gunmetalTrevan

Hey, all. I finally got my performance issue from my last two threads fixed -- all that research and junk on my end and all it needed was a proper air filter.

After that, the tranny went out, but it's been running beautifully since that got fixed.

But, about a week ago I started having temperature problems. I think about a month ago, my coolant light started popping on and off occasionally, so I checked my levels and it was always full. For the past few months it has been running warmer than it did when I bought it over a year ago, but nothing crazy. Now the coolant light is on basically all the time, and I think it's just a dirty sensor, but a couple days ago the temp gauge would go into the red zone only while idling, and when I gave it some gas it would cool off a little. Today, though, it went up into the red zone while I was driving down the road, and at a stop light it stuck up at 260 for a number of seconds. I immediately killed the engine and I could hear some kind of bubbling/boiling up front.

A few other times it has gotten very close to 260 while driving down the road, and the check gauges light would come on before the temperature suddenly dropped quickly.

I'm going to pick up a new thermostat today, my fans appear to be running okay and I want to do a coolant flush ASAP, but I just don't know if the thermostat is the issue. Does it particularly seem like something else?

shoebox

Have you been checking the actual level of the coolant?

moparman

Be sure the front air dam is still on the car.

gunmetalTrevan

I've been checking it regularly, and it hasn't been low. I just checked it this afternoon, though, and it was actually very low. Would probably explain why it didn't even cool down while driving this morning... odd. Think I could have blown something? I bought a bottle of the yellow fluid and topped it off, and after sitting in shade for five hours, the motor still got up in the red zone after a few minutes of driving.

I also saw a bunch of gunk near the end of the dipstick, kinda muddy-looking stuff. I've never seen that before, is it just more noticeable because it ran low on fluid? After I filled it up, it dissipated -- I just hope nothing is clogged, too. :/

I'm getting the coolant flushed now, and I'll throw the new thermostat on after. Any other ideas?

Injuneer

Are you checking the coolant level in the radiator (where the level sensor is located) or in the reservoir? A full reservoir does not necessarily mean the radiator is full.

HardcoreRM125

You are bleeding the air on via the two bleeders aren't you?

gunmetalTrevan

I haven't checked the levels on the radiator itself -- I'll make sure that's all set. I also forgot to mention the water pump has been replaced sometime this year.

Yep, I bled out any air pockets that were present. My fluid was actually low because it boiled over so much, before it got flushed. After, it was more stable for a little while but eventually boiled over again while I was going down a country road, so I think I'll need to bleed air out again. I was sure to pull over and kill the engine as fast as I could before anything got damaged. I keep coolant in my car, so I topped it off and made it home.

BUT, better news. I let it sit for a couple hours, then I put in the new thermostat (the old one looks pretty new) and drove around for about 20 minutes along with some heavy idling, and so far it's not getting terribly hot, so at least it's better than before so far.

What is the normal idling temperature for these cars? Driving down the road it sticks around the 1/4 line, but it gets much hotter idling. It doesn't seem to go into the red zone anymore, but it sticks around the 3/4 mark which I feel is cutting it a little close, especially after seeing it jump to 260 so quickly without me noticing.

moparman

At idle, on a hot day, the temp will easily go towards the 3/4 mark. Fans should kick on and begin cooling it down.

gunmetalTrevan

Alright. Well, I drove it on the freeway to work this morning, and so far I'm having no issues at all. Looks like it was just the thermostat!

Normally my car's issues are not something as simple as a $10 part I can change in like 5 minutes, so I was preparing for the worst. I'll keep you guys' words in mind, thanks a lot!

I do have to ask, though. If my car got hot enough to boil over two times, one of which was particularily bad, is there anything I should check to make sure the car is still in proper condition, or should I be on my way?

Injuneer

Are you sure you got the correct LT1-specific thermostat? Typically they cost upward of $20. Parts stores will usually sell you the t'stat for a Gen 1 SBC, and that is not correct.

http://shbox.com/1/tstat.jpg

To be sure you are filling the system properly, and bleeding it properly, refer to Shoebox's guide:

4th Gen LT1 F-body Tech Articles

1994BmtZ28

Ditto what Fred said...also ya might look to see if the thermostat you removed is LT1 specific. If not, that may be the root cause of the problem.

gunmetalTrevan

If you're talking about there being a portion of the thermostat below the struts (not sure what else to call them), I have the right one.

This is the old one: https://i.imgur.com/26kUfS7.jpg

All I did was go into O'Reilly and tell them my vehicle info, and they brought me my new one. It looks almost identical, just some minor appearance changes. It's the Murray Temperature Control Plus, only $10. Murray® Temperature Control Plus 4218 - Standard Thermostat | O'Reilly Auto Parts I drove around all day today in the heat and experienced absolutely no problems. The past few days, it would overheat within 10 minutes of a cold start

Are you saying the wrong one would be shorter like this? http://www.lingenfelter.com/mm5/grap...ges/8210wb.jpg

There was a $20 one that opens up at 160 degrees instead of 180. It was tempting, but long-story-short I needed to be frugal.

shoebox

You're good.