rustypigeon

I have a '94 22RE. I am planning on a coolant change and a new thermostat.

From my research, the dual stage seems to have been developed to solve problems in '84 model trucks. Apparently the heater core would cool the coolant enough that the thermostat would not open enough. Has the heater design been changed since then?

Would it benefit my '94 to have a dual stage?

Robert m

iTrader: (2)

I had the temp overshoot problem in my 94 after I changed out the thermostat. I used a fail safe thermostat and was going to drill a small bypass hole but instead I removed the little jiggler valve and the problem disappeared.

Odin

I have a 91 and I don't know what kind of thermostat is in there right now but it's doing the warm up temp overshoot.

I think they don't do it if you install the two stage thermostat because one opens at a lower point than the other thereby allowing coolant to circulate a little sooner.

Normally the recommended size of hole to drill in a thermostat to help bleed the air out is 1/16 inch, removing the plug from the jiggle valve accomplishes the same thing.
That hole should allow some coolant to flow at all times eliminating the problem but causing a slightly longer warm up time.
I know of one instance where a person complained of alot longer warm up time in a colder climate when he removed the plug from a Stant Superstat. He didn't give a specified drill size, just mentioned the hole was two sizes bigger than 1/16 inch.



More info http://www.4crawler.com/4x4/CheapTri...tml#Thermostat


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muddpigg

iTrader: (1)

Funny story: the first t-stat I put in my 4rnr I got a little over zealous about the drill a little hole trick and drill multiple. Took forever for engine to warm up.

Odin

Don't now if you've seen this thread but there is a cheaper alternative to the Factory dual stage thermostat.
-IF- you want to try it. He said he hasn't had any problems with it. Murray 41492

https://www.yotatech.com/forums/f116...mostat-284848/

teaMJPx

+1 to the dual thermostat (the one with TWO holes), that should take away your issue.


What happens is that your heater-core "cools down" your coolant too much and when it hits the thermostat it closes, but since your engine is hot it keeps getting hotter... of course, problems after that


Anyway, the dual stage will allow a minimal amount of the coolant to flow even when the thermostat is closed, thus, eliminating the issue of your engine not getting any coolant.

I found out the hard way and used one from Oreilly's with only one hole and blew my head gasket because the truck over heated badly... caused a whole lotta issues...