How common is it for the ECTS to fail (or go out of spec) without tripping a trouble code (88 Dakota 3.9)? Engine runs great when cold -- not so great when warmed up. If you apply just a little throttle above idle, it stumbles pretty good; a real dead spot -- but if you elevate the idle above that dead spot, it comes right to life and roars like it should). Also, if you rev engine, the idle hunts and revs up and down for a good 10 seconds before settling. Also... this thing runs RICH and has very noxious exhaust, even after warmed up (it has a new oxygen sensor). Currently, there are no error codes stored in the system (it has 160K and has the original CAT). Last question... what were the primary symptoms when ya'lls CAT's failed?

 

Also... (I am going to sound stupid -- oh well) where is the Coolant Temperature Sensor on this engine? There is a two-wire sensor close to the thermostat -- is this our guy?

 

The 2-wire by the thermostat is the ECT, yes. And yes, it can go off and not trip a code. But I'd be more apt to check O2 sensor and MAP; then again, ECTs are cheap, I'd replace that with the age of this truck. Also triple check ALL - as in EVERY SINGLE - Vacuum line!

My primary symptom when my cat failed was that the truck had no oomph - because the cat plugged since it was rapidly reaching diesel status ("Fill the oil and check the gas!")

RwP

 

Likes "fill the oil and check the gas" -- never heard that one before; think I'll use it myself from now on: genius.

So I removed the old ECTS -- covered in scale, rust, corrosion, barnacles. Will be putting a new one in tomorrow. But... upon discovering the condition of the ECTS... I knew I had to replace the thermostat, and discovered the monkey that replaced it previously cross threaded the front bolt on the thermostat housing -- so it sheared right off after a few turns. Fantastic. But the rear bolt (which would have been trouble had I found that one in the same state -- it's harder to get to and harder to drill out). So I will have to drill out that front bolt, rethread the receiver, and purchase a new bolt. Lotta extra work a rookie mistake like that creates. Not looking forward to it -- always the potential for complications when drilling out a sheared bolt that is part of the engine block. Ick.

And since this truck had been running in this state for years with the failed ECTS... very good chance the CAT is fouled, clogged, and in need of replacement (and one of the culprits for the aforementioned problem). So I will post an update once these repairs have been implemented to let ya'll know if it fixed the problem. Thanks for your help Ralph. I will also check the MAP sensor and inspect all the vacuum lines per your suggestion.

-Travis

 

Try left handed drill bits. there is always the chance it will catch and screw the sheared remains out. if not its still a drill.

 

This.

ALWAYS drill for your ez-out with a left handed drill bit (unless it was a left handed bolt, then use a right handed drill bit.)

Something about how it relaxes the strain, not only that, but if it grabs, at least it's driving the bolt OUT not IN.

RwP

 

Heh.

The motor was at about 500 miles/quart on 15W40 when I had it overhauled.

So far, with 5,000 miles on it, I've topped it off with the 5 quart jug I used; and it's a bit below "FULL" now.

Just in oil savings, I'll pay for the motor overhaul in a few years! Not counting better gas mileage ...

RwP