Oil Pressure/Temp Gauge Retrofit

[batook]

I want to install oil pressure and temp gauges in my Previa. I have found at least 2 places where this can be achieved. The first is where the factory oil pressure sender unit is screwed in at the bottom of the engine, which has a M10x1.0 thread pitch. The other option (my preference) is a larger plug in the oil pump near the RH engine mount that takes an 8mm allen head to remove. I pulled one from a junkyard van and have determined the threads are M16x1.25 on that one. Here's a picture of the plug in question:

http://i744.photobucket.com/albums/xx86/bat00k/previa/oil_pump_plug.jpg

Most aftermarket senders are 1/8" NPT. Ideally what I'd like to do is run a stainless steel braided hose from this port to somewhere out of the way, then attach an oil pressure distribution block with standard fittings for oil pressure and oil temp senders, and then run their wiring through the firewall to attach to the gauges. So far, I've only been able to find hoses with M16x1.5 fittings, and one company that could create custom hose fittings, but that's probably $$$. Anyone looked into doing this before? Maybe I need to search through the MR2 and Supra forums, since they are more likely to have done this mod, and they probably share similarly sized ports. I could also use an adapter to go from the M16x1.25 to something more standard, but again the challenge is finding such a thing.

If I can't make the larger port work, I could use the M10x1.0 port of the factory OP sender, run a hose off to another out-of-the-way location, and get a 3-way distro block for installing the factory OP sender and aftermarket OP and OT senders. I have read some posts that seem to indicate that doing this will give inaccurate temp readings, presumably because the oil might cool some in the hose as opposed to take a reading directly at the block, so I may have to use a different location for the temp sender.

Last ditch solution would be to interface with the oil drain plug, but it's so low that I'd rather not have anything else sticking out of there, even a hose end to run to a higher location. What do you guys think? Thanks, Eric.

[timsrv]

I have a work-around for this sort of problem. 16mm is slightly smaller than 3/8" Male Pipe Thread. You can find 3/8" MPT - anything adapters at your local hardware store, then simply use a 16mm die to chase the threads into what you want. I've changed 3/8" MPT brass adapters down to 16mm X 1.5 pitch before and the threads were perfect. 3/8" MPT is slightly bigger than 16mm though, so it will take some effort to start the die, then some patience to cut new threads. You could possibly get the adapter with the 16x1.5 threads you were talking about, and chase those threads into the 1.25 pitch. I think that would work fine, but the threads might not be perfect (due to starting with a smaller diameter). Here's a link to the die you would need: http://www.amazon.com/16mm-Carbon-Steel-Hex-Rethreading/dp/B005KLVWV0/ref=sr_1_1?ie=UTF8&qid=1332777061&sr=8-1 & here's a picture of one of my modified 3/8" MPT fittings:

http://i8.photobucket.com/albums/a23/timsrv/t-stat.jpg

Here's a picture of a couple of them installed:

http://i8.photobucket.com/albums/a23/timsrv/whatever/IMG_8970.jpg

When it comes to a remote sensor location, oil pressure is not a problem, but the temp sensor would be very inaccurate (unless there's another path for oil to circulate back to the block). Even then it will still read lower than the oil in the pan. For accurate oil temp readings I usually put my sensors right into the pan. To do this I find a brass fitting with matching threads to my sensor, then cut it off and braze the threaded part inside the pan. Here's a picture of a transmission pan I modified when I installed a transmission temp gauge. Tim

http://i8.photobucket.com/albums/a23/timsrv/08brazingpan.jpg

http://i8.photobucket.com/albums/a23/timsrv/09insidepan.jpg

http://i8.photobucket.com/albums/a23/timsrv/10sensorinstalled.jpg

[batook]

Thanks Tim...boy do I love your work-arounds! I completely tore down the engine from my 91 Auto that I replaced with a JDM and have all its component parts in a box in my shed, so I have an oil pan handy already to install the oil temp sender into. Your idea to cut the threads of a 3/8" MPT down to M16x1.25 is also a great idea, and should be a lot more economically viable than trying to find something already that size (proving hard to do) or having one made for me. Now I just need to decide on what gauges I want and get the senders. Ideally, I'd like a 3-gauge mini-cluster that I could mount above the factory one that includes OP, OT, and tach. I'll see what I can dig up online. Thanks again! Eric.

PS: What die handle do you recommend? I've tried some in the past that I wasn't very happy with (not enough leverage to apply enough force to turn it or the die would slip out of the center). Even the tap handles I've used performed worse than just clamping a tap with vise grips... (maybe I need to stop shopping at Harbor Freight and Lowes, at least for this kind of thing!)

[timsrv]

I'm not sure about the handles. My handles & holders were purchased about 25 years ago when I was a machinist. I got the quality stuff like SPI from special order catalogs. That was then, not sure how or where to get the stuff now. Good luck. Tim

[batook]

Gotcha. I'll look into professional tool suppliers like Snap-On and Matco for this, since it's clear I need something of a LOT higher quality than I've been able to find off the shelf. Eric

[batook]

I thought I'd follow up on this here and post what I've decided to do. A member of the Yahoo Previa group pointed me to M20 oil filter sandwich adapters that screw onto the oil filter bracket and provide 2 or 3 1/8" NPT ports for adding senders. I've decided to go with the Mishimoto MMOP-TPS adapter for about $50 from SummitRacing, Amazon, etc because it has a lifetime warranty and appears to be very good quality...there are cheaper ~$25 options on ebay that are made in China but this is NOT an area where I want to skimp and risk a possible oil leak/loss of pressure due to a failed adapter. Here's a pic so you can see what I'm talking about:
http://i744.photobucket.com/albums/xx86/bat00k/previa/gauges/MishimotoMMOP-TPS.jpg
For the gauges, I've decided to go with the Auto Meter 2391 tri-gauge panel for $68, and match it with Auto Meter's 2242 oil pressure sender and 2258 temp sender. There are cheaper gauges by Sunpro or Equus but I've read that they can break within a year, or even when trying to install the senders due to their poor construction. I'd rather get quality parts that will last, and the Auto Meter gauges/senders are highly reputed on the Bob Is The Oil Guy forums where they frequently do this thing of mod. Here's a link to the gauge panel I'm getting...I think it looks pretty cool:
http://i744.photobucket.com/albums/xx86/bat00k/previa/gauges/AutoMeter2391.jpg

Now I just gotta figure out where to mount it...I wonder if I can squeeze it into the single-DIN slot under the tape/radio where the pocket is normally? We'll see...it might just be an ugly install using 3M double-sided tape stuck on the dash above the factory cluster, which is how I have the aftermarket tach "installed" in my 91 LE Automatic... :rolleyes: Eric

[timsrv]

That's really cool. Perhaps I'll go the sandwich route with my 89 van. This way I can keep the idiot light and have the gauge as well. Tim

[cvtroger]

Sorry for the resurrection!!!

I've been going over the next projects for my van. My idea was to do a filter relocation, and I came about people doing oil coolers. Then I was thinking I want to keep track of the oil pressure and temp.

When it comes to electrical stuff, I dont know squat. So this thread is a good idea.

Great info Tim! I'll probably have to go out and find an oil pan and drill it out for the sensor.