Thermal gun highest reading at different areas on motor and hoses is 210 degrees and needle is at the bottom of (N), heater dash vent is 92 degrees, ambient temp 45 degrees. Is this normal?
New thermostats are 180 degrees.

 

210 seems a teensie bit high, but depends on conditions? Does your AUX fan kick on around there?

 

A bit high, yes.

In 45ºF ambient conditions the cooling system ought to be able to hold something closer to thermostat rating temps. August in downtown Las Vegas would be a different story.

What reading are you get right at the thermostat housings?

Cheers
DD

 

No, it does come on in Summer time at a higher temp.

 

All hoses and thermo housing 135 to 165. Valve covers 140, lower block 190, upper block 200 to 210, intake manifolds 135.
When driving needle stays half way between C and N parked idling bottom of N and a little below.

 

Will take new temps today and will write down each temp and where. Also getting another thermal gun and compare,

 

IR thermometers have a DTS ( distance to spot ratio which will be listed on the IR) this means the spot that the IR uses to read temperature grows larger the further the IR is from the source, the IR also averages ALL measurements in the spot. You need to be careful when using one to measure engine temps that you are not measuring the exhaust. The best place to measure is the BLACK hoses.

Personally I use a K type thermocouple and a Fluke DMM.

 

Any shiny metal gives inaccurate readings on an IR thermometer too. As Warren says, a flat black surface is the most accurate read off.

 

I placed it no more than 2" away from target, away from exhaust and have not had time to do re-measurements.

 

I did not aim at anything shiny, directions say not to. You would be at a loss trying to find a shiny object on my motor, LOL
As I recall rad hoses near stats were well below 180,I need to take new measurements and write them down. I have 7 vehicles that I try to drive or ride at least once every couple of weeks, PITB, LOL

 

While driving gage only goes up 1/8" above the center of C, parked idling little below 1/2 between C and N

 

If the needle continues to climb you have an issue. As long as you have serviced the cooling system and rod cleaned or re-cored the radiator you should be good.

My car the needle runs 1/2 way between C and N for the most part, this is probably where the thermostats are just opening. In HOT weather with AC on the needle climbs to about the middle of the N and stays there.

 

I found you can't really go by the needle position, as each car is a bit different depending on the sending unit. I've changed a sending unit and the needle sat in a different position when the engine was at the same temperature. I'd measure the hoses and find out what "normal" is for your car and verify that is a proper temperature with the thermometer and then when the needle moves away from that you know you have a problem.

 

Water doesn’t boil until 212 degree F coolant increases the boiling point as does pressure. As long as the coolant isn’t boiling there is no trouble. You don’t have to “fix” something that isn’t broken.
I understand some people are worried and think that cooler is better. Well you are just wrong. It’s a balance. Warm enough to operate efficiently but cool enough so there is a reserve.

Want to point it at something that will honestly tell you what’s going on? Try the radiator. The coolest will be on the lower right hose where it’s going into the engine. Anything around 180 is good. Hottest will be upper left where it comes into the radiator. Over 230 you have trouble.

 

When should the electric fan come on? I got mine a bit warmer than usual in traffic yesterday (top of the N) and found my radiator hoses were around 210 via IR thermometer. Electric fan was not on. Ambient was about 60.

I know there's a list of cooling system maintenance for "new to you" V12s, and I should just do it, but I already have a pile of parts to put on the Mercedes and another pile of parts to go on the Jaguar. I've told myself I won't buy more parts until I put on the ones I've already bought.

 

I wanna say 94ºC is the switch point but can't 100% swear to that. The reading is taken at the water pump

Cheers
DD

 

If you have a V12, then 85 degrees C in the water pump inlet is the OEM thermostatic switch setting. This equals about 95/96 in the tophoses, I think. Worth checking the fan circuit though, just bridge the thermostatic switch terminals, ignition on, to check it.

 

I see. One more thing for my to-do list.

 

This is from 01/07/2020

This is for thread ------Is Jaguar XJS overheating.