[91NissanTruckOwner]

Hi all,

I have been here before and you guys were very helpful with my last problems, well now I have them fixed and now I have 2 minor issues, not a big deal, but I just wonder if it's worth worrying about and what would cause it?

Okay first problem seems to be that my engine temp gauge NEVER stays at halfway anytime I'm moving. If I'm sitting still, it will creep up to halfway and sit there no problem. I suppose "underheating" is better than overheating but I wonder if this is normal? I have a feeling this has something to do with my idle issues as well. I have changed the thermostat and it's the exact same issue before I changed the thermostat. On the really cold days where I never sit at any lights the gauge will just barely be above the "C" and the heat will be lukewarm until I sit at a light or something.

Okay second minor issue, my idle is also a little high anytime I'm moving a lot and then sit at a light (usually around 1000-1100rpm.) I suppose it's the engine is just trying to warm itself back up and if I sit long enough it will idle normal (isn't about 750-800 rpm normal?)

Also, after I've been on the interstate for a while going anywhere between 60-70mph after having the engine at 2500rpm-3000rpm for a while not only does my temp gauge stay unusually low but also once I'm done on the interstate the next few lights I'm at the engine will idle at 1500rpm for a while and it makes shifting feel strange because the engine also slows down a lot slower than usual (if that makes any sense,) and if I'm trying to go slow during this time it's not easy with the engine trying to push 1500rpm constantly I have to mess with the clutch a bit. So far it seems to fix itself but I'm afraid it's gonna start getting stuck eventually.

Otherwise the engine runs very well considering the nearly 270000 miles I have put on it!

Thanks in advance, also sorry if this has been asked before I suck at using the search function.

 

[srh007]

I am having the same idle problem. I also just did an emissions test and failed on my hydrocarbons at 40km/h. At idle they were fine. Everything else was almost perfect. Any ideas? I just changed plugs, plug wires tested fine, put in some seafoam, and did an oil change. Nothing seems to help.

 

[timritter]

I had the same problem on my 93. I tried replacing the AIC, but no luck. I drove it for 6 years with the AIC disconnected until one day I decided to clean the MAF sensor and I found out the throttle position sensor was not adjusted properly. After adjusting it, the truck warms up at around 1100 RPM and then settles down to 750. 2wd, 5-speed, KA24E.
Hope this helps!!

 

[zanegrey]

if it is under heating replace the cooling fan clutch..

this will prollie take care of the other symptoms...

 

[91NissanTruckOwner]

Hi,

I actually have already replaced the fan clutch because it was leaking and would never actually blow on the radiator properly causing overheating at long idles. The new one is working just fine and I know for a fact that it's not stuck on because it rarely ever "whirrs" unless I idle for long enough when I rev it up it whirrs for maybe 3 seconds then stops whirring which I assume is normal. Otherwise I rarely ever actually hear the fan kick in which I assume once again is due to this "overcooling" issue.

When I'm idling the temp will creep up to halfway and stay there and my idle will be 750-800 once the temp goes upl which I also assume is normal. It's only when I move faster than 30mph that the temp goes down and the colder the weather outside the worse it is.

The thermostat is a stant thermo designed for 170 degrees is that a good thermostat or what?

Also, is this "overcooling" bad for the engine any? How urgently should a problem like this be fixed? I assume it's certainly not near as critical as overheating but how is it for the engine in the long run?

I can deal with lukewarm heat if it won't damage my engine.

 

[zanegrey]

if the fan clutch whirs at all it is not right.

overcooling sends the wrong signal to the ecm resulting in the wrong fuel mixture..\

if it is overcolloing it is the fan clutch..

 

[91NissanTruckOwner]

No, no I am 99% positive the fan clutch is operating normally. I don't know what you think I mean by "whir" but I'm saying the fan clutch just takes a very short amount of time, 3 seconds at the most, to stop spinning the fan so fast, which is completely normal in my opinion. Just like when you first start your car, the fan is running full blast for a short period but then slows down because the radiator temp is too cold to need full blast. Well the same thing happens when I idle long enough for the engine to reach operating temperature. The fan clutch engages the fan to blow across the radiator at about 750-800 RPM (same speed as the engine idle), then once the engine is revved up and the fan is blowing too fast, the clutch disengages the fan, but this process is not instantaneous.

Correct me if I am wrong though. I don't want to sound smug or anything, it's hard to express yourself without sounding like an ass in text over the Internet, I greatly appreciate your suggestions though.

I'm beginning to think that this new Stant thermostat is stuck open. I'm gonna replace it but can any of you guys suggest a good thermostat brand that hopefully won't fail on me like this one? Any particular store I should go to other than Auto Zone or Advance Auto Parts for this? I've heard some suggestions for NAPA people say they've gone through Stant after Stant that would get stuck open, then they finally got a thermo at NAPA which fixed their issue.

Also, what's a better temp rating for the 'stat? 170 or 180? I'm talking year-around too.

Thanks

 

[91NissanTruckOwner]

Hope I'm not breaking any rules by posting again, but I couldn't find the edit button for my previous post.

Anyway I purchased an OE-type (180 degree) thermostat from NAPA auto parts. I will be installing this new thermostat tomorrow and I hope it cures my problems!

 

[zanegrey]

start by check all vacumn ..

start at aiv and work back toward engine..

plug and unplug egr to see if it makes a difference..