first though.
On the Honda the fix was to either ignore it or replace the engine. We chose to ignore it. Strangely enough, after another 60,000 miles, it went away by itself.
Not a problem to be concerned at 118K miles. Doesn't mean a lack of oil circulation either. Just a lifter that loses its prime. Once again that's normal wear. Be concerned if it stays noisy.
Use a higher octane fuel. The knock is probably of minimal importance to an engine with 118K miles on it.
I own a 94 Pathfinder with 185,045 miles and had the same tapping sound at start-up as you describe and had a slight knock at acceleration also. First off, Pathfinders have a known issue with the exhaust manifold bolts breaking off in the head, which was the case with mine also, the tapping noise would go away after about 5 to 10 seconds at which time the heads would be warm enough to expand and hold the bolts tight. As was the case with my pathfinder, I had to replace the exhaust manifolds because they had warped but if caught early enough, you should be able to avoid replacing the manifolds, and I replaced the exhaust studs with stronger hardened ones. Now as for the knocking at accel problem, I tried different heat range plugs untill the knocking didnt happen anymore upon acceleration, I cant remember the heat range of the plugs that I used though. Do a search on the net and you will find alot of other people with the same tapping sound at start up and 9 times out of 10 it was caused by broken exhaust studs tapping around in the head. I hope this helped a bit.
"Jim Rojas" wrote in message news:A8W3d.3231$C8.2058@trnddc05...
It's only a fair comparison if the two vehicles have the same motor.
Somebody said exhaust manifold and broken studs. I've heard that plenty. Even seen it twice in person as a couple good friends own a very busy muffler shop. Motors in that vehicle (95 Pathpuppy) of that design did have exhaust and manifold issues.
It's not the bolts tapping. It is the subsequent exhaust leak that causes the "tapping' noise. Typically, this goes away after the manifold warms up. Mine did it for 60,000 mmiles and I never did get around to fixing it. The fix is to have the warped manifolds milled flat and replace all of the studs. If you buy new manifolds, they will simply warp again.
The cause of the problem is the manifolds warping. If you take one that is already warped and mill it flat, it will stay flat. The new ones will eventually warp. (this is what an experienced nissan tech told me anyhow).
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