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I'd check oil pressure against another source before condemning it. The gauges are often inaccurate. The behavior you describe, high pressure when cold and then diminishing as oil temp comes up, is exactly the behavior to expect from healthy components. It's also why Mazda went to an "idiot" gauge starting in 1995. Sigh.
That's the general impression I was getting from everything I've been reading. I don't think I've come across an actual instance of that gauge reading badly and there actually being a problem.
I just got home and dug out an old VDO pressure gauge and sender (I could have sworn it was a temp gauge but this is perfect). Hopefully this weekend I'll wire it up and report back.
Here's a video of the problem I'm having for posterity sake.
That's the general impression I was getting from everything I've been reading. I don't think I've come across an actual instance of that gauge reading badly and there actually being a problem.
The instant drop to zero makes me think it's a sender/gauge issue, not a mechanical oil pressure issue. If it were actually losing all pressure I would expect it to drop smoothly all the way down, not go from ~ 10 psi to zero in an instant.
I kid you not, the next god damn day after my last post asking about bad oil pressure I drove the car to work and ended up having to have it towed home.
The car started making some pretty brutal rattling noises under the hood and died. I was able to barely get it started again and get it off the freeway. Lots of black smoke on cranking and a real resistance to cranking some times as well as a hell of a lot of oil coming out the front crank seal area.
Here are a couple poorly shot videos of what's going on.
http://youtu.be/zYXohZ92qIc
http://youtu.be/M7120YYj8sY
(I have no idea what that squeaking is in the second video but it's also new)
I'm tearing into it right now, the turbo sounded a little weird after shutting the car off, so I checked the cold side to make sure nothing was rubbing, also pulled the oil feed line and cranked it to make sure it was getting oil, everything looked good there.
Compression test comes in at ~100 on all cylinders with really low crank and a shitty harbor freight gauge. The car holds idle fine so I don't think I dropped a valve/keeper or anything into the cylinder.
Pulled the valve cover and watched things turn. Everything looks fine on the top end.
So. I'm pulling my radiator, disassembling the timing and am going to pull the oil pump to see if it's disintegrating. Past that I'll have to pull the motor to get a look at the bottom end.
Right now my strongest guess is that I dropped an oil squirter and its being banged around inside. Next is that due to poor lubrication (see earlier oil pressure concerns) I may have spun a bearing. I'm not sure what that sounds like but I don't thing it's quite what I'm hearing.
Waiting on an engine hoist now so we're taking bets on what happened!
Still figuring out the main cause of failure but ultimately I'm left with disintegrated Rod bearing, a thrust bearing that fell out and got mangled and an oil squirter nozzle that hit piston skirt and broke off.
So it looks like I'll be buying a new piston Rod, new thrust bearing and a new set of rod beatings unless I can buy just bearings for just one. I'll also need some new seals :/
Check back sides of the other main caps to see if the crank has been machining them, that's usually what happens before the thrust bearing falls out. If so then you'll want to pop one of the cam caps off to see if those bearings surfaces are still OK.
If it has machined the main caps then it's likely everything in the engine is junk, unfortunately.
Long over due updates! I sourced another long block out of a 95, sent it off to the machine shop, crammed all my parts into the new motor plus a few new shiny bits like a super miata damper and basically did the whole thing over again. Its amazing how much faster things go after the second, third and fourth time you've done some of this stuff.
Plopped the rebuilt engine back in and was able to to start it up flawlessly first crank. Went through the original break in using SAE 30 oil for the first ~15 miles of drive time, then changed to a cheap dino 5w30 for the next 100 miles, 1 more at 600 miles then switched it to Rotella T6 after 1200 miles. This is my first experience with T6 but so far I've been happy with it, I dont plan on ever sending my oil off to be analyzed but the motor keeps quiet and seems to be very happy so I plan on sticking with it.
I did the first 1k miles or so at a wastegate psi of around 5-7psi, trying to keep it out of boost completely for the first 50 miles or so was really tough considering how quickly the 2560 spools, especially while I was trying to climb higher into the revs to get a good seat/pull vacuum on the way down. I've read a lot of different opinions on break in and never felt super sure of any of them but this was about the best one I think I've ever done.
The lady and I took it for a trip into the mountains on a hot day in May and the coolant temps really weren't happy, even while being driven pretty mildly. We reached 230* and it wanted to run away with the temps a couple times, I suspect the big issue here is that it was having trouble with the steady hills we were climbing in the heat at relatively lower speeds. Either way, this made me realize that I had never really driven the car through the peak of summer heat and that something needed to be done.
Per TSE's advice for pairing with the huge Trackspeed radiator, I added a single 13" Spal fan. And also picked up a Garage Star upper radiator shroud.
(Only picture of the fan I could find on my phone)
I was able to wire the fan strait in by snipping the SPAL pigtail and soldering on the 2 wire pigtail from my factory fan. Worked like a charm and doesnt really bog the car down when it kicks on which is nice. The Garage Star radiator shroud fit nicely but needed a little massaging where the hood latch sits in order for it not to rub against the latch and get stuck open or closed. I probably filed that whole section down about an 1/8 of an inch or so with my dremmel and the rubbing issues are gone. I ran a length of split vacuum hose over the edge parallel to the radiator, pushed it up so it sealed off the small gap that was remaining and sinched the bolts down. Im happy with it.
I never really expected that it would be this hard to keep these cars cool. I now have one of the most highly recommended radiators I could find, a coolant re-route, a ~1710 cfm bitchin' fan and the upper ducting piece, distilled water, about 10% anti freeze/Water Wetter and although I saw huge results from the radiator and the fan (I now very rarely break 210* in traffic or other driving on ~90+ degree days) I can certainly still climb into 220+ temps if im flogging the car on some of my favorite middle of nowhere windy roads and not paying attention to it. Yes, I know. Ducting is on its way.
The car has been running at 15psi for the past 500 miles and is super quick. Im having some battles with Tuner Studio ditching all my fuel table changes every time the laptop is restarted but I'll figure that out eventually. I'm still on the factory pea shooter exhaust (1 1/2"?) and am hoping to get the car to one of my local shops for a 3" treatment within the next 2 weeks. I'll probably take a leap of faith and opt for the **** off huge Magnaflow muffler that people seem to like here because I can't abide noise at 4k rpm 70 mph cruising. Im hoping the sound still comes to life through that muffler when the car is really being driven though.
So far I'm at about 1500 miles since the new motor was put in and the car has been running very very well. I am a happy man.
03-02-2016, 08:24 PM
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