Network Ninja

I am having a really hard time locating the coolant sensor. I have looked at several diagrams, but can't find any for my '88 3.0. I have a bad feeling it's under the intake manifold which hovers on top of the whole engine. I really don't want to take that apart just to get to a sensor to test/replace it.

Just FYI, I am testing if the sensor might be causing my lack of overdrive. I get overdrive after a while on the freeway, but it seems to be taking longer and longer, and it's killing my MPG.

So if any of you could in detail point out where the sensor is, or ideally post a picture, I would greatly appreciate it.

fillsrunner4

its in the very back on the lower intake manifold. I dont think you have to remove anything to get to it

mt_goat

I have some pics of my old 3.0 out of the truck on a stand. I'm pretty sure its one of those sensors in the middle of the heater hoses, just above the crossover:

Green93

It is the sensor with the light grey end in MT Goat's picture above. I have a new sensor sitting on my work bench waiting to go in. The problem is whenever I have time to work on it, the engine is hot and difficult to work in that area. I'm hoping it will solve all my problems as well. Although mine are idle speed problems.

Just so you know, there is a quick test for it in the FSM. Mine didn't check out too well.

Jason

Network Ninja

That's the one I though it was. Thanks all for the replies. I did read the FSM about how to test it, and it's simple enough. I went out tonight, and located the sensor. So I can work on it tomorrow morning when it's cool again. I will post what happens, in case anyone has the same issue in the future.

BTW, the only FSM I could find online was for the 22XX engines, but nothing on the 3.0 Anyone know where I can find a copy?

mt_goat

Here's the 93 FSM it has both engines:

http://personal.utulsa.edu/~nathan-b...fsm/index.html

If you have a hard time reaching the sensor you could always take the hood off and get it out of the way.

thook

Do yourself a favor........take the hood off! It's great. Then, you can climb up on the engine bay to get to it. Much easier than taking the plenum off.

Green93

Has anyone had this sensor out before? The new one I got from Toyota has a probe on it about 1 1/2" long. Do I need to drain some of the coolant or is it located high enough up that no coolant will pour out?

JAson

mt_goat

Yeah I'd drain some first.

MIKEMOKAS

mine turned out to be bad and was sending incorrect signaly to the temp guage.

https://www.yotatech.com/forums/f116...hlight=coolant

ttyl

thook

The coolant temp sensor is not for the gauge. That's the temp sending unit. Two different functions and circuits entirely.

Network Ninja

Well an update for you all, I disconnected the sensor wire, and the temp gauge stayed at 1/2. I thought maybe I didn't have the right sensor, so I tried the same with all three sensors hanging out back there, no change. From the diagram in the book, it shows the sensor on the driver's side. But I wanted to be sure. This was all with the engine warmed up, which really sucks working back in there, BTW.

So does this show that my actual gauge is bad? If so, how easy is it to find/install a new gauge?

EDIT: I am re-reading the posts here, and am now confused. There is a Temp sensor and a Temp sending unit. What are their purposes? Until I understand their functions, ignore this post, and it might be idiotic at this point.

MIKEMOKAS

my bad i thought he was messing with the sending unit.

Network Ninja

Just to issue some closure to this, I replaced the coolant thermostat, it instantly fixed my issue.

BoostinChick

I am bumping this back up because I tried to tackle this today. I even took the hood off! My problem is I don't think I have a deep socket large enough for it. I tried a 19mm and 3/4 with no luck. It fits around the sensor portion, but not the base where the 6 points are. Anyone know what size it could be so I can get the right deep socket size?

What is weird is that the new sensor I bought (from Toyota), seems to fit a 19mm deep socket just fine? Did they give me the wrong sensor?

Innervision

Make sure that you are pulling the correct sensor. I put an '88 in my 94 (both were 3vze) and the sensor block was different from '88 to '94. The '88 does not have the rubber hose connected to the block of sensors like the 94 did. Also the location of the temp and other sensors were shifted around.

BoostinChick

Looking downward (from the passenger side) it's to the left of my TVV sensor.

thook

Grey connector? Between the TVV and the heater hose? That's the one, if so. Should be a 19mm. But, if you can't the socket down to the hex head, try using a plumber's basin wrench. Pretty cheap tool and can be used elsewhere in otherwise hard to reach applications. (I've done this.)

abadgti

Im having the same issue getting the stock coolant temp sensor off. Does anyone know if its bigger than 19mm?

thook

Um......it may be, and I may have been incorrect on the size. I admit, I don't have to get back there very often and go by memory a lot of times. Maybe 21 or 22mm?