AudioFunk

I've read all the articles about overheating and I can't figure out why mine does, My lude has always had an overheating problem, when I bought it a year ago It overheated for the first time, I drained the coolant to only see 80% water and 20% anitfreeze with glitter particles in there, no thermostat. A year later when the temp starts getting warmer the temp starts to climb after 15 min of driving always at the same spot everyday pulling in the parking lot at work and backing up my lude at home, goes up a bar then down, if I continue driving eventually it will get to H and fluctuate. I put in a new radiator since my old one had nasty stuff in it and it looked clogged, also leaked from the edges. I bled the system with my big funnel and the next day it got to work fine, backing up in the street when I got home it goes up a bar then back down quickly, I shut her off in uber disappointment. Later that night I decide to drive around to see what would happen, after 10 min coming to a stop the temp starts playing again, goes up a bar, then 2, then 3, it started to go down eventually staying at 1 over normal, then it climbed all the way close to H, turning on the heater made it worse I think. got it home and shut her off, waited like 4 min opened the hood and turned her on, fans came on not soon after and temp stayed at normal, after a good 10 min with the hood open the car didn't even go up a bar, I shut the hood and go inside, then bam up 1 bar then back down, stayed at normal for a good 5 min, then I pop it in drive and press the gas and no kidding I was going like 8 MPH went down 3 houses in like 3-4 sec and it already went up a bar, did a u turn to go back to my driveway and it was already creeping near H by the time I parked in the street that was a total of no less than 20 sec since I popped it in drive, I was like how does coolant get that hot in so little time. I cried, literally. Water pump started to leak and replaced it as well as timing belt, New thermostat, radiator, and cap and all within a 2 month period. burped the air and still overheats, fans come on and come on at right time since I observed the temp and the fans. No white smoke, no loss of coolant, 180 PSI across all 4, checked overflow and it stayed at where I filled it up when I replaced the rad. I have the exhaust manifold heat shield off but I doubt it can cause a car to overheat. I'm gonna flush the block again since I didn't when I replaced the rad, and take out the thermostat till summer ends. Any ideas? I'm in a dead end right now Btw what should the temperature be when I point my infrared thermometer to my top rad hose when at temp?

holmesnmanny

If he was using tap water the minerals in the tap water could have eaten away the fins of the water pump.

SnlpeR

temp sensor?

AudioFunk

I thought that too, but the old water pump started to leak and I had it replaced it 2 months ago.

AudioFunk

I might try a sending unit

98vtec

Do you happen to have access to an infrared temperature meter?

98vtec

There are two coolant sensors. There is one for the ecu and one for the instrument cluster.

There are test procedures that a manual will want you to do (in the event you don't have a scanner to read temps) in order to determine that the sensors are working properly prior to making expensive repairs.

Most temp sensors are negative temperature coefficient sensors which means as the sensor reads hotter temps, the resistance decreases and works on a set scale of resistance which can be found in the factory service manual and most likely by using google.

You can probe the sensor pins with a multimeter to get the resistance value or if you have a scanner with data reading, you can watch the coolant temps and compare it with your instrument cluster dummy gauge.

Standard operating temp is between 195 to 210 degrees F.

Being that the tach meter and the ecu coolant sensor are next to each other, you should see the same fluctuations.

AudioFunk

Yes, I have a cheap one from eBay. It overheated 2 bars shut her off, opened the hood and took the temp of the top hose it was fluctuating it read 210 then 218 then back to like 207 etc. Lower hose about 194 or so

AudioFunk

I noticed the past owners cut the front bumper and put a metal mesh on it and stuck the license plate right in the middle, so I thought to myself maybe it's blocking airflow, so I took it off and took her for a spin, I drove for a very long time and it stayed at normal temp, way longer than before where it would overheat around the same time every time, It still overheated but it lasted wayyy longer now, but it got real hot on the gauge like usual, turned her off and opened the hood and I noticed the radiator fan was still on when the car was off, I haven't seen it so that in a year lol, waited like 3 min turned her on and stayed at normal fans came on etc, close hood get in car and take off and as soon as I pick up speed it overheats, it went up a bar, then went down to normal eventually, decided to go another block and she overheated again and then finds its way to normal again, so I'm gonna put the heat shield back on and bleed my coolant again and see what happens.

holmesnmanny

Three possibilities jump out at me, the gauge is bad, the fans are running backwards, the fans are not going fast enough. I suppose there could be a blockage in the block or water pipe.

snobordboy

Since this is only happening while driving, it seems to be a load issue to me. I would suggest getting the system pressure tested, to see if once it builds more pressure under load, that is the issue.

You said the compression is good, otherwise I would say the head gasket is suspect, although it is still on my mind for sure.

Last issue could be a blockage for sure. If the water pump is good, the water pipe or the heater core/ hoses could have a partial block.

Also ensure when you bleed the system, that the heat is turned on fully, and you are getting good heat through the core when the engine is running.

AudioFunk

I don't get heat at idle, but as soon as I pick up speed the heat starts coming out pretty good.

LostStranger

Do you have this solved?

My 93 has two fans, one that runs for low speeds and a second one that kicks on to provide additional cooling at high speeds. Does yours have this too and if so, have you checked the fan which is for cooling at high speeds ? It is possible that the second fan is bad, so you would only see it over heat at higher speeds. I'm not sure at what speed the second fan would engage, but I would guess 45 to 55

adamthc4thgen

sounds to me like a water pump issue ...that is if you have no leaks..

AudioFunk

In my case, no. I have replaced everything in the cooling system and still have an overheat, today it got hot real fast, after leaving it sitting for 4 days without driving it, it overheated. It only went up 1 bar then back down, coming to a parking lot it went up a bar again, but never went past the first overheat bar, after shutting her off the rad fan came on, let it sit for like 10 min then went back home, overheated 1 bar once again, opened the hood then checked the temp of the hoses, top hose was 210-213, bottom was 185-190, does this seem right? Few sec later rad fan came on, temp dropped to 203 or so, my fans do work, new rad, water pump, and thermostat, I;m gonna check the thermostat tomorrow to make sure it's not sticking, hey maybe it's my temp sender, but idk. I really really don't wanna go through the trouble of replacing my head gasket, last time I checked compression was a solid 175-180 all . I need to re check that again. I might even leave the thermo out for the rest of the summer. I also bled the coolant with my spill free funnel like 3 times

adamthc4thgen

what is your coolant mix ..? too thick maybe ..? could be your temp sensor ... and if it was your head gasket youd smoke white wouldnt you ?

MKCSRet

Even "New" parts can be bad (or wrong). Have you verifies sufficient water flow through the radiator by running the engine ( "When cold" ) by viewing it through the open radiator cap ? It should be fairly static until the thermostat opens up. what was the operating parameters of your thermostat again ? Always troubleshoot using the KISS ( Keep It Simple St_ _ _ _ ) First, "Start From The Start ), then get fancy. If no water flow, suspect the thermostat, then pump , then passages. If Yes you do have water flow, suspect air flow, then coolant mixture. If all that is good, my bet is Head Gasket, as a faulty gasket will leak more during higher cylinder pressures ( under Load) than it will at idle ( No Load ).

holmesnmanny

Sounds normal. Make a video of the temp gauge i would love to see it. It sounds like the sender might just be bad.

AudioFunk

I will if she acts up again, today I went ahead and took out my thermostat, I left the gasket in and put it back together, it opens with my hand, but I haven't put it in hot water yet. When I was bleeding the air small bubbles come out when the heater core is accepting coolant, so small bubbles kept coming up and sometimes big ones, but that was just water entering the radiator if that makes sense cause the water dropped, but after the fans came on the bubbles stopped! The level dropped and I took off the funnel, the water was flowing and no bubbles were coming up! The RPM was about 1k maybe a little above that, before the coolant would overflow the radiator, the RPM's would sit around 1200-1400 when that happened tho.. I also flushed the block with a pressure gun. I know it's bad to leave the thermostat out, but my car still gets to temp cause It's hot here, come fall I'll put in a new thermostat again. The overflowing was being caused by either RPM's too high, the thermostat, blockage or HG leak. Cause if the headgasket was bad wouldn't I see bubbles regardless? I'm scared because even if it didn't overheat at idle maybe the leak happens under load. I'll see what happens over the next couple of days. Here's a lil vid I took. Btw if it overheats again I'm gonna try a new temp sender, if that doesn't fix it then the only thing left is, well you know what. https://www.youtube.com/watch?v=ZbMH...ature=youtu.be

AudioFunk

OEM thermostat rated I believe is around 176 degrees or so, could be wrong. If the head gasket was leaking would it be able to pass smog? Cause I remember it passed when it was overheating, just didn't overheat when The guy was testing it, it did overheat once he got out of the car and I got in.

AudioFunk

Na, overheated still, but it would only OH 1 bar, then back down to normal, stays there for a few sec then back down. I went ahead and purchased a block tester, I'm gonna find out early next week if I need a headgasket or not.

MKCSRet

A faulty head gasket is more prone to leak past under load than at idle under no load, as the firing pressures are higher under load. Yes, that will put air in the system. If you continue to repeatedly have to bleed air from the system, then a faulty H/G would be a viable cause. When was the last time you ran a "Radiator Flush". Could be as simple as internal passages coated with muck.

AudioFunk

I have never used a radiator flush

nemesis25

Try running a new ground from the chassis to the cylinder head, I had a similar issue a while back on my 92 Si which was fixed by running the mentioned ground.

holmesnmanny

There was nothing out of the ordinary in that video. If you run your car without a radiator cap it's completely and totally normal for coolant to spray out. That's kinda the job of the water pump, to pump coolant. If it really does overheat it would be best to actually record a video that shows the car overheating.

If you want, you can compression test your engine to see if the head is warped.