Pulsing oil pressure

Topic: Pulsing oil pressure (Read 2949 times) previous topic - next topic

Pulsing oil pressure

July 22, 2007, 04:31:44 PM

Took out my oil pressure idiot light switch and installed a pressure gauge. This is a tool, no electronics involved.
The pressure pulses or more accurately flicks to a lower pressure.
Fresh oil change 10w-30 cold fast idle bouncing between 60 and 70.
Warmed-up slow idle 35 to 45.
Have not had a chance to run it and get it real hot yet.

Like I said it spends most of its time on the high reading and flicks to the lower reading. Wondering if anyone has had a gauge on a 3.8 and what you saw.

Pulsing oil pressure

Reply #1 – July 23, 2007, 09:26:45 AM

sounds like the pressure relief spring. i would just put a new pump in . on the 3.8 its real easy. just like a buick 231. right in the timing cover.

Pulsing oil pressure

Reply #2 – July 23, 2007, 09:49:24 AM

what he said,,,,,,,,,
in the timing cover there is a freeze plug you pop out and remove the spring and proportion valve. Its likely all you need to do is clean it up in there.

the new gear set will come with the spring/prop valve/freeze plug.

also, the new gears have dots like for timing while the old set in the car will have an "S" marked on one area. I dont know what this info means,, never seen it before in the manuals.

My 3.8 oil presure was 45 cold and about 18 hot. Id did not fluxuate though. Your oil presure seems good to me so no need for the pump at this time unless you dont like the reading with it warm.

Pulsing oil pressure

Reply #3 – July 23, 2007, 11:44:20 AM

I'm so glad to see this post, I recently changed the oil in my 87 TC and began noticing my levels on the factory guage dropping to the bottom and then sometimes almost all the way to the top. When it drops I slap it in neutral and coast for a minute while idling and watch it raise back to the normal position. Doesnt do it all the time, just now and then, So I'm assuming I need to change that spring and valve as well?? The car just hit 80,000 miles Saturday and surely isnt worn out eh?

PS: Just RE-READ the post and see that he's speaking about a 3.8 engine, whats up then with my 2.3??

Thanks Again for a Great Forum

Pulsing oil pressure

Reply #4 – July 23, 2007, 04:05:52 PM

I was just wondering if it's possible to change the oil pump gears without taking out the whole timing chain cover? Which freeze plug are you reffering to... is it the small one you can access after removing the timing chain cover?

BTW. The Sealed Power set I got has "S" stamped on the gears.

Pulsing oil pressure

Reply #5 – July 25, 2007, 11:54:46 PM

Quote from: ATSMusic;162807

PS: Just RE-READ the post and see that he's speaking about a 3.8 engine, whats up then with my 2.3??

Thanks Again for a Great Forum

then why dont you post a topic,,, its rude to jump in on someone elses problem and try to work in yours.,, sorry if i sound rude btw.:hick:

Pulsing oil pressure

Reply #6 – July 25, 2007, 11:57:55 PM

Quote from: Shevretti;162862

I was just wondering if it's possible to change the oil pump gears without taking out the whole timing chain cover? Which freeze plug are you reffering to... is it the small one you can access after removing the timing chain cover?

BTW. The Sealed Power set I got has "S" stamped on the gears.

have fun figuring out which direction to lay that one flat oil pump gear. i never ever found the answer to that question i posted on the old Ez Board.

anyway,, the freeze plug is on the back side of the timing cover iirc. It pops out with a drill and whatnot. your new oil gear set should have come with a replacement.

i honestly dont think you need to do that type of replacement with the symptoms you have,, matter of fact,, in all reality, your oil presure is fine.
i would lay money your real issue is probably the screen in the pan having debris in it.

that could cause plusing and eventual lower presure.

good luck

Pulsing oil pressure

Reply #7 – July 27, 2007, 12:25:58 AM

Well then let me apologize for that.

I figured since your post was about the same problem as I'm having then whoever answered you may know what my issue was. Didnt want to start a duplicate thread for the same problem but now I know, I am new here and still need to learn the rules I suppose.

Once Again My Apologies.

Pulsing oil pressure

Reply #8 – August 11, 2007, 05:29:32 PM

Put a mechanical gauge on it to check it. If the mechanical gauge drops like that, yep, better look closer. The OP switch, fuel gauge, and temp sending unit share a power supply from the ICVR (instrument cluster voltage regulator) These go bad too. Mine would read nearly a 1/4 tank of fuel when the little E was actually about to fall over and turn into W for WALK. Temperature gauge kept climbing on me, yet I could find no evidence of it actually running hot. Replaced ICVR, and problems solved. Actually, I replaced the whole cluster after a stealership managed to fry my digital odo/speedo, stereo, alternator, and a few other things. (they hooked the battery up backward, I'm sure of it)

If you're gonna go through the trouble to put a mechanical gauge on it, and while you have the filter off to do that, you can pull the pump without much trouble. As jcassity said, it's in the t/c on the 3.8's. Take the cover off the pump and remove the gears to check them for wear/lash, as well as make a thorough inspection of the timing cover where they reside. If you see any scoring in the t/c, immediately drain the oil through some sort of filter to check for metal shavings. A nylon stocking works well for larger particulate that would damage the pump. However, anything that would have made it to/through the pump to damage the t/c has already been removed by the filter.

Next, if that all turns up clean, drop the serp belt and see if you can thrust the crank at the harmonic balancer. I don't know the exact numbers for thrust, but something like .020 in. comes to mind. Gotta have some because of heat growth, but any more than spec, you got bigger problems that are just gonna get worse.