coolant still gets to the back of the t-stat by following the oil cooler circuit.

 

Until he put the bypass he had that removed also. I'm assuming that would be one of the first things to be removed if someone is willing to go to the extreme to pull the heater core out in order to remove lines from the engine bay.

 

Well, your bypass brought in cool water, from radiator outlet, correct? I'm going to route mine from the rad inlet, therefore warm coolant will flow to the thermo.

I still don't understand why a full cooling system wouldn't warm up the backside of the thermo? If the coolant isn't flowing due to a closed thermo, isn't the coolant just behind the thermo going to warm up and open the thermo?

And yes, no oil cooler here.

 

^ ah, yeah, without the oil cooler circuit you're gonna have a much harder time getting coolant to the back of the t-stat. thanks for clarifying.
i wrote this (again) because i've seen over and over people on here say that the bypass hose feeds the back of the t-stat, and, without it, you won't get flow to the t-stat. while the bypass feeds the block near the t-stat, the oil cooler circuit plugs directly into the t-stat housing. so for someone with the stock (or near stock) coolant routing, coolant still gets to the back of the t-stat by following the oil cooler circuit. the oil cooler hose plugs into the smaller nipple (see below).

 

Also keep in mind that the HR does not have that nipple on the thermo so coolant only enters through the bypass on the lower driver side of the engine; therefore, the oil cooling route is not necessary for normal cooling cycles. I put an HR thermo on my DE so no nipple for me. Now I am just running through ideas on how to cleanly reintroduce coolant back into the engine while the thermo is closed. I can put the DE thermo back on to use that nipple, or I can drill and tap a hole in the block off plate where the original bypass hose entered. Either way, I am going to have to route a water line over from pass side to drivers side which kinda defeats the purpose of doing all this in the first place, decluttering and simplifying... ugh

 

either of these would work. You could always run the hose down under the block up to the side so you can't see it OR you could weld a nipple onto the radiator like the OP did.

either way, the thermo is closed and no hot coolant will get to the spring unless you have something mounted behind it.

Or wait, i just thought about it. You could drill a hole in the t-stat so some coolant will always flow through. I wouldn't do this route but if you're worried about cluttering your engine bay that might. I would guess it would take forever to bleed it though.

 

Actually, a 180* rated thermostat only STARTS to open at that temp. It is not fully open until 15*-20* later.

 

Removing the stat will narrow the cooling capacity due to a narrow difference between the engine coolant temps and the radiator coolant temps. The stat acts as a restriction, even when fully open, to allow the coolant to stay in the radiator for a longer period of time so that the coolant has more time to dissipate heat.

Just my$.02.... went over this in class last night

 

but you're forgetting one important thing, the fluid in the radiator stays in it slightly longer but that means the fluid in the engine stays in slightly longer therefore picking up more heat.

The amount of difference between the valve being removed and fully open is almost negligible.

 

I hate when internet mechanics try to correct someone that actually builds engines. Read the service manual. It starts opening at 170*. Once it's open it doesn't start closing until 161*

Section CO page 23 in the Nissan service manual. I took a screen shot in case you've never read the manual.

 

correct. in all fairness, though, the FSM varies by year. the info for the 2005 G35 (my car) is attached.

 

Thank you for your correction and your benevolence.

I apologize for not reading the FSM in its entirety.

 

that's wild since the thermostats are the same part number between those 2 years and even between a/t and m/t.

 

that and the fact that thermostats are rated at what temperature they are open, not what temp they start to open. My oil cooler thermostat is a 180* thermostat and it starts to open at 130* due to it's design.

 

tell me about it! when i looked them up last year on courtesyparts, there was no distinction between 5AT and 6MT, yet the FSM says there's a difference. at the time, i thought maybe that was why some people said their temps never got out of the 190s while others regularly see 205. beats me man

 

eh, that wouldn't be a reason why the difference in max temps because once the thermostat opens it doesn't play a part in heating up the engine further or not. Maybe tolerances on how far they open aren't the greatest which means the ones that open further have more flow therefore lower cruise temps.

 

On the coolant pipe on the back of the engine, there was a nipple that I was not using for warming the intake. I went from that nipple to a new nipple that I drilled and tapped and put on the block off plate the previously blocked off the heater/bypass line. The thermo opens now, and at an idle, I'm running about 185-195deg F so Im a happy camper. The line I ran also runs from the back of the engine so I didn't have to do some hideous crossover on the front of the engine. Do you guys typically leave that intake manifold coolant lines alone or remove them?

 

i left mine alone because i'm lazy.

sounds like you got it working. That's all that counts.

 

Here is the cooling flow chart, and why my first setup did not work, and the second what I will be doing to get flow to the rear of the stat.

Spent any pics of what you did?

 

I'm running from the "to intake manifold collector (upper)" to the left cylinder bank inlet with a 5/16" fuel line I had lying around the fit the nipple on the backside. I'll try and get some pictures up tommorrow.

But, ya, there is no reason your second setup should give you problems. Your first was just feeding in cooler coolant so the thermo probably wasn't opening as fast as it needs to. Are you going put a new fitting on the rear water pipe? It really is convenient to use that intake nipple since you're not using it... I was going to use the "to heater" nipple but the engine is so close to my firewall that the hose was kinking.