98 k1500 knock

found alot of usefull info on this site, hope someone can help me a bit again. ill try to get all my info in a short story. 1998 k1500 5700 engine, auto transmission 90000 miles all stock except 4.10 gears.(its actually a gmc but thought might get more responses here) everything going good, pulled camper everything aok when i got home, couple weeks later started up, drove to gas station and back, about 6 miles, oil pressure gauge down to 0 and check gauges light on at idle, speed up a bit it come up. needed to use pickup and thought maybe just sender. engine sounded fine. pulled camper 90 miles no problem except light on at idle. did some site seeing not pulling camper. hooked up to come home and now slight knock once in a while. played around abit and seemed to be worse in drive and less in overdrive, no noise at idle or at hard throttle only at light load. got home now is worse, makes knock when you rev engine. installed pressure guage. engine hot, 4psi at idle, 8 psi at 1000rpm, 20psi at 2000rpm. my chilton manual shows this should be in spec, seems kinda low to me. if so why would i all of a sudden loose oil pressure? if my knock is a rod or bearing, would i have made it 90 miles pulling hard without a complete failure? my experience with rod bearings is once they go it goes quick. before i pull pan and check out, does the oil pressure sound ok to anybody? could the knock be from something else? if i hold rpms at about 1500 and turn the a/c on it really knocks, turn it off and it goes away, i think is just putting the right amound of load on it. i had one guy tell me that if a knock sensor is terrribly bad it can actually make an engine knock, anybody agree? anybody have any experience like this? it idles smooth and not a bit of noise. sorry it got longer than i thought. any help please. there has not been any previous engine work, tranny work, exhaust work. only oil changes. thanks in advance

Sounds like you are either very low on oil or your oil pump is near death.

You can run pretty low on oil (3 qts) before you see any signs on the pressure gauge. Usually stays above 40 psi, but as oil goes down, idle will drop it to under 40, but return above 40 when revs are up. Very low oil will drop it near the 10psi redline at idle and some lifter tapping may be heard. I ran it down once to that point, and just as I was pulling off to check it, the light came on. WHEW! Needed 4 qts of rest-stop quality, overpriced oil. But it got me home with kids and car in tow.

Probably wouldn't hurt to check the plugs and cap & rotor terminals for build-up and oxidation, too.

I have had a "rod knock" in mine for the better part of 90,000 miles and up until last month not one reliablity issue. Real loud when cold, hardly noticable when hot. I say "up until last month" because my son left the cruise control on in the mountains and it kicked down doing 65 up a hill and sucked a valve:banghead:.

That oil pressure sound way low though.

i have owned since new. oil changes every 2000 miles, never run low on oil, always warmed up before driving. well i see how that worked out for me. dropped front diff and oil pan this evening and checked bearings. #3 main bearing is spun. now for decisions. shortblock? longblock? rebuild myself? bad thing is ive been thinking of trading it off for a while now. looks like im married to it now. does anybody know why the back of the bearings are stamped with the date and .0006? bearing im used to using in ag equipment are stamped on them if they arnt standard size. ive heard of peaple building 383 stroker engines for these pickups but i have never found out if they can be left fuel injected or if they need to be converted to carb, does anybody here know? what are peaples experiences with reman companies and best places to buy if i go that route? thanks again.

I struggled with the "what to do" also until I found a guy that gives a 5 year warranty and uses only new cam shafts on long blocks so I ordered it.

Jasper Engine and transmission do a pretty good job for rebuilds and give a decent warranty as well.
The other option would be to regrind the crank, rebuild the engine and have no warranty.
Auto parts stores will get you engines, but I can't say what kind of quality or warranty you will get. Advance auto in a real pinch!