ppuxley
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| posted on 1/4/06 at 12:16 PM |
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Toyota 4AGE Oil Pressure
Calling any Toyota 4AGE experts
I have just put a 1989 MR2 Mk1 engine in a Locost
I have an oil pressure warning light that is activated by a switch at 20psi,it is just flickering at an idle of 800rpm,under power at higher revs it
is achieving at least 60psi.
Should I be worried? Engine had done about 80k,but sounds sweet.
Patrick
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nitram38
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| posted on 1/4/06 at 01:00 PM |
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Try changing the pressure switch. It is the cheapest otion !
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ppuxley
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| posted on 1/4/06 at 01:18 PM |
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Pressure switch is brand new from Merlin,and pressure gauge tallies with the 20psi they say it should switch at.
Question is..whether 20psi at idle is a problem or not
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Nick Skidmore
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| posted on 1/4/06 at 01:50 PM |
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As a rough guide, 10 psi per 1000 rpm was the norm. but modern engines do run lower pressure.
I would say your lower readings are ok, for upper reading see how far this is off stated oil pressure relief valve operation pressure.
My Hayabusa makes 10 to 15 psi on a hot day at idle, and about 85 psi on full tilt which is just afew pounds off the relif valve pressure.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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ppuxley
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| posted on 1/4/06 at 02:43 PM |
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Thanks,Nick
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Megatron-UK
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| posted on 1/4/06 at 06:47 PM |
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A mk1 MR2 should actually have a pressure sensor and not just an idiot light (meaning you can get an actual reading from it and not just a low
pressure signal) - If you have the original sendor you should be able to wire it up to an electric oil pressure gauge.
When I swapped out the 4AGE from my mk1 MR2 with a 3SGTE from a mk2, we swapped over the mk1 sensor in place of the mk2 sensor - the mk2 is just a
warning light, whereas the mk1 unit can work a gauge.
... but for reference, at idle the 4AGE was around 1/3 to 2/5 on the standard Toyota pressure gauge... rising to 2/3 - 3/4 at higher rpm. Not sure
what that translates to in bar or psi though; though as long as it's not really low and doesn't increase with engine speed I
wouldn't worry - the 4AGE is a tough little bugger.
[Edited on 1/4/06 by Megatron-UK]
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ppuxley
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| posted on 1/4/06 at 07:03 PM |
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Thanks.
I have a telemetrix oil gauge and sender and a pressure switch connected into an LMA adapter which screws into the block where the old Toyota sensor
used to be.
Unfortuneately I've now let go all the bits I didnt need from the donor and I never did see what it read on the MR2 dash before it came out,
because as I found when I stripped the engine out ,the oil sensor wire was broken just by the spade connector.
Still it seems to be running fine and showing plenty of pressure under normal running revs
Patrick
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Megatron-UK
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| posted on 1/4/06 at 07:17 PM |
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Yep, I wouldn't worry - mine had sat for 8-9 months unused, fired up within a few turns and was reading between 1/3 and 2/3 after a few minutes
- tough buggers.
All on a ~100k mile, , filthy, completely un-cared for engine!
Oh, here's just how long they can last when you really, really want to break one (no water, constant redline, no airflow):
http://media.putfile.com/Death-of-a-Mk1
... this is by one of my mates, a mk1 mr2 specialist of all things! 
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bimbleuk
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| posted on 2/4/06 at 10:22 AM |
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The 4AGE does have an efficient oil pump and doesn't run particularly high pressures. It does though have a high volume of oil pushed around by
the pump. On earlier engine this can be a problem as the head oil return isn't big enough (or the feed is too big!) and oil gets pooled in the
head.
Later revisions had an external oil return on the back of the head. This helped but on track a oil can still pool up top.
I've been told that you can restrict the oil feed to the head and also remove some webbing in the head casting as well.
Seems the 20V 4AGE has all this sorted.
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