The Cooling System Issues Continue...

[Connor280ZX]

Here's the update: Did one more flush, this time from the rear heater line with the engine running. Result was OK, got some brown crap out and a bit of sand, but i would have liked to see more come out. Installed new plugs one heat range cooler (BPR-7ES). And i advanced timing all of the way forward (Maybe 10 - 15 TDC, still looking into making a new timing mark) Forgot to mention i'm using a 240Z points dizzy. Installed a new 160F thermostat.

 

Took it for a spin and the gauge stayed at around 140 for a bit, but once i started going it instantly went up to 175-185 Deg. Fustrated, i drove home, shut the car off and just stared at it for a few minutes. Then i wondered "Well, what if my gauge isnt working right after all?" I popped the rad cap, turned the engine on and the gauge read 175-180ish. Stuck a thermometer in the radiator and got 140-145 degrees... Could this whole thing be because my gauge is off? Did i check the coolant temperature properly?

[Tony D]

How are you coming up with these numbers? 140/150...180/190... 200-220?

Do NOT use the dashboard gauge.

This was one of the first posts in response to you originally. (Post #6 in the thread, to be exact!)

 

NEVER use the dash gauge as a reference. They are NOTORIOUSLY inaccurate! First step of ANY troubleshooting is the VERIFY your readings independently.

 

Skip the basics, go on wild goose chases with no end in site.

 

What you just did now, was what you should have done before crawling down your self-imposed rabbit hole!

Edited August 22, 2014 by Tony D

[Connor280ZX]

NEVER use the dash gauge as a reference. They are NOTORIOUSLY inaccurate! First step of ANY troubleshooting is the VERIFY your readings independently.

 

Skip the basics, go on wild goose chases with no end in site.

 

What you just did now, was what you should have done before crawling down your self-imposed rabbit hole!

Lol alright Tony, i'll admit it. It was dumb of me to not check the coolant temp with a different method at first. BUT, that was the correct way of taking the coolant temp, correct? I doubt the temp would drop 30-40 degrees before entering the radiator again.

 

Personally, i don't like the idea of installing a new temp monitoring system yet. Taking the dash apart, routing wires, machining a new hole in the thermostat housing for the sending unit etc. I Just want to drive the car knowing that nothing will blow up on me. I'll replace the original 43 year old temp sender to see if that helps. If not, whatever. As long as my engine continues running at 140-150 i'm satisfied.

[Tony D]

You still haven't detailed how the specific numbers were arrived at.

 

You are sayng your needle didn't budge frol the far left of the stock gauge...

 

And then suddenly went to the rightmost leg of the "M" in "TEMP"?

 

Dead center is NOT "operating temp" and the list goes on...

 

Spanning to 120C on the gauge gives odd readings most people don't expect.

 

The gauge is proportional, the key is to know what the temperature ACTUALLY is in relationship to gauge sweep.

 

They ALWAYS read HIGH (safe) - that is not a problem as long as you know how much. With simple parallel resistors in the circuit (or a single half watt trim pot) you can dial the needle position to right where it needs to be.

 

I wouldn't waste a cent until you TEST ....

 

You seem big on replacing things blindly in a shotgun methodology before verifying what is actually going on.

 

Take the time to TEST things so you know what is REALLY going on...

 

Or, like so many others we will see another "I changed the XXX XXX and XXX sensors, and it still does the same thing!" Post.

[Tony D]

140-150 is too cold, even for me.

 

160-170 is hot enough to off gas contaminants. 140 is sludge factory territory, BTW.

[Connor280ZX]

After the coolant flush and t-stat replacement, i started the car up, left it idling for 10 min and temp rose to about 140ish on the gauge if i were to guess. Literally a few seconds after i started to drive the car, the gauge needle moved very quickly to the middle mark (Maybe within 20 seconds). I tested the coolant with the thermometer with the engine running at idle after a 3-5 minute drive around the block.

 

No, i don't consider the middle mark to be operating temp. I base the operating temp on what the t-stat is rated at, in my case 160F.

 

Yes, i do have a habit of just buying a bunch of parts more so than i test the current parts i may have. 

 

Well, i personally would wrather have my engine running a bit cool than a bit hot. If sluge build up is a price to pay, then so be it, and bring on the SeaFoam...

 

I'll look into adjusting/re-calibrating the gauge once i read up on removing the dash.

[Tony D]

Sludge is not good. You should probably rethink that philosophy.

 

The L-Series (injected) will likely not get to 160 at idle. Mine doesn't either. It has to be moving and under load...

 

The serviceable limit is about 160.... That will mean proper FI function, and most importantly have the oil at minimum proper temperature for proper lubrication and of gassing of contaminants.

 

Seafoam does not help fight acid etched bearings from low operating temperatures. This is why taxis and police cars that idle a lot have more wear on their internals.

 

There is a minimum operating temp, and it's warmer than 140/150! The lowest thermostat the factory supplied in tropical climates was 72C. That would control at max flow to 82C tops (180F). That gives everything you need in the engine. Below that, life will be shortened through various mechanisms.