Overheating saga..

General discussion about our beloved Tercel 4WD cars
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stefando
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Posts: 39
Joined: Sat Apr 28, 2018 9:14 pm
My tercel:: The Caribou: 1983 SR5
Location: Norcal

Re: Overheating saga..

Post by stefando »

Hey all,
So _ overall the car is running great now, definitely a huge improvement to have a clean EGR and new exhaust valves, there's more power available everywhere but especially noticeable while climbing hills on the highway. The smell of coolant in the exhaust is gone (sure sign the head gasket was compromised) and after 400 miles I set the valve clearance again and tightened the head bolts as I'd read in other threads. The only thing that's weird is that the temp gauge just always reads higher than normal, the fan doesn't kick on till the white line, driving around it will creep past the line towards the red zone BUT if I hit the dash with my hand I can sometimes get it to drop to a normal level for a few turns, after which it will jump back up to a level about an inch higher on the gauge. It's about 50 deg F here and in the summer when it's 110 (I know, crazy cali) I almost never used to have it go up above the line. I checked the connection at the temp sender but since it's reading at all it seems it's sending (unplugged it goes to 0). Has anyone seen a gauge that is inaccurate? Coming up my driveway (requires EL 4x4) always raises the temp past the line but it just doesn't show signs of overheating otherwise. I don't have a lazer thermometer but I do have a mercury thermometer and I'll tape it on the reservior today.. I've been just assuming this is wrong considering everything is new (HG, thermostat, radiator, hosing, water pump) but I know that could be a dangerous assumption.

Anyhow, I think I have a gauge issue, I'll sort it out eventually. Glad to have the car back on the road! Thanks everyone, this car is really coming along and it's teaching me loads about patience, tinkering, trouble shooting, etc... all good stuff:)
1983 SR5 Brown
Salmon River California
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Petros
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Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Overheating saga..

Post by Petros »

I have found the factory gauge very reliable and accurate, though rarely the sender do go out. you must determine if it is indeed running hot or not, you risk severe engine damage and extensive repairs if your assumption is wrong.

you can buy inexpensive mechanical temp gauges at most autoparts stores (less than $40 in most cases) and worth it just as a diagnostic tool. pull out your regular sensor and install the aftermarket temp sender and than drive it around watching the after market gauge (duct tape it to the dash or steering column as a temporary measure). if the temperature stays in the normal range, than likely you need a new senor and your engine is good.

OTOH, if it heats up, you need to find the cause, and fix it ASAP. before you damage the head gasket.

good luck.
'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
stefando
Member
Posts: 39
Joined: Sat Apr 28, 2018 9:14 pm
My tercel:: The Caribou: 1983 SR5
Location: Norcal

Re: Overheating saga..

Post by stefando »

Alright so here's an update post winter mazama trip. the head port on the 3a is too shallow for this aftermarket temp sensor, so I borrowed a laser thermometer and I monitor it with that aimed at the coolant outflow. even when it jumps high, I never get temps higher than 205 on the laser thing. I'm waiting on a hose fitting that will allow me to use this temp gauge but for now I'm gonna just monitor the temp when it jumps around.
1983 SR5 Brown
Salmon River California
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: Overheating saga..

Post by Petros »

you did not mention you had an after market temp sensor. that would explain the behavior. should be easy enough to get (or fabricate) a pipe fitting that extends the sensor mount. I like the factory temperature gauge for reliability and accuracy. It has no graduations, but the factory did a good job of making it reliable and consistent.
'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
stefando
Member
Posts: 39
Joined: Sat Apr 28, 2018 9:14 pm
My tercel:: The Caribou: 1983 SR5
Location: Norcal

Re: Overheating saga..

Post by stefando »

Sorry, I wasn't clear about that: I do not have an aftermarket temperature sensor installed. Since this erratic behavior of my stock sensor and gauge, I thought I would put in a dash mounted gauge and aftermarket sensor in the port where the OE one goes (to have a more accurate idea of what's actually happening) but it didn't fit in the port. I like the idea of the extender but overall I feel pretty satisfied that the cooling system is working properly and I'll work out something of another solution ASAP. My dad was also surprised about the behavior of my stock sensor and gauge, but today same as always it was hanging around center and then took a left turn and up it jumped above the line- quick knock on the dash and it was back at center. Other than that, Monroes went on the other day, new bushings up front.. drove me through the snowy mountain pass today with no issues and even picked up some good jazz on the radio.
1983 SR5 Brown
Salmon River California
User avatar
stefando
Member
Posts: 39
Joined: Sat Apr 28, 2018 9:14 pm
My tercel:: The Caribou: 1983 SR5
Location: Norcal

Re: Overheating saga..

Post by stefando »

Hey everyone, Update is that the temp sensor started working correctly after thorough cleaning of grounds in the back of the dash gauge unit. Car does not overheat- never over halfway unless climbing up our steep driveway in 4wd. The big thing of value I can share is that the head bolts really needed that secondary tightening described in other threads. When I opened up the valve cover after 500 miles and adjusted valves and tightened the head bolts, they all took a little bit to get back to 43/44. It wasn't much but they all moved (engine warm). Just thought that was worth adding onto this thread along with the goofy electrical stuff.
1983 SR5 Brown
Salmon River California
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