Add-on gauges: oil temp vs. water temp

General discussion about our beloved Tercel 4WD cars
Post Reply
User avatar
garyfish
Highest Ranking Member
Posts: 889
Joined: Sat Nov 19, 2005 4:22 pm
My tercel:: 1985 Tercel SR5, stock; 1987 T4WD DLX wagon, manual tranny
Location: North Coastal California

Add-on gauges: oil temp vs. water temp

Post by garyfish »

If you had to choose one, which would it be?

Or, if you had the money, would you have BOTH?

I guess my question is: What is the difference, if any, between the information provided by oil temp vs. water temp.

Some background: I'm planning to install some aftermarket gauges in my '85 T4WD, but I'll be keeping the idiot lights & their associated senders. Right now I have room for 5 add-on gauges. These are the gauges I have in mind:

oil pressure
water temp
vacuum
digital voltmeter
ammeter

Using info provided on this forum, I've discovered that installing an additional sender for oil pressure might be problematic, due to the tight clearances involved and potential difficulties (and costs!) associated with T-ing into the existing sender port. See viewtopic.php?f=2&t=1852 for some info on this. Also, the existing sender has an uncommon thread (1/8" x 28 BSPT thread = British Standard Pipe Thread), and the adapters I've been able to find online are relatively pricey.

So, I did a little online research and have determined that it would be far easier, and probably less expensive, to buy an oil filter block adapter -- a.k.a., an oil filter "sandwich" adapter -- which has 3 threaded ports (1/8" NPT) for attaching accessories such as sensors and oil coolers. Cheapest source I found for my 3AC engine (3/4 UNF-16 thread on the oil filter) had 'em for $30.
http://www.glowshiftdirect.com/oilfilte ... nf-16.aspx
Same company also has an eBay store: same item, same price:
http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT

Which brings me back to my original topic: I definitely want to have an aftermarket temperature gauge (either oil or water), and it would be relatively easy to install an oil temp sender in the sandwich adapter. But if I go with a water temp gauge & sensor, I'd have to have another port on the 3AC that taps into the coolant system. I'm unaware of such a port... so it seems like I might have to purchase a $15 adapter to install in the upper radiator hose (1.25" ID).
http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT

Or could I tee into the existing water temp sensor port on the top front of the engine? Would that give accurate-enough temp readings if the sensor probe was somewhat removed from the hot-water stream?

Just trying to save a few bucks... and get good feedback on engine status and performance at the same time.
1985 Tercel SR5 4WD wagon, 300K
1987 Tercel DLX 4WD wagon, 6-speed manual, 274K -- got this one running Jan. 2015 (had been sitting for 2 years); this has been my daily driver since 2016
User avatar
sdoan
Top Notch Member
Posts: 392
Joined: Sat Jun 23, 2007 2:02 pm
My tercel:: 1983 Tercel 4wd DLX 2nd owner (sold), 1984 SR5 3rd owner (sold), 1984 with 4A engine and factory sunroof SR5 3rd owner.
Location: Bellingham, WA

Re: Add-on gauges: oil temp vs. water temp

Post by sdoan »

The one time I ever saw an oil temp gauge used was blasting across Baja during the LaCarrera vintage race and we had to slow to under 120 mph to keep the oil temp under 300 degrees and that was an old cast iron pushrod engine putting out about 1hp/cubic inch. My Bro was worried about oil breakdown over 300 degrees because we had to drive the car 1500 mile home after the race. It seems to me that the 3A in our cars is way under stressed and will never heat the oil up unless your doing 24 hrs of LeMons and it has lots of ring blowby, or you boil the water out. Water temp gauge makes more sense to me. I've seen a 3A thermostat housing (or is it cylhead water outlet?) with an extra opening that would be an easy place to put the sending unit - check the wrecking yard for other A series engines in FWD cars, you'll probably find what you need.
danzo
Highest Ranking Member
Posts: 537
Joined: Fri Dec 05, 2008 11:01 am
My tercel:: '86 SR5 6 speed
Location: The Colony, TX

Re: Add-on gauges: oil temp vs. water temp

Post by danzo »

Your oil will degrade and cause damage well before it ever gets to 300F. Most engine oil thermostats try to keep the oil at or below 190F. There's a good article in the latest www.grmotorsports.com magazine on this topic, and they will even send you a free copy if you wish.

Thanks garyfish for posting this link for the sammich adapter. Just by coincidence I was looking for such a product a few days ago. I too discovered the stock oil pressure idiot light sending unit uses a strange thread not used by my aftermarket gauge. Knowing both the oil temp and pressure helps you make an informed decision on what oil type/viscosity to use, in addition to telling you engine condition/bearing wear.

If you want to install a coolant temp gauge (mechanical ones are most accurate), there is what I believe is a coolant drain port in the block. It's easily accessed on the driver's side near the oil filter IIRC. Not sure what kind of threads it has, maybe someone here knows. Of course this port won't tell you the temp at the thermostat, but it will let you know if the cooling system is working properly. Water temp, no matter where it's taken from, should be fairly consistent once the engine warms up.

But from that list of gauges you want to install - I would go with oil press and temp, water temp (assuming you don't have the SR5 gauges), and maybe a vacuum gauge since they are so easy to fit. You can also do the voltmeter and ammeter gauges if you like lotsa gauges, but they don't really tell you anything crucial. They tell you when your battery and/or alternator go bad, but this is easily determined with a $10 hand held voltmeter which you prolly have already. But of course it's your call.
It's a scientific fact that in a twin engine aircraft, when one engine fails there is always enough power in the remaining engine to make it all the way to the crash site.
User avatar
sdoan
Top Notch Member
Posts: 392
Joined: Sat Jun 23, 2007 2:02 pm
My tercel:: 1983 Tercel 4wd DLX 2nd owner (sold), 1984 SR5 3rd owner (sold), 1984 with 4A engine and factory sunroof SR5 3rd owner.
Location: Bellingham, WA

Re: Add-on gauges: oil temp vs. water temp OT

Post by sdoan »

danzo wrote:Your oil will degrade and cause damage well before it ever gets to 300F.
It was a couple decades ago so maybe I'm remembering the temperature wrong - perhaps it was 200 degrees (and 180 mph :mrgreen: ). But degrading faster does not necessarily mean it will cause damage because most oil systems are engineered with a safety margin, though it does mean you should change the oil more often. Air cooled engines, especially cast iron ones like that in my old Ariel motorcycle run HOT and get more frequent oil changes.
User avatar
ARCHINSTL
Goldie Forever
Posts: 6369
Joined: Sat Apr 30, 2005 1:52 pm
My tercel:: Goldie is a 1986 SR5 attualmente con Weber/also owned the first T4WD in STL in late '82
Location: Kirkwood, a 'burb of St. Louis

Re: Add-on gauges: oil temp vs. water temp

Post by ARCHINSTL »

garyfish wrote:Also, the existing sender has an uncommon thread (1/8" x 28 BSPT thread = British Standard Pipe Thread), and the adapters I've been able to find online are relatively pricey.
Just happened to think of something - have you tried places that sell parts for old BritMobiles? My old Morris Minors with the "A" motor used a light and not a pressure gauge (or any gauges, save for speed and fuel), so for two of them I built a new instrument panel, using gauges from Spridgets. I don't recall the thread size for the fitting, since this was over 40 years ago, but I'd bet that some BritMobile used such a size.
I'd go to Moss Motors or similar and look for this fitting for whatever kind of car. Maybe then a salvage yard would have it - or check with your local MG/Triumph/A-H/Jag clubs for sourcing.

sdoan - WOW! An Ariel! A storied BritBike! Which model did you have?
Tom M.
T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"
"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
User avatar
sdoan
Top Notch Member
Posts: 392
Joined: Sat Jun 23, 2007 2:02 pm
My tercel:: 1983 Tercel 4wd DLX 2nd owner (sold), 1984 SR5 3rd owner (sold), 1984 with 4A engine and factory sunroof SR5 3rd owner.
Location: Bellingham, WA

Re: Add-on gauges: oil temp vs. water temp

Post by sdoan »

Apologies for the thread hijack.

Bitsa Red Hunter.

Image

Here it is on a camping trip last year. It looks like a 1939 because of the girder forks and the large head light, but most of it is a few years newer.
takza
Highest Ranking Member
Posts: 4414
Joined: Fri Apr 02, 2004 4:28 am
Location: Tibetan plateau

Re: Add-on gauges: oil temp vs. water temp

Post by takza »

Are you saying that's a BSA?
Give a boy a gun-give a biatch a cell phone-and pretty soon you almost got yourself a police state.

Orwell said: War is peace! Freedom is slavery. Ignorance is strength...

Image
User avatar
sdoan
Top Notch Member
Posts: 392
Joined: Sat Jun 23, 2007 2:02 pm
My tercel:: 1983 Tercel 4wd DLX 2nd owner (sold), 1984 SR5 3rd owner (sold), 1984 with 4A engine and factory sunroof SR5 3rd owner.
Location: Bellingham, WA

Re: Add-on gauges: oil temp vs. water temp

Post by sdoan »

takza wrote:Are you saying that's a BSA?
No, "Bitsa" means bitsa this and that. It's a British term for bikes built from pieces, in other words not original. Ariel was another manufacturer, eventually bought by BSA and out of business by 1965. The designer of this engine (Valentine Page) went onto design the similar BSA Empire Star which became the Goldstar when it exceeded 100mph at Brooklands.
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Add-on gauges: oil temp vs. water temp

Post by Petros »

Oil temp and water temp measure two very different aspect of the engine's performance.

The oil temp varies with torque loading and rpm, the faster and more torque on the engine, the higher the oil temp. It is a direct measure of the amount of friction at the bearings. The oil temps varies quite a lot with driving conditions, even well after warm up. For normal street driving it will rarely get high enough to be an issue. Oil temps should stay below 200 deg. On an engine that you push hard at high rpm, an oil temp gauge is a good idea. If it runs high at your high demand driving conditions than you need a oil cooler, which is were those filter adapters come in handy. You can likely adapt the factory Toyota cooler and adapter from a Corolla GTS, MR2 or from a Corolla All-trac, all of which have axillary oil coolers.

The water temp tells you how well the cooling system is operating. IT is usually the first indication you have if your coolant is low or your T-stat is bad (if you actually keep an eye on the temp gauge). With a properly functioning cooling system, there should be little change in the water temp after warm up, unless you are in an extreme driving condition (high load and slow speeds as in driving up a steep grade in hot weather).

For performance driving both temp gauges are important, along with oil pressure, and assist you in monitoring in real time engine conditions. For normal daily driving, all the extra gauges just become decoration if you do not use them.

As a side note, I am not sure I have ever found an ammeter useful (I have has several cars with them). If you are not generating enough amps the amp light illuminates. What else do you need to know? If you have a lot of heavy electrical demand, it might let you know if you have a large enough alternator, but you can do that with a simple test and a hand held gauge. The volt meter I have found useful, because it tell you the condition of charge of the battery, alternator output voltage, and can tell you the demands on the system (making the ammeter redundant). Others may have good reasons for adding these gauges, but in my experience I have not found them useful.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
keith
Highest Ranking Member
Posts: 1249
Joined: Sat Sep 30, 2006 1:04 pm
Location: Tennessee

Re: Add-on gauges: oil temp vs. water temp

Post by keith »

The ammeter will tell you more about the condition of your battery than a voltmeter ever will. If you understand what its doing, it will tell you when its time to replace the battery.

You already have a water temp gauge

A mechanical oil pressure gauge is not to hard to connect using a commonly available tee. I say not too hard but there isn't much room if you have AC.

Oil doesn't begin to significantly break down until about 300-450 (reg-syn) but oil usually gets hottest right after shutdown when the remaining film of oil has to absorb all the residual heat the engine is shedding.
teranfirbt
Highest Ranking Member
Posts: 519
Joined: Mon Mar 30, 2009 12:58 am
My tercel:: '86 SR5 4WD, 5AFE, lifted rear, 195/70/14 tires
Location: Seattle, WA

Re: Add-on gauges: oil temp vs. water temp

Post by teranfirbt »

How does an ammeter tell you about the condition of your battery?
keith
Highest Ranking Member
Posts: 1249
Joined: Sat Sep 30, 2006 1:04 pm
Location: Tennessee

Re: Add-on gauges: oil temp vs. water temp

Post by keith »

teranfirbt wrote:How does an ammeter tell you about the condition of your battery?
It will take a higher charge than normal. Ie, you first start the car and the ammeter goes to 30 amps, but in a minute or two, its down to one or two amps. If it won't go below something like ten amps without a good reason (heavy load), then the battery is going bad.
User avatar
dlb
Highest Ranking Member
Posts: 7305
Joined: Mon Jul 06, 2009 9:03 pm
My tercel:: '87 sr5, '83 dlx parts car
Location: bc, canada

Re: Add-on gauges: oil temp vs. water temp

Post by dlb »

resurrecting an old thread here. the oil light in my all trac started flickering at idle sometimes so i stopped driving the car until i could test the oil pressure. i got an oil pressure gauge and went to hook it up but the adapter supplied in the kit didn't fit. since then, i've had a hell of a time because none of the parts stores have had any idea about what thread the oil pressure sender used and what adapter i would need to connect the gauge. i figured it was probably the same thread in the tercel so i pulled the OPS from my parts car and i was correct. then i searched on the forum and found that garyfish had posted the type of thread used. incidentally, he found it on autozone.com by looking up the OPS for a tercel--some of the OPS's listed there mention the thread.

once i knew that the OPS used a 1/8" x 28 British Standard Pipe Thread, i started looking for 1/8" x 28 BSPT male to 1/8" NPT female adapters. i looked online and found some on amazon.com. they were $10 but fast shipping was an additional $20! i called around to the local hardware stores and didn't have much trouble finding an adapter close by for only $7.50.

so if you're looking for an adapter for an aftermarket oil pressure gauge, 1/8" x 28 BSPT male to 1/8" NPT female is likely what you need, and most auto, hardware, or hydraulic stores should have it for a good price.

after three weeks, i'm very excited to finally check the oil pressure on that car!
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Add-on gauges: oil temp vs. water temp

Post by Petros »

I found that most kits have a thread that is close, but not exact. With the soft brass fitting I just put sealant on it and thread it in until i felt the threads yield a bit. got about 4 threads in, not ideal but it has held okay. Good to know, if I ever change it out I will look for the 1/8-28 british (wonder why Toy choose that? min bidder on the sender supply?).
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
User avatar
dlb
Highest Ranking Member
Posts: 7305
Joined: Mon Jul 06, 2009 9:03 pm
My tercel:: '87 sr5, '83 dlx parts car
Location: bc, canada

Re: Add-on gauges: oil temp vs. water temp

Post by dlb »

Petros wrote:wonder why Toy choose that? min bidder on the sender supply?
i wondered this aloud at the parts store and the guy there said something interesting about toyota not having metric pipe threads but refusing to use any standard imperial stuff. BSPT would be the only option left, i guess. don't know how true that is but i thought it was neat anyway.
Post Reply