View Full Version : Knocking. Barely. Annoying!!
04-24-2003, 01:59 PM
Well, here's one I just can't figure out. When I start up my car on a warm day, but the engine's still cold, it'll make a slight tapping noise for about 30 seconds or so, and then stop completely. It doesn't do it at other times, and the engine hasn't been under too much stress (if any at all.) My oil's fine, rather fresh, new plugs,full coolant, new thermostat...Just about everything! any ideas on what's tapping away in there just to drive me crazy? It doesn't seem to mess with the engine's performance...
04-24-2003, 03:52 PM
Sounds like a lifter. Probably doesn't have enough oil when you fire it up. After the 30 seconds there's enough oil and the sound goes away. Common problem with many many vehicles on the road.
04-24-2003, 08:10 PM
Mine does the same thing. Its a sign of a worn rod or main bearing. When you start a car, theres no oil pressure for a second or two. Since the bearing is worn, and there is little to no oil in the bearing to make up the difference, you get a slight knock. Once you get oil pressure and oil in all the bearings, the oil makes up the small difference and prevents the knock.
As far as it being a major concern... its hard to say. I've seen motors last like this for 2 weeks, or 2 years... Just keep oil in it, and change it every 3K and you should be alright for a while.
Hydraulic lifter tappets can get sticky if they don't get enough oil, and can sound like this until the engine warms up - one 5m-ge of mine did it like yours, then all the time. Havn't gotten around to fixing it yet but Im pretty sure thats what it is.
05-09-2003, 12:07 PM
my 85 does the same tapping type noise, its driving me crazy! :mad
the problem is the valve adjusters are weak (266000miles), im planing on replacing all of them with the oil pressure regulator on top of the head. anyone know where i can get them cheaper than at a dealer?
05-09-2003, 11:58 PM
The lash adjusters can stick from varnish and carbon build-up, as can the lash adjuster oil pressure regulator valve. Some members have suggested using ATF in the engine oil to help free them up. 30 seconds is way too long for a bearing knock to quiet down. I've also heard that the forward most lash adjuster(s) can sometimes develop an air pocket internally after engine shut down. I had a similar problem with one or two lash adjusters on my 85 but never actually dug deep enough to find the actual cause. Switching over to synthetic oil helped quite a bit though in my case.
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