Bad thermostat?

[blk\blk90]

I wanted to run this by y'all and see what y'all thought. I recently started a new job so I don't have a work truck anymore. I got one of my 91s inspected and registered(finally) so that between it and my 02 tundra w/320k miles I'd always have a way to work.

On my way to town the temp was nearly pegged by the time I got to where I was going. It took a full gallon after it cooled off, and wasn't full. I figured that would get me home. I ended up having to pull over twice on the ~10 mile trip home. I could feel boiling when I touched the rad cap. After I got it home and it cooled off I was gonna fill it up only to find it was already full. I ran it with the heater on just sitting and it was creeping well past normal again, and I was getting no heat out of the heater.

Is this a bad tstat, or could it be a bad rad cap? WP is brand new.

 

[ISHOU]

Both are cheap and easy to replace. Do both then see what happens.

 

[zoomlater]

If a gallon went it the first time, then did it leak out or was it not filled completely before (or do you have a leak somewhere). Was the spare coolant bottle empty as well or was it full?

 

[blk\blk90]

If a gallon went it the first time, then did it leak out or was it not filled completely before (or do you have a leak somewhere). Was the spare coolant bottle empty as well or was it full?

It didn't leak. I guess when the wp was done they didn't refill it. I think I found the issue...

 

[blk\blk90]

Well, I've got the heater back, but the temps seem high. Could be the ect sensor acting up. I put in about another half gallon but I don't have one of the burping bucket things to put in the radiator. I'll get one and burp it properly soon.

 

[zoomlater]

its usually between the O and R, so that looks about right

 

[luigisho]

Love that avatar pic. How old are the system components? There is always a chance that hard parts like pump and thermo are likely. If the hoses are old there is a chance of hoses collapsing internally or even able to be seen as well. I had that on a GenIII. Make sure the oil is coolant free to be safe.

 

[blk\blk90]

Love that avatar pic. How old are the system components? There is always a chance that hard parts like pump and thermo are likely. If the hoses are old there is a chance of hoses collapsing internally or even able to be seen as well. I had that on a GenIII. Make sure the oil is coolant free to be safe.

The upper and lower hoses are newish. They're pretty pliable. The rad is more than likely factory. I do have a 2 core in the other 91 I'll eventually swap in here. I didn't see any oil specs in the coolant, so I'm assuming there won't be coolant in the oil.

I did find this today though:



Looks like tires are next on the list. I'm thinking about going with 235/45zr18 instead of the 225/40zr18s that are on it, mainly to get the speedometer a little more accurate.


I figured I'd change my avatar to be a little more fitting, seeing as how I'd had that old one for almost 20 years now. That was from when I did my upper 60k about 3 years ago.

 

[luigisho]

I remember back in the day more than a few washing parts in teh dishwasher. Made me chuckle every time. Yeah that tire is toast!

 

[Tim Brand]

Well, I've got the heater back, but the temps seem high. Could be the ect sensor acting up. I put in about another half gallon but I don't have one of the burping bucket things to put in the radiator. I'll get one and burp it properly soon.

View attachment 82204

If you don't have a long funnel just run the passenger front wheel up on a curb to make the rad the highest point the bubbles will work themselves out this way

 

[FastCAD]

I wanted to run this by y'all and see what y'all thought. I recently started a new job so I don't have a work truck anymore. I got one of my 91s inspected and registered(finally) so that between it and my 02 tundra w/320k miles I'd always have a way to work.

On my way to town the temp was nearly pegged by the time I got to where I was going. It took a full gallon after it cooled off, and wasn't full. I figured that would get me home. I ended up having to pull over twice on the ~10 mile trip home. I could feel boiling when I touched the rad cap. After I got it home and it cooled off I was gonna fill it up only to find it was already full. I ran it with the heater on just sitting and it was creeping well past normal again, and I was getting no heat out of the heater.

Is this a bad tstat, or could it be a bad rad cap? WP is brand new.

View attachment 82200

If you did not get a "low coolant" warning light in the dash then your ECU coolant temp sending unit is bad. Its mid way down the drivers side (rear) engine block facing the firewall with two wires. The other sending unit (one wire) is next to the t-stat this is for the dash gauge.
Does you rad fan worK? If you have no leaks then apparently the coolant steamed off and you have no coolant flow ie: t-stat, fan, radiator wp. Double check the condition of the wp it may be new but the extreme heat could not have done it any good and if it is damaged then you are surely looking at a bad cps down the road so the wp condition "is important". Flush your cooling system with a good rad flush to get out any obstruction(s). For the t-stat spend a few extra bucks and get a "failsafe" t unit that will never seize closed mine has worked for more than 5 yrs. after many failures with the 5$ t-stats. After you correct the problem(s) you can use water to test that the cooling system is working correctly and there are no leaks but after that drain the system and use 1 gal. of straight anti-freeze and the rest 50/50 anti-feeze and (no) extra water. Use 50/50 to ocasionaly top off. I regularly check my overflow bottle for correct fill level (HOT) and top off with 50/50 (when needed) and I get very good results and I don't wait for the idiot light.
Best to ya.

 

[BaySHO Performance]

First off, pull the KOEO codes to see if you have one for the ECT (21):

EEC Self Test Procedure - V6SHO

If it's bad:

ECT Coolant Temp Sender (Masterpro)

2-9362

$29

O'Reilly

You might also want to pressure test the cooling system. Buy or borrow one of these. Will also enable you to check the rad cap:

https://www.oreillyauto.com/detail/c/evertough/tools---equipment/rental-tools/rental-tools--air-conditioning---cooling/12095d53bcad/rental-tools-evertough-radiator-cap-test-kit/ren1/67085/v/a/5544/automotive-car-1991-ford-taurus?pos=3

To refill the system, Cover the alternator with a large plastic bag to make sure you don't short it out. Fill it up and run the engine. The coolant will expand as it gets warm, so keep a large funnel in the filler hole for the radiator and a catch can under the car. Feel the upper radiator hose on occasion. You will feel it get warm, then suddenly hot with bubbles felt when the thermostat opens. When this happens, the coolant will suddenly go down a lot. Keep on topping it up until the level stabilizes.

 

[BaySHO Performance]

Forgot to mention, Beau. Did that replacement thermostat have a jiggle valve like the old one? Couldn't see one in your pic. A no-no if not.

 

[blk\blk90]

Forgot to mention, Beau. Did that replacement thermostat have a jiggle valve like the old one? Couldn't see one in your pic. A no-no if not.

It didn't. I drilled a 1/16th hole in the top and put it in.