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Daddybender

Another not-enough-heat thread

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Just got this rig.  Check my intro post here:

Been driving her for three weeks now, about 60 miles a day.  30 miles each way, all at highway speeds.

 

Previous owner replaced fan and clutch, thermostat (170), timing belt/wp, and all hoses.  I'm not going through any coolant.  After a 30 minute drive, upper radiator hose is hot and hard, lower hose is cold.  Heater hoses are same temp as upper radiator hose.  Temp gauge has never gone any higher than 1/4 (halfway between bone cold and straight up).  Has been running SUPER rich.  Like, 12mpg rich.  First time I started her, it was inside a garage.  Ran her for probably 15-20 minutes.  Definitely wasn't running rich then.

 

Today I'm changing cap/rotor/plugs.  Wires are in route (local wanted $110, RA was $45.  Yeah.  They can wait.)  Air and fuel filters are new.  I'm getting another thermostat today.  I'll probably swap it out too along with some fresh coolant.

 

Just curious if there's anything else I should be checking regarding the low heat?  Another fan clutch is also in route.  Ordered that before I found d out it was already replaced.

 

TIA

-Bender

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I cant think of anything outside of the thermostat. Even if the fan clutch was always fully engaged the operating temp should still be normal.

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Only thing that even points me in the direction of the clutch is I can hear it engaging and disengaging while she's warming up in the morning.  And it's in the 30'sF at that time.  IF the clutch is functioning correctly, other than the initial engaging, shouldn't it stay disengaged until it gets overheated?  Or even just REALLY warm?

 

-Bender

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It’s a fluid coupler that slips less and less as it heats up. I think the service manual tells you the slip rate, or I might be confusing something I saw on google from a while ago when I was having overheating issues.

 

Anyway you can sort of test it’s health by getting a feel for the difference in resistance to turning the blades by hand when the engine is cold and warmed up. Kind of a subjective test but a diagnosis for a seized clutch is easier to determine than decreasing efficiency. And a seized clutch will roar like a tractor trailer even after the engine is warmed up.

 

 

Sent from my iPhone using Tapatalk Pro

 

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The clutch fan doesn't really cycle. If you have the push-button HVAC, you may be hearing the aircon compressor cycling (the aircon kicks on in defrost mode to act as a dehumidifier).

 

If the engine is staying cold, the EFI may not be going into closed loop, which would explain the lousy mileage. Thermostat's my first guess too. My temp gauge seldom goes past half way but certainly more than 1/4.

 

When you swap the coolant, make sure to bleed it. There's a bolt on the upper intake plenum (towards the back, on top, marked "do not open when hot"). Fill the system from the rad, put the cap back on, take that bolt out, and squeeze the upper rad hose until coolant comes up to the hole. Then, while holding the hose, put the bolt back in and snug it up. Then take the cap back off and top up as needed.

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@SlartibartfastThe dehumidifier function makes sense.  Yes, I do have the push button HVAC (the AUTO function even works!!!).  Would it be a slow on/off cycle?  Pretty sure mine is a slow cycle, but I'll pay more attention to it next time.

Also the closed loop sounds right to me.  Before I started working on it today, I fired it up and backed it up a few feet.  Left it running and jumped out to smell the exhaust.  Smelled perfect, which it would in a "cold-start mode", I would think.

Friday when I got home, I didn't even need to get close to the tailpipe and my eyes were burning.

So, when cold, mixture is good.  When warm, WAY rich.

Failed/ing O2 sensor?

The thermostat that the PO put in...I've never seen one where the valve (the flat part that moves) had a rubber coating on it.  I figure if anything,  that would make it stick closed (it was closed when I pulled it out)...but wouldn't a stuck closed thermostat lead to an overheating condition?  The one I installed did not have any rubberized coating.

 

THANK you for the bleeding g procedure!!!  Just went and put my eyes on it.  The coolant that came out sure wasn't a nice clear green.  It was actually kind-of...dirty?  Almost like it was some of that reclaimed stuff you can get at wrecking yards.  Come to think of it...the thermostat had this dark, almost sooty coating on it.  Wiped off easy and not oil-based...

 

As for the spark plugs.  Last person who did it only changed the easy, passenger plugs.  Those three were nice and golden white.  Driver's three...2 & 6 were darker than the passenger side, but serviceable.  #4 was definitely running rich.  Posts inside the cap were pretty carbon-arced,  and the rotor actually had a burnt look to it.

 

Got the thermostat in, new plugs in, new cap and rotor in.  Tomorrow I'll button everything up (found some loose lower radiator hose clamps), clean the MAF, and replace the air filter (I have one, sooo).  Looks like a new radiator was installed too.  No debris in the fins.

 

If I still don't get up to OT, would there be  any harm in running without a fan but leaving the clutch on?

 

Sorry th for the long-winded post.

-Bender

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Come to thinking of it deeper....if it's running as rich as it is, shouldn't the plugs be...black?  How long does it take to foul plugs?

 

-Bender

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Posted (edited)

It does sound like the thermostat is opening early. Normal temp is usually between 1/3-1/2 on the range. Simple thing that is old guys do in colder climates have been doing for decades with our trucks that run too cold in the winter is to use a piece of cardboard and partially block off the radiator. 

 

Years ago, Nissan had a TSB for the engine coolant temperature sensor in the 93. I know this because mine is one. The original one was yellow and the revised one is blue. This is the 2 wire sensor screwed into the coolant outlet pipe near the top radiator hose. The single wire one next to it is for the gauge. If the sensor is lying and reporting to the ECU that the engine is colder than it really is, it will cold start and run ok, but tend to run rich when at operating temperature. Check and see if you have the blue sensor. The plug is yellow, but if the sensor is yellow too, I would swap the sensor out and see if that helps. 

The 12 mpg thing is my life with mine. Last fill-up, I found I was down to 10 mpg. Understandable due to the less than a mile commute I have for work, the cooler temps, the extended idle, and playing in the snow in the mountains here with that last tank. I normally get about 13 with the crappy E10 fuel I get here. Ethanol free and 60 mph on the highway will usually give me about 16 even with my lift, 33x12.50 MT's, and all the crap I carry around. 

Edited by Mr_Reverse

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As much as I hate to say it....if 12-13mpg is the best I get outta her....I may just put her back on CL and get something else.  I got this because I didn't want the MPG of a Ford 4.0 or a GM 4.3, but both of those powerplants get way better than 12-13.

Hell.  My old service truck was a 2012 Ram 3500 with a 6.7 turbodiesel, and IT got 14mpg.

 

This rig is smaller and lighter than a Ranger/Blazer, albeit with a smaller 6, but still.

 

My '88 Samurai with a 1.6 16v gets 15.  She's a 100hp/2500# setup.  25#/hp.

The Pathy is 153hp/3850#...25.16#/hp.  Theoretically,  I should be able to get about the same mpg.

Not arguing, this is just how my mind works.

 

I should also note...when I made my first trip to go look/work on it, the insides of the tailpipe were spotless.  That was telling me it was running close to perfect.  So, this running rich thing is something that has changed since I brought her home.

 

Could there be something up with the Carter fuel pump I put in?  No.  That's the job of the FPR.  I checked that hose and it was connected, but I can't see back there to check for cracks.

I'm gonna pull that hose and just make sure it's not cracked.  I'm also gonna check the ECM for any codes...well, I'll get her put back together and running, THEN check the ECM.  The FSM has instructions to check the O2 sensor AND the mixture sytem.

 

-Bender

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My sammi also runs on the cold side.  I went as far as to fabricate an aluminum plate that bolts on to block the radiator.  With it installed, I get JUST enough heat to keep the windshield 'somewhat' defrosted.

We get alot of snow around here, so cardboard don't last long, but I get what your saying.

 

-Bender

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If the gauge ECT sensor was bad (gauge wasn't working), could the ECM ECT sensor have failed as well?

 

Messed-up coincident if the ECM sensor failed during/after the rig was stolen.

 

The FSM shows me how to test it, so that's on my to-do list for tomorrow. 

 

-Bender

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Has the o2 sensor been touched? If it looks old or original just replace it. Made a big difference on my 95. My temp never goes above 1/3 on the gauge. I run a Nissan T-stat but they do run kinda cool. You can also change to a 180F one if you want.

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Posted (edited)
3 hours ago, adamzan said:

Has the o2 sensor been touched? If it looks old or original just replace it. Made a big difference on my 95. My temp never goes above 1/3 on the gauge. I run a Nissan T-stat but they do run kinda cool. You can also change to a 180F one if you want.

With your gauge not going above 1/3, what kind of heat do you get out of the heater?

In my wife's BMW (1997), I cant take it if it's set above 75 with fan on medium.  In the Pathy, I have the hot/cold on max hot and the fan on max and after 20 minutes on the highway (after a 15 minute warm up), the cabin is finally 'warm'.

Am i expecting too much of the heater in this rig?

 

When you say "a big difference", how do you mean?

 

-Bender

 

If this 170 doesn't make a difference, I may just skip the 180 and go straight to a 192.

Edited by Daddybender

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The temp gauge in my '93 doesn't go to the center, either. The heater's no face-melter, but it's adequate. If the coolant was manky, you may need to flush the heater core. I don't let mine sit and warm up much unless it's single-digits cold out, and it's usually warm by the time I've driven the four highway miles into town. And yes, you can run it without the fan. If you remove the whole fan assembly (blades and clutch), make sure you've got something else holding the pulley to the water pump.

 

#4 being darker than the rest could suggest a leaking injector, which would explain the foul smell and lousy fuel economy. If all you've done doesn't improve how it's running, pull the plugs again and see if #4 still looks richer than the rest, or if it smells like gas.

 

+1 on the oxygen sensor. These use primitive old-school oxygen sensors that pretty much just read "rich" or "lean." When the ECU's in closed loop, it adds fuel if the sensor reads lean, and reduces fuel if it reads rich, bouncing the ratio back and forth across where it should be. The sensor can slow down as it gets old, meaning the mixture strays farther from ideal before correcting. There's a test mode for the ECU (EF&EC section of the manual) that lets you monitor how fast the sensor's switching back and forth. The sensor can also fail entirely and make the computer see a lean condition regardless of what's actually going on, which will make the computer add more and more fuel as it tries to compensate. A fault with the oxygen sensor or the coolant temp sensor would cause an issue across all six cylinders, though, not just the one.

 

I'm happy to hit 16 mpg in mixed driving. I've seen 19 on long flat highway trips. But I have also seen 12-13, especially in the winter. Short trips, locked hubs, screwing around in the snow, that kind of stuff's hard on fuel economy. Add yours running rich and the 15-minute warmups and I'd be surprised if it didn't get lousy fuel economy. Still, at its best, my Pathfinder's mileage is about on par with my dad's V8 Tundra, which is depressing given how much get-up-and-go the Tundra has that the Pathfinder doesn't.

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@Slartibartfast

The clutch is held on with studs that aren't threaded all the way down.  That's why I was asking if I could just run fan-less...until I got some new bolts.  I'll just leave the clutch on it as a spacer for the nuts.  My sammi hasn't had a fan on it since I stuffed the 1.6 in it.  Even in triple digits it's fine, just cant let her sit still for more than a couple minutes.

 

Read you guys on the O2 sensor.  Since the PO installed a brand new clutch, I'm gonna return the one I ordered and get an O2 sensor coming.

 

As for mileage, I'd be totally content with 15.  That's what I'm used to now.  As for power, she's got enough for me right now.  I'm no hot-rodder left-foot anymore.  It took me until I was 35 to learn that lesson, but I learned it.  That's what I got the Bimmer for....and the Sammi.  I just want this to be a comfy ride to and from work, and around town.

 

Swapping in some manual hubs is the NEXT thing on my list.

 

-Bender

 

Oh.  And the ECM ECT sensor is a bluish-green one.

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Welp.  All that work done.  Definitely not AS rich, but still a bit rich.  And that's by my nose, so, nothing scientific by any means.  Still has a little miss, so I'm gonna bet dollars to doughnuts I got at least the one injector leaking.

 

I did the FSM testing for the O2 and mixture, and both checked out 'ok' by the book.  Still gonna replace the O2 sensor.

 

I can without a doubt confirm that my clutch fan is pulling a SIGNIFICANT amount of air through the radiator.  I can also confirm that it is slipping at idle and cold, but only by the noise.  Did the newspaper trick and the fan started shredding the newspaper, so definitely not slipping much.

 

I did the old-timer trick and covered probably 90% of the radiator with cardboard.  I'll either make something out of plastic or...conveyor belt material.  Yeah.  I got LOADS of that at work.  First test drive I had half the radiator covered.  Temp gauge was maybe a needle or two farther towards the center.  After the 20 minute highway drive, I can hold my hand on the upper hose and the heater hoses, so still not what I would consider 'operating' temp.  Lower hose definitely warmer now than it was before.

 

-Bender

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Posted (edited)
19 hours ago, Daddybender said:

With your gauge not going above 1/3, what kind of heat do you get out of the heater?

In my wife's BMW (1997), I cant take it if it's set above 75 with fan on medium.  In the Pathy, I have the hot/cold on max hot and the fan on max and after 20 minutes on the highway (after a 15 minute warm up), the cabin is finally 'warm'.

Am i expecting too much of the heater in this rig?

 

When you say "a big difference", how do you mean?

 

-Bender

 

If this 170 doesn't make a difference, I may just skip the 180 and go straight to a 192.

The only time I don't find the heater adequate is when it dips below -30C around here. When that happens I'd just leave in on recirc and it works well enough. But yeah my Golf has much better heat.

 

The o2 replacement gave me an extra 2-4 mpg depending on my driving style. Either the NTK or OE Style Bosch will work fine. The o2 can cause misfires as well. Had that happen years ago on my old one.

 

I've never seen worse than 15 mpg in mine. Maybe in 100% city driving but that makes sense as idling just pisses gas away.

 

Also the 192F t-stat was not available before when I was doing all the work on mine. That's an aftermarket part, the OEM ones were only ever 170F or 180F. I don't see how the 192F could hurt anything though.

Edited by adamzan

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Sorry, been away for a while. I just run the regular grade fuel in mine. Mostly from Sam's or Costco pumps. The compression is so low that even mid grade raises the emissions slightly. Anything more than regular is a waste in these engines. 20 years ago when I bought mine, I was averaging 19 city and 24 highway. However that was back when it was completely stock rolling on the stock sized 31x10.50 AT's. Also, didn't have ethanol in the fuel either. It did have 128k miles on the clock and 6 years old when I bought it. 

 

Size wise, it is pretty much the same size and weight as an S Blazer or Exploder from the same era. However, mine might have been a special one, but tended to put the power down and definitely worked off pavement better than the GM and Ford compacts that friends had. She seemed to give similar fuel economy too. Now the old XJ that a friend had was lighter and the 4.0 I6 seemed to have plenty of torque. Most of my local friends ran full sized with 35 being the common tire, but after a few runs, they all had great respect for the little Nissan and had no concerns that it would have trouble on the trails. Was also the popular one for the ride home after the trails because it was so comfortable. I miss that old truck, the lifts, bigger tires, age and abuse have reduced the comfort greatly. 

 

I suggest a hotter thermostat, your engine is just running too cold. I haven't had an engine driven fan in mine for at least 14 years. I currently have a pair of 14" electrics running off of a thermostat in mine. I simply took the studs out of the waterpump and replaced them with some bolts to hold the pulley on. Common size, 6mm 1.0 thread. Quick, simple change that frees up a lot of room and a little bit of a reduction in rotating mass/drag on the engine. 

 

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Well, we just got back from a 308 mile trip, and only used 18 gallons.  That comes out to 17mpg.  Granted, it was 99% 60-65. Couple small towns, couple elevation climbs of probably 1000'+.  I'm ok with that.

 

After changing the thermostat and coolant, temp gauge now gets to where the needle just touches the bulb on the thermometer on the temp gauge.  And that's at the top of a good climb having to drop to 4th for the last mile or so.  Wife and I, and a full tank.  We actually had to turn the heat down.  So, while it's not face melting, it is in fact adequate.  I also have to remember I have at least double the volume of air to heat up as my Sammi, and it ain't no Bimmer.

 

Thanks for all the help guys.  I really do appreciate it.  I'm gonna try to create some other posts on here when I get to other to-do's.

 

Hubs.

DeeDeer guard.

Injectors

-Bender

-.

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