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How long is normal to wait for oil pressure to come up? Is 2-3 seconds OK? Car makes normal pressure at all other times.
Setup is
-built engine, slightly oversize crank/main clearances
-boundary eng oil pump from 949
-oil cooler/thermostat/etc
-autometer oil gauge on long extension line (so the sender isn't bouncing up and down directly attached to the T for the turbo oil line
-5w40 T6, clutch disconnect, etc
My feeling is that the 5w40 stuff drains out of the engine real easy and I'm just repressurizing everything each startup. I just don't want to lose my new engine over something stupid.
Update for resolution: (props to m2cupcar below, he was 100 percent right on everything)
Symptom:
Couple of seconds of no oil pressure on startup every time
Cause of problem:
Did not put an OEM style paper gasket between the oil pickup and the oil pump when assembling engine
Used right stuff instead of a gasket and it did not seal properly. Right Stuff is great RTV, but not for this.
As a result, car sucks air for a couple seconds before it sucks oil
Solution:
Remove front subframe, pry off oil pan, remove pickup tube
Clean RTV off gasket surfaces, install 6 dollar paper gasket
I use the same oil, but on a stock bottom end. I installed an electronic sending unit and logs show oil pressure starts to rise as the motor comes off the starter and over 50 psi by two seconds after startup.
The oil filter should have a check"valve" built in to prevent the entire oil system from draining. You'll see a black or orange flapper through the holes in the top of the filter.
At this point I would guess it's a guage issue, air in the line might add a delay. If you have good pressure once it starts I wouldn't freak too bad.
I have a very similar oiling setup (stock pump) and see full cold oil pressure (after sitting for a week) in about a second after the engine starts running (counting one one thousand two one thousand three one thousand). Did the builder install a gasket between the pickup flange and pump? I originally did not and had severely lagging oil pressure on cold start. Installed the gasket and it was fixed.
Ordered a borescope, mentally preparing myself for the inevitable suffering involved in dropping the oil pan and putting everything back together afterwards.
I really hope it's just something stupid like the gasket and not a stuck relief valve or something.
extremely delayed edit- I just realized the relief valve is directly exposed without taking off the oil pan, so I could actually disassemble it without removing the pump.
Last edited by AlwaysBroken; 06-17-2017 at 09:38 PM.
Bore scope says I put a dab of some Right Stuff on the mating surface. Pic below from the turbo drain port. Maybe I missed a spot and air is getting in?
If I drop the subframe I can inspect the relief valve while I'm in there.
Does anyone think I'm going overboard and making a big deal about nothing? The oil pressure is rock solid at all times other than the first couple of seconds after startup.
Nice job on the borescope image! fwiw- I used rtv on mine and there was none on the actual mating surfaces when I took it apart. It was all stuck around outside edges of both pieces. I googled and it's regularly stated not to use RTV on the pickup/pump flange. But it's a question of what you're ok with. I was concerned about it enough to do the job, knowing it's not how it should be. BUT I also wanted to add another shim to my oil pump AND modify part of my oil pan- three things requiring pan removal.
If the car has been sitting a while (weeks), crank it over until it builds pressure then start it. If this is happening after refilling the gas tank or whatever, there's oil still on the bearings and load is minimal, hydrodynamic effect will keep everything ok.
If you're really worried about it, there's trick accusump setups or aux electric oil primer pumps out there.
I would pull the motor to pull the oil pan, long before I would consider dropping the subframe and pulling the oil pan.
If I was doing another rebuild, I'd pull it again without hesitation. But after messing with the steering rack and all that nonsense down there I feel confident I can get it all back together more easily than hoisting it all out. This way instead of removing all my plumbing and wiring I just put a block under the tranny housing while I yank the pan. I think I can do it in one easy weekend vs several. Plus I have the Firestone 12 month alignment so I can get everything checked out when I'm done.
If I was doing another rebuild, I'd pull it again without hesitation. But after messing with the steering rack and all that nonsense down there I feel confident I can get it all back together more easily than hoisting it all out. This way instead of removing all my plumbing and wiring I just put a block under the tranny housing while I yank the pan. I think I can do it in one easy weekend vs several. Plus I have the Firestone 12 month alignment so I can get everything checked out when I'm done.
The problem I have with dropping the subframe, is that you still have to use something to hold up the engine. I would use my engine hoist, which then has the silly legs under the engine bay which gets in the way of pulling subframe and all. You also need to drop the trans I think to get the oil pan off. I think the stupid rear main seal adapter will be in the way with the trans still on. So to me it really does not make sense not to pull the engine. I also have done several dozen engine pulls, so I can usually get the engine out of a miata within a few hours.
Also is your firestone alignment not lifetime? I signed up for the lifetime one about 2.5 years ago. One of my good friends works at the local firestone and he will hit all my alignment specs perfectly. Firestone at least has not started checking vins, so I bring in all my miata's and get them aligned without anyone noticing or caring. I also tip my alignment guy with some cash so that also makes him happy.
I happened to have the lumber laying around being a long time home owner. I think both have pros/cons. The lift made the difference for me- but I also did not want to have to break all my fluid connections right before a road trip.
Originally Posted by shuiend
Also is your firestone alignment not lifetime? I signed up for the lifetime one about 2.5 years ago. One of my good friends works at the local firestone and he will hit all my alignment specs perfectly. Firestone at least has not started checking vins, so I bring in all my miata's and get them aligned without anyone noticing or caring. I also tip my alignment guy with some cash so that also makes him happy.
The problem I have with dropping the subframe, is that you still have to use something to hold up the engine. I would use my engine hoist, which then has the silly legs under the engine bay which gets in the way of pulling subframe and all. You also need to drop the trans I think to get the oil pan off. I think the stupid rear main seal adapter will be in the way with the trans still on. So to me it really does not make sense not to pull the engine. I also have done several dozen engine pulls, so I can usually get the engine out of a miata within a few hours.
Pulling the oil pan does not require removing the transmission. I think there are four bellhousing bolts that need to come out, but the rear main seal holder only bolts to the block, not the pan.
When I first installed my turbo I drilled the oil drain hole in the pan in the wrong spot, so I had to take it off and fix it. I did it with the motor still in the car, supporting the motor with an engine hoist and the subframe with a floor jack. The two most annoying parts to it were cleaning all the RTV off the block before reinstalling (hard to get access) and lining up the steering column with the splines in the rack while jacking the subframe back up.
I was wondering about that, but isn't it just the 4 easy to reach bolts on the bottom of the tranny? I was planning to secure the engine by holding up the PPF from the bottom and using the engine hoist bits on the head to hold it to the shock tower brace and a 2x4.
IIRC from a few months ago, the rear main seal has a little bolted on half-moon thing around it on the bottom, which gets a funky shaped rubber thing between it and the oil pan. And the oil pan basically just gets a heaping amount of Right Stuff. Instead of putting right stuff on the block and lowering the oil pan over it, I could just put the Right Stuff on the pan and raise it to the block. But I don't see why it wouldn't work.
IIRC, also the oil pump bolts on to the front of the engine, basically wrapped around the crank and sealed to the front of the engine with Right Stuff in a long bead. The oil pan seals up against the bottom of this in the front. So I should be able to remove the pan without messing with the harmonic damper.
My main worry with puling the engine is that it involves way more disassembly than I feel is necessary, which means way more opportunities for me to **** up the reassembly. Like forgetting a 3 dollar gasket in the middle of the process.
I put the RTV on the pan and raised it up to the block. Tip: use several spare bolts you can cut the heads off to thread in as guides to align the pan when raising it to the block.
Your cold oil pressure delay you describe sounds normal to me.
Similar build to yours and with the "o" ring fitted and a mechanical oil pressure gauge fed from the sandwich plate, mine takes a couple of secs to hit 80psi on 10:50 oil and is "normal" the rest of the time. Been like this for about 6 years no issues to report. After all it a mechanical pump releying on increasing rpms to hit the required pressure so a delay is to be expected plus the further away the sender is the longer it will take to register a reading.
For oil pressure, I am at the stock location (sort of) I removed the stock oil sender (which is garbage on the 97) and replaced that empty hole with a steel braided line that goes to an Autometer electric sender (which goes to my gauge pod)
My oil circuit looks like:
oil pan > pickup > BE pump > adapter attached to stock oil filter location > 10AN line to 3/4 16 filter housing (IIRC) > oil filter from a mustang (5" L x3" diameter) > thermostat > oil cooler w/fan > return to adapter on stock oil filter location > rest of engine
I run the oil filter I run because I did my oil cooler/filter relocation about a million years ago when there weren't any miata specific applications. I also did it on the cheap. I ended up rigging together an oil cooler setup from a bunch of stuff designed for a ford v8. On the upside, the filters are readily available (something like 5000+ ford applications and like 5x the size of the miata filter).
06-16-2017, 11:10 AM
oil pressure on startup
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