2000 Blazer, 4.3, 4wd. Code W, 212K miles.

On about 8 or 10 occasions I have experienced a start up and what sounded like one or both banks of lifters being collapsed. Oil pressure was at 40 lbs cold. Turned off and restarted several times. Same thing; after about 20 to 30 secs it would start to go away and all would be fine. This does not happen every time but certainly one time too many. Have changed oil and filter (got rid of quick lube type), but did not seem to help much at the time, although it has been less frequent since.
Normally on start up, there is a few ticks that go away almost immediatley. Then the engine sounds as if new; smooth and quiet.

Oil is clean and filter did not have much crud that I could see. When I first got the car I changed to non DEX coolant.
Is there a bypass in the remote cooler/filter that I should clean or replace?
Where in the oil circuit is the pressure being monitored?
Any ideas will be appreciated.

 

Sounds like you have sticky lifters. There are not a lot of proven methods aside from lifter replacement to cure the problem. Some have had luck with engine flushes or additives in the past.

 

First of all, thanks for response.

All lifters at once, and with good oil pressure! This only happens occasionally?
Anyone else?

 

I have quite a few lifters stick at the same time on older and/or somewhat neglected engines. And not all of them have to be collapsed to cause tapping that makes you think they all are.

At 800RPM, you will have 160 taps per second if all lifters were collapsed. That's a LOT... Without hearing that frequency of taps to compare it to, do you think you could discern between 160 taps per second and 80 or 40? Since you have nothing to compare it to, it would be awful difficult.

 

I'm trying Auto RX in mine. I have a little valve train noise at start up. Oil pressure is good, near 60 cold and holds 40 warm at idle in gear.

I just changed the oil and filter. Added the RX. I have yet to put the 2500 to 3000 miles on it but the wife is headed to OH tomorrow so it'll be soon enough.

187k on the engine / trans now.

I have no idea of the history of the vehicle, carfax just tells you who owned it. Oil I drained was reasonably clean, truck seems to have been maintained. Has newer ball joints and tie rod ends. I did the idler arm when I did the t-case vacuum switch.

I've heard great things about Auto RX. Never tried it, a buddy of mine did and it worked well to stop a small main seal leak as well as remove years of buildup under the rocker covers. I do have a small main seal leak as well as the seemingly requisite remote oil filter hose leaks.

We'll see. I'll post again after I complete the treatment and run the rinse cycle.