Nissan overheating mystery

Looks like IAT is high
 
Idling with the AC on it got up to 213 with the gauge needle in this position.
I don't know if the gauge is wrong or if this temp is actually getting close to the danger zone



ai130.photobucket.com_albums_p275_nissan11_Mobile_20Uploads_IMG_4519.jpg
 
I just pulled out my new thermostat to test it. The guy at advance told me it was a 170 but today I noticed it has 180 stamped on the bottom. The factory stat is a 170. Can this new stat cause my truck to be running 10 degrees hot?
 
In your first post you said it would get hot on the highway but at idle it would cool back down. So it now gets hot either idling or on the highway?
 
The condenser is clean.


Now it DOES get hot idling AND on the highway, but it's worse when the motor is under load. Going up a hill on the highway the temp will go from 197-204. It stays at about that range until I idle with the AC at a higher setting or start driving up inclines.
I can drive with the truck not overheating if I don't use the AC. With the AC it runs hot. It got up to 222 idling in my driveway with the AC full blast today and that was as hot as I've seen it get.
 
air from leaking head gasket ?
 
I seems to me you are not getting rid of the heat fast enough that the engine is building. Maybe time for a new radiator. I Know you said you've replaced it once already but you might try a bigger or custom one. I know they're $$$ but so is an engine that melted.

Actually after re reading most of the thread. It's got to be the fan clutch. You said it spins freely when hot. It should not do this. When hot, the fan clutch is supposed to lock up and flow more air through the radiator. Also after looking at the pic, you might get a new blade too. That one looks like it's missing some bits here and there.
 
rattlecanpaint said:
I seems to me you are not getting rid of the heat fast enough that the engine is building. Maybe time for a new radiator. I Know you said you've replaced it once already but you might try a bigger or custom one. I know they're $$$ but so is an engine that melted.

Actually after re reading most of the thread. It's got to be the fan clutch. You said it spins freely when hot. It should not do this. When hot, the fan clutch is supposed to lock up and flow more air through the radiator. Also after looking at the pic, you might get a new blade too. That one looks like it's missing some bits here and there.
Click to expand...


I will replace the fan clutch next, but I just dont see why the truck woud run hot on the highway if it was a bad fan clutch. The truck gets plenty of air at 70 mph, right?

The radiator was cleaned and the shop said it was flowing like a new one. They said they guarantee the radiator isnt the problem.
 
Then about all that's left is head gaskets.
 
You can have a bad head gasket/cracked head and not get coolent in oil or oil in coolent. You could be just getting combustion gasses into the coolent. If you have access to a coolent pressure tester i would try that..
 
Or see if you can find a shop with a head gasket tester for the coolant. Uses a chemical reaction with a sample of your coolant and says whether or not there are excessive hydrocarbons in the coolant.


Sent from Your Mom using Tapatalk.
 
Today I finally got around to taking the truck to a dealership. They said everything check out fine except for the fan clutch which they claim is stuck in one position. They say its spinning but wont spin fast enough to pull adequate air when driving around with the AC on.
This doesnt sound right to me because I thought the fan was supposed to spin at one speed (the speed of the crank pulley) and then when it gets hot it is supposed to disengage and spin freely so that when Im on the highway the air hitting the truck at 65 mph will pass through unobstructed?

If the fan is stuck on, then how is it supposed to spin any faster at idle with the AC blasting?
 
If it's stuck in one position it's broken no matter which position it's in. It may be only slightly freewheeling when it's suppose to be completely locked up or completely unlocked. Suck it up and put a fan clutch on there so you know it's good. At this point the diagnosis is out the window because you've tried too many things.
 
Update. I replaced the fan clutch a few weeks ago but had no overheating problems over the winter with the cool temps. This weekend I went camping in the mountains and as I was climbing the hills, even at low rpm, after about 1 minute of ascent the temp needle started climbing above normal operating position, so the fan clutch was not the problem after all.

So, here is the list of what I've done:

Problem diagnosed by DEALER as fan clutch
Fan clutch replaced
Radiator flushed / flow tested
Both coolant temp sensors
Thermostat replaced twice
Water pump replaced
Fan shrouds replaced
Radiator cap replaced



A new, possibly related clue has surfaced recently.
While on the mountain trip, when I had to climb a steeper hill at 3k rpm or more for 15 seconds or longer the check engine light popped on and started flashing until the rpms dropped. I checked the code after the trip and got a p0302 cylinder 2 misfire. Is it possible coolant is getting into the cylinder which could explain both problems?
When the CEL is flashing the truck does not run any different or rougher than normal.
Also, keep in mind the dealer checked the coolant for hydrocarbons and said the head gasket/head was not the problem.
 
I just read this entire thread for the first time. My first thought early on in the thread was that the lower radiator hose was sucking closed because you mentioned it got hot on the highway or when at raised rpm, but not sitting still idling. That is why there is a metal spring inside all lower radiator hoses. Later on you said it gets hot idling with the A/C on, so that doesn't sound like the lower radiator hose. Sorry, but I've got nothing else.

I know of a very good and honest mechanic who works for himself in a shop behind his house in Colfax south of I-40. The guy has helped me out with some problems in the past. A few of the times, I just stopped in and he told me what to try myself. I'll pm you his name and number.
 
Nissan11 said:
Update. I replaced the fan clutch a few weeks ago but had no overheating problems over the winter with the cool temps. This weekend I went camping in the mountains and as I was climbing the hills, even at low rpm, after about 1 minute of ascent the temp needle started climbing above normal operating position, so the fan clutch was not the problem after all.

So, here is the list of what I've done:

Problem diagnosed by DEALER as fan clutch
Fan clutch replaced
Radiator flushed / flow tested
Both coolant temp sensors
Thermostat replaced twice
Water pump replaced
Fan shrouds replaced
Radiator cap replaced



A new, possibly related clue has surfaced recently.
While on the mountain trip, when I had to climb a steeper hill at 3k rpm or more for 15 seconds or longer the check engine light popped on and started flashing until the rpms dropped. I checked the code after the trip and got a p0302 cylinder 2 misfire. Is it possible coolant is getting into the cylinder which could explain both problems?
When the CEL is flashing the truck does not run any different or rougher than normal.
Also, keep in mind the dealer checked the coolant for hydrocarbons and said the head gasket/head was not the problem.
Click to expand...
Yes it is. Stop by a shop and have the use a combustion leak detector. It goes on the top of the raditor and checks for exhaust gas in the coolant. It is a fluid that turns from purple to green if dectected....
 
Thanks for the replies. A nissan dealership has already tested the coolant for exhaust particles and said it was clean. Im going to pull plug #2 and have a look. If I dont see anything wrong I am going to give drkelly's mechanic a call. I am about at the end of what I can do with this problem.
 
Combustion gas to coolant test isn't perfect.
Ive seen hg lose coolant into cylinders and not show up on a test.

Have you verified the water pump ?
 
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