Hey there been quite a long time since i posted in the forum.
I recently just changed the radiator and a freeze out plugin my 1995 Chevy Blazer. Engine has 75,000 original miles. Once put all back together and all was good. Upon driving it I noticed the oil pressure gauge fluctuating. It would read almost zero when stopped at read about 40 when driving. Check gauge light would blink on and off. Then service engine soon light came on as well. The following day when i went out to check the problem the gauge was working and the lights where out.
Upon driving it again the oil pressure gauge dropped light blinking and noticed a tap from the top of the engine. Sounds like the oil is not getting to the top of the engine. Could this be a oil pump issue? Is there away to check oil pump, and if the oil pump needs changing, what does changing the oil pump out entail. Looks and sounds like a big job. Thanks for reading and any information is appreciated.
Thanks,
Dustin

 

First thing, check the oil pressure with a mechanical gauge as the oil pressure sensor is not of the best design.
Oil pressure sensor is located under and behind the distributor....not easy to get to. This is where to connect the mechanical gauge. If the mech gauge shows the same thing, then we will go from there.

 

+1^ Lanny... yes more than likely it's just the sender. But it is better to be sure with a mechanical gauge as stated

 

Hmmmm...last guy that had an oil pressure "gauge" issue posted on here a couple weeks ago ended up blowing up his brand new reman engine (due to no oil pressure).

 

hey, that's why I agreed in checking it first.... you never know! lol

Sorry for the guy who didn't and blew engine up. SMH :-/
You know what? Also shouldn't have taken that so insignificantly in a new reman.... not until thoroughly broken in at least. Should pay attention and verify everything even more.

 

One of the first rules in engine replacement is: whenever a new engine is installed into any vehicle the oil pump should be spun using an electric drill and adapter to verify oil pressure. Either use a mechanical gauge or the vehicle's oil pressure gauge can be used provided the fuel pump fuze or ignition fuze is removed so that the engine does not start.

Now there is not much room to do this in the Blazer...perhaps a right angle drill could be used...but after a new engine is installed, oil pressure should be verified BEFORE actually starting the engine.

 

^^^Yep, I primed the **** out of mine and had a mechanical gauge hooked up from the first spins. My point of pointing that out about the guy that happened to is so as not to take the OEM gauge lightly. True they aren't the best...but if my stock gauge was indicating poor readings I would not chalk that up simply to a gauge problem. I'd throw a mechanical gauge on before I next started the engine. But that's just my opinion

 

I agree 1000% that a mechanical gauge is the best route to take. If the stock gauge was fine prior to engine replacement it could be used, but still a mechanical gauge is best.

 

Thanks for all the feed back. Much appreciated folks. Trying to get my hands on a oil pressure tester. To run the diagnostics. I really do not understand how a bad oil pressure sending unit has anything with the lifters tapping tho, The sending unit is just a sending unit right?. If someone could clarify. I will let you all know what I find out once i test the oil Pressure.
Thanks To You all,Dustin

 

A bad sending/bad gauge unit give improper pressure readings, which means it could be indicating more pressure than you really have. If you have too low oil pressure then oil may not get to the top of your engine and lube the rocker arm assembly as it should. No lube makes a tapping sound.