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Thermostat replaced = still running hot. What next


dkas

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Looking for some suggestions. '94 3.4 DOHC cutlass convertible. Thermostat replaced. Temp guage seems to read more accurately now and does show the car running hot. Fan is not kicking in until the car is about 3/4 of the way to the red on the guage. Car will not start when it is hot.

 

Now what do I replace? Fan works, thermostat replaced, coolant good and levels good. Looking for some suggestions please?

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Was the coolant *fully* bled after the thermostat was changed out?

 

This, x10. You need to be absolutely 100% sure that it's bled properly or you will have all sorts of issues.

 

I've got bleeding one of these down to a science, and it's not easy to do.

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First, I would thoroughly flush the cooling system, and make sure the air is completely bled out of the system afterwards. May as well change the hoses at that point, too (unless they were done recently). Also, you may want to look at the temp sensor if the fan's not kicking in at the correct temp, as well as the water pump.

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....sounds like the fan is coming on when it's supposed to.

 

factory calibration is setup for 223* for fan 1, 235 for fan 2.

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Looking for some suggestions. '94 3.4 DOHC cutlass convertible. Thermostat replaced. Temp guage seems to read more accurately now and does show the car running hot.

How can the temp gauge read "more accurately" if you didn't do anything that would "fix" it?

 

How do you know it's MORE accurate now? How have you verified the actual engine coolant temperature versus the indicated reading on the dash gauge?

 

Fan is not kicking in until the car is about 3/4 of the way to the red on the guage.

Could be normal. I'm thinking my '92 and '93 start the lower-temp fan somewhere beyond "1/2" on the gauge but before "3/4".

 

Do BOTH of your fans work? Not just the higher-temperature fan?

 

Car will not start when it is hot.

Failed sensor/wiring/ignition module? Do you not have spark, or do you not have fuel, or do you not have both? The engine DOES crank...right?

 

 

Now what do I replace? Fan works, thermostat replaced, coolant good and levels good. Looking for some suggestions please?

No way to know until you do some diagnosis.

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Is this overheating when parked? Or when being driven? Cuz I know the factory didn't install those air deflectors underneath the front for nothing. Curbs love to smash & destroy those things, just a thought.

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Guages more accurate - the temp guage never moved above the first line yet the car seemed to be overheating. I am assuming the guage is working now since it moves all over the place since the thermostat has been installed. Don't ask me why it appears to be working now. Maybe it is not working correctly now and was before. I don't know.

 

I have never seen the second fan come on. I have only ever witnessed one fan coming on and the temp guage did go down slightly when it came on. The fan I know is working is on the driver's side. Is that the fan that kicks in first or second at the higher tempature?

 

Car will not start when hot - sometimes you turn the key and it completely dead. Like it has no power, but most of the time it will crank and crank. No idea if it has spark or gas. One not the voltage guage is really low as well.

 

Maybe I should replace the ignition module and see what happens?

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Might need a radiator

 

How so? Are you thinking it might be blocked? The outside of the rad looks to be in good shape and really it looks fairly good. I have only had this car for less about a year. It is far from perfect.

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How so? Are you thinking it might be blocked? The outside of the rad looks to be in good shape and really it looks fairly good. I have only had this car for less about a year. It is far from perfect.

 

Sounds like you may have other problems then

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Sounds like you have blockage in the radiator or water hose lines or the water pump is not doing it's job. Is the heater core good? Any history of this problem with previous owners? INSTANT FIX, drive car into garage, jack up car, unscrew radiator cap, back up old car from underneath radiator cap, drive new car under radiator cap, install cap on new car, start new car with old radiator cap and drive the hell out of it!

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INSTANT FIX, drive car into garage, jack up car, unscrew radiator cap, back up old car from underneath radiator cap, drive new car under radiator cap, install cap on new car, start new car with old radiator cap and drive the hell out of it!

 

:lol::lol::lol::lol:

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If the gauge is really bouncing around it does sound like it is not bled. There are 2 bleeders that need bled on an LQ1. One on top of the thermostat housing and another on the heater core line up next to the brake booster. If you're sure it's bled, I would guess either an radiator. You might make sure the AC condenser isn't to far blocked with bent fins and that there isn't a collection of garbage between the condenser and radiator.

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Sounds like you have blockage in the radiator or water hose lines or the water pump is not doing it's job. Is the heater core good? Any history of this problem with previous owners? INSTANT FIX, drive car into garage, jack up car, unscrew radiator cap, back up old car from underneath radiator cap, drive new car under radiator cap, install cap on new car, start new car with old radiator cap and drive the hell out of it!

 

Love the instant fix....lMAO

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My car does the same things with the cooling system, needle moves around a bit but it never fails to start, hot or cold.

 

One thing that is not real convenient but might make it easier to start again when hot is when you shut off the engine, put the key in position before starting and let the fan(s) run for a few minutes to cool things down. This is a good idea only if the battery is newer though.

 

It is unlikely that you have enough radiator blockage to cause any real overheating.

 

So what about the other bullshit under the hood? Spark plugs in good shape? Spark wires in good shape, not corroded or rusted at the connector points? Coils not rusted at posts? Fuel pressure good and the FPR hose is not cracked? Air filter in good shape?

It is not likely that these things will be a "magic fix" or anything, except maybe the rust on the plug wire connectors or the coil posts.

 

Also, make sure the A/C is shut off before trying to start it, no need for more drain on the engine when starting.

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  • 2 weeks later...

Not sure if this is true for all cars but my mechanic tutor guy showed me that the 3.4 sort of air locks.

 

To get all of the air out we bled it like normal, let it get hot and open the bleeds until you get a good stream of coolant. Then leave it run a bit longer and when you know its really completely warmed up (takes a while) turn the engine off and open the bleeders again, letting out steam until you get a solid stream of coolant. I had to repeat this several times, letting pressure build while the engine is running and then shutting it off and bleeding again. Just keep an eye on the reservoir. I was REALLY shocked at how much air we got out after I thought it was done. I was glad he helped!

 

Maybe this is common sense, but I never would've known to do this from the manuals.

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probably why there are at least 2 air bleed locations on every LQ1 i've played with.

 

right but is the LQ1 more difficult to bleed than other engines? We all know there are two bleeds. I'm still learning but I had a good stream out of both bleeds after about 25 minutes and still found out that there was a lot of air in it.

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I have a helluva time getting the LQ1 completely bled. Air tends to like to stay in the upper radiator hose even when coolant is shooting out the bleeder while the engine is running. I will perform the normal bleed procedure, then once the engine cools, I will spend awhile doing this procedure to get the remaining air out of the system:

 

1. Open radiator cap.

2. Open t-stat bleeder.

3. Squeeze upper radiator hose and HOLD.

4. Close t-state bleeder.

5. Release upper radiator hose, observe coolant level in radiator dropping.

6. Repeat steps 2-5 until coolant level in radiator stops dropping, coolant comes out of the bleeder when you squeeze, or coolant level in radiator is too low to see.

7. Top off radiator.

8. Replace radiator cap.

9. Top off reservoir.

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Have you actually had the temp checked? Just thinking your gauge might be playing with you. We had a little Toyota and it always seemed hotter than normal inside the car. One day I pulled into the repair shop, told them I think it's getting too hot. They came out with some fancy gun looking scope thing that read temp just by shooting a laser at stuff. They took temp readings off everything, the radiator, motor, hoses, inside vent opening, exhaust, even the underside of the hood. They even told me I wasn't running a fever! LOL

 

After they finished they took all the data somewhere in a office and came out and told me it was running with-in normal operating temps. Turns out some previous owner replaced the front carpet once and never put dyna matt or pad down under the new carpet, so the heat from that little 4 banger was coming right back to the firewall and heating up the passanger compartment.

 

Anyways, It's just a suggestion, I think all shops must have that temp laser thing. After the car sat a little, they even popped the raditor cap off and took a temp of the collant.

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