low oil pressure..

[TheFirm]

I am on the hunt for any reasons that could explain low oil pressure in a freshly rebuilt 12Ht, assuming all the bearing clearances are in spec.
The machining was done by a trusted friend so i am ruling that out as a last resort for now. If need be i will pull the sump and double check with some flexigauge.
The oil pressure is ~8psi @ hot idle, and ~38psi @ 3500rpm. I have confirmed this with multiple mechanical gauges. It has a new genuine oil pump and relief valve/spring.

Some ideas i am yet to explore are:
- wrong oil pump? Could i have fitted a 2H oil pump by mistake? If you introduced 6 oil squirters and a turbo oil feed to a 2H it would likely lower the oil pressure!
- Oil restrictors? Are there any restrictors (internal or external) that i could have missed? I have heard of some engines having restrictors to limit oil flow to the head etc.

Any ideas would be muuuch appreciated!

 

[Doug384]

Assuming that your work was competent on the crankshaft then you need to look somewhere else. Did you guage and or replace the camshaft bearings?

 

[prado t]

When your 12H-T was being rebuilt , did you or your mechanic use (cam greese on the new bearing surfaces). If so your oil filter could be plugged and your low oil presure could be a result of it getting bypassed via the presure relief valve . ---Just a thought


---- Are you using 15-40w?

 

[TheFirm]

- Camshaft bearings were replaced by the engine machinist
- Those oil pressures were taken with 15w40 oil.
- I have since changed the oil and filter (twice) and it is now running 20w60 to observe the pressure change.
Oil pressure is now
Cold idle 68psi (15w40 was around 42psi)
Hot idle - 10psi
Hot 3500rpm - 40psi

Keep the ideas coming guys!

 

[Hulsty]

I am on the hunt for any reasons that could explain low oil pressure in a freshly rebuilt 12Ht, assuming all the bearing clearances are in spec.
The machining was done by a trusted friend so i am ruling that out as a last resort for now. If need be i will pull the sump and double check with some flexigauge.
The oil pressure is ~8psi @ hot idle, and ~38psi @ 3500rpm. I have confirmed this with multiple mechanical gauges. It has a new genuine oil pump and relief valve/spring.

What are the actual toyota specs? Pressure doesnt seem to bad to me. Isnt the general rule ~10psi per 1000rpm?
~700rpm 8psi idle
~1700rpm 18psi
~2700rpm 28psi
~3700rpm 38psi

 

[Tapage]

IIRC my FSM said for 2H minimun 4.3 PSI @ hot idle and 36 or more PSI @ 2K rpm ( not sure about 2K or 3K rpm but have in my mind the 2K number )

Edit: are basic the same numbers and range compared to 1HD-T and 1HZ engines .. but in the 1HZ and 1HD-T was up to 3K rpm

 

[David*BJ70]

Toyota 2H, 12H-T Engine repair manual

Page LU-3

HTH

 

[VTCDN]

If I saw 5 PSIG oil pressure .REAL with a gauge .

I'd freak .
Anyone look for the spec for the oil pressure that the oil switch cut's off at ? for the 3B EDIC ???

How can 4.3 psig , besides in a FSM be accurate ??
Them little red winking lights would be going off in my head.

And after a recon :The oil pressure is ~8psi @ hot idle, and ~ after a new oil pump as well.

Something is not right in my thinking .. But Hey , the FSM is 4.2 or was that 4.3..


VT

 

[Radd Cruisers]

If I saw 5 PSIG oil pressure .REAL with a gauge .

I'd freak .
Anyone look for the spec for the oil pressure that the oil switch cut's off at ? for the 3B EDIC ???

How can 4.3 psig , besides in a FSM be accurate ??
Them little red winking lights would be going off in my head.

And after a recon :The oil pressure is ~8psi @ hot idle, and ~ after a new oil pump as well.

Something is not right in my thinking .. But Hey , the FSM is 4.2 or was that 4.3..


VT

I had a 2h rebuilt many moons ago, at idle hot around 30psi and at 2500 it was nearly 88psi.

~Rob

 

[Hulsty]

I had a 2h rebuilt many moons ago, at idle hot around 30psi and at 2500 it was nearly 88psi.

My rebuilt 13BT shows similar figures to that.

 

[Tapage]

My rebuilt 13BT shows similar figures to that.

damn .. that's high .. I only can saw that at cold start ..

 

[VTCDN]

Those are acceptable numbers now !

4.3 psig is WTFrigg ,
Red lights of sugar plums is going off !! in my head.

20-60 WOW .

Stop driving, the tools to dio oil systems are large and messy.

Firmware , fill profile


VT

 

[prado t]

I am going to say shame on me. I was just reading my Cat 3306 Engine Manual and due to the power of suggestion from the FIRM I figured something was wrong so I posted something that could have helped. But really SHAME ON ME. Cause I know Toyota B and H engine have lower numbers than the machines I use for Work.

P.s While I was reading the 3306 Engine manual the readings are WAAAAY higher

 

[TheFirm]

Well, its good news and bad news..

The bad news, i pulled the motor out again to look into what was going on. With the sump off i checked the obvious things first.. When nothing obvious turned up, i began checking the bearing clearances with plastigage..
It turns out that i had been supplied the wrong main bearings by the machinist to suit the crank grind! unbelieveable! After kicking myself for an hour or so for not plastiguaging everything the first time around (on my mechanics recommendation) i vowed to never assemble a motor again without plastiguage!!!

The good news is the motor is ready to go back in the car, this time assembled with the correct bearings and plastigage'd to make sure the clearances are in spec!

I also replaced the conrod bearings as the low oil pressure looked to have worn them enough to make the few extra $$ well spent.
Upon looking at the rod bearings some more i am a little concerned that something more sinister may be going on..

From the pics above, you can see that half of the rod bearings are scarcely worn, and the other half seem to be worn excessively towards the edges of the bearing. My mechanic suggested it may be a sign that the injection timing is too advanced.. Is there any other reason that could explain this wear?
So far i have set the timing up so that the lines on the pump body and end plate line up, but now i'm concerned to start the motor like this again incase it is too far advanced!
One explanation i thought of, was that because the main bearings were a full size too small, the crank would have had a lot more movement that it should have, perhaps creating an angular wear on the outer cylinders rod bearings?

Any ideas would be great!

 

[lostmarbles]

Never trust ANYONE - not even yourself. Always double-check! (This is a policy that tends to "come with age" IMO and probably arises from experiences of mishaps just like this.)

Anyway ... I can't see how incorrect timing can cause immediate damage to conrod bearings. (But having said that .... someone here posted that it can "explode glowplug tips" and I find that hard to believe too!)

IMO you have no choice but to run your engine with what you have done and hope for the best.

I'm sure you'll waste no time getting the timing to "acceptable running position" and once there .... it can't possibly cause damage ...even if it is still not spot-on.

I reckons the odds of success are on your side. (I doubt the crank wobble would have been sufficient to do anything further than "mark" those BE bearings. At worst ... maybe it damaged your front/rear seals too depending on how long you ran it like that.)

 

[TheFirm]

Thanks for the reply marbles..

Are you saying that if the engine starts and runs/revs/drives smoothly and without major hiccup then it should be safe to drive it like that?
Even with the low oil pressure it seemed to rev and sound normal, so perhaps there is nothing wrong with the timing? The only tell that things weren't right was the oil pressure guage, and it got a bit less smooth and more vibey once the oil temp rose (oil thinned out and it couldn't sustain as much pressure)
Maybe i will start it up, but book it in to have the pump spill timed early next week. I dont have the gear to time it at home so i will have to drive it how it is anyway really..

Actually, is there an easy way to spill time it @ home without having to buy specialised parts?

 

[VTCDN]

My mechanic suggested it may be a sign that the injection timing is too advanced..

Well I have Never heard of that , OR how anyone could see that with those bearing shells. What I see is good bearing wear for mis-use and you made the correct decision of replacing both bearings.
Your Big end / rod lowers show me wear from oil starvation (NOW because of the story you told us) .

New brgs , plastigage , and i use white assemble grease and valuate the difference,, than dry so i protect the brg.

Recheck all , and retorque , seal up , Should be great to run in , then after all is dry and happy , recheck valve clearances & timing (with oil pan on.)


VT

 

[lostmarbles]

......Are you saying that if the engine starts and runs/revs/drives smoothly and without major hiccup then it should be safe to drive it like that? ....

Correct.

I have heard of people attempting to get their timing "spoton-first-time" using the awkward "spill timing method" yet still having to revert back to "minor adjustment and then see how it runs/drives" to improve it anyway.

This discussion makes me recall a dodgy mechanic's business near where I work. I once saw him driving a diesel around the block that was clearly not tuned right (assuming it wasn't a worse problem). It was pouring out black smoke and the "diesel knock" was incredibly loud. Anyone who drives a vehicle in such a state is simply an idiot and seeing him do that made me instantly decide to talk anyone out of using his services (if I found anyone at work considering it). IMO it should have been obvious as soon as it was started that it was not at all right (without having to go for a "foot to the floor test drive"). ...... I'm sure you wouldn't treat your cruiser like that.

So what I'm saying is .... Unless you're an idiot (like this local "mechanic") ... starting and running an engine while getting the injection timing right is highly unlikely to cause damage.

A competent mechanic would have marked the IP pump position (if it wasn't on the factory marks) and then reassembled everything the same way it came off and realligned the marks as a starting point ....

And if your engine runs well (ie starts easily, idles smoothly, revvs freely, has good power on the hills, doesn't produce excess smoke etc) .... then consider it all done.

Paying someone to do the job (who as all the dials and gizmos) isn't going to achieve anything more than lightening your wallet IMO.

 

[Scalci]

Sorry to high jack your thread.

Since I got my LC 1HD-T I had low'esh oil presure. I did the cylinder head a few weeks ago, and took it for a long run this weekend (1200km) towing. I notice the oil presure in the cruiser was half way beteen the L and the 1/4 mark... Very strange. When I started this morning, it was running between 1/4 and the 1/2 mark.

Any ideas?

 

[gbentink]

Sorry to high jack your thread.

Since I got my LC 1HD-T I had low'esh oil presure. I did the cylinder head a few weeks ago, and took it for a long run this weekend (1200km) towing. I notice the oil presure in the cruiser was half way beteen the L and the 1/4 mark... Very strange. When I started this morning, it was running between 1/4 and the 1/2 mark.

Any ideas?

If they are hot and cold numbers that you are refrerring to, then its very normal to have higher pressures when engine is cold or on a short run.