Oil Pressure / Oil Temperature Measurement

I had once asked on another list about measuring the oil pressure & temperature. I was told the best place for pressure was to drill out one of the oil galley plugs and place a 90 degree fitting there with a gauge, and to install a thermometer in the sump. Can anyone expand on this? I would really like to have the smallest gauges possible up near my instrument cluster for real-time monitoring.

Thanks!

 

well, step a is to have a place to take off the pressure reading. If your bike has an oil pressure light, then the thing to do is to find that sending unit.
Then remove the sender & place a "T' fitting in that hole. Thread the stock sender into that hole, & a oil pressure line kit- since its metric, you can probably find this stuff at a VW dunebuggy/hotrod shop. Any auto store has a line & assortment of brass fittings as a kit, too, but it would be threaded SAE, not metric. Follow so far? Gauge are rather universal, oil filled ones- to dampen vibration- very common in the HD world. I have a 100 lb SW gauge on my old Triumph Ive had 25 yrs, tho, not oil filled, just heavy duty.
Im not entirely sure what your oil filler is like, but "meat thermometer" type gauges showing oil temp are, again, common in the HD world. It doubles as the dipstick, & has a dial thermometer....my decriptive ability is not too good, feel free to ask me to clear things up...mutt

 

Just so you know, the XJs do not have an oil pressure sensor. The oil light is triggered by a sensor on the bottom of the sump and it indicates a low oil level, not pressure.

 

Ah, yes....i remember reading that startling fact in the owners handbook that came with her machine...is there a threaded plug from the drilling of the oilways thats readily acessible?
i can see where the "oil low" light might be useful for people new to bikes...or cars for that matter. Nothing like some sort of pressure idicator, tho, to tip you the oil filter has unscrewed, or the pump ate a bit of mystery swarf. thx for the heads-up, mutt

 

OK, let's go back to my original post...lol. I know that I have an oil level light. What I'm interested in is measuring the pressure. If you look for a pair of huge allen hex plugs below the crank (one one each side), these are the oil galley plugs. This is the entry pressure to all of the moving parts needing lubrication. My question was directed more toward "has anyone measured their oil pressure here, and were they happy with the results". The same goes for measuring the oil temperature.

 

I wouldn't drill out anything on the engine. The line going to the oil cooler is a good place to install oil temp and pressure sensors. If you don't have a cooler that's no excuse because everyone needs one unless they drive where it's always cold.
I installed something like a "T" but it's really a cross in the line on my Seca and installed the temp and pressure sensors for my VDO gauges there. For reference the pressure varies between 60-90 PSI and the temp runs around 120-180F, just like any other engine. Without a cooler it goes way over 200F and the pressure drops to ZERO! That's not good for the main bearings.

 

ArizonaSteve,

I am putting the finishing touches on my oil cooler now. I needed to buy all new o-rings and seals for the setup, so when they arrive I'll put it together and take advantage of the higher pressure and lower temperature.

Because I do drive during the winter (NW Ohio) I put in a Jagg Bypass valve. That way I don't cool the oil down too much in the winter. During the summer it'll be wide open.

The oil galley has plugs on each end that take a big allen wrench to unscrew. I was going to take one off, have a friend mill a new one that had a thicker shoulder on so I could put in a 90 deg fitting on the shoulder. I'm not sure how much the pressure backs up from the oil galley. back through the oil filter and into the oil cooler hose. In the long run, removing the plug isn't physically hurting anything, so I may test it at both places to see what the difference is.

Michael

 

hmm ye i was wondering

what those big hexes were!

one was leakind so i tightened it a bit,

does any one know the torque specs for them?

 

I read in another list that some of the XJ's had an oil drain plug with a magnetic screw through it. Some mentioned that it was here that others had modified the plug to receive a temperature sender for measuring the oil temperature.

Anyone here have this mod? Any pics?

Michael

 

I wouldn't think the drain plug had any pressure in it as the sump is not a pressurised place. Any measurement would have to be from one of the galleries directly off the oil pump.

Maybe a line off the oil cooler pipe.

 

It's a probe-hole drain plug, used to check oil temp during EGA testing.
Generally aside from this plug, there are 2 type drain plugs ( magnetic and
non-magnetic ).
The magnetic plug being used on models having the oil level sensor.
This is to collect metal particles which might interfere with oil level
sensor performance.
I myself would use it in all applications, I don't want metal floating
around in my engine, oil level sensor or not.

 

Hired_Goon,

I was going to measure oil temperature from the drain plug.

jdrich48,

Thanks for the info. I don't think I have a magnetic drain plug. I should probably look into that, however, I do think that since the sump is where the oil and any metal falls too, is then sucked up by the oil pump and filtered out before returning it to the engine. I could see that it would effect the oil pump life the greatest. Regardless, having a magnetic oil drain plug is highly desireable over not having one.

 

You can measure the oil temperature at the drain plug by getting a VDO sensor with the same size threads and screwing it in the hole in place of the stock plug. They make one for installing in the oil pan of air cooled VWs that will fit. It's a nuisance to have to remove the wire from the sensor each time you need to drain the oil though.

 

Here I am a previous owner of a 1973 Dual Port VW, and I can't remember the thread size. Any idea? Or that of the XJ drain plug?

I think I am still leaning towards using the oil galley as that is the temperature of the oil coming in, but measuring sump temperature has it's merits also.

 

so no torque specs on the galley hexes?

mine were real looose so i tightened them a bit!

but would like to know how tight i can go :?

 

I couldn't find any specs for tightening the oil galley plugs in my Haynes manual.

 

The VDO oil temp sensor for a VW has a 14mm diameter and 1.5mm thread pitch. I have no idea where it fits on a VW but it fits in place of the drain plug on my bike.

 

Here's a store online that sells the VDO oil temp and pressure gauges. They also have the head temp gauge, which is nice but quite fragile and tends to break after a short period of use and needs to be repaired.
The prices are a bit high, you can find them cheaper on ebay.
http://www.bus-boys.com/bbvdo.htm

 

cool i might try that , ive got 8 beetles at my house , but none have oil temp from sump. ive got a few with pressure coming of a t on the sender. anyway ill have to look into it
cheers brenton

 

ArizonaSteve,

What does your oil sump temperature run at when you idle for a period of time versus riding for a period of time? Where did you find was the best place to mount the gauge?

If you're in Phoenix I'll be there the first two weeks of March for a training class. Maybe we can hook up.

Here is a better site I found for the Vision VDO gauges. I should have remembered it since it's where I bought the gauges for my '83 VW GTI. The Vision VDO gauges more closely resemble our Yamaha gauges in color and lighting, except the VDO gauge needle is lit by fiber optics.

Autotech

Here is a less expensive site selling the standard VDO gauges:

BusDepot