running without a T STAT?
Thread Starter
Seasoned Member
Joined: Jan 2013
Posts: 341
Likes: 1
From: Irvine Ca
Year: 1989 2 door
Model: Cherokee
Engine: 4.0
i recently changed the waterpump and tstat and i think my tstat dont open up.. my buddy told me just to remove the Tstat and run without one.. he said he does it on his cars...
should i?
should i?
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
In all seriousness, run one. Get an OEM unit to save the hassle of dealing with cheap replacements. It takes all of an hour if that. Your friend... I can't speak for him. Running without a t-stat in a passenger vehicle makes no sense to me.
your not gonna have very good mileage if you don't run a tstat, and if your cel isn't on it will be.
easy to change it out....my 11 year old son did ours last weekend, with supervision, of course.
and get a oem.
easy to change it out....my 11 year old son did ours last weekend, with supervision, of course.
and get a oem.
CF Veteran
Joined: Mar 2010
Posts: 6,685
Likes: 6
From: Jacksonville, FL
Year: 92
Model: Cherokee
Engine: 4.0
Absolutely zero reason to run without a thermostat
Senior Member
Joined: Aug 2009
Posts: 838
Likes: 0
From: Tulsa,Oklahoma
Year: 97
Model: Cherokee
Engine: 4.0
but again its only money and a $4 thermostat so leave it out and burn around $20 extra a month in fuel, no biggie
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Junior Member
Joined: May 2011
Posts: 92
Likes: 0
From: By Detroit
Year: 2000
Model: Cherokee
Engine: 4.0
As an actual bad side effect, your oil will start to get acidic and chew at the bearings if you run it that way for the long run. The oil needs to get up around 180 degrees before it can start cleaning out the water that causes the acid.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
I've run a reducer (looks like a big washer) as a backup when the thermostat failed. That worked well for me for a few years. You can drill a few small holes in the thermostat outer ring to ensure that if it fails, and doesn't fail in the open position, the water will still flow. Your best bet is to keep a spare thermostat and gasket or RTV in your toolbox just in case.
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