Powers on for a short time upon start up and helps to heat the converters to quicken the burning of emissions.

 

OK. That makes perfect sense. I was seeing it early on when I fired the car up. Data logs are delivering solid information now that the idiot got it right.

 

Well, it wasn't the sensor. Put the new one in today. Drove it and it started soaring again. I let it go until the check gauges light came on and then shut it down. Then I played back the data log. At no point did it show over 196 degrees and only the low fan had been triggered. I'm going to pull the thermostat next and test it.

 

How much should the thermostat be open at full rolling boil? Only seeing about 1/8 to 1/4 inch gap. Not sure if that's enough. All help appreciated.

 

Crickets. Crickets. LOL.

How can you confirm the water pump is actually moving coolant?

 

Is the entire radiator hot to the touch of your hand? If yes, then the water pump is pumping coolant. Upper hose should be hot. Lower hose, much less hot. For my LS-equipped El Camino, its probably 25 degrees cooler within the low hose compared to the upper hose.

Try a new thermostat and get a new gasket to go along with it. This thermostat should have a small valve built in to assist in purging air. After replacing it, I find it best to disconnect the top radiator hose at the radiator and pour in at least a gallon of coolant into the hose to assist in purging air from the water jacket. I also disconnect the steam vent hose and let air emerge from it during the initial warm up. Pour any discharged coolant from the vent hose back into the radiator.

Rick

 

Tested the thermostat in a pan of boiling water. It's working. Hoses feel warm to the touch so I think the pump is working. Pulled the sensor, grounded it to the car and dumped it into a pan of boiling water. Gauge in the car read about 180 and my IR gun was agreeing with that. Cooled down some as I moved from the kitchen to the garage. I bought the kit to test for a head gasket being blown. I'll test that as soon as I can.

I'm beginning to suspect the seller knew it had a blown head gasket and sold it to me without revealing that. I hope I'm wrong.

 

Question on running the block test on an LT1. Do you put the cylinder in the radiator neck or the overflow bottle?


Here’s why I ask.


I had drained down the coolant a few inches in the radiator and had it shoved into the filler neck on the radiator. Fired it up, fluid was blue and I was seeing a few bubbles coming through. It stayed blue for several minutes. I decided to let it run a while just to be sure it was up to temp so I walked out of the garage. After musing how nice the late dusk sky looked I went back in and the cylinder had gone from the normal level of fluid and blue to almost full and green, full of coolant!


Is it normal for the coolant to rise in the radiator like this?

 

Yes, it is normal for the fluid to expand a little as it gets hot. You need to drain more out of the radiator to preclude getting raw radiator fluid into the plastic cylinder. I don't test at the overflow bottle, I test at the radiator cap.

Rick

 

Thanks! I'll try again tomorrow night.

 

Re-ran the block test today. It stayed blue so it's not a gasket.

But then I did this. Kinda makes me think the water pump ain't getting it done at idle.

 

I swear that reminds me of air in the system.

 

For what it's worth, I drill a small hole in my thermostat (just in case it fails)

 

So do I. The reason I say it reminds me of air in the system is because I’ve seen cars overheat from the vapor telling the sensor it’s so hot but when you bring rpm up on the engine the cooler liquid gets to the sensor and gives a more accurate reading.

 

I decided to spend the day ruling out air in the system.

I have a steep driveway so I backed the car out into the drive. I repeated the procedure found on http://shbox.com/1/4th_gen_tech2.html#radflush about 6 times. I did get air at the top bleeder screw the first 4 times but the last 2 times it was all coolant.

Now it does seem to take longer to get hot and the heater is most certainly working at full capacity (sweating my *** off in that car, lol) however the long term problem of it creeping into the 260 range on the gauge remains. I can drop it quickly by bringing up the RPM. I drove it and while cruising and maintaining RPM it stay at or just above 180. As soon as I slowed down or sat still with the car idling it went back up. Data logs still say the car isn't hot although it does show the car getting to 210 or so and it shows both fans running at that temperature. Fans have been verified as coming on and moving air.

I have 2 more easy things to try before tearing into the pump. First I want to swap the radiator cap. Then the thermostat, even though I tested the existing thermostat in boiling water and it seemed to work. If those parts don't give relief I think it's time to yank the pump and see what we see in there.

 

I found this thread while searching if the rotation of the water pump matters. I am wondering if the 'new' pump on your engine is turning in the wrong direction. In my searching for a replacement for my own pump, which is starting to make noise, I found sites that specify the rotational direction (o'reilly) of the pump, but other sites don't (napa, summit). I ended up here trying to figure out if it matters. Found some other sites just now that say it does matter. So something to check. Seems like your symptoms could be explained by a pump not turning in the correct direction. This is one of the pages I was reading: water pump running backwards

Now I have to figure out which way mine is supposed to spin based on my belt pattern so I get the correct one. I know which way it is running, but want to make sure it is correct.

 

I dunno... last time I did a head swap I thought it would be a good idea to keep the front up in the air while adding coolant. Ended up with a bunch of air in the system regardless of bleeding. Try doing it on a flat surface. The stock water pump is a direct drive. It's either working or it's not regardless of RPM.

 

Unless it's an electric pump wired backwards or a replacement pump that has the wrong impeller on it an LT1 Water pump cannot run in the wrong direction. It's driven off of the cam gear via the water pump drive and driveshaft so it's mechanically not possible to turn it the wrong direction. The only way it could be done are the two I've listed and you'd have to take your reman or new pump apart and compare it to a known good pump to prove whether or not the wrong impeller was installed on it. I find it pretty unlikely.

If you have a belt driven water pump, you sir are in the wrong forum, gen 2 LT engines don't have a belt driven water pump.

 

I likely am in the wrong forum for my engine, got here just searching the entire site. Mine is an LS6 and it definitely has a belt driven pump. Still learning about all these LS variations.

 

no big deal. This is how we all learn.