To the OP, I think your temps are fine mate relax about the temps. I see you are no stranger and have already have been exposed to a forum, and it has to be assumed you can see that a lot of the posts have genuine and valid points but you also have to sift through the BS as well.
Brian894x4 raises a valid point, he said 'if you have all new OEM components then the system should read 181', I doubt that particular temperature could be cast in stone Brian, as Flank pointed out there are too many variables but, your running temps should be within the manufacturers specification and this seems to be where the confusion lies.
The manufacturers specification for any engine is the ONLY true guide, so let us get this all into to perspective.
You need to use a number of specifications to tell you what is the normal operating temperature of any given engine, lets us look at the thermostat, now guys bear with me here as I have a diesel but the principles remain the same, my engine creates heat and it needs to be controlled just as a petrol engine does.
So my figures are for MY engine.
My thermostat should START to open at 165 - 172 F (variable) but be FULLY open by 194 F, note there is NO variable allowed here at FULLY OPEN. There was a mention that the thermostat is not designed to control engine temperature but is simply there to get the engine up to temperature quickly (and of course gives us a heater). I do not totally agree with that statement, I would argue that the above range indicated is where the manufacture would like the engine temperature to be kept under NORMAL conditions. If this was not the case why use a variable thermostat, why not simply have snap open/snap shut valve at 'X' temperature?
The A/C switch cut out is shown as 226 F, this IMO is the maximum operating temperature where you are exceeding the boundaries of the standard system.
Toyota states quite clearly that THEY believe a coolant temperature of 230 - 248 F is too high, again note the variable, this means the A/C cut out is only just below the POTENTIAL overheating point, that is when the pressure cap opens and you start to vent coolant into the expansion tank, you are in effect starting the overheating process, any loss of coolant to the expansion tank is a loss of available coolant to the engine, so the temperature rises ad infinitum.
So we have a normal running temperature 'RANGE' variable of 165 to 194, this would put Brian's figure of 181 F very close to the 179.5 F that would be the middle of the range of the thermostat at it's minimum open temperature. Now take the upper scale of the minimum opening temperature and note the 'middle is 183 F, a bit of a coincidence to Brian's figures? IMO this make sense, the thermostat not continually opening and closing as a snap open/snap shut valve would have to do to maintain that acceptable operating range temperature, it just so happens to be damn near the middle and can gently open and close according to the environment/workload.
Now note the disparaging gap between the thermostat operating range, and the actual engine operating temperature, if the coolant moving through the block and head of an engine working hard for example a steep hill perhaps A/C on, the engine is hot, the coolant is hot, the thermostat has just reached it's maximum opening point of 194 F, the very fact that the thermostat is fully open tells us the coolant is at 194 F, but wait a moment......the coolant has only just left the cooling medium i.e. the radiator, which means the temperature at the TOP of the engine is way above this figure 194 F, perhaps 25+ F and if the load increases then it is about to get hotter, I cannot give a definitive answer to how much hotter, and the 25+ F is speculation but cannot be far from the real world figure of a working engine, add the 194 max of the thermostat to my speculated 25 F degree rise through the block/head now gives a figure of 219 F, now weigh that against the A/C cut off temp of 226 F means you only have around 7 degrees to play with?
I will just throw something else in here whilst I am at it, I work with OBD pretty much every day of the week and have some pretty good gear, OBD sensors can be two or three degree's/volts/OHM's or more off and still have no distinct affect on the engine fuelling but they may well show on the scangauge, so if two apparently perfectly running cars show slightly different scangauge readings, as per Flank I would not be reaching for the tool box.
A shot in the dark here but, I am going to say that most 80 owners (including myself) purchased our cars second or even third, forth and perhaps even further down the resell list? It then follows that a lot of vehicles are running around with non OEM parts (remember Brian's comments'), also as many if not more have seen wrenching by less than professional mechanics. This combination makes fault finding very difficult, in particular if you have only just purchased the car or, perhaps you purchased it in the winter and when summer comes around you find you have problems.
I often see the phrase I have 'base lined' the engine cooling system, only to see the same poster having a problem a few months later, it then turns out it has aftermarket this and aftermarket that parts fitted, and then he or she is chasing their tail trying to find the problem with the engine running hot. Or you will see advice as water pump, fan clutch, thermostat but, you never hear someone say 'remove the cylinder head and remove 20 years of rust/calcium/lumps of instant gasket/ the old rusty freeze plug jammed between two cylinders oh and don't forget to take out that old nut and bolt while your in there'! I have been around engines for more years than I care to remember, but that is what I have actually seen cause overheating issues. I also see so much BS and generalisation with no real evidence that just adds to the confusion.
I am doing a lot of testing on my own (diesel) engine with the VC cooling fan removed and an all electric system fitted. Facts again dictate thus far that this is working as good and in some cases better than a VC or mechanical fan but, I would concede that unless the system is specced very carefully with some redundancy built in as mine has, then it may not have the reliability of the mechanical fan but, I reckon once the trials are complete it may well outperform mechanical fan in the environment that I use the car in, a bold statement? Check out the link in my sig and see not speculation but instead, repeatable facts and figures.
regards
Dave
I'm looking for some additional insights as I'm chasing some temp issues. I've been doing LOTS of reading on the topic but could use some thoughts from you guys.
