Has anyone fitted an oil temp gauge. Christmas is coming and I am thinking of asking Santa.

I have some questions if anyone can help, please:

• The temp sender could go into the spare hole blanked off in the gauge sender/warning light casting, with an adapter to make the hole a bit longer so the sender will go into it OK, or
• It could go into the sump plug as a fitting threaded into a smaller hole in the plug. You can buy such things ready made, but I do not know what the sump plug thread type and size is.
• I could use an oil filter sandwich plate, but it will place the oil filter bottom only about 1/2 inch from the exhaust and I do not want to heat the oil, so I am not too keen on that plan.

What are your views guys, on the best place for the sender?
Anyone know the sump plug size and thread? All help gratefully received.

Greg

 

Did think about it in the very early days, BUT, the memories of the oil temp gauges in the Road Train (engine, trans, diffs) gave serious second thoughts.

Some of those temps were carzy high at times, and you realize there is precious little you can do about it except slow down (haha), or stop and wait. Realistically oil today is capable of higher heat handling than anything from the '80's etc. A good dose of common sense in those days saw no failures for me on that Rig.

The sump plug to sump thread is 1/2" NF from memory??.

On the Rig (MAN V10) the engine oil temp sender was in the sump adjacent to the drain plug. Some of the Detriot/Rattlin Cat guys had them in the cooler pipes on the "cold side", but we have by-pass oil cooling down here on the V12's (mostly), some markets have full-flow, so that placement will work for them.

 

Like grant said, what are you going to do?? Why do you need to monitor it. The only reason it would change is if your car was overheating, in which case a coolant gauge would be more useful.

Spend the money on a replacement oil cooler and know it is cooling well instead, I just don't imagine an oil temp gauge coming in much handy on an XJS

 

Thanks guys. Like Grant, I have bypass cooling and I was wondering when I rebuild the engine (nearly all parts and tools are in stock) wheterh to alter the oil cooling to full flow. So I wondered if an oil temp gauge would show me if it was worth doing or not. Oil cooler is brand new, by the way!

Anyone any thoughts on bypass vs full flow cooling?

Greg

 

Greg,

I reckon you and "wifey" need to spend that oil temp gauge $$ on another weekend away IN the XJ-S, some nice wine, food, whatever.

Too much info in a V12 is scary, better off not knowing sometimes, and trust the car as you always have.

I rarely look at the dash when I am driving any of them, city or outback. I know how they sound when all is well, and any slight note change of any sort gets a quick look, but at my usual cruising speeds that is not a good idea. Too many Roos and Wombats wandering around. The V12 at 6000rpm has a sound all its own, and if its "off song" you know.

 

I will let her know your advice and hope she agrees to abandon the nippers to Granny for a W/E !

Ignorance is bliss, I must say it has always worked for me in life..., and as you say, trust the car as I always have. So that's the oil temp gone.

What about full flow when the engine is being rebuilt Grant? It seems all I need is a full flow head and connections to the cooler, block up the cooler return to the "sump & pump" inlet from the old system.
Greg

 

Yep.

If you are doing a rebuild and can swap the bits as you mention, go for it. It will do NO harm.

Only thing I did with an '88 Conv, whilst the radiator was out and the cooler hoses were off for new ones, was to have the radiator guy fit a drain spigot to the RH cooler tank, so the 2 odd litres of oil can be drained from time to time.

It took a bit of messing around to get the "angle of the dangle" for the spigot tube in the right position, but it worked a treat. NO snaps, those were the days of "film cameras" for me, so records never entered the brain.

 

What about mounting some kind of add on to the camshaft feed pipes?

 

What do you mean getting rid of the bypass? As in the cooler?

 

Some markets got what is called a "by-pass" engine oil cooler, where only some of the oil travels via the front cooler.

Your market got what is called a "full flow" engine oil cooler, so ALL the oil travels via the front cooler.

The by-pass sort of makes sense for colder climates, but that reasoning simply does not fit with the cars in the real world. Our temps here are straight up full flow in MY opinion, but by-pass we got until about '88 somewhere.

The retro to full flow is a sensible one.

 

all what you guys say, go for full flow oil cooling.

i still have the 1978 bypass oil cooling , and going by non-contact readings(here in central Texas) my coolant temps measured at different points around the run at 180-185,in 90+ambient F. so my engine cooling system is working fine.

but reading off the top of the cam cover, they around 225-235F, that is oil splash off the cam lobes.

its kinda borderline, i have no probs. but like any of us , i have been thinking of a better oil kool system!

 

Daim
That was my first bullet point on the post. There is an outlet blank with a threaded blanking plug on the oil feed inlet by the pressure senders. With a lengthening piece to atke the sensor probe, it would work. IF Grant had not told me not to bother, that is! No good asking for advice and getting it from the Great XJS Prophet and not taking it !

Greg

 

RB, Grant, thanks for the replies. Interesting the temps you mention RB.

For those interested, the conversion is not that hard to do. You need the full flow filter head and the steel pipes that come out of it to the cooler from a later car, but after that it is doable at home. The two systems work as follows

SS, The bypass system was on all XJSs up to about 1987 or 8. It only sends oil to the cooler that is released by the oil pressure relief valve. This is set at something like 75 psi, so it seems oil will not go to the cooler on a bypass system if your dashboard gauge is reading under this. Next time I do a blast along the motorway (sadly not until the spring) I shall feel the cooler and see if it is hot or not. If not then no oil is being cooled and all my oil cooler is doing is blocking air to the rad!

The bypass oil filter looks like this:

AS you can see there is only one large pipe coming out of it and running forward to the oil cooler. Above this pipe is the exit for tiny the "question mark" pipe that goes to the sump. The fitting on the head that this tiny pipe comes out of is the pressure relief valve. Below it, as you can see, is the casting from which the oil cooler pipe comes out. Oil only goes into this casting when the oil pressure relief valve is open, so only goes to the cooler when it is open. The return from the cooler on the bypass system does NOT go back to the filter head.

On the full flow system, there are TWO large pipes that are joined to the filter head and it is differently configured inside. On this system all the oil goes to the cooler in one pipe and back to the filter head in the other. The engine itself is the same in this area, but NOT the same in one other place.

This other place is here at the front of the engine on the RHS:

This is the casting that the return line from the oil cooler in the bypass system is attached to. It leads the oil back from the cooler straight into the oil pump directly above. In the bypass system the oil pump has TWO inlets to it. ONE from the cooler and one (the main supply) from the sump pickup. THis is what the oil pump inlet looks like inside on the bypass system:

The round inlet is from the casting, the pipe going along to the inlet at 90° to it is from the sump oil pickup.

The conversion to full flow (DIY mode) is as follows:

• Change the oil filter head to a full flow one. get the solid pipes that go with it.
• Connect the oil cooler to these pipes
• Unbolt the old bypass system return casting from the sandwich plate. Inside it there is a tube that fits into the actual round hole in the pump. carefully pull it out past the O ring and then block the tube with something that WILL NOT COME OUT.
• refit the blocked off tube and the casting, or blank off the sandwich plate with a flat plate, but make sure it supports the blanked off tube inside..

You now have a full flow system ready to go.
Greg