Jump to content
SAU Community

Recommended Posts

Hi guys I'm reposting from here and here as this is going a bit beyond the scope of the original threads.

Anyway I've just had the Driftworks oil cooler kit install completed on my R34 GTT:

  • Mocal/MIH 19 row Oil Cooler
  • Mocal 92 degree thermostatic sandwich plate
  • Braided oil cooler hoses
  • Sandwich plate fittings

The cooler seems to work well - in fact too well - as I can't seem to get my oil temp up to the recommended range even after a long drive.

Test drives so far (all light cruising until I sort out the temps):

  • Melbourne to Torquay, 1.5h freeway, Defi oil temp is reading 55-60 degrees, ambient temp just under 20
  • Torquay to Melbourne, oil temp ~60 degrees, ambient temp 25
  • Suburban driving, slower speed, oil temp 55-64 degrees, ambient temp 25

...

I can think of a couple of potential causes:

1. Maybe the thermostatic wax pellet in the sandwich plate is not working and the cooler circuit is stuck open or opens too early? Trying the core by hand it's hot but not unbearable. It's definitely flowing a lot of oil during each drive, and well below the expected 92 C opening mark. Also driving a couple of k's from cold start you can feel the oil cooler feed hose getting warm straight away whilst return stays cool.

2. I previously had the temp sensor in a separate sandwich plate with oil flowing through it. For this install the workshop removed the factory pressure sensor and teed off that point – I'm guessing this might be after the filter as opposed to before, which would explain the lower reading?

Here's how the Defi temp sensor is sitting at the OEM oil pressure sensor location (the other end of the T-piece is currently blank waiting for the Defi pressure sensor):

24160402470_0ab647bd3b.jpg

I did some quick temp measurements off the sump earlier tonight (externally using a laser thermometer) and found the following:

  • Defi oil temp reading 53C – sump 68-70C
  • Defi oil temp reading 61C – sump 76C
  • Defi oil temp reading 64C – sump 75C

This might support the theory that the OEM oil pressure sensor point is not ideal for getting oil temps?

What do you guys think: a faulty thermostat, incorrect temp sensor location, or both?

There will always be some oil circulating through the cooler.

What was your oil temp before you installed the cooler?

Use your laser thermometer to track flow through your sandwich plate and see if you have picked the wrong spot for your sensor.

The big difference between the sump temp and oil gauge temp suggests the cooler is not overcooling.

There will always be some oil circulating through the cooler.

What was your oil temp before you installed the cooler?

Use your laser thermometer to track flow through your sandwich plate and see if you have picked the wrong spot for your sensor.

The big difference between the sump temp and oil gauge temp suggests the cooler is not overcooling.

Yep I spoke with a Mocal distributor today and they explained the same thing that a certain % is always going through the cooler.

What I'm wondering though is if I have the right thermostatic pellet in the sandwich plate, since it seems like it's not just a trickle going through it? Assuming the temp sensor is currently post-cooler (as opposed to previously pre-cooler) it looks like I'm getting a pretty significant temperature drop at temps well below the previous standard operating temp.

Oil temps before the oil cooler installation were 80-90 degrees in normal driving. The same Defi sensor was sitting in a (different) sandwich plate so the oil was flowing through it, as opposed to sitting at the 'end of the line' like it is now.

So your oil temps were perfect, before the cooler was fitted.

Put a sheet of cardboard over the cooler and see what your temps read.

If back to normal id say the unit is open allowing full cooling.

If the same low reading, wrong location.

There is no flow over your Defi temperature sensor!!!!!!!!!!! It is not measuring the temperature of the oil flowing in the system. It is measuring the temperature of the oil in that dead leg, which being brass, will lose heat and be cooler than the rest of the circuit.

/basic physics.

  • Like 1

So your oil temps were perfect, before the cooler was fitted.

Put a sheet of cardboard over the cooler and see what your temps read.

If back to normal id say the unit is open allowing full cooling.

If the same low reading, wrong location.

Correct, the oil temp was always spot on in street driving.

At the track the temps shot up to 120C after pretty much a single hot lap, though this was on a 37C day.

I'm yet to try blocking the cooler, good idea, I will aim to do that tomorrow.

There is no flow over your Defi temperature sensor!!!!!!!!!!! It is not measuring the temperature of the oil flowing in the system. It is measuring the temperature of the oil in that dead leg, which being brass, will lose heat and be cooler than the rest of the circuit.

/basic physics.

Ok so exactly as I thought, thanks mate!

Next question: Where do people place the temp sensor for an accurate reading with this type of sandwich plate? It doesn't have a sensor port.

As far as I can figure the options are:

  1. Run an inline AN10 male-female fitting with a sensor port – is there enough oil flow in the cooler circuit at <thermostat temp for this to work reliably?
  2. Run a second sandwich plate for the sensor – not ideal
  3. Drill a sensor bung in the sump – sounds like a big sump-off job
  4. Get a Greddy/GREX sandwich plate that has both a thermostat and fittings for temp/pressure sensors – not ideal since I already have a sandwich plate

Would option 1 work? Any other suggestions?

I drilled and welded a bung on the oem oil filter bracket to install the sensor.

Thanks mate, that seems like a good solution.

I've just ordered this AN10 inline sensor fitting, might try that first: http://m.ebay.com.au/itm/AN10-10AN-JIC-FEMALE-to-MALE-GAUGE-SENSOR-FITTING-ADAPTER-1-8-NPT-PORT-BLACK-/231353204035

Keen not to swap the sandwich plate again as I already have the previous one sitting on the shelf..

Why no plug it into the stock location after the oil return ?

I didn't realise there was a stock oil temp location on the RB25DET? Whereabouts is that?

I have a Greddy/GREX sandwich plate and have the oil temp and pressure sensors stuck in there.

It might be easiest (and best) to sell your sandwich plate and invest in one with pre-tapped sensor holes.

Do it once, do it right!

  • Like 2

I have a Greddy/GREX sandwich plate and have the oil temp and pressure sensors stuck in there.

It might be easiest (and best) to sell your sandwich plate and invest in one with pre-tapped sensor holes.

Do it once, do it right!

I would tend to agree :) The one thing I like better about the Mocal one is the 92C thermostat (if it works?!) - I believe the Greddy plate comes with a 80C one.

What temps are you seeing in normal driving over summer?

Just block it off with cardboard or plastic. For daily driver you don't need it.

I've considered that too, the issue being that it sits between the rad and intercooler so would block off airflow to other components as well...

Put a fitting on the side of the sump and run the sensor in the sump. It will be the closest to correct oil temp without putting it into a new/doubled sandwich plate. it's currently reading at least 10°C low, which is only so useful.

I would tend to agree :) The one thing I like better about the Mocal one is the 92C thermostat (if it works?!) - I believe the Greddy plate comes with a 80C one.

What temps are you seeing in normal driving over summer?

Yup, it opens around 80C. I see temps around the 80-85C mark in summer with just normal suburban driving.

Temps go up to around 110-115C on track with mild (~20-25C) weather.

  • Like 1

This is what ive always used to get a sensor into the sump

http://www.ebay.com.au/itm/OIL-TEMP-GAUGE-SUMP-PLUG-ADAPTOR-FOR-NISSAN-S13-S14-SR20-SKYLINE-R32-R33-R34-ASQ-/121748884691?hash=item1c58cc8cd3:g:It8AAOSw3xJVbtGl

Just put a plug onto your sensor wiring so you can disconnect it for oil changes...

That's pretty cool. So many options!

So your oil temps were perfect, before the cooler was fitted.

Put a sheet of cardboard over the cooler and see what your temps read.

If back to normal id say the unit is open allowing full cooling.

If the same low reading, wrong location.

Just block it off with cardboard or plastic. For daily driver you don't need it.

I did a run with the oil cooler blocked off, suburban speeds, ambient temp 20C:

  • Defi oil temp reading 67C – sump 80C

So it's about 5C higher at both points than with the cooler unblocked. Note this is in slow speeds so the cooler wouldn't be very efficient anyway.

The temp sensor is definitely in the wrong spot, I'll get that sorted. The jury is still out on how well the sandwich plate thermostat is working.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Either the WG is reaching full opening, or it is not. The "it is not" case could only occur if there was not enough time available to swing the valve fully open during that boost event. I would consider that to be unlikely, as this is a commercial product that is in use elsewhere, so it really should work. But in your case, because there is definitely SOMETHING wrong, it should not be assumed that things like that are working as they should. You should put a video camera where it can see the actuator (if at all possible) during a run to see how far it is moving.
    • I think you're mostly on the ball there. With the straight gate, I suspect the weight of the spring will determine how quickly the gate can close, when not run with active pressure drive on both sides of the diaphragm. Otherwise, with drive on both sides of the diaphragm, you could almost go without a spring at all, only needing one to make sure that the thing was actually closed while completely off boost and not having pressure available to drive it closed. Butterfly valves have mostly symmetric loading when there is flow going through them, meaning that the gas hitting the upstream part of the blade is balanced by the gas hitting the downstream part of the blade, which means you don't need actuator torque to overcome any non-symmetric flow induced loads. But the gas flow does impart a purely normal load against the shaft, which transfers into the bush/bearing at each end of the shaft and does increase the torque required to make the shaft turn. Only a little, but it is there. I have no feeling for the amount of force involved in a WG application, but it certainly could make an argument for a decent spring weight being required. But all of this is just peripheral to the actual problem here.
    • The answer to this would be I followed the documentation from Turbosmart which said each spring pressure could achieve a maximum of 5x it's rated pressure so the included smallest spring being the 6psi had a range up to 30psi. I went with the 12 because I figured it'd likely hover around 15psi as a base pressure however I was obviously wrong.    I have a log here that I'll dig out that is purely wastegate and no Mac valve controlling anything.   If it can't hold anywhere near 12psi, does that mean the straight gate is virtually wide open during a run? Or am I thinking about this all wrong.   I could Tee Piece into the cooler pipe pre intercooler where the wastegate gets its feed, and send that to the ecu and see how that reads, I just don't have a spare pressure sensor currently that's all.
    • lol nice, I wouldn't worry about sanding back the filler to check for rust then. Yep very much a thing. Personally I don't do the panel beating, its very easy to have a panel beater sort that out for you. If they aren't doing any prep work the actual panel beating generally doesn't take long at all.  Have you taken before pictures before you started this project? I'd be keen to see the before and afters when you're done.
    • Some good discussion in here, for the most part I can't really add too much to it - thought I'd add some notes to the datalog screen shot that probably aren't news to anyone but a good prop... this is assuming 25psi-ish should be the boost ceiling given the first post refers to 23psi.   To state the obvious, this issue seems super weird.  Turbo speed seems pretty lethagic to build, like the turbo isn't getting as much drive as it needs - and it doesn't help that wgdc keeps rising AFTER boost target then completely shuts duty at a point, which in theory should have the straight gate dump heaps past the turbo and funnily enough causes the huge drop off.  It seems like pretty blunt boost control tuning but I'd not call that the primary issue, so much as possibly not helping the situation. I'm curious, what does a pull look like with purely mechanical boost control?  Like purely wastegate?   There are things in this log and story that make it sound like there could be a significant restriction in the intercooler piping or something - but then it's also overshooting boost target which is NOT what you'd expect with a restriction.   I can see where people are coming from with the non-linear wastegate bypass (not that any valves are linear for this kind of thing), but it still doesn't make sense that it can't hold <20psi on a 12psi spring.    Have you, or can you try measuring pressure pre-intercooler?  Be pretty interesting to see what's happening there vs in the intake manifold - sorry if I've repeated old ground, I've kinda skimmed over but I could have missed something.  In terms of comments regarding the wg spring being closer to boost target, I haven't used a straight gate but part of the reason for having close to wg target is about fighting backpressure as well - I might be wrong, but I'd have thought that part of the point of using a butterfly valve like the straight gate does you actually don't have to resist pressure at all, on EITHER side of the gate.   It shouldn't need too much leverage to start opening, the spring being more to do with where it triggers opening as opposed to resisting boost & EMAP, though smarter people can correct me if I'm wrong there.  
×
×
  • Create New...