Can't seem to get up to ideal operating temp

[Bradsp8]

Stock 75 Sport with 302. Recently replaced my water pump and also installed new thermostat. New T-stat was a 190. Went with a 190 as engine seemed to always run cool at about 170.

I still can't seem to get engine temp above 170. Dash gauge seems to be off but not terribly. Infra red thermometer gun reads 168 at location where temp sending unit is (top of engine behind distributor).

I've placed a sheet of cardboard over half the radiator and it still won't reach 180 or 190. Upper radiator hose is hot as coolant is circulating so I'm wondering if the T-stat is opening too soon? Any ideas or issues I should check?

 

[AxlesUp]

remove your Tstat and drop it in a pan of water. use a thermometer to see when it actually opens and closes. there is a lot of variance in Tstats these days.

when you reinstall it be careful to make sure it stays seated and its properly oriented.

also if your using an aftermarket housing make sure it is sized properly. the last couple i bought were so large on the inside it was allowing the thermostat to flip on its side....

 

[sykanr0ng]

/\/\ What he said +1

There are very good reasons why Robertshaw (that is how it's spelled) thermostats cost more and people pay it.
WH carries them.

 

[SHX669]

I'm using Robertshaw 190* t stats in both Broncos -I can highly recommend them.
Did you happen to put in a "hi flow " tsat from Mr Gasket ? Only reason I ask is that I had that problem when i had one in my '68 . The t stat never closed all the way it would however open all the way.

 

[B RON CO]

Hi, to get a true temp with your heat gun take it for a drive and shoot the upper hose just after the thermostat housing. You won't get an honest reading at idle in the driveway. Your 190 T stat may be opening too early, but I think you will be good, as long as the heat is good inside. Also, when cold with the cap off, no coolant should flow through the radiator. If coolant flows when the engine is cold, the T stat is stuck open. I would wait till summer to see how it looks then. If your engine really doesn't come up to temp you should get a top quality T stat. Good luck

 

[Bradsp8]

Thanks for the ideas and check list.

I did test the T-stat on the stove in a pot of water and according to my thermometer it opened up at slightly less than 190. I figured "close enough" and went with it.

I made sure I installed it correctly with the spring inserted internally or toward the rear of the EB. Also used the OEM housing as mine is still in great shape and I’ve heard new ones are terrible.

It was not MR Gasket but CarQuest part. I may try the Robert Shaw brand eventually.

I may be OK but I fear running at 170 is not ideal and will increase wear and tear internally as I think hotter is almost always better than cooler as long as not overheating.

 

[Broncobowsher]

You are right, hotter is better. But 170 isn't a death sentence. So the engine will only last 140k instead of 150k.

I've had a handful of random thermostats over the years that were stubbornly cold. It was as if the rated temp was the full open temp and not the cracking open temp. But I couldn't tell you which ones they were. The best I remember, OEM ford thermostat. From a used engine. That sucker stayed shut until it was good and hot.

 

[rmk57]

I block mine off partially with cardboard in the spring and fall. Seems to work.
The 170 six never gets above 190 all year without messing around with t-stats.

 

[bronconut73]

Living in Central Florida and fighting heating issues for 30 years with my eb....The title of this thread just pisses me off....
There I said it....

 

[Bradsp8]

Bronconut, I laughed when I read your post but I know it isn't funny. It is in fact weird to have this issue and I'm sitting here going WTF?!?!?

 

[jbawall]

I have the exact same issue, never gets above 170 except in the hot months of the summer, which here are only 3 or so. I am thinking I will change the thermostat and see what happens, this one has been in there for a long while.

Bronconut, your post made all most made me spray the beef jerky I was chewing all over my monitor. I feel for ya!