Evilfrog

I really ned some ideas here. I had my license suspended because i havent got my car to pass emissions. The car over heats everytime i take it in. And because i cant get through a test, i dont get to apply for the waiver if you spend over $450 dollars in repairs trying to get it to pass

Everytime i take the car in it over heats, the tempature going there 140 degrees. Leaving there, its 140 degrees. Durring the test it shots to 250 within the first two minutes.

I have on my car
Electric water pump
New 180 degree thermo(i had the 160 when it first started overheating, it was the first thing i changed)
Fans are wired to stay on at all time(will go back to the switch when i get done)
Brand new raidator(has been in the car for 23 hours as of this post)
new coolant(kind of a must when changing the raidator)

And im out of ideas. When it does overheat, the heater blows cold....but restarting the car stops it.

Two options are, get the car to pass within the next to months, or list the car as in-operatable. (which i can't do, because i need a car)

Hotwire

you sure the pump is running? made sure you got all the air out of the system? can you pull the cap off w/ the pump running and see coolant churning in the radiator? is your bottom hose collapsing?

I would lean towards pump or air in system.

good luck.

schpenxel

This cold air blowing makes it sound like either water isn't circulating and or there's air in the system. Check out that waterpump, I'm not familiar with the test but make sure whatever they do isn't somehow messing with your waterpump since it's electric.

Carson

Evilfrog

Ok....ill re-bleed it now. But yes, we can see coolant running throw it with the car on and the cap off. Also, we re-wired the pump (some of the the wires were corroded pretty bad) and we plugged it into a hot wire real quick and it ran just fine.(you can here it when the car is off)

And as for the test, they put it up on a roller, hook a hose to the exhaust and put a fan on it. Im kinda thinking it has something to do with airflow, but than again, other camaros in the state most pass.

Hotwire

pull the thermo and make sure the block is full, you have to have the block full in order for the pump to start sucking coolant out of the radiator since it's lower than the top of the motor.

i don't think that's the problem, but had mine overheat like crazy when i first got it back together from lack of coolant in the engine and the pump not being able to pick any up.

jbird

i would check on your lower hose as stated above. You could always put a stiff spring in it as extra insurance, seems cheap compared to some of the other crap you've gone through.

Evilfrog

What would i been checking for in the lower hose? Also, when the temp reads 250, shouldn't there be steam, or coolant boiling out of the raidator?

HardcoreRM125

I'd imagine there would be, If you pop the hood, is it actually getting hot, or is your gauge just flipping out ? For emisisons, they hold the car at like 2500 RPMS ( About, I think ) for like a minute or two. I dont see why it would be so cold with you driving it but super hot when a fan is on it and its running ... Its weird

Robs97Z28

I would think if you not losing coolant and there isn't steam. I would double check the the gauge is correct.

did you replace the radiator cap with the new radiator?

jbird

Lower hoses sometimes collapse (squeeze up) under pressure. The more I think about it the more I'm w/the guys about checking your guage out. Especially since there is no steam or anything. Actually, I would kinda think that there's air in the system, but it sounds like you've bled it more than once.

White Knight 95

If there is any chance that your coolants may have been mixed (Dexcool w/ green) then you may have some clogged lines. This has happened to me and it caused similar strange coolant temperature behavior.

ricoace

My question exactly...Yoy should have boil over at that temp...My Camaros gage is 15 degrees off...Have it scanned and compare the readings to your gage.

Evilfrog

Ok, checked lower hose, it appears good. Now im going to take the thermo out and make make sure there coolant is up to there, if not, im going to fill it up there instead of the raidator cap. Then we are going to check the polarity of the water pump to make sure it is running in the right direction.(Im not sure if i would find anything, because it runs cool most of the time) Ill have to wait a week or so on the gauge test, unfortunely; my budget for the month has ran out.

Edit: Right now, im waiting for the car to cool down.

Evilfrog

Ok, waterpump is pumping great, coolant level is great.(i took off the thermo god i hope i didn't get any on the opti) anywho, i found this......

Found this info, which someone may find useful:

Several people with LT1/LT4 powered vehicles have noticed that the temperature gauge reading seems to fluctuate greatly, depending primarily on whether the vehicle is moving or not. It has also been noticed that the PCM indicated engine temperature does not always agree with what the gauge shows, leading many to believe that their instrument cluster temperature gauge is inaccurate or faulty. I can assure you that in most cases the temperature indicated by the gauge is absolutely and totally accurate, for the POSITION on the engine at which the gauge sending unit is MOUNTED!!!

To understand this, first note that there are two temperature sending units on the LT1/LT4, one for the gauge and one for the PCM. The one for the gauge is mounted in the side of one of the cylinder heads, while the PCM sending unit is mounted on the front of the engine directly in the water pump. B/D-cars (Impala, Caprice, Roadmaster, Fleetwood) and Y-cars (Corvette) have the gauge sender installed in a tapped hole in the rear of the RH cylinder head, between the #6 and #8 spark plugs. F-cars (Camaro, Firebird) have the gauge sending unit mounted in a tapped hole in the front of the LH cylinder head, between the #1 and #3 spark plugs.

Now remember that this engine is reverse flow cooled. This means that cold engine coolant entering the engine from the radiator is directed to the heads first, which is exactly why the gauge sending unit reads low compared to what the PCM sending unit sees. The PCM sending unit sees actual engine coolant temperature, and is not hit by the flow of cold coolant directly from the radiator.

If there is a problem with the gauge at all, it is certainly NOT that it is inaccurate. The gauge is perfectly accurate, but the SENDING UNIT for the gauge is mounted in the WRONG PLACE to get a "correct" reading. Unfortunately there are no other tapped holes in the water jacket to mount it unless you drill and tap another location. There is a tapped and plugged hole in the opposite cylinder head, but that would offer the same gauge readings, in fact it might read even lower temperatures since the tapped hole in the LH head it is mounted more towards the front of the block, closer to where the coolant first enters the heads from the radiator.

I have verified with scan tools which can directly read the PCM indicated temperature, as well as a digital Cyberdyne gauge sending unit mounted in the stock gauge sending unit location, that the two stock temperature sending units (gauge and PCM) will read temperatures as much as 60 degrees different while moving at high speeds on a cool night. If you stop and let the car idle long enough, eventually the radiator coolant temperature in the head equals what the actual coolant temperature in the block is, and both readings are relatively the same. As soon as you start moving, the temperature read at the gauge sending unit in the head will drop rapidly, however the actual engine temperature, and that which is sensed by the PCM sending unit, remains about 10 degrees above the thermostat setting.

Note that you cannot run both the gauge and the PCM off of the same sending unit. The gauge sender is a simple one wire sender where the body is grounded to the engine block. I believe it runs on 12v through the gauge and sender to ground. The PCM sender is a two-wire sender with a 5v signal and a digital PCM ground (not chassis ground). The gauge cannot be run off of this sender without messing it or the PCM up.

In any case, this anomaly CAN be corrected, in fact I have known about this "problem" for several years now, and have intended to correct it all along. Now I will finally be getting around to it due to my upcoming LT4 engine installation.

The proper way to correct this temperature reading anomaly is to mount the gauge sending unit in the water pump housing, in the same water passage as the PCM sender is now. There are two ways to correct the problem. One would be to drill and tap a hole in one of the existing unused sending unit bosses in the water pump to mount the gauge sending unit in the same water passage as the PCM sending unit is located. With the gauge sending unit in the water pump, instead of in the LH cylinder head, the gauge will now read correctly in concert with the actual engine temperature, which is also the temperature the PCM sees. This method requires that a proper sized hole be drilled, tapped, and then the gauge sender can be installed. Then the existing sender wire must be lengthened and re-routed over to the new location.

A more elegant method of correcting this problem would be to simply replace the existing PCM sender with a new dual purpose sender that GM has recently been offering on other applications. This is a new GM 3-wire sending unit which includes both the PCM and Gauge senders in one unit, and which installs in the existing PCM sensor location.

GM has begun using a 3-wire dual purpose sender on some new engines. It combines both the PCM and gauge senders in one unit. This is ideal as no additional holes will have to be drilled or tapped, this new dual purpose sender can replace the existing PCM sender.

Here's the information on the 3 terminal coolant temperature sensor.

Part No Description Cost
10096181 PCM/Gauge sending unit $14.81
12102748 Connector pigtail (incl. terminals) $17.29

This connector pigtail is a complete connector with terminals and wires installed, which would have to be spliced to the existing wires. Alternatively, you can get just the connector shell and terminals, which you could crimp onto the existing wires. Unfortunately most dealers are not able to get Packard electric parts through GM.

Part No Description
12078090 Packard connector including the seals
12103881 Terminals (three required



Another alternative would be to get the connector and terminals plus wire from a junkyard. It's the same connector that is used on the throttle position sensor of the LT1 and many other engines.

The new sending unit is wired as follows:

Pin A = Black, PCM sensor ground
Pin B = Yellow, coolant signal to PCM
Pin C = Dark Green, to Gauge

Hotwire

hmm, sorry to send you on the goose chase, never heard that. maybe see if the inspection station has a infrared temp gun, point it in the two different locations and see if they correlate w/ the pcm/gauge. ??

good luck man, hope ya pass.