Napster134

Hello all,

I have a really weird overheating problem that I cant seem to figure out.
Last night, I was on my way to a friends house and I noticed that my temp gauge was climbing... It was right in the middle (220) when I noticed this.

This was right before I had done a WOT run so I thought it might have just heated up a bit because of the run. As I continued to drive, I noticed it continued to heat up past the middle mark on the gauge. I then got on the freeway thinking that the extra air would cool it down although the gauge continued to rise...

Soon enough, I reached the red 260 mark so I turned the engine off and cruised down to a stop.

I started looking over the engine bay and underneath the car. I noticed that I was leaking water/coolant from underneath the water pump so I thought I had found the problem.

I filled the radiator back up with water and headed to my destination. I barely got there before I had to turn off the engine again. When I got there I noticed there was some poping coming from what seemed to be the engine... normally, when my car is actually overheating, I get a bunch of bubbling coolant from the overflow tank although that was not the case this time.

It was midnight so I thought I'd wait till morning to figure it all out. In the morning, I noticed there was no water underneath the car so I thought it must have all drained out. I began to fill the radiator and as soon as I began to fill, I started hearing dripping from the water pump again. The drivers side water pump gasket was leaking.

I bought brand new gaskets, removed the water pump and put the new gaskets on along with silicone. Bolted everything back up and filled with coolant.

Started the engine back up and began to watch the temp. gauge as it idled.... it climbed past to 220 and right back into 260... Overheating again. This time, no more coolant leak.

At this point, I'm thinking the thermostat might be stuck so I removed it but no go... still overheating.

If I give it some throttle while the temp. gauge is climbing, it will stop the temp. from climbing for a few seconds and then start heading back to the red.

I looked at my oil and there was no signs of milky oil... I then noticed something... the drivers side fan was not turning on.

The passengers side fan is controlled via the head temp. switch.
The drivers side fan is controlled via the ECM (EBL Flash)

I pulled up my laptop and noticed that the CTS temp. the ECM was reading was not going past 195 yet... This explains why my 2nd fan was not turning on. Although it doesn't explain why the gauge temps are not matching the ECM temps.

The ECM pulls its temp from the coolant temp sensor that is located right next to the thermostat on the intake.

The gauge pulls its temp from the coolant temp sensor that is located in the cylinder head between spark plug 1 & 3 I believe.

So, gauge is reading extremely hot, while ECM thinks everything is fine and reading normal temps so I replaced the coolant sensor on the cylinder head...

Same problem. the temp gauge just climbs slowly. It takes about 4-6 minutes for it to reach 260... While the ECM continues to report normal temps between 190-210.

So before I ended the day, I thought I'd do one last risky test...

I let the engine idle for a few minutes after the temp gauge hit 260... I reved it a lil and just continued to let it idle while I made sure that the ECM was reporting regular temps...

Everything seemed OK... til I heard a small pop... I then turned the engine off and went over to see what happened. Everything looked fine but I could hear a bunch of popping coming from what seemed to be either the water pump or the thermostat housing... After the pressure went away, the popping slowly died and went away and the pressure on the radiator hose was gone.

The weird thing is that I only have to wait about 2-3 minutes so that the temp. gauge comes back down to 220ish and I can start the engine back up again. Normally, if my engine actually overheats I have to wait forever for the coolant temps to come down.

I have no idea whats going on! :/ It almost seems like something is plugged up? Any ideas?

sofakingdom

iTrader: (1)

First thing to do, is replace the temp gauge sending unit in the driver's side head.

Next thing will depend on what you find.

In this day and time, it makes no sense to go around guessing about things like temps, when it's SO EEEEZY and SO CHEEEEEEEEP to get a measuring instrument for it. IMO an infrared pyrometer and a DMM should be in EVERY would-be "mechanic"'s toolbox. Go get yourself one of those (HF has em for like $30); find out what your engine temp REALLY is; then you'll know whether to start troubleshooting an overheating problem, a leak, a weird noise, or what. Right now you're the classic blind man in a dark room trying to figure out what color the walls are.

Dakota W.

Shouldn't the one in the passenger side be causing the second fan to come on too? Revving the engine to get it to cool down sounds like your waterpump could be bad. There are 2 temp senders, one in each head and one in the intake manifold. The one in the head is the pass. is secondary and the one in the manifold is for the temp gauge. Get an IR pyrometer and see how hot things really are.

sofakingdom

iTrader: (1)

Right: pass side one is the fan switch.

Wouldn't have much effect on the temp gauge. At least, not directly. Which is why I said

The sending unit in the driver's side head is for the gauge, as mentioned above. The one in the intake manifold is for the ECM. The one in the pass side head is for the fan.

Napster134

I know I wrote a lot so it was probably easy to miss that.

Anyhow, I'm going to buy a temp gun before I go into class tonight. I thought about the temp gun but never used one before. I'm sure there's a bunch of videos online but since theres two sensors reading two different temps, should I just point it at each sensor location individually? What type of things can these guns read though? The heads and intake are made of aluminum.

Thanks for the help!

Napster134

I have my dual fan setup a bit different. Passenger side head coolant switch turns on the passenger side fan. Then the drivers side fan is wired to a relay that the ECM activates at 195. Then there's two coolant temp sensors. The CTS on the intake manifold next to the thermostat provides the ECM with the coolant temp. The CTS on the drivers side cylinder head provides the temp reading for the gauge in the dash.

The sensor I replaced was the drivers side cylinder head CTS that provides the dash reading that is currently telling me that I'm overheating.

I'm thinking I'm going to try 2 more tests before I remove the water pump again to check the internal pump fins...

1. Check temps with infrared gun.
2. Remove thermostat and let the engine idle now that the CTS is replaced.

Napster134

Yup, all that is correct. Drivers side head sending unit is giving me the scary temps... The one in the intake manifold is telling the ECM/EBL that everything is perfectly fine. Fans are turning on accordingly with the values being provided to the ECM.

Napster134

I forgot to mention this...

Before I replaced the CTS on the drivers side cylinder head... I took the car out for a drive... As soon as it began to reach the red mark, I heard a pop and white smoke started coming out of my engine bay like crazy... I popped the hood open to find that the heater hose on the top passenger side of the radiator popped off. This was not touched at all and has never popped off before so it makes me think that there's a ton of pressure building up in the radiator... Just thought I'd add that in.

Todd84Z

I hate to say it, but when I first got my car I had a few overheating issues. Although the car never actually overheated, it would jump up to 260 degrees and the reserve tank would boil and overflow. After replacing a few relays, the problem persisted. After a few fixes and a few trips to my mechanic I finally decided to go to Advanced Auto Parts and replace both the radiator cap and resevoir tank cap. Both, I think were about $5.00 each. I have not had the problem since. Apparently nirther cap was holding pressure. I learned about this on the thirdgen.org message boards. My mechanic was pissed.

Dakota W.

The TBI cars must be different then, with my LB9 the driver's side told the left fan to come on, and the pass side was an emergency sender set for a higher degree(don't remember the degree) and if it go to that point, or the A/C was turned on the pass side fan would turn on.

Napster134

Ok, so I bought a 35$ infrared temp gun at harbor freight. It doesn't seem like anything is overheating. I ran the engine and pointed the laser at the thermostat housing, the top radiator hose, bottom radiator hose, radiator itself, and the drivers side CTS.

Everything read underneath 200F while the gauge is still inside the car going past 260... the only time the gun read above 200 was when the laser hit the header.

I notice that after the car runs long enough, the popping starts back up again... its like boiling/popcorn every 3-8 seconds popping... On every pop, the top radiator hose sort of flinches... The top radiator hose also seems to be inflated with a ton of pressure ... but maybe its just me.

I'm removing the thermostat tomorrow and trying again without the thermostat...

I'm thinking either, there is air in the system, or something is wrong with the water pump or possibly the thermostat?

Btw, my car use to overheat legitimately in the past, during the overheating my overflow tank would boil and overflow with coolant which is not happening during this problem. Also, when I use to overheat in the past, I remember I would have to wait on the side of the road for a good 20 - 30 mins before the temp came back down. Right now, I turn off the engine and my temps are back to normal (200ish) after about 3 - 5 minutes.

91interceptorZ

iTrader: (3)

I would agree that you might have air in the system, or a faulty t stat. what happens if you run the engine with the cap off the radiator? do you get a bunch of bubbles really quickly...this would indicate a blown head gasket or bad head. Is your radiator clogged perhaps, peak down inside and see if it's corroded. when it's cold un hook one of you heater hoses and start the car, see if it has a good flow of water out to make sure water pump is working correctly, maybe the blades are gone or spinning on the shaft (I didn't read that you replaced it, just replaced gaskets). lack of flow would boil the water in the block, but the water not would be at a lower temperature which would give you those temperature readings. How fast is the needle moving up, like how many minutes at what ambient temperature at idle before the gauge reads hot and popping sound starts?

antares57

iTrader: (8)

I didn't notice it above. Have you replaced the radiator cap? Is it new or an old one? That should be alleviating the pressure buildup in the upper radiator hose. Just a thought.

Napster134

It takes about 5-10 mins for it to fully heat up according to the gauge... It takes about another few minutes of running it within the RED for the popping to start...


Here's an update!

I wanted to make sure all the air was gone so I removed the top radiator hose and stuck a water hose into the radiator neck... a bunch of bubbles came out of the intake thermostat hole then a nice flow of water. I then placed the thermostat/hose back on and removed the intake CTS sensor and stuck a hose in the radiator neck and a few more bubbles came out of the CTS hole so there was air in the system. I then placed the CTS back in and removed the thermostat but left the hose on and made sure I got a bunch of water gushing out back towards me when I put the hose in the radiator neck. So I was pretty convinced that the system was bleed of air.

At this point, I turned on the engine without the thermostat...

Same problem, it began to show I was overheating after about 5-10 mins...

At this point, I noticed that I was hearing some weird whining noise that I never heard before... It seemed like a bearing type whine...

I removed the serpentine belt and let the engine run without the water pump, AC, or power steering... The whining went away...

At this point, I can't think of anything other than 1. the water pump is shot, 2. radiator is clogged or 3. I have a serious problem with my heads/engine.

Napster134

Or 4. my radiator cap is bad. The radiator cap I have came with the champion 3-core aluminum radiator I have installed. I can replaced it before I decided to remove the water pump again to check the blades.

I cant see how the cap would go bad though, it seems like a pretty simple setup, I can press down on the cap and the spring will allow it to go up and down pretty smoothly... Maybe you cant tell when they go out? Not sure.

TallTim

iTrader: (2)

+1 for the rad cap replace. Miracles have been worked by that cheap and simple change. Maybe not yr prob but at least that's off the list easily.

Ransford2987

Of all the things that are happening, you can't ignore the fact that you are clearly overheating. Regardless of what your temp sensors read, you can physically tell there's some overheating going on. My 2 cents: check that water pump and make sure you have the flow you need. Clearly something isn't allowing the coolant to be cooled, and since you have a new(er) rad, you can probably eliminate that one. You can replace that rad cap too if you want, but if it's new, chances are it shouldn't be that bad.

You can try to let it run without the rad cap on and no thermostat and watch the coolant circulate, but you probably wouldn't be able to tell the difference between good flow and poor flow like that.

Napster134

To do list (Should be done by Saturday, maybe tomorrow if I have enough time):

-Replace radiator cap.
-Flush radiator.
-Remove water pump and check fins...

I still have my old cast water pump that works fine...
The water pump in it now is a stage 2 Stewart aluminum pump.
I bought it on 03/31/13 so considering its got a 1yr warranty I might be able to get another if that's the culprit.

http://www.summitracing.com/parts/emp-23123/overview/

Oh, and I just finished cooking up some water in a pot with the thermostat in there... It's working fine and opens right at 190-200. It's also one of the fancy stewart thermostats with the lil bypass holes so thermostat seems to check out fine!

Napster134

Ok, so I think I'm onto something bad ...

I took out the water pump and unfortunately, it looked perfectly fine...

I then stuck a water hose in the drivers side water pump inlet hole on the block... the water will not pass through! It's like the block is clogged. I do everything I can to make a pressure tight seal and all the water just wants to blow back up on me from the same hole... This doesn't seem normal to me... I can see why the water pump is having such a hard time passing water through and why it blew the drivers side gasket in the first place.

The passengers side isn't anywhere near as bad... If I stick the hose through the passenger side pump inlet it will flow out through the top of the intake where the thermostat inlet is.

The weird thing is that the engine seems to run perfectly fine. It still has power and starts right up...

Could something be wrong with the block or heads?

Napster134

Now that I think about it more...

Not only does this explain why the drivers side gasket blew off... but it also explains why the drivers side head temp. sensor is reading the high values it's reading... it explains why I'd hear the popping and why everything felt so pressurized...

It also explains why the coolant sensor on the passenger side of the intake is reading OK temps since the passenger side doesn't seem to be clogged and flows the water out through the thermostat outlet which is near the intake temp. sensor...

So I guess my next step is removing intake unless anyone else has any ideas? ...

antares57

iTrader: (8)

Don't know if it's relevant. Are you discussing the vehicle in your profile - the '91 Pontiac Firebird? I checked the link to SummitRacing for the water pump you have installed and when I went to the application tab the Firebird was not listed as compatible with the water pump. Your setup may be different to adjust for that, but I just wanted to be sure and mention it.

Napster134

Well, its worked fine for 8 months. You could do a search on here and find that those are the pumps that they use for these cars but I remember doing research a while back when I first bought it and made sure it was the right one. If someone confirms that all the back-pressure I'm getting from the block's cooling passages is normal along with the passenger side flowing easier than the driver side then I'll just throw my old water pump back on. There was never anything wrong with my stock iron one, just wanted to upgrade.

redneckjoe

try sticking a coathanger in there and see if you can find some blockage. pull the thermostat housing and see if you can push the wire threw the intake, into the head. its probably plugged up there.
hopefully you get it flowing and can flush it out.

Napster134

Thanks!! I'll give that a shot! I hope it turns out to be something this easy!

Napster134

Ok, so this makes no sence at all...

I started poking around inside the intake from the thermostat housing to see if something was plugged up on the intake ports.
I couldnt poke anything past through to the inside of the head...At first I thought it was just the walls of the head but that couldnt make sence because I couldnt find where the water would enter.
So I poked the passenger side pretty hard and bam the screw driver went through! I then put the hose into the water pump passenger side inlet and the water flowed better.
I then did the same thing on the drivers side... and I poked a hole through what seemed to be thin metal.

I then put the hose into the drivers side water pump inlet and the water began flowing 10x easier through to the top of the intake from the hole I poked.

So, now I'm thinking, did I put the gaskets on wrong? What doesn't make sense to me... is how the hell did this work for 2-3 years like this?
I'm so confused!!! lol... but it feels like I found the problem.

That, or I screwed something else up.

redneckjoe

glad to hear you found your issue/problem. probably a smart idea to pull the intake and see whats going on?

i kinda doubt you put the gasket on wrong and it lasted 2-3 years?

my guess would be that your not using antifreeze? just a guess. then you can develop a build up of corrosion over time where 2 disimilar metals meet. is your intake aluminum? little by little over time that passage starts closing up and becomes a blockage. if you've been using straight water for a long time, your radiator is probably half plugged up too.

who knows, there could have been something stuck in your block?

i've seen where guys have left rags in ports while cleaning the heads during an intake swap, and forgot to remove them. duhho!

let us know what you find out.

Napster134

Ya, the plan is to stick a few more holes into each side just to make sure I have enough flow. I'm then going to put everything back together in the morning and start it up to make sure I'm not overheating anymore.

When I was looking inside, the block off plates looked way to perfect for it to simply be corrosion. If it was corrosion I would think they would not have looked so neatly installed and wouldn't have poked through like a tough soda can. I could feel the metal where I poked the holes through and its like the sharp metal you get when you make a hole in a soda can just thicker/stronger metal.

Actually, I am using antifreeze, I started using the antifreeze about a year or so ago when I put on the new radiator. Before the new radiator I was only using water. Both intake and heads are aluminum.

If the overheating goes away then I'm going to take the intake off when I have more time. Going to college and working full time and sacrificing room in for my fbird because I can't stand it not being okay even though I don't drive it on a daily basis and it bugs me especially when I don't know what's wrong with it lol

Napster134

Problem resolved!

No more overheating after putting everything back together.
I noticed after I put it back together I took off the radiator cap and reved the engine a bit... while reving I could see the water circulating like a hurricane inside the radiator which is something I've never seen for years and after all the cooling upgrades I've ever done.

I believe its safe to say, not only is the problem fixed but my cooling system is working as it should unlike what seemed to be a half ways working cooling system.

The CTS temps will not go past 160-180ish which is not usual... before I would be around the 190-200's just cruising around town.

Anyhow, thanks for everyone that helped me with the problem! the wire idea was what brought me to figuring out that the front intake to head ports were blocked off.

When I get out of school I'll probably take off the entire intake and remove the block offs completely so it doesn't look like a torn apart soda can between the heads/intake ports.