TeamCapri

Tech, Repairs, Upgrades => Non-Capri Usable Car Parts => Topic started by: capriBill on October 06, 2013, 05:57:14 PM

Title: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on October 06, 2013, 05:57:14 PM
My Oil Pressure Sender does not look to be working correctly. Sometimes it drops near the red for no reason and later gets good again. I looked at it and it looks like it is leaking too.
I was looking for a replacement. They are not sold anymore and the old ones available are too expensive. I did find a Miata version. Have any of you tried that? It is at this web site: http://www.partsgeek.com/gbproducts/DC/8532-05268552.html?utm_source=google&utm_medium=ff&utm_content=DN&utm_campaign=PartsGeek+Google+Base&utm_term=1990-1994+Mazda+Miata+Oil+Pressure+Sender+With+Gauge+Standard+Motor+Products+PS-261+90-94+Mazda+Oil+Pressure+Sender+With+Gauge+1992+1993&fp=pp&gbm=a&gclid=CPq03siZg7oCFdFDMgodHy8Adg

Also, how hard is it to get the old one out to replace it? I was under the car cleaning the connector to it. It took a while to get it off, clean it and put it back on. I am worried if replacing the sensor will require removing other pieces. Have any of you done this?

Thanks,

Bill, 92 XR2
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on October 07, 2013, 02:04:49 AM
Welcome to TeamCapri!

The old sensor comes out real easy, it's just a pipe thread. You may need an adjustable wrench.

Those are expensive senders, maybe try a junkyard unit first?

I will say, out of all the Capri's I've owned not a single stock oil pressure gauge has ever worked correctly. My newest XR2's gauge works sometimes but other times just sits at zero. And that's the best I've had so far. The accuracy when it is working (like that of the boost gauge) is questionable as well. I haven't really looked into it, and even so the sender may be fine and it could be a bad connection on the start/charge harness (the OPSU wiring is separate from most of the other sensors) could be an issue with the gauge itself too.

Personally I feel investing in an accurate aftermarket gauge would be the best option. For the price of that sender you could purchase a nice electronic gauge with its own sender. There are much cheaper mechanical gauges too but some folks don't like an oil line running through the firewall.

My 2¢ anyway :)
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: blueamber on October 07, 2013, 02:44:58 PM
I don't know the answer to your question.  You need to find out the thread area length of the sensor, the thread spacing and diameter numbers, and the output of the sensor based on pressure it sees.  Finding an equivalent new part would be a good project for someone to benefit all of us with senders we can't rely on.  I personally would love to stop the car and have it towed in with a very low pressure indication, rather than guessing that this low pressure reading was just like the last time, and I could ignore it...Chris
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on October 07, 2013, 07:13:12 PM
But how do we know it's the sender that is the culprit of the poor gauge situation? Has anyone sat with a multimeter directly on the sender's terminal to see if the signal drops out when the gauge does?

The 1.6 Miata uses the same block (89 thru 93 IIRC) and should use the same pressure sender threading, providing it taps it in the same location.

Now, is it electrically compatible with the Capri? That'd be my biggest concern

Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: blueamber on October 07, 2013, 10:03:56 PM
A Mazda 323 sensors would probably work, but you would still be looking at finding used parts off a 20 year old car.

The sensor is a one wire unit, looks like a variable resistance.  That wire goes directly to the dash cluster, straight to the meter.  If it screws into the hole, and is a one-wire sensor, it would work, with the only question being if the gauge accurately reflects true low and true high oil pressure.  Its just a resistor, no harm could come with trying other sensors.

I don't have the specs on what our meter measures under various pressures, but this might be dug up somewhere, and compared to other sensor types.  If I find it, I'll share the info.

You said it yourself, these sensors are all over the place on accuracy.  I know that heat kills electronic components eventually, and a part screwed into the block of an engine stands a good chance of failing eventually, or at least going intermittent...Chris
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Greg_B on October 08, 2013, 01:43:36 PM
In a previous job I worked for a comapany who built pressure sensors and gages for heavy truck, off-road equipment, Mercury Marine, OMC etc.

I did some checking after I got my 93 N/A 5 years ago, so this is all from memory.  The single wire sensor varies resistance based on oil pressure.  There is a resistance table in the FSM, for checking gage, at various pressure readings, or needle position on gage face.  Find that table, use an ohmeter from sender terminal to ground.  If it is close to table readings sender is OK.  Dirty internal contacts can cause changed resistance.  I have a decade box that I have used to simulate a good sensor to double check my gage.

I did find a replacement sender with a resistance curve close to what the gage needs to see.  But the thread in the block is a Japanese? pipe thread 1/8-28, not the us standard 1/8-27.  Never did finish looking for the adaptor.

I think the miata part is either just a switch, or a fixed resistor so the needle stays in one spot, unless it is from an early miata, somewherethey changed to a dumb sender.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: blueamber on October 08, 2013, 05:03:53 PM
OK, I found a Miata thread where a guy put a aussie capri oil sender into his early 90s miata, worked great, he got it at a junk yard.

If that is true, then the Miata substitute you found would probably work, it's a Standard Motor Products PS-261 sensor.  These are on ebay, cheapest today is $50 from a questionable seller, or $89 from a better seller, free shipping.

Ebay ads claim the sensor works for 90 to 94 Miata, 93 to 95 Ford Probe..Chris
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on October 08, 2013, 10:59:47 PM
4cylinder or V6 probe? I have a '95 probe GT engine at my shop I can check.

The 323/escort/protege 1.6 & 1.8 sending units are all just switches for a low pressure light. Won't work with our gauge. They're significantly cheaper though, if you wanted to wire in a light
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: blueamber on October 09, 2013, 12:02:50 PM
Spec sheet says 95 Probe V6 uses that Standard Motors products also.  That company looks big into Miata parts sourcing.

I just gotta believe our big old clunky sensors are mechanical relics inside, just waiting to go nuts all kinds of ways due to temperature and old age.  With only one wire attached, it is probably just a big old volume control type rheostat attached to a mechanical arm that pushed the rheostat back and forth.  Newer units are 100% electronic, with voltage supplied to the sensor, which is probably something called a strain gauge that senses pressure with no moving parts.

Looking through ebay, I didn't realize that an adapter was available, probably for our cars, that fits between the oil filter and the engine.  It has 2 holes in it that could be used to fit your own oil pressure sensor and oil temperature sensor.

I also think adding idiot lights would be a good thing.  I used to be more attentive to instrument readings, but not so much anymore (not even the speedometer so much), so a warning light/siren/whoopee_cushion_vibrator letting me know the coolant temperature is in the red, or oil pressure is gone, would be helpful...Chris
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on October 11, 2013, 09:03:46 PM
The reason I think it is the sensor is that all of the gauges have been good except the temperature (often) and oil pressure (seldom). I have had to replace the temperature sensor 2 times during the life of the car. I only have 76,000 miles on the car. The last temperature sensor I found has been working great, no longer shows a too high reading, and only cost $3.53. I found it here, and purchased an extra one for the future: http://www.rockauto.com/catalog/raframecatalog.php?carcode=1196658&parttype=4748

I am looking for a new sensor with a warranty that we can all use for the oil pressure. I do not want to buy an old Capri one at an outrageous price. I did see that same Miata thread about using a Capri sensor in a Miata and it worked great. That is why I hope the reverse is true.

My gauge shows a good reading 99% of the time, it is only sometimes that it all of a sudden drops. After a while it goes back to good. I do see oil on the sensor indicating to me that it starting to leak. I do think that the reading is lower than it used to be, but cannot be sure.

Have any of you replaced the sensor from under the car while the engine is still in the car? I do see what looks like an engine mount that makes access to the sensor difficult. Did you remove the mount to do the work?

Thanks,

Bill 92 XR2
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on October 11, 2013, 10:45:45 PM
I will check the 2.5L V6 OPSU and get back with the results
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on February 20, 2014, 06:41:24 PM
I will check the 2.5L V6 OPSU and get back with the results
Car has been buried under snow all winter. I'll Check when it warms up a bit.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on April 20, 2014, 10:19:15 PM
Hi Rocketman,

Are you going to be able to try this soon? My oil pressure is good 70% of the time, then drops almost to the red part of the gauge and stays there for a while. That is why I think it is the sending unit. Do you think the Oil Pump will only work 70% of the time? I assume either it works or does not work. I did try cleaning the connection to the sending unit, but that did not solve the problem.

If you are not going to be able to try it, I will just buy the part and replace the sending unit and will hope it works. I again ask, do other parts need to be removed to get it out with the engine still in the car?

Thanks,

Bill
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on April 20, 2014, 11:42:42 PM
I've put in ZERO wrench time on the V6. Weather hasn't been great and the nice days I have had, have been spent casting in the foundry. I'll try to get to it soon.

Correct, if the oil pump wasn't working, your engine would seize in a matter of mere seconds.

You may have to remove the oil filter to get easier access to the OPSU. Maybe the intake manifold brace. You might be able to get at it without removing anything, with the right socket/wrench
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on June 06, 2014, 12:48:04 AM
Hi Rocketman, the price of the part is going up.  :'(

Do you think you can try the one you have soon? I am thinking of just buying one and trying it myself, but just hate to waste over $100, time, and most likely skin, if it does not work.

Are you going to the Mid-America Capri Gathering in Freeport Illinois? I'd like to see your car. Mine is a perfect, except for this sensor, 92 XR2 with less than 80K miles. It is 98% stock.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Rocketman on June 07, 2014, 10:37:10 AM
It's not likely I'll be able to get to it anytime soon. I'm running out of time & money for my car projects. Have not touched the V6 since last fall. :(

As for the MACG - I don't know yet. It's a busy summer for me, I'd really like to attend. If I do go I'll probably be in my red ressurwreckted XR2 - the GTXR2 needs a complete overhaul before it can be reliably driven again.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: mitch1204 on June 10, 2014, 12:36:15 AM
On the Roo-sport website they have a fix for the oil pressure issue. They said to take the ground strap off the passenger fenderwell near the strut tower to the engine and clean it good. I did that and my oil pressure gauge worked good for awhile. It drops now on occasion but works much better than it did. I noticed all my ground straps were corroded so I cleaned them all and used dielectric grease on all the connections to prevent future moisture/corrosion problems.
If that ground fix worked for awhile I'm going to change the strap and see if that helps because corrosion can build where the cable is crimped.

As far as the sending unit Advance carries them for $12

http://shop.advanceautoparts.com/c4/oil+pressure+switch-sender/-49998129?isAllVehicle=false&showTitle=&vehicleIdFromReq=21430&vehicleIdSearch=21430

The 1994 Mazda MX-3 has the same body and threads but has a blade pole instead of a round pole to connect to. I would say the same for the Miata.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: blueamber on June 10, 2014, 11:07:34 AM
Could you supply link data to this being compatible with the Capri?  There are literally hundreds of sensors that will screw in the hole, most are dumb switches that just turn a light on and off.  I can't find any data on the WELLS  part other than fitting early 90's ford trucks...Chris
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: mitch1204 on June 10, 2014, 02:02:45 PM
The SWE-2185 is the one I have on my car. I'll look for specs on it and cross reference it.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: mitch1204 on June 10, 2014, 03:38:22 PM
Could you supply link data to this being compatible with the Capri?  There are literally hundreds of sensors that will screw in the hole, most are dumb switches that just turn a light on and off.  I can't find any data on the WELLS  part other than fitting early 90's ford trucks...Chris


You're correct. I'll do some deep researching on this. I do know it's a 1/4-18 fitting, it has a blade connector and the resistance is opposite from most with low readings having the greatest resistance. Then there is the sweep of the needle to take into consideration whether it's 180* or 270*.

Those I pointed out turned out to be dummy lights so I'll tell Advance.

This is going to be hard to find but not impossible.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on June 12, 2014, 04:37:50 PM
I purchased this from Ebay. It has now arrived. It is kind of big. I just have to see if I can get it to fit in the car. Have to climb underneath. I will try removing the oil filter first. This is the right kind since it is for a gauge, not a light or the dumb single position gauge that Miata starting having later.

http://www.ebay.com/itm/Engine-Oil-Pressure-Sender-With-Gauge-Standard-PS-261-/180825926259?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a1a10aa73&vxp=mtr

One Miata owner did say they used a Capri sender and it worked. I am hoping the reverse is true.

I will write back after I try to get this in.
Title: Mazda Miata Oil Pressure Sender Does Work!
Post by: capriBill on June 12, 2014, 11:17:37 PM
I now have it working great!  :)

I am not sure how to attach the image I have. If you send me your email, I can email it to you.

This is the part I used:
http://www.ebay.com/itm/Engine-Oil-Pressure-Sender-With-Gauge-Standard-PS-261-/180825926259?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a1a10aa73&vxp=mtr

I had to remove the starter mount bar and oil filter to replace it.

It is bigger than the Capri sender, but with some work it does fit but very tightly. It did get bent a little on the top when I tightened the starter mount bar.
I found that if the starter mount bar pressed to hard against it, it caused the gauge to pin. To resolve the problem, I put a washer between the back of the starter mount bar and the engine around the bolt(s) that hold it on the bottom. The bolt is shown with the red arrow in my picture. I did strip the other bolt at the bottom, and will need another one if someone has an extra part. I learned how to install the starter mount bar to get it in with the bigger sender:
1. First put in the bottom bolts, with a washer between the mount and engine to make room for the sender, but only screw them in a little. The red arrow shows this.
2. Put the top bolts in, and tighten them. The orange arrows show this.
3. Tighten the bottom bolts. The red arrow.
4. Put in and tighten the starter bolt. The green arrow.

The sender is shown by the white arrow. If you look closely, the wire comes out pointing towards the top-right to avoid shorting against the starter mount bar.

Changes I made to it are:

1. I moved the rubber on the sender up to cover the connector so that it does not short against the starter mount bar.
2. After tightening it, I turned the connector so the wire connects from the top-right to avoid the starter mount bar.

The picture shows that it gives a little higher reading than then old sender, but it looks good. I show both what it looks like when driving and idling.
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: twopass on June 30, 2014, 09:44:31 PM
have a look here got to be 1 that will work.

http://www.summitracing.com/search/part-type/gauge-sending-units/gauge-type-application/oil-pressure
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: XR2Man on August 03, 2014, 05:50:23 PM
Hi there guys!

    I joined the forum a few months ago. I purchased a 1991 XR2 with turbo engine and have spent some time getting to know the car and working on it cleaning it up and fixing some things. One of the things is the Oil Pressure sender unit. When I get to take the car out for a drive, the oil pressure gauge reads near the red line or sometimes it reads up about an 8th to a 1/4 higher. Then again sometimes it reads way up on the gauge. Doesn't matter if its driving it around town or on the highway. Still shows the same on the gauge. I have taken the braided ground cable off and cleaned the ends of the cable and the mounting spots and put the cable back on and no change. Now here is the fun part. I have worked for a truck dealership for International Harvester Co, which is now Navistar, in the truck division. Worked there for 43 years!!! Anyway, if you look at the oil pressure sender picture at Modern Capri parts, we sell a sender that looks EXACTLY like the one for the Capri!! The part# is 584051C2. I DO NOT know what the specs are for this sender. It is used on gas engines in trucks. It is still available and it is priced WAAAAAAAAY under $100!! Now! If I knew the specs on the one for the Capri and what poundage between low and high it is, I might be able to inquire with International specs dept and see what poundage theirs is. I worry about mine whenever I drive it. I also worry about the fact that the car has 118,000 miles on it and I don't think the timing belt has ever been changed yet. That is another adverture I have to look into.

P.S......I have seen the senders on Ebay for sale under the part# 584051C2
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: Jolls on August 03, 2014, 07:45:25 PM
XR2Man,

I have exactly the same issue with my XR2 over here in Oz and have been researching high and low to find an OEM replacement that will fit.

Sender rating - O to 700 kpa (7 Bar/100 psi)
0 kpa/bsr/psi) - 116.2 ohms
200 kpa/2 bar/30 psi - 49.5 ohms
400 kpa/4 basr/60 psi - 31.3 ohms
600 kpa/6 bar/90 psi - 17 ohms
700 kpa/7 bar/100 psi - 13 ohms (this has been extrapolated from the 90 psi and 120 psi readings for the gauge).

If you can't find the tech data they are easy to test if you are able to make a schrader valve (tyre) to oil pressure sender fitting. You measure the resistance between the output and the base . You can check the curve by applying X air pressure and reading off the resistance.

If it looks exactly the same as the one from the Capri it is probably a VDO sender unit (our OEM gauge and sender were VOD made specifically for the Capri - why???). My research indicates that VDO don't make a sender init in the same specification range. The closest is a 120 psi gauge that reads 100 ohms at 120 psi but is close at the low end. I would need to dig out the specs. I have found a wells unit that is bloody close but it is larger and I need to see if it fits behind the manifold bracket. Unfortunatley I didn't get to it over the weekend.

I trust this helps. If you can confirm the data I'm in for one of the sender units.

Cheers and Beers

Craig
Title: Re: Will Mazda Miata Oil Pressure Sender Work?
Post by: capriBill on October 17, 2014, 12:08:55 AM
The is still working well since June. I was told afterwards by Russ Carlson that the starter mount bar does not really need to be put back. It is just over engineering. If it is not put back, there is more than enough room for the larger Miata sending unit I used. It is a "Standard Motor Products PS261 Oil Pressure Sender".