2001 I30 overheating at high speeds - cools down upon slowing down

[sciachir]

I just bought this 2001 I30. The problem is, after driving the car on the hghway for a while, it eventually overheats. The strange thing is, once you slow down, the car starts cooling down. You speed up, the temperature gauge creeps back up. What can this be?

We've replaced the heater core, and the same thing happens. We checked the belts, and they are fine. Could it be the water pump? If so, we cannot locate it. Shouldn't it be somewhere where the belts are?

Can someone please post some information (service manual) for the water pump and its' location?

Thanks very much!

[qship96]

Why did you replace the heater core? Maybe you meant the radiator? If you are having trouble even locating the waterpump, it suggests to me that you are not that mechanically minded under the hood, if true then your best bet is to take the car to an Infiniti dealer for proper diagnosis,as overheating a aluminum engine, even momentarily often causes major irreversible damage

[Q45tech]

Only incompetent owners and mechanics can truely destroy a vehicle.

Water pump driven from timing chain is inside engine - any Nissan Technican knows that.

Study Factory Service Manual

[sciachir]

Did I post this to the wrong section of the forum? I didn't claim to be a mechanic. I found this forum yesterday looking for help with an Infinity I30 I bought a couple of days ago. The car overheats when driving at higher speeds (on the interstate) and then would cool down when decelerating. I was asking for opinions on what others thought the problem might be... I'm mistakenly said that the heater core was replaced.. It was the THERMOSTAT.. sorry!

Any thoughts? I appreciate your help!

[fourdrinie]

check the simple things first...is your coolant level full? are your fan belts tight enough? do you have visual blockages in the radiator fins prohibiting the effectiveness of the radiator cooling?

[bullittandy]

Only incompetent owners and mechanics can truely destroy a vehicle.

Water pump driven from timing chain is inside engine - any Nissan Technican knows that.

Study Factory Service Manual

You missed a great chance to educate people about what causes a car to overheat at high speed. What a shame since I'd like to hear the theory behind this occurence.

[sciachir]

check the simple things first...is your coolant level full? are your fan belts tight enough? do you have visual blockages in the radiator fins prohibiting the effectiveness of the radiator cooling?

Yes, Yes and No. Any other suggestions on what this might be? Thanks in advance!

[jimbyjimb]

Am I the only guy that thinks maybe the first thing to do here is make sure the gauge works correctly? Electronic gauges go funky sometimes, man. Get a laser and check the block temp and compare with gauge reading. Your block when warm and idling should be 180-210. Does the gauge raise and drop quickly or slowly? If the temp gauge shows a temp increase quickly, I.E. from normal temp to overheating in less than a minute or two, or is it a gradual heat up?

When the car is cold remove the radiator cap, then start car. If the pump is working you should be able to see coolant moving, a current so to speak. If the radiator is working it should be a minimum of 10 degrees cooler at the bottom of the radiator than the top of the radiator. Its usually a big enough difference to tell by touch. The best way is to grab the upper hose after warm up, it should be very hot. Then grab the lower hose also while at operating temp and running, and it should be cooler than the top hose since the top hose is out of the engine and the bottom hose is into the engine. Do these tests first, then report back if further diagnostics are needed. Always double check electronic gauges.

[qship96]

Take it to a professional IMMEDIATLY before you destroy the engine by overheating.....$100 diagnostic is dirt cheap compared to the THOUSANDS it will cost if you cook the aluminum engine and need a quality transplant fro the junkyard.

[jimbyjimb]

His overheating problem isn't at idle, or at least the gauge isn't reading hot at idle. All of the tests I gave him to perform are done at idle. They are the same things a shop will do first. Always always always confirm the gauge is accurate before chasing demons. But, if you aren't a DIYer, I totally agree about getting to a shop and having it checked out. Aluminum warps real easy.

[Q45tech]

While a used V8 may need $3,000 at purchase, a V6 costs less and a FWD V6 even less to fix the DEFECTS that made it up for sale in the first place.

Never buy a used car out of warranty without paying an expert to document the defects found after spending a few hours testing all systems.

The few hundred you pay will make you walk away 2 out of 3 times on the pretty piece of junk offered for sale.

Used I30 on the whole are some of the best used car products out there, if 66% have problems hopefully you understand how bad the other 7 years old are treated by owners.

Be sure to have a hydrocarbon test [combustion gas leakage] done to coolant to make sure the head gaskets are ok [from a previous overheat].

http://www.reds-headers.com/ht....html

"Overheating is usually from combustion gases leaking into the coolant. If there is coolant in the system, the water pump impellers are turning, and the radiator is not plugged, suspect combustion gas leaks.

In the above example, the reason I suspect combustion gases leaking into the coolant is because the overheating comes with increased load on the engine. This can happen even though the leak is small, and there may not be any water in the oil or visible water vapor in the exhaust. The cylinder pressure goes up with throttle opening. This increased pressure may cause enough hot gases to push into the coolant that the radiator can't get rid of the heat fast enough. Then the temperature goes up and up, unless the load is decreased."

While I have sympathy for the young on buying a used car, 56 year olds having driven for 40 years should know better in not having an expert prebuy analysis!

For about 20 years Nissan has used a fail open thermostat, that if anything causes a slow warm up and cold heat in winter.

[odyyss]

im not sure if it has a clutch fan. that would be what i check first just from how it heats up as you go faster. it sounds like the clutch isnt working

[qship96]

im not sure if it has a clutch fan. that would be what i check first just from how it heats up as you go faster. it sounds like the clutch isnt working

Never seen a front wheel drive v6 with a transverse{sideways} mounted engine use a mechanical fan with clutch....always electrc driven

Check for spongy radiator hoses that may be collapsing under slight vacuum {suction} at high rpms.