Cooling problems on 99' Q45t

[mahmudb]

Hello I am new here. I just acquired a 99' Infiniti Q45t with 128k mi. I have a couple of questions about the car. First I accidentally put in 89 octane and I got the SES light. I filled it with premium and cleared the codes and its running ok. But the problem is that the Temp gauge does not stay in the middle, it fluctuates and the temp increases alot but never overheats. Is this normal? Also does the radio require any code if the battery is diconnected? Thanks for your help!

[maxnix]

Welocme to NICO!

No, fluctuations are not normal, but neither is the gauge accurate.

Get the temperature readings off an OBD II analyzer and report back.

Never had a code problem for the radio.

[mahmudb]

Do you think that the cooling problem is related to me putting in the wrong gas? It really was driving fine before I put the wrong octane in. I'm thinking that if I just drive it a couple of days it will be ok.

It cools ok when I drive it on the highway and sometimes in the city, but when it is heavy city driving it starts to increase. Thanks for the help!

[Skibane]

the Temp gauge does not stay in the middle, it fluctuates and the temp increases alot but never overheats.

Assuming that you aren't low on coolant (or have an air bubble in the coolant system), it sounds like you may be experiencing an airflow problem.

If the temperature only increases while you're moving slow, it probably means that you're not getting enough airflow through the radiator (either due to an obstructed radiator or a worn-out fan clutch). The front of the radiator tends to catch a lot of crap that you can't see or easily clean out, due to the A/C condensor being mounted in front of it - Here's a picture of mine, at only 73K miles:



You really can't clean it without removing it. However, removing it also gives you an opportunity to replace the coolant, fan belts, hoses, and maybe the water pump - all easily done while the radiator's out.

The fan clutch tends to slip more as it ages, resulting in lower fan speed for any given engine speed. Eventually, this makes the engine run hot at low road speeds, due to less air being pulled through the radiator by the fan.

A good fan clutch will make the fan difficult to spin by hand (after the engine is warmed up), and the fan will stop rotating immediately after you spin it. A bad fan clutch makes the fan easy to spin by hand, and the fan will continue to free-wheel for a few revolutions after you spin it.

[Rex]

After you confirm there the coolant's not and there's no "air" in the system, I'd hedeg my bet that your thermostat is starting to stick. Very common to see slightly warm in traffic and normal to cool on the highway with a sticky T-Stat.

If you don't know if it's vere been changed, get some coolant, a tstat, all radiator hoses, belts while you're in there, and do a complete cooling system flush and clean with tstat replacement. There's probably a gasket or RTV, so don't forget that either.

[Q45tech]

Historically Nissan thermostats stick open rather than closed which show up as a long warmup in winter or failure to ever reach operating temperature in cold weather. [They should be replaced every 4 years regardless of mileage].

Overheats are usually radiator induced [blockages inside or out].

Worn out fan clutches, belts, bad sensors or motors for auxillary cooling fans.

PURE AND SIMPLE a lack of adequate maintenance..........Abusive owners!

[Qproject]

once again,

you guys are the bomb!

[Skibane]

If you don't know if it's vere been changed, get some coolant, a tstat, all radiator hoses, belts while you're in there, and do a complete cooling system flush and clean with tstat replacement.

I would only add that after you've got the coolant drained and the hoses removed, it's only 20 minutes more work to pull the radiator and clean the exterior air passages - well worth the little extra effort, IMO.

[mahmudb]

Well it seems as the radiator may have a leak. The orignal owner had just replaced it 6-7 months ago so its still under warantee. I am taking it in to get it checked out. Thanks again for all your help!