Hello, I have been lurking around this message board for several weeks. It seems to be the best place to find info on the Chevy IFS. I recently bought a 1992 full size Chevy Blazer. The truck has 136K miles and the engine is a GM Goodwrench crate motor with 68K miles. This is my first truck and I really like the ride. She needs a little work here and there but things are coming along nicely. Now for the possible bad news. About a week ago I noticed some erratic oil pressure readings on the stock gauge. Out of nowhere the idle oil pressure drop to about 20 psi but under acceleration would go up to about 40 and crusing on the freeway would normally see about 30-35. Now yesterday cruising on the freeway doing about 2K rpms on the stock tach and keeping the speed constant the oil pressure was at about 32 and would raise up to about 37 and then fall back to 32. Now when I got home I sat in the driveway in drive and the oil pressure was at 22. I put the truck in park and the pressure ran up to 28. I revved the engine a little and it went to about 32. I am not sure what to make of this right now. At this point I thought about replacing the sending unit for the oil gauge. But if the gauge is accurate does this seem like a faulty oil pump? Any suggestions or troubleshooting advice is appreciated.
I think any action right now is premature. Maybe try an oil change? driving in city traffic on hot days with the AC on effects my oil pressure in weird ways[img]/wwwthreads_images/icons/crazy.gif[/img]
Thanks for the quick reply. Here in Arizona there are a lot of hot days and the A/C is almost always on. I changed the oil a few weeks ago when I initially bought the truck. I put some Valvoline 10-30 in. Then after I noticed this erratic pressure I changed it again thinking maybe the oil filter had a problem or something. I also thought maybe I should try a slightly thicker oil. So I changed it out with Valvoline 10W-40 and a new AC Delco filter. It seemed to help for about a day or so. So I checked the oil thinking maybe it was getting contaminted by another fluid such as coolant or gas. No signs of coolant in the oil but the oil had a faint gas smell. But I would imagine any oil in the engine will have a faint gas smell after a few miles. I am hoping it is just a problem in the oil pressure sending unit. Other than that the truck runs awesome. It doesn't even give a small puff of smoke when first started like I see with a lot of Chevy small blocks. BTW, I just added a Dynomax catback with a 3" catco cat. The truck has a nice rumble to it and feel I got my money's worth.
It wouldnt hurt to do a compression check on the motor just to see where its standing. my 89 with 200k on the motor is pusshing 140 to 150 on all the cylinders, at least thats what I think it was its been while since i checkes it.
16x8 bajas wrapped with 285 TXRs, T-BARS cranked to level, and minor trimming
your oil pressure sounds fairly normal. if you want, take it down to the dealer and have them use a mechanical oil pressutre gauge on thetruck while they run it. costs about $55. i'm sure you could probably do that yourself.
i don't like 10w40 oil...mainly because there are a lot of additives...which are not always good for protection. here's where i say switch to mobil 1 10w30 synthetic. here in south texas, 100* is everyday occurrences. i trust the synthetic tohandle the heat a lot better than the conventional oil. of course, if you do switch you need to take into account the condition/age/mileage of the engine as well as the costs of the synthetic oil.
<font color=blue>Shorts</font color=blue>
Your what is stuck? [img]/wwwthreads_images/icons/crazy.gif[/img]
I don't use 10w-30 anymore, its too thin for the heat, also down here in south Texas, but i can't use synthetics since my '89 has far too many miles on it. I use pennzoil 20-50 and change it at 2500 miles. Still have good oil psi.