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89 coup auto 104k all stock except for new ZZ4 short block just installed.
Engine just assembled , primed and idled a few times for 20 minutes stints. All running well. First ride out today for 3 miles under 25mph.
Brief recent history: had lower oil pressure of about 8 psi at hot idle about 3 months ago. Engine running fine. So I replace the oil pressure sender, and oil pressure still low at hot idle, but now went down to 4 psi with red oil light coming on. Decided to drop oil pan and check oil pump and screen – screen was clogged up with gunk (old gaskets and RTV) . See pic. Looking further I noticed the piece of piston side in the screen. That prompted me to look further and find a bent piston (#6). Which then turned into a big project of replacing block with ZZ4 short block.
So with it all back together - new block, new melling oil pump/screen standard flow I was expecting the pressure to be up there, the digital dash gauge is now reading as low as 5 and sometimes 4 with the red oil light on at hot idle. (Just like before I replace the engine). I have it timed at 6 degress BTDC, so it does idle only around 600. At 1000 rpm it goes up to 18 psi. I do get about 10 psi per 1krpm. At cold start, idle starts up around 30 and works its way down to under 10 when engine/oil temp gets around 200 F. It sounds like it is running perfectly. I’m running on 5W-30 for break in (500 miles) and then was planning to go to Mobil 1 10W-30.
What should I do to diagnose this, considering it’s a new engine, maybe putting the older oil sender unit back in to see if that one reads more (easy to do since I still have it), should I do a mechanical oil pressure test – how and where do I hook up for that? Is there anything in the oil cooler assembly that I ported over from my old engine that could cause this? Any other good suggestions considering I have the same readings before and after new engine install)?
Checking other discussion boards, some say this may actually be considered OK for new ZZ4. But for me, something else may be at play since I have experienced this low oil pressure before and after engine replacement.
That Sucks big time. Can u bring it back? Whats the Warranty? I think u have Diagnosed it Already. A brand new short block with about the same inner clearance wear as ur old 100,000 mile engine.
But u need to hook up a mechanical gauge to verify thats the pressure u really have by pulling the factory bell sensor and hooking it up there.
No way would I'd be happy with a new short block like that unless its got Full Grooved Mains set at .003 thou and .002 on the rods with the camshaft lifter bores bushed and in that case I'd be running 6800 rpm red lines and a big block high pressure/high vol pump with Forged Slugs and a Mechanical Valve train
the only EASY thing about alof this, other than hooking up a mechanical gage you trust, would be to pull the pan and try a new oil pump; I'd try one of the newer small block pumps with the larger 3/4" inlet, and, my personal preference, high volume. But the pressures you're experiencing do seem low.
Any other ZZ4 shortblock users out there care to comment?
Wait a minute. Just went over ur post again. Damn Dude, your old oil cooler and lines would of been full of all that crap in your photos. Tell me you flushed all that out and flushed it out a couple of times?
And is the oil on the dip stick coming out real clean. Hardly able to read the level? Is the oil on the dip stick, foamy, full of bubbles after running?
My ZZ4 oil pressure was good at about 60 at start up then usually ran about 35-40 normal operations. with above, try a mechanical pressure gauge to get a good reading....suspect that cudamax is on to something about your oil cooler and lines. Two different engines with the same issue...something is off.
My oil was a little overfilled so may have been foaming somewhat, I siphoned about 1/2 quart out and checked it last night. It's still low, went down to 11 psi at idle hot (oil temp 189F). The oil I siphoned is a little mucky considering it only has about 10 miles on it. But that may be due to that foaming along with the assembly lube that was used.
But u need to hook up a mechanical gauge to verify thats the pressure u really have by pulling the factory bell sensor and hooking it up there.
I think that'll be my first step - to get a gauge in there. That'll help in the final diagnoses for an accurate reading.
Wait a minute. Just went over ur post again. Damn Dude, your old oil cooler and lines would of been full of all that crap in your photos. Tell me you flushed all that out and flushed it out a couple of times?
Good advice, that'd be a good 2nd step. I did clean it out simply by spaying carb cleaner in there. Sounds like I'll need to drain the oil, and take off the oil filter adapter and clean it that way. To be clear, the oil cooler lines have nothing to do with the oil pressure, they just allow heat exchange between the oil filter assembly and the block. It's the oil filter adapter that may have some gunk in it, correct?
The engines runs great, but my old engine with the bent piston and the crud in the oil pump screen also ran great - just had the lower oil pressure then and now.
My ZZ4 oil pressure was good at about 60 at start up then usually ran about 35-40 normal operations.
That'll be the time I can celebrate - I'll go thru a few checks, search the forums, and report back.
I was thinking if its foaming maybe its sucking air instead of oil and as far as flushing. From your photos of all the old crap, that stuff was nasty and if their is any chance that some of that stuff is caught up in the lines. It can cause a major restriction and chew up everything in your new engine. At least I'd dump the oil, pull and cut open the oil filter to inspect it and add gas to the lines and blast em with compressed air. Thats the only thing I can think of thats ur fault that could be wrong, besides building the short block.
Thinking about it now. I'd be on the phone letting them know I'm bringing that one back and would want another one. Then flush the crap out of the lines and cooler and Try it again, with a different one
Just took the vette out first time nervously on the freeway for a few minutes to pick up the oil pressure gauge and stuff, the oil pressure looks much better. Now at idle hot (park or in gear) it sits nicely at 20 psi (600 rpm). Cruisin at 55 with RPM about 1800 it sits at 35 psi.
I am thinking that the overfilling of the oil by about 1/2 quart caused the foaming and lowered oil pressure. Also - probably that even after I drained some oil yesterday, the air bubbles may have been there causing me to think the low oil pressure was still there.
So thrilled it's running well - and it handled the freeway. BTW - I never had oil pressure above 38 psi at cold start up ever on the old motor, not sure how I hear some many getting 50 psi.
I'll closely monitor it - and now I have the mechanical gauge to check things out. Is there a place to hook it up easily besides the oil pressure sender fitting?
They will take it back, Right? or did u get some discounted returned No Warranty Midnight Deal 1/2 off shortblock Crap
I bought the ZZ4 shortblock directly from GM ($2300) and installed it myself. It's the labor that was tough, took me a couple months to take the old one out and install the new one - my first big job. Did it all by myself, I had some friends ready to help but was able handle it.
Kool but I would say that you should still change out the oil and cut up that oil filter and check out the paper for debris and for sure get a magnetic drain plug to check for problems on the next oil change.
There should be a pipe plug below the front of the intake off towards the pass side above the timing cover, may be hard to get to. Believe thats an oil port.
Kool but I would say that you should still change out the oil and cut up that oil filter and check out the paper for debris and for sure get a magnet drain plug to check for problems on the next oil change.
Beat me to that one...
the oil is mucky that I siphoned out when I over-filled, I wouldn't drink it myself even if I was a really thirsty car: I aerated it out thoroughly, got the first fragments caught, and assembly lube muck running around,
I bet if I change this murky oil now, with new filter with another dino 5W-30 for the next 500 miles, then go to synthetic Mobile 1 10W-30, I'll be even better than it is now.
I'll cut the oil filter and also send the oil samples out for analysis.
Like the old saying goes, YMMV - Your Mileage May Vary. You might be just fine and I don't want to alarm you, but here's my take on it.
I used to have a '90 Corvette which had a mild rod knock. When I rebuilt that motor, I was super careful and paranoid about the contamination of the oil galleys and passages within the engine from that one bearing that disintegrated. While most shops would have done a quick rebuild, I went all out and had a reputable machine shop hot-tank the block with all the freeze plugs and oil galley plugs removed. The oil passages were completely cleaned out and even then the shop told me to use an engine cleaning kit or a rifle brush and scrub them out one more time when I got home before installing all new freeze and oil galley plugs back.
The reason for this is that I knew all the expensive and shiny new parts inside would be ruined and in the very least, experience greatly accelerated wear if remnants of the bearing material was still stuck in the oil galleys. I just didn't want to take a chance since debris like fine bearing material and pieces of old gasket material can wreak havoc and ruin a freshly rebuilt or new engine very quickly. If it doesn't spin a bearing or wipe a bearing clean, it can easily clog an oil passage or critical oil feed hole to the bearings.
After going through the whole nine yards to do it right, there was no way I was going to put that old oil cooler back onto the freshly rebuilt engine. The inside of the oil cooler has multiple fins that catch and hold a ton of debris and crud inside and you cannot scrub it out. After trying to source a new one without success, I decided not to run one in my fresh engine, choosing to run Mobil 1 synthetic instead (but only after a proper break-in period). This is what Chevrolet did on the later C4 (non Z51) models like my '95 LT-1 so I knew it would be okay. I have read on numerous occasions that it was decided that the superior lubricating properties of the Mobil 1 synthentic was what enabled them to eliminate that oil cooler on base models in subsequent years.
On other car forums that I frequent, especially exotic car forums like the Lotus Esprit, I have seen countless expensive new or rebuilt engines ruined when the mechanic did not properly flush out the oil cooler lines and replace the oil cooler to prevent contamination of the next engine. On an Esprit V8, this can easily turn into a $10,000 to $20,000 mistake. (on my previous '90 Corvette, there were no oil cooler lines containing oil, just the oil cooler which was above the oil filter)
Anyway, as with anything, just because something can likely happen does not mean that it necessarily will so please don't shoot the messenger. However, with my luck, I just know if it were my car, it would cause major damage. My luck just isn't that good. Personally, if it were mine, I wouldn't risk it. All that work and a new ZZ4 shortblock. I would not even start it, let alone drive it again until I removed and replaced that oil cooler with a virgin fresh one, especially after seeing that first picture of yours with all that debris. That oil cooler must be loaded with the stuff. If it is circulating in your oil, your new motor won't be new for long. In the very best case scenario, the debris will result in accelerated wear...in the worst case, low oil pressure or a spun bearing.
If a new replacement oil cooler is not available (like many other original C4 parts, not sure if they have been discontinued already), then I would either eliminate running one (it is easy to remove and you can still re-use the oil filter attachment pad after you clean it) or find an aftermarket alternative.
Think of it like an oil filter, but worse...a finned thing that catches debris, but offers no filtering capability. We all know how quickly oil gets dirty again when one chooses to change the oil, but not the oil filter. Imagine fresh, clean oil running through a virgin new engine, but only after it constantly goes through a bunch of fins loaded with debris...the thought is terrifying to say the least.
I agree about cutting up that oil filter. If there is any doubt in your mind that the oil cooler may have contaminated your new engine, that will either raise a red flag or put your mind at ease. Also if the former does turn out to be true and it likely will, in addition to a new oil cooler, I highly recommend that you drop the oil pan (it can be done in-car on a C4) and clean it out for the future longevity of your new shortblock, depending upon the severity of the debris or contamination. Multiple oil and filter changes afterwards would be very cheap insurance to help make sure any foreign matter still stuck within the engine will be flushed out.
I wish I had better news, but if you search around on the internet, I'm sure you will find plenty of instances where a new or rebuilt engine was ruined by oil contaminated by debris from a previous failure that remained in an oil cooler.
Last edited by LANDSHARK1; 08-28-2014 at 01:30 AM.
You have reminded me of what I used to do a long time ago with the deburring and grinding and thread tapping and all the gun brushing of all the oil passages and the hot taking/boiling out of the block.
Even running 2qts overfill for slash up to the cam for break in on the old flat tappets.
I sure wouldn't want a new motor with low pressure. I'd be pissed and freaking out what going to happen in one season or a little down the road. It only takes a vary little to wipe out the bearing and rings
08-26-2014, 06:27 PM
'89 First Ride w/ZZ4 - Low Oil Pressure
with above, try a mechanical pressure gauge to get a good reading....suspect that cudamax is on to something about your oil cooler and lines. Two different engines with the same issue...something is off.
