Have we discussed thermostat operating temps before?

[goglio704]

The need for the correct thermostat with the bypass port blocker has been discussed before, but have we ever talked about the operating temp rating? If we have point me at it, and I'll delete this.

You can get 180°F, 192°F, 195°F, and probably some others. Beck Arnley seems to consider the 192°F as equivalent to OEM, but my 82 FSM lists 180°F as standard on page LC-18. I used a Beck Arnley 192°F recently, and it seems to keep the gauge slightly above the halfway point.

What are the advantages and disadvantages to the different ratings?

[asavage]

I run 192°F thermostats in both mine, and the dash temp gauges looks like this:



I like that.

If I tow with the '82 or run it very hard, the needle will rise very slightly above horizontal. Never more than that, ever.

[83_maxima]

I'm curious too. Trying to use the A/C this past weekend (on the highway) and I couldn't keep the gauge below 3/4. This is very frustrating considering the effort I put into the A/C to get it back up and working.

I have a sinking feeling that "pitansk" never installed a new thermostat in this car before he flipped it.

[davehoos]

the temperature reference is the point that the t'stat starts to open.

in cold weather you increase the temp to help trap the heat into the engine metal.if the radiator heat transfer was very very good you could use a 105c stat.

there is also a temp that is the fully open point.

the dia of the hole is also important as it affects flow and the flap movement.

the responce time of some stats is dreadfull,the temp may have dropped without closing the stat.

temp increase using a/c is not unexpected.it depends on how good the air transfers heat.
it will also depend on gas pressures,condition of metal fins and the air flow.a lot of visco fan hubs are not adjusted correctly with old age or the "fan belts slip".

we have a lot of problems with stat quality,a good stat ive used is a mazda diesel unit with 2 temp valves.a small 80+c and a larger 88c.it has no flap that LD28 need..

[kassim503]

think the radiator is clogged up?

Id replace the T-stat and see if the problems go away.

Talking about the a/c, when I turn mine on, the engine speeds drop to 400-500 rpm, I think the vaccum box that bumps idle speed might be broken or disconnected. I wouldnt usually care, except when it drops low my oil pressure gets pretty shoddy, even with the new pump.

[asavage]

On the A/C idle-up: mine didn't work for years. About a month ago I replaced all (three?) vacuum lines to it, and it suddenly began working. Since those small vacuum lines split (both diesel and gasser), I suggest buying 10' or so of the tiny vacuum line and replacing every bit you find.

[83_maxima]

After a trip to 8300 feet and up the "steepest county road in the country" in my wagon, with the gauge nearly to the "H", I feel the need to revisit this thermostat/overheating issue.

Last week I replaced my "bogus" thermostat with the OEM one found in the 81 parts car. Original thermostat, stamped 83' C (181.4' F). It is working, and regulating the temp OK, but takes forever to open (I think I can attribute it to the age) and the car runs as hot as it did with the "bogus" thermostat.

Doing 70 mph, in 90' weather down the freeway, the temp stays constatnt in the middle of the gauge. get into town and slow down, stop and go, temp rises up near 3/4 and is very hesitant to come back down unless you get back on the freeway.

Climbing the 2-mile incline up to our destination, I had to drop the tranny into 1st and pour on the coal to get up as I watch the temp gauge climb to the top. It had me worried, I was just crossing my fingers that we would make it.

I want to attack this problem and solve it. Could it be a waterpump issue? More likely a partially-clogged radiator?

[asavage]

I would swap out the thermostatic fan clutch first, since you have a spare, and it's merely a few screws, four 10mm hex nuts, and some blood . Next most likely (in my mind) would be the radiator, yes.

The fan clutch would give you symptoms like you have. If it ran hot on the freeway too, I'd be looking at the radiator first.

If you have the opp, you might do the thermostat test in a Pyrex cup and a coffee heater and a stick thermometer, see if it opens far enough. I have seen one thermostat that wouldn't open quite as far as it should. Does wax get weak?

And you know that running a t-stat up to red once can toast it. But most often it just won't shut again.

[83_maxima]

Thanks for the input Al.

I will try a swap of the fans and boiling the thermostat. I need to just order a new one on principle (26 yrs is probably enough). Then install it when I flush the cooling system.

I know about overheating a thermostat, but noticed no change in oper. temp as we made our way back home.