Used truck problem: Low temperature reading

I bought a '90 today and an odd thing is the temperature needle takes forever to get into the normal band and when it does, it stays right at the lower limit and sometimes dips below. My '89 always stays right in the middle. I checked the wiring to the temp sensor and the loom had been split open and the black wire was cut and reconnected. The other wire is yellow and green I think. So I guess someone else was trying to figure out what was going on, too.

The overflow tank is nasty with sediment so obviously it needs to be flushed out. Definitely a new thermostat and maybe a new water pump.

One more issue is valve ticking noise.

Other than that it's in pretty good shape. 104,000 miles, no squeaks, good power. I guess it needs a timing belt because I don't know the last time that was changed.

bad sensor would cause that, or a lot of crud buildup in or around the sensor. May need the lifters flushed or replaced.

Is there a "best" method for a coolant flush? I've heard everything from kerosene to hooking it up to a garden hose.

We just started to use the BG cooling system cleaner and it seems to work pretty good. But it wouldn't hurt to bypass your heater core while doing it so you don't clog it up. It also comes with a additive to use after the flush.

Shit. Now I'm freaking about the the ticking noise. It wasn't there when I bought the car this morning but when I was cleaning the engine this afternoon I noticed it. I hope the engine's not about to blow up. :shrug:

I'm going to take it to a shop I work with tomorrow and let the pros handle this.

If the coolant looks that bad, I'd take it to a radiator shop that has the proper equipment to do do a hot flush with a little more pressure than a garden hose and a recovery system. Coolant is pretty nasty stuff. Well worth the price.

If the valve ticking goes away after it warms up then it the sticky lifter problem they all get eventually.

Change out the thermostat first. If the sysyem was clogged up your gauge would most likely read abnormally high.

Try some sea-foam or marvel mystery oil for your lifters. Wouldn't hurt to check valve clearance either

Thanks for the tips guys. You are the best.

My business neighbor has an auto shop and he said it would be around $500 for a water pump, timing belt, thermostat, coolant flush, valve cover gasket, front seals and taking a look at the lifters. It's a lot but I have no inclination to be down a truck for however long that would take me to DIY (probably forever). I need it done same day because I get like half a day off per week and I don't need any "jackstand stress."

My other business neighbor has a quick lube. He said the oil was full but black. Then he pulled out a bottle of Rislone and said it works great to clean up ticking lifters. "Mitsubishis all sound like that." So he said he'd do lube and check fluids after the maintenance stuff. I went into the pit to have a look underneath and other than some leaking from the oil pan gasket, everything looks surprisingly good and clean. There's some slop in the steering but I'll do the idler arm rebuild later.

I have posted about using Rislone on here for years - use it in all my vehicles at every oil change. Been using it since my first car - a 69 rambler - that sounded like a thrashing machine compared to our trucks and it quieted it down in 10 minutes of running. It will also slowly and gently clean out the motor and definately quiet the hydraulic lash adjustors.

$320 later, my guy didn't change the thermostat like he said he would. I am disappoint.

The good news is it's running a hell of a lot better. But it's not purring. Yet. He replaced the front pads and said the timing belt didn't need to be replaced and the front seals were all dry. That's good. He did the valve cover gasket and did the usual tune up stuff. But some ticking is still there. Going to flush the coolant, replace the t-stat and try Rislone. Also going to freshen up a few other gaskets, change the O2 sensor and clean the EGR and throttle body while I'm at it.

I guess if you want it done right you have to do it yourself...

So after work Saturday night I took it over to the quick lube place and we changed the oils. When I drained a quart of the oil it got less than 5 miles earlier at the shop it looked OK on the dipstick but came out black from pan so I dumped everything. My quick lube neighbor buddy suggested 20W-40 along with Rislone. While we were at it, we drained the coolant, transmission oil and differential. The oil was disgusting, like molasses. In all my years of monkeying around with vehicle nothing makes me want to puke as bad as the smell of burned transmission oil. While I was in the pit, the only problem I saw was a leaky but not gashed upper ball joint on the passenger side.

With the new thermostat, the engine came right up to temperature and the truck drove and shifted so much smoother with fresh oil front to back.

This Rislone stuff is amazing! I took it for a long drive that night to knock the cobwebs off and get its juices flowing again. Within 10 miles the truck went from sound like a time bomb to quiet as can be. I'm totally sold on Rislone. Great product. There's still some ticking when it's cold but it quiets down after it comes up to temperature. Another flush should help. If not I'll swap HLAs from a spare head I have.

With the old transmission oil, the truck popped out of 1st coasting down a hill by my house so I was worried either the clutch was shot or the synchros were trashed. But with the clean oil, it stays in gear and doesn't overrev.

Check out this nasty 1mm thick layer of sediment at the bottom of the bucket I used to catch the radiator water. I have Prestone coolant flush in there now, I'll dump that after a few more hours of driving and see if it cleans any more crap out. Flush your damn coolant every two years, y'all!

Attachment 12186

I'm always grinning to myself reading and seeing for myself how much abuse and neglect these trucks can take but they always seem to bounce back with a little routine maintenance. Timex Trucks.

Next up is getting the rattling heater fan cleaned out and cleaning up the suspension and steering because it handles like it's on roller skates.

Quote:

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Originally Posted by noahwins

So after work Saturday night I took it over to the quick lube place and we changed the oils. When I drained a quart of the oil it got less than 5 miles earlier at the shop it looked OK on the dipstick but came out black from pan so I dumped everything. My quick lube neighbor buddy suggested 20W-40 along with Rislone. While we were at it, we drained the coolant, transmission oil and differential. The oil was disgusting, like molasses. In all my years of monkeying around with vehicle nothing makes me want to puke as bad as the smell of burned transmission oil. While I was in the pit, the only problem I saw was a leaky but not gashed upper ball joint on the passenger side.

With the new thermostat, the engine came right up to temperature and the truck drove and shifted so much smoother with fresh oil front to back.

This Rislone stuff is amazing! I took it for a long drive that night to knock the cobwebs off and get its juices flowing again. Within 10 miles the truck went from sound like a time bomb to quiet as can be. I'm totally sold on Rislone. Great product. There's still some ticking when it's cold but it quiets down after it comes up to temperature. Another flush should help. If not I'll swap HLAs from a spare head I have.

With the old transmission oil, the truck popped out of 1st coasting down a hill by my house so I was worried either the clutch was shot or the synchros were trashed. But with the clean oil, it stays in gear and doesn't overrev.

Check out this nasty 1mm thick layer of sediment at the bottom of the bucket I used to catch the radiator water. I have Prestone coolant flush in there now, I'll dump that after a few more hours of driving and see if it cleans any more crap out. Flush your damn coolant every two years, y'all!

Attachment 12186

I'm always grinning to myself reading and seeing for myself how much abuse and neglect these trucks can take but they always seem to bounce back with a little routine maintenance. Timex Trucks.

Next up is getting the rattling heater fan cleaned out and cleaning up the suspension and steering because it handles like it's on roller skates.

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They are extraordinarily forgiving to abuse and neglect.

Any cooling system that has been neglected will benefit from removing the radiator and having it cleaned out by a radiator shop. A radiator shop has the expertise to remove the tanks and run cleaning rods through the core tubes. A garden hose will never do as good a job as they can. Flush the system regularly and it won't get to that point. ;]

He that hath ears let him hear...

A radiator that looks like it's flowing at the top can be clogged with no circulation at the bottom.

And when a truck won't warm up the thermostat is most likely stuck open. It's a common occurence.

PS...Rislone is great...

I have another radiator off a 2.0 that I know is good so I think I'll replace the cruddy one. And maybe take the HLAs from an old 2.0 MCA head and replace any collapsed ones. I'm going to get the aluminum radiator for the 2.0 anyway.

glad everything worked out

Thanks.

Half a tank in and it's getting about 12 MPG. No bueno. It's hunting around a bit at idle. So maybe it doesn't know what temperature it is? It's dumping fuel for whatever reason. New O2 sensor and fuel filter on order from Rock Auto and, while I'm at it, I'll pop open ECU open and see if the usual Rubycon caps are leaking. I bet $1 they are. Clean the EGR and take a look at the MAF and IAC, too, eh?

With my 90 i would get 21-24mpg, what rpm does the idle at,also rember there are two coolant temp sensor one for the gauge and one for the ecu

I don't have a tach in the truck or on my light but it was hunting in a range of around 200-300 RPM. Rough idle and rich condition (bad MPG plus high CO and high HC on the previous smog test) being consistent with a bad ECM.

Attachment 12220

No name rebuilder with a "born on" date inspired by those old beer ads. Doesn't look too promising. I googled the number and one of the first hits was a DSM guy complaining about shoddy work this guy did.

Oh no. I'm voiding the warranty.

Attachment 12219

Opened it up and found globs of solder everywhere.

Attachment 12218

Capacitor ooze and burn marks left on the board. I'm not an electronics expert but this looks like crap to me.

I don't know what it is about Florida and ECM rebuilding. It's a cottage industry there. I ordered an A1 Cardone rebuilt one off Rock Auto with a core charge instead of hassling with send-in-to-repair.

Do you have a part number for the temp sensor that hooks into the ECM? Can't see it on the fiche or Rock Auto.

If you look in the link section there is a re-builder in there bluemax found that gives a life time warranty and was a quick turn around. I think it's a sticky.

isn't a very clean solder job but as long as it isn't bridged across a trace and the "gobs" are shiny they work, if they're dull and grey then it's a cold solder joint and won't work. a lot of the discoloration is from the electrolyte leaking out of the cap. it affects the Phenolic material the board is made out of. as long as the traces are still adhered to the board it works. it looks like they gobbed the solder to re-enforce the trace material that could have been broken.

yeah, not a factory job, guy on a bench in the garage IMHO. looking for a ECU?

PM'ed you.

Quote:

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Originally Posted by noahwins

I don't have a tach in the truck or on my light but it was hunting in a range of around 200-300 RPM. Rough idle and rich condition (bad MPG plus high CO and high HC on the previous smog test) being consistent with a bad ECM.

Attachment 12220

No name rebuilder with a "born on" date inspired by those old beer ads. Doesn't look too promising. I googled the number and one of the first hits was a DSM guy complaining about shoddy work this guy did.

Oh no. I'm voiding the warranty.

Attachment 12219

Opened it up and found globs of solder everywhere.

Attachment 12218

Capacitor ooze and burn marks left on the board. I'm not an electronics expert but this looks like crap to me.

I don't know what it is about Florida and ECM rebuilding. It's a cottage industry there. I ordered an A1 Cardone rebuilt one off Rock Auto with a core charge instead of hassling with send-in-to-repair.

Do you have a part number for the temp sensor that hooks into the ECM? Can't see it on the fiche or Rock Auto.

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These photos are why I'm fine with a carbed 2.6...gas hog that it is. I just don't want to deal with that 'check engine light' crap and all kinds of electronics BS. YUK. LOL.

Sounds like you got a handle on it. :thumbup: