tedo007

iTrader: (6)

I have changed radiator and I changed the thermostat. I don't know what is going on. I have searched the ORG can't find a soultion. Help me out.

If I cruise 60mph it stays a normal temp. Soon as I pass 65mph mark, temp needle start going up and if I slow down it comes back to normal.

tedo007

iTrader: (6)

If it makes easier I took it to dealer and they couldn't even find a solution. Need serious help please.

asma123

iTrader: (2)

Is your coolant level staying the same? maybe a hose is clogged weird problem. could be your cluster though.

Mr. Brett

iTrader: (7)

I feel bad seeing this thread go untouched, but it is an odd problem. Maybe he's right, though. Is it possible that a guage is on its way out? The oil pressure guage on my Z sits at 120 PSI all the time because something in the circuitry is effed.

How about trying this: If you can borrow a laser thermometer and a friend's Maxima, drive it for 20-25 minutes and measure the under-hood temperature. Then drive yours for 20-25 and see if there's a big difference between the two. Just a thought.

Honestly, I would have a full coolant flush done. By flush, I mean actually run some semi-pressurized water through the system to see if there's a clog or scaling anywhere.

I would think at highway speeds, your engine would actually be cooler because there's so much air moving over the engine.

jrflores

iTrader: (3)

Ive had way too many cooling issues, and yes usually your engine cools better at higher speeds.

a random thought, maybe at certain rpms or higher rpms you have a voltage or current spike that could cause a faulty reading...idk if that even possible though.

If you were local i would let you borrow my infrared temp gun. I think this would be a good way to check if your actually overheating.

Gemner

iTrader: (4)

weird problem since as long as your coolant is flowing (which it is since the engine isnt overheating) then you dont even need fans to cool it at those speeds. Try downshifting to the equivalent RPM (at 65 MPH youre maybe doing 1800RPM in 6?) try driving in 5th at the same or higher RPM and see if you get the same problem. It would seem that your problem has to either be in the cluster or within the coolant pump/tubing

Amave

ya i agree it is a strange problem.


i'd say get it up to 65 mph and hold it there for a few seconds until the needle get close to red, then pull over as soon as you can and pop the hood and see if the overflow is boiling over. If it is indeed overheating , you'll see the coolant overflow smoke and watnot.


If no obvious overheating issue is there i'd say the gauge is messed up or the coolant temp sensor to gauge is bad

sontakke

If you can buy or borrow a decent scanner with live data monitoring capability (about $150), you can watch the coolant temperature and see if that is going up

rroderiques77

iTrader: (45)

It may have an air pocket, thus preventing proper coolant flow.
Did you try leaving the bleeder screw open all night? Then bleeding the system the following morning?

pionkej

iTrader: (4)

The air pockets is a very valid suggestion.

This may be a longshot, but do you have your front splash shield installed? At high speeds, the fan is not cooling your car, airflow is, BUT air also takes the path of least resistance. This means if the splash shield is gone (allowing the air to flow through the fascia then under the car instead of forcing the air through the radiator), that could make your problem worse.

A way to see if something electrical is going wrong is: once the engine starts to overheat, turn the heat on as hot and as high as it can go. If your needle starts dropping back down, then your electrical system is fine and you have something else going on.

tedo007

iTrader: (6)

I got my radiator flushed twice already after this happen. may be i have a crack head or something. how can you tell if you have a crack head?

by the way its my other maxima and its an auto.

pionkej

iTrader: (4)

You can usually tell if there is a crack in the head if you car burns coolant (it burns white and smells sweet usually) or if there if oil in your coolant or coolant in your oil. You didn't mention you coolant being low, that would occur if you had a leak that bad. It would likely overheat once your radiator was nearly empty, so I doubt that is your issue if your radiator stays full.

foodmanry

iTrader: (15)

To check for head gasket problem let the car sit overnight and pull the dipstick. If there is coolant in the oil you'll see murky, whitish sludge on the dipstick. Also, pull the cap on the coolant reservoir to check for any oil pooling on the top. If both are clear then no head gasket issues.

Since you are letting it sit overnight, open the bleeder screw and allow the air to bubble out. I would recommend you follow the FSM procedure on bleeding air from the system.

Warm up engine to normal operating temperature without
radiator cap installed.
I If coolant overflows radiator filler hole, install filler cap.
6. Run engine at 2,500 rpm for 10 seconds and return to idle
speed with radiator cap installed.
I Repeat two or three times.
Watch coolant temperature gauge so as not to overheat the
engine.
7. Stop engine and cool it down.
I Cool down using a fan to reduce the time.
I If necessary, refill radiator up to filler neck with coolant.
8. Refill reservoir tank to MAX level line with coolant.
9. Repeat steps 5 through 8 two or more times with radiator cap
installed until coolant level no longer drops.
10. Check cooling system for leaks with engine running.
11. Warm up engine, and check for sound of coolant flow while
running engine from idle up to 3,000 rpm with heater temperature
controller set at several positions between COOL and
WARM.
I Sound may be noticeable at heater water ****.
12. If sound is heard, bleed air from cooling system by repeating
steps 5 through 8 until coolant level no longer drops
I Clean excess coolant from engine.

foodmanry

iTrader: (15)

If that doesn't help then try driving the car at high speed where it starts to overheat and turn on the heater full blast as recommended earlier. This will definitely rule in or out an electrical problem with the temp sender or the gauge.

Montego Murph

iTrader: (1)

Nobody's mentioned this yet... Is there something blocking the radiator fins where the wind should cool it? Does the fan spin freely?

Chris Gregg

iTrader: (59)

This makes the most sense as opposed to just throwing parts and labor into this any further. If the OBDII can read engine temp plugged in and while driving, then just do that. I'd hate to think you'd have to take it back to the dealer to do this though.

Being unfamiliar with how the 5th/5.5th gen gets the signals, are there two temp sensors like on the 3rd gens? 3rds have one for the ecu and another for the guage cluster. Or, on the 5/5.5 gens is there only one sensor which sends the signal to the ecu then up to the guages? Just wondering what is the communication path for the guage?

foodmanry

iTrader: (15)

Block over the front of the radiator may make sense, but not the fans. Even with the fans off, at those speeds the car should keep plenty cool.

foodmanry

iTrader: (15)

Actually...the turning on the heater at full blast once the car starts showing overheating the easiest, quickest check.

6SPD02SE

iTrader: (2)

I had this problem on my old Mustang and the head gasket was leaking. There was no oil in the coolant and no coolant in the oil. The head gasket was leaking combustion into the cooling system, thus making it overheat while driving. The higher the rpms the more combustion will leak into your cooling system, which may be why it only overheats at highway speed (sustained higher rpm). Not saying this is def your problem, but a possible cause.

Chris Gregg

iTrader: (59)

Not necessarily....not sure what this would "check" for. I'm not sure that turning the heater on when an engine is overheating is as useful a diagnostic tool in actually tracking down the problem. It is more a method to help ensure the car makes it home without blowing its top. That is of course assuming you have enough coolant to run through your heater.

Actually, if you are leaking/low on coolant and turn on your heat (opens the coolant valve to allow the flow of coolant through the heater core......which is otherwise closed), then you could further rob your engine of what little coolant is circulating and actually CAUSE the engine to further overheat. Also, if the water pump is going out, then also running the heater will further strain the pump and will likely contribute to further overheating.

Check the sensors as indicated above, use OBDII. If everything looks like you are getting a correct reading...change the water pump.

If this is not a sensor issue....then I'm calling a bad WATER PUMP. I've seen where a pump looses blades and so at a certain rpm, it fails to move enough coolant to cool the system. Slow the engine rpm's back down, and the damaged pump will appear to work again, flowing just enough to keep the engine from overheating.

foodmanry

iTrader: (15)

True, but you missed the part where he has checked the coolant levels and no issues...actually flushed the system a couple times and level are good.

So...the turning on the heat would determine if it is a temp sender/gauge problem or a problem with the cooling system itself. This would narrow the issue down significantly.

artemz28

i had this b4 too, on my old 03 max. it was a leaky head gasket, good thing i found this out within a week, car was a lemon, sold it back

jrflores

iTrader: (3)

I'm currently overhauling a vq30 engine and the water pump looked like it had steel impellers...kinda surprise they can go out.

RR5

iTrader: (6)

Won't you see bubbles if you remove the radiator cap and rev the engine to 3,000 RPM? Or does that exhaust in the coolant problem only appear when the cooling system is pressurized and the engine is under load?

6SPD02SE

iTrader: (2)

You may see bubbles. I would have a compression test done

Darkrock

2 If the thermostat is functioning properly, the temp gauge should rise to normal quick and stay there. If it doesnt rise to normal quickly or over heats the thermostat should be removed or checked or replaced.
3 If the engine takes a long time to warm up the stat is stuck open, whack it.
4 If the engine runs hot, check the upper hose. I f the hose isnt hot the stat is stuck shut, whack it.
5 The short cut here is Pull the stat and run it without it if it fails to heat up or overheat, whack the stat.

Chris Gregg

iTrader: (59)

Any updates?

Feldman

iTrader: (1)

I didnt really read everything above thoroughly but there is another thermostat like valve on the drivers side of the engine block called the flow control valve i think. It opens up as a certain temp and allows coolant to flow to the lower end of the block or the head i cant remember which one but you can find it in the FSM under engine cooling.

I would think you have some air in the system but this may be something else to check out

Nelsito65

^^ "Water Control Valve", and, yes, it allows coolant flow to the cylinder blocks. It's a strange issue he's having and it could be that this valve plays a role if it's malfunctioning and the blocks are not properly cooled. I actually purchased one a week ago for some overheating problems I was having, but in my case it turned out to be a dead fan assembly.

P. Samson

To clarify.......the thread originator's car is a Gen. 5.5 which does not have the coolant control valve like a Gen. 5. The bleeder screw was also deleted on the Gen. 5.5 cars. As he's changed the rad already and once he confirms that the "overheating" indicated on the temp guage is genuine, then this does look like an insufficient coolant flow issue. Checking the thermostat for being fully open at 203 deg. (it should start to open at about 180) should be done as well, but after that it does appear to possibly be a pump issue whereby the impellor blades are badly corroded. Someone on this forum not all that long ago went through this same deal and it turned out that the pump impellor blades had been reduced to rusted stumps.

Nelsito65

Thanks for the clarification, I didn't realize that.
That "someone" you refer to could be me, although my overheating issues were not related to just cruising at some higher speed.

Not meaning to scare the OP, but here are some pictures of my old water pump next to the new one:

CMax03

iTrader: (3)

pressurize the system and look for any leaks or if no external leaks are found then maybe you've got a cracked head....I doubt it! How does it run at idle if it sat in one spot idling for 30 minutes or so? Sounds almost like a collapsing hose...to me....

Chris Gregg

iTrader: (59)

As I suggested, the pump.....and it seems it keeps leaning that way.

Great pictures BTW! Pics are worth 1k words! I've seen pumps go out like that several times, I've had it similar happen twice on me through the many Maxima's I've owned. But, that sir, is about the ugliest pump I've seen! I wish I still had the image of the pump I pulled out of the allegedly 30k mile VG30ET engine I bought for my turbo project!

Where is the update Tedo?

jrflores

iTrader: (3)

wow! thats some terrible corrosion. did you run the right coolant? how many miles on your car? I pulled my water pump out after 190K and it look as good as your new one.

CMax03

iTrader: (3)

Riddle Me this?????? What is preventative maintenance, an annual/bi-annual coolant change, distilled water or Water pump lubricate?????

jrflores

iTrader: (3)

, here you go pal.

"Most of the antifreeze products on the market currently are ethylene glycol base material with additives to prevent corrosion, lubricate seals and water pumps and aid in heat transfer to the coolant from the metal of the engine. Antifreeze should be mixed with distilled water (tap water contains high amounts of minerals such as calcium and iron that can precipitate and coat internal parts) at the ratio of one part antifreeze to one part water. This gives freeze protection down to minus 34 degrees and boil-over protection up to +265 degrees. Never use pure antifreeze in a cooling system without using at least 30 percent water in the mixture. Most antifreeze products sold for the past several years have been the traditional "green" coolant. This type is good for two to three years and up to 30,000 miles. The green antifreeze contains silicates, phosphates and / or borates as corrosion inhibitors to keep the solution alkaline. As long as the solution remains alkaline, corrosion is controlled and the system is protected. Over time, the corrosion inhibitors will be depleted and the corrosion protection is lost. It is for this reason that green antifreeze should be changed every two years or so. Aluminum is especially vulnerable to corrosion and many vehicles have heads, radiators and other aluminum components in the cooling system. If the coolant in an engine cooling system is changed before corrosion inhibitors reach dangerously low levels, corrosion damage is prevented."


I can google more stuff for you if you want, just let me know

Nelsito65

That's how I got the car from the previous owner at 132k miles. I have no idea if the coolant had ever been flushed before that. When I flushed it for the first time, what came out of the radiator looked more like diluted tomato juice than anything else. I'm running Prestone premixed now.

tedo007, update please...

jrflores

iTrader: (3)

Good thing its in good hands now .

OP, any updates?

barrylaud

iTrader: (6)

Sounds to me like air pockets. Anytime you put in a new radiator, or break the system open. This is a common problem.

Anyone have the OE repair procedure for removing air pockets?

RR5

iTrader: (6)

Here's the Lubrication and Cooling fsm PDF download link.

http://www.mediafire.com/file/znmmnk2zvtj/LC.pdf