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adamh
05-11-2015, 01:48 PM
I like to post up my experiences with an oil pressure problem i had recently.

i brought an aftermarket oil pressure gauge and installed it on a TEE from the oil filter housing so i could also plumb in the original sender.
When i installed the TEE i did not tighten the 1/8npt thread enough or didnt use any liquid thread sealer, whatever it was and the TEE and it leaked a few drips enough to see on the garage floor after 50 miles road testing.
I decided to remove the TEE and A/M gauge and in doing so accidentally sheared the Hollow thread of the TEE by applying torque perpendicular to the thread instead of radially. So, it sheared, if you worked on this sender you would know how difficult it is for access to swing tools, mistakes happen easily.

the thread i sheared had a 3/16 hole , with a wall of abou 0.060"
One piece of thread was left in the oil filter housing casting, nicely flush so i could not get a grip on it, the other piece was of course in my hand.
Wether or not a small piece of brass found its way into my oil system i can not confirm at this stage.

i was lucky (very) to be able to back out the hollow broken TEE piece from the housing by using a suitable 1/4" drive screwdriver bit and a small
Bit Ratchet , a sharp torx bit grabbed it and backed it out. I didnt have any screw extractors that would have worked also.

After removing the broken piece (shaped like a tyre) i very carefully put a small screwdriver up the oil pressure switch hole with some tissue wrapped around it, made some circles on the bore to try and catch any possible small bits of broken off brass , but i did not find any.

after removing the screwdriver i checked it still had all the tissue.

put in the new sender and cranked the engine, i saw the red oil light on the dash and thought perhaps an airlock where the sender feed hole points downwards a little and bled off a little oil when i removed it. I thought the pressure would build back up after a minute of driving down the street.

It didnt, and by the time i got to the end of the street, my turbo was stalling if i tried put my foot on the gas , so, with the garage less than 300feet, and i decided to turn back and creep up to the garage.

The sound i recorded will be added later (turbo stalling is almost identical to this noise HERE (http://s837.photobucket.com/user/mintycloth/media/IMG_6140_zps496kkvde.mp4.html))
i removed the air pipe from turbo to inlet manifold to find that when the noise came the air flow all but stopped, hence, it was the turbo stalling. All starting to make sense why the van cut out half way down the road when i was reversing . (no air to inlet when it stalled!)

So, why no oil pressure? All i did was change the oil pressure sender back to original.
i loosened off the sender until it was floppy in the thread, disconnected glow plug power, tried cranking without starting to bleed the sender. nothing!.
i tightened that back up and disconnected the turbo return oil pipe (flexible one with heatproof fibre shielding) and cranked again for about 20 seconds, a number of times in quick succession, noting, not even a drip...
I blew down the return pipe to make sure it wasnt blocked , it was free and no blockage.
So, there was apparently no blockage at the turbo either, tried again loosening the sender, no change .

I figured if nothing was bleeding there may be a blockage somewhere, but how!?.
I ran out of ideas and actually took it to main dealer (first time in 15 years) i took it because at that stage i could not prove that the sender was not faulty and the oil pressure was faulty with the tools i had , although it looked very likely oil pressure itself as i had earthed out the gauge sender wire
and the light came on the dash so wiring looked ok.


They tried getting an oil pressure tester on the housing but could not reach it. So i suggested an oil and filter change to purge all the air the correct way (if there was any) and some inspection of the oil feed hole from the filter on the housing,.. maybe to squirt some oil UP the filter housing hole to try and fill up the sender oil way , anything, its all easier when the car is 6 feet above you on a lift.

I got a call today saying the oil pressure was back, excellent!, BUT... it remains a mystery what caused it to block, the technician said they put an airline up the oil filter housing hole and pulled the trigger, they said there was a kind popping noise and when trigger released and moved away oil came flowing back out of the filter housing hole.. they checked the oil but there was no residue or lumps in the oil that spilled out.

So,.. wether or not something was blocking the way and has been fired deeper into the pipe between oil filter and sump strainer (oil pick up)
, i may not ever find out , this is frustrating, but for now oil pressure has returned to full so i am pretty happy about that.


I will question the tech when i go to pick it up about exactly what he heard.

ideas i have:
1. when adding an aftermarket oil pressure gauge perhaps some of the liquid thread sealent i used to attach the senders to the TEEwent hard and found its way into the oil system (small chance)
2. a small piece of brass found its way in there ?somehow backflowing from the broken tee i find hard it to believe as the branch that holds the pressure sender is about 2" long x 5/16 bore, i dont think it flowed towards pressure, it should always go away from it. but, i may have pushed it deep by using a small screwdriver. putting it into the flow of the main line to the filter
3. something else.

as you can tell im frustrated by this :LOL2:
but the issue is resolved for now.

Any other ideas?

adamh
06-21-2015, 05:01 PM
i think i found out why i had no oil pressure that time.....
It seems, the oil pump does not prime when the system is emptied or bled in some way shape or form.

2nd experience of the same problem:
my engine was fine for about a thousand miles testing. One day i rotated the crank by hand to get a picture for a timing discussion, next time i went to start the engine no oil pressure again (red light on dash).
nothing was apparent to me at the time, except the oil pressure troubles i had before had returned.
unfortunately, i ran the engine for about a minute without oil pressure, i tried blipping the throttle a few times to try an increase the pressure, turned it off for a while, tried starting again... nothing changed, except i could hear the turbo whining to a halt slowly when i turned the engine off, eventually after a good few times trying i got oil pressure.

I took the vehicle for a run but almost immediately i could hear a sound like a wailing cop siren in time with the turbo spooling and slowing down with the throttle (i could play a tune with my foot).
Within about 30 minutes the sound had increased almost ten fold and i lost boost (gauge reading zero).
so.. the turbo gave up due to oil starvation to the journal bearings.


I spent this last week removing the sump pan, checking the sump for signs of any blockage which may result in no oil pressure, dirt or tissue or sump sealer or something . the sump was clean apart from about a finger nail of sludge (enough to cover your little finger nail about 0.020" thick, not much sludge i thought.

Since the turbo was now removed and the sump i blew down the turbo oil feed /return pipes with some air tubes, and the oil filter feed hole also.. no blockages, nothing.. i could hear air coming through the other sides.

Figuring no blockages in the oil feed/return pipe or oil filter feed hole, or sump strainer even, i resealed the sump pan, refitted the original old turbo, filled up with oil and coolant. tried starting again, still no oil pressure.
times like these after spending a week stripping and rebuilding its very frustrating revisiting a problem you cannot put your finger on.
it allready ate my new turbo, i am beginning to feel like chucking in the towel with it.

So, after some online research, it appears that some vehicles and some oil pumps do not always prime themselves, and that some people fill the oil filter full up first before screwing it on to help with priming when replacing a filter, as not filling it up can give an airlock in the oil system. I have not experienced this before with toyota engines and i have rebuilt 4 different varieties, never primed one, never had an oil pressure problem like this

it had to be worth a shot, so i removed my new filter, looked down the hole.. no oil, not even a drop. tried filling it, and starting again, waited 10 seconds, still no oil pressure.

i removed the filter, put a bucket under the van and started the engine , wanted to bleed it once and for all, tried starting a few rotations /stopping no joy, tried running the engine for just a few seconds ... it finally bled some oil into the bucket, that was good... so confident the pump was primed i screwed the full oil filter back on and started.. result: instant oil pressure, light was out within a second. happy time after suffering a week under the van.

i'm looking back in disbelief, that an oil pump/system cannot prime itself without removing a filter and bleeding into a bucket.
i do not have much experience with this vehicle, i am not a full time mechanic, times like this reinforce there is a lot of learning to be had the hard way

One thing is for sure, if you see a red oil light on the dash on the turbo charged version, do not be tempted to blip the throttle you'll damage your turbo bearings, and possibly your mains/big ends.

so how did the original oil pressure problem appear?, by removing a oil pressure gauge and creating an airlock.

The second time i had the oil pressure problem; i rotated the crank backwards and forwards by hand.. i am guessing the pump (meshed gears) lost its prime by reversing and feeding oil back into the pump reverse feeding into the strainer, this is my best guess.

i just found if i bleed the oil through the filter hole.. and use a full filter, it bleeds.
But with the filter dry and fitted, in this particular vehicle, it did not prime.



I know there is a pressure relief valve in the oil pump, but i am unsure if in someway as a check valve (one way valve) ,
from what i understand the clearences (or lack of) in the oil pump gear lobes act as the check valve by essentially creating a near vacuum to draw the oil up , can anyone confirm this?.
i.e; no oil can seep back through unless its rotated backwards.
I think (cannot confirm this yet) there may also be some other check (one way) valves in the oil system , the manual i have says there is one behind the starter motor the manual shows a ball/spring design. but it does not say what the function is and for which part of the oil system.
i looked there and there seems to be a hex fitting screwed into the block just above the sump in about the right place behind the starter, at this stage i need more time and experience and willing to pull off the starter to check out this check valves operation, if it is a check valve. and it would be good to confirm about the bleeding of the oil / priming the pump, more experience is required, hopefully, it will not be at the cost of the turbo or the mains/big ends.

if there is a method of doing something easily on this engine, so far its got me beat.

Please post up your relevant experiences with this

Gunflint
07-06-2015, 12:05 PM
Hi Adam.

Interesting. Sorry my timing questions caused such a big headache for you.

I'm curious if it is a good idea to fill the oil filter when changing the oil. I have only changed the oil once on my van, but definitely put the filter on dry. I had no problems. I am going to change it again soon.....and now you got me thinking......

Matt

adamh
07-11-2015, 04:11 PM
let me know how you get on when you do. i still need investigate the check valve fitting behind the starter but i will not do that until next oil change