Oil Pressure Concern on rebuilt 355

94BlueZ28 · 09-02-2009, 06:15 PM

Most folks that have followed my post know what I've got done, but here it is. I have a freshly built 355. Polished stock crank, forged Eagle H beam rods, with some forged speed pro 2 valve relief piston's.. Heads are ported and polished and pretty much every mod that can be done to the car. So I changed the oil at about 25 miles and then I'm right on 127 miles total. So I'm 102 miles since the last oil change. My problem is that I took it for a ride today and the oil pressure was up around 50 on start up and then my car temp was right about the 180-185 mark. So when heated up to operating temp the car runs roughly 20-40 when goozing it abit, but not much because it's freshly built but then when I bring the car to a stop it drops to right above the red about 5-8 or so. It's really pissing me off because it has a brand new oil pump brand new sending unit and I have no clue. I cut open the last filter and didn't see any copper shavings. What should I do or look for. Like I said it has 127 miles on it and the last thing I want to do is fuck it up. I would say I have about 12-15 heat cycles that started very easy 3000 RPM, then working upto 3500, then to 4000, 4500 and upto the max of 5000 rpm which was like once TODAY. I'm letting the engine simmer almost down to a stop and then getting into it a bit to seat the rings but the oil pressure thing is mind boggling. My rev limiter is set to 6900 RPM. It's not like i'm WOT by any means, what the hell????????

94BlueZ28 · 09-02-2009, 06:41 PM

Couple other things, I'm running Valvoline 5W30 and a fram oil filter, I was reading that the fram oil filter could be a bad choice but I was thinking for break in it would be good. It's a tall boy to because I got rid of the oil cooler because of an EWP and the housing that I bought no longer had the fittings to hook up the hoses. They where welded shut and I have 20 AN fittings for the flow and return and some braided lines for hoses. Looks bad ass for sure. Just lost with these pressure shit! I hit the 5000 RPM today about an hour ago and it ran fine like it had some power and alot more to give. I'm running the 306 comp cam by the way.... SO guys what should I check or do????????? Change the oil again and take it for another ride tomorrow and watch the gauge, switch filter's as well. Surely the brand new pump and sending unit can't be bad with only 127 miles on it it.

djjab57 · 09-02-2009, 06:53 PM

Where did you get the sending unit ?

94BlueZ28 · 09-02-2009, 07:02 PM

Autozone,Oreilly part, or NAPA...I can't recall which one because I've bought sveral different sensor's and things from them during this rebuild. I think autozone though. If the sending unit is bad does that mean the reading would be fucked up but yet at the same time I'm getting suffeicent oil through out the motor or what????? Help is appreciated at this point considering I have about $5000 rapped up in this motor! Don't want to be fucking shit up at this point!

derekderek · 09-02-2009, 07:16 PM

I would say your best bet would be to put a mechanical gauge on it and take it for a drive. It will give you an accurate reading and peace of mind.

94BlueZ28 · 09-02-2009, 07:28 PM

Never really dealt with a mechanical before. Not even sure how to hook it up although I'm sure it's easy as hell with some guidance or instruction. I mean hell I work on a 2 billion $$$$$ aircraft, lol B-2. I installed everything on this car my self although I had the machine work done from a machine shop so I would almost have to say it's precision built!

djjab57 · 09-02-2009, 07:30 PM

I hear ya im almost done with my 355 LE2 build, the reason i was asking is because myself and 4-5 others have had low readings once we put on a sending unit from Advanced. If you have one that is on back of the intake I have a NIB gm unit i got from GM parts direct. They sent me the wrong one. I needed the one that goes on the oil pan. But like said above i would put a mechanical gauge to make sure. If yours is bad let me know if interested, im sure we could work out a good price

derekderek · 09-02-2009, 07:48 PM

I also had problems with my stock gauge not reading accurate. Not as bad as your but still a big difference once I put an aftermarket gauge on it. Now reads like 25-30psi higher than it did before on stock gauge.

94BlueZ28 · 09-02-2009, 08:24 PM

How much where you looking to get for the sending unit that you have djjab57? I think mine was like $12 or so. I know it was fairly cheap. I snapped my original off upon removal of the engine because I didn't remove it because I thought I had enough clearance. Anyway to check this out to see if it's bad???? So how did you all run the after market mechanical gauge??????, I mean where does it tap into an how do I wire it up or what not???? Thanks guys for keeping with me on this!!!! I just know for a completly rebuilt 355 it shouldn't be acting like a retard and having shitty oil pressure. My shit was doing this for about a year or 2 before the rebuild as well. I figure with everything new but the crank I would be good so maybe it is my gauge! My gas gauge is being retarded as well now so maybe they go hand in hand. Gas gauge starts out reading 1/2 tank then drops to a 1/4 and then cruising goes upto 3/4's of a tank. So I just fill up when it read a 1/2 tank. I've done the running out of gas thing before and burned up a fuel pump. I know have a 255 Walbro. The sending unit and whole assembly was replace about 3 years before the last fuel pump went out. Yes I've had 3 in the car since I've had it all though I hear camaro's are Notorious for that!

RamAir95TA · 09-02-2009, 08:40 PM

As long as you have ~6psi @ idle and 10psi for every 1k RPM, that's within GM spec. You can try a heavier weight oil and see if that helps too.

Also, definitely try a mechanical gauge to verify pressure. There is an auxiliary oil port above the oil filter that you can tap into. Pretty sure it's 1/8" NPT.

94BlueZ28 · 09-02-2009, 09:15 PM

So if it ran it the route your saying RamAir95TA I would still have both gauges then correct, with the mechanical and stock?????? Yeah it's damn near sitting on the first red line prior to bottoming out to the last red mark. Mother bitch of a car. I've done nothing but tried to keep her up to date and new and she shits on me still! You would think after 20 years she would be loving me with the maintenace i've kept up with to her, lol!

94BlueZ28 · 09-03-2009, 12:36 AM

Come on people, out of 44 people that have looked at my post, 3 people have an input, what do you think folks?????

2XR95Z28 · 09-03-2009, 01:02 AM

get a mech gauge and tap into the side of the block. Simple to install. Get the better copper i believe it is line. DOnt use the cheap plastic, just something that could easily tear so for 10-15 bucks the metal line it worth the peice of mind. Line goes into the plug on the DS of the block, and the other end of course goes into the gauge. I drilled a small hole in my fire wall and ran in under the dash. Make sure to get the fitting on the gauge nice and tight so no oil leaks inside the car. Only wiring you need is for the light in the gauge, simple power (i would tap into a keyed power) and find a ground and bam your done!

Stock gauge will still works as this is completely seperate gauge and spot on the block...

Hope that helps!

RamAir95TA · 09-03-2009, 05:44 AM

Quote:

Originally Posted by 2XR95Z28

get a mech gauge and tap into the side of the block. Simple to install. Get the better copper i believe it is line. DOnt use the cheap plastic, just something that could easily tear so for 10-15 bucks the metal line it worth the peice of mind. Line goes into the plug on the DS of the block, and the other end of course goes into the gauge. I drilled a small hole in my fire wall and ran in under the dash. Make sure to get the fitting on the gauge nice and tight so no oil leaks inside the car. Only wiring you need is for the light in the gauge, simple power (i would tap into a keyed power) and find a ground and bam your done!

Stock gauge will still works as this is completely seperate gauge and spot on the block...

Hope that helps!

For diagnostic purposes, I'm talking about a test gauge - not a permanent install.

RamAir95TA · 09-03-2009, 05:45 AM

Quote:

Originally Posted by 94BlueZ28

So if it ran it the route your saying RamAir95TA I would still have both gauges then correct, with the mechanical and stock?????? Yeah it's damn near sitting on the first red line prior to bottoming out to the last red mark. Mother bitch of a car. I've done nothing but tried to keep her up to date and new and she shits on me still! You would think after 20 years she would be loving me with the maintenace i've kept up with to her, lol!

Like I said, 6psi @ idle and 10psi for every 1k RPM after that is normal. No sweat.

94BlueZ28 · 09-03-2009, 09:51 AM

Quote:

Originally Posted by RamAir95TA

Like I said, 6psi @ idle and 10psi for every 1k RPM after that is normal. No sweat.

Then I'm most likely good. This is exactly how it seems! I cranked it up and pulled it back in the garage after it cooled down for a couple hours and hell it's good oil pressure. It was about 55-60. It's most likely fine but with a new motor I'm just a little hesitant on messing shit up! Thanks and I'll look into the mechanical gauge!

94BlueZ28 · 09-28-2009, 07:27 PM

Ok so I went home over the weekend and drove the car a bit, yeah I've been TDY, military shit down in texas but anyways the car's oil pressure shit is crazy. After warmed up, the car blows my mind. When I mash the gas the oil pressure drops down from 20 to about 10 and then when I let off the gas it gets back upto about 15-20. Various. I always thought that when you mash the gas that the oil pressure goes up. That's what it was doing for a while but now it's acting funky. Little scared when I pulled it into the garage though. It dropped down in the red and the check guages light came on. I'm lost! what the fuck. I'll have to do the mechanical guage when I get back but what could it be possible. Both the oil pump and sending unit are brand new. It has to be throwing oil up top because, my K&N filter on the valve cover had oil coming out of it and it leaked on the header and smike was rolling. Yeah my dumb ass broke the stem internal part off so I could pour oil through the neck faster. It was prefureated so I thought I could bust it out and be fine, but I think that kept the oil from coming back up throught the filter. Anyway's anyone have ideals????

AChotrod · 09-28-2009, 08:09 PM

Definitly put a mechanical gauge on it, and get your sensors from napa or gm. AZ shit is junk. Anytime I ever get anything form them its faulty or doesnt work the same.
On my 355 its like at 70 cold, 50ish at idle and 80 wot.
For break in I let it idle for 25min, changed oil and filter, then drove it around to make sure there were no leaks + goin WOT a few times to check oil pressure and seat the rings then drove it to speedinc to slap on the dyno, to really seat the rings good.

94BlueZ28 · 09-28-2009, 09:23 PM

Quote:

Originally Posted by AChotrod

Definitly put a mechanical gauge on it, and get your sensors from napa or gm. AZ shit is junk. Anytime I ever get anything form them its faulty or doesnt work the same.
On my 355 its like at 70 cold, 50ish at idle and 80 wot.
For break in I let it idle for 25min, changed oil and filter, then drove it around to make sure there were no leaks + goin WOT a few times to check oil pressure and seat the rings then drove it to speedinc to slap on the dyno, to really seat the rings good.

So I should be good at this point with 150 miles on it to open her up WOT?????? Just nervous about the oil pressure although the guage could be faulty I guess. It seemed to do this about 3 years ago on a stock motor as well. I'm installing a mechanical first thing when I get back home. I'm back in texas right now but was asking for when I get back home to deal with it,although if it's shooting oil out my filter on my valve cover ld think it would be good. I hope my pressure is up where your's is at with a mechanical guage. I need to get mine on a dyno and get a dyno tune. I have a mail order as of now, which seems to be fine!

myltwon · 09-28-2009, 09:35 PM

the sooner you go WOT the better imo as long as you have some kind of tune