Thermostat - Won't crank over?

[mrgrim333]

On a recent long drive, my sho putted out and died on the side of the interstate. You could tell it was over heated, and bad. So I let it mellow out and cool down for about an hour before getting it started again and to a shop. The dude checked the coolant, still full.

He pointed reference to the Thermostat. He said that's probably what caused it.

So a month later (today), I get back from a day of driving, let my car sit for 3 hours and go to start it and... It won't even crank?!

The engine is still pretty hot for having cooled down for 3 hours, do you think it has to do with the Thermostat or am I in deeper trouble?

 

[Kens1992mtxSHO]

Sounds like your CPS is failing. When was your last 60k?

 

[mrgrim333]

I haven't a clue when my last 60k was, haven't had the car to long.
ps. How do I check my codes?

 

[Brett]

How to check your own engine codes.

Most auto parts store will either do it for you or borrow you a code reader as well.

 

[TimboSHO]

You could tell it was over heated, and bad.

How could you tell it was overheated? Was the guage pegged? Did you smell anything? Overheating one of these motors is usually catastrophic. If it still runs well, you're probably lucky. If it did overheat bad enough, it would shut off, but that doesn't explain the most recent one. As stated, check your codes, sometimes the crank sensor will throw one.

 

[mrgrim333]

Ok, now that I replaced the thermostat, the car starts (YAY!)...
It's slips a little when starting now too... (takes a good 3 cranks before it hooks, never did that before)
But..

It's still running hot, so I pulled some codes.
The koeo reports 11 (It's fine)

So I ran the koer, it said 73 (No Throttle Position Sensor (TPS) change in "goose" test. Must get at least 25% throttle rotation - TPS)

So I tried again, same thing, so I gunned it a little more and it gave me a 25.
(Knock sensor not tested (ignore if not pinging) - KS)

:scared:?

 

[Kens1992mtxSHO]

Running hot as in overheating?

If you get the 73 code it's because you didn't give enough throttle but I guess you figured it out already.

 

[TopGunnYFZ]

If its running hot, did you notice your fans come on when you did the KOEO test?

I had problems with the fans in my 94 sometimes they would work and others they wouldn't, i just wired mine straight up into some switches i hid in the car. I can control the temp of my car pretty good now.

 

[mrgrim333]

Yeah, the fan works on the KOEO test... But now that you mention it, the fan never seems to be on

 

[TopGunnYFZ]

ECT sensor, is what they told me when my fans didnt come on. That wasen't my problem but it could be yours?

 

[Storm-Chaser]

The ECT has a relatively narrow range of resistance values it feeds to the ECM, and will set a code if it tests or goes outside those ranges. The ECM uses those values to signal the fan relay/relays, which in turn then provide power to the fan/fans. While it is possible for the ECT to not [indirectly] turn the fans on when it should, in the absence of any other information on how hot the engine *was* running, there's no way to determine if the ECT is working properly.

You've not defined "overheated" or "running hot". What did the TEMP gauge show, and what other indications did you have that it overheated?

In the absence of any actual engine temperature values, the engine may be running exactly as it should and the crank sensor like Ken (Kens1992mtxSHO) stated is the more likely problem. However, the crank sensor will set a code even if the failure is momentary and/or intermittent. The "takes a good 3 cranks before it hooks, . . ." comment is indicative of a bad cam sensor, which can cause starting problems, and not set a code.

Also, if the electrical system is having issues, it will result in all kinds of problems if the voltage regulator is not maintaining the proper output.


So let's start there . . . .

What year SHO and what transmission type.

What did the TEMP gauge show when it "overheated", and what other indications did you have that it overheated?

What did the TEMP gauge show when it was "running hot", and what other indications did you have that it was running hot?

 

[mrgrim333]

Okey dokey.

1991 Manual

As far as the temp gauge goes, that thing hasn't worked right since I got the car. When my car overheated and died on the hiway it was probably at halfway point.

When it was "running hot", it said a little below halfway point.

 

[Storm-Chaser]

So how do you know it's running hot or overheating? What symptoms did you observe?

Could you hear the water boiling when you opened the hood?

Was the motor spark-knocking?


Early this year, AutoZone began carrying an inexpensive infrared thermometer. The IR thermometer costs $19.99 and is made in China. It has a temperature range of -31°F to +689°F . . . .

. . . . although I have no idea as to their accuracy, as there is no information on the product packaging. Maybe a few here that have purchased one and can comment.

OEM Infrared Thermometer - $19.99

AutoZone part number - 25245

AutoZone SKU number - 951642

Warranty - 90 Days
​

 

[mrgrim333]

Yeah, as far as the whole boiling water thing, when I broke down on the highway, to cool it down we dumped water on the block. SSSSssssSSssSSsss *boils*

 

[Kens1992mtxSHO]

You know you can crack your block this way right?

 

[mrgrim333]

I do, but the grease monkey that did, didn't seem to know

 

[Bob Gervais]

I do, but the grease monkey that did, didn't seem to know

You need to find a new grease monkey, the current one, to put it in New England terms, is wicked ********.


So getting back to basics, dumping water on the engine and having it steam off is fairly normal when the car is at running temp.

When it overheated, did you notice coolant spewing from the reservoir?

Without a working temp gauge it's hard to determine whether or not the car is actually overheating. Your best bet may be to grab that IR temp sensor, often referred to as a pyrometer, that Keith mentioned.

Since the thermostat has absolutely nothing to do with the car cranking, we'll call it circumstance that after you replaced it the car fired up, and assume that your problem still exists.

I agree with the other guys, crank or cam sensor. In fact, since you don't know when the last service was, it's probably not a bad idea to go ahead and do the 60k on it. Chances are your water pump is leaking onto the crank sensor, and once it dries off the car starts fine.