T-Stat Hosing - Aluminium or Cast Iron?

desertred · Feb 12, 2017

Just finished replacing the radiator and t-stat (both leaking) in my 88 XJ and, as luck would have it, I still have a leak from the t-stat housing. I've decided to replace the housing in case the current housing is warped. The auto parts stores have the housing available in two different materials - cast iron or aluminum. Which one would be better to use?

Bobbie · Feb 13, 2017

I like aluminum.everyone has there on taste.Your problem my be not good and clean.Don't over tighten for they will crack.

desertred · Feb 13, 2017

I don't think cleaning is the issue (although anything is possible). The block cleaned up nicely. The current housing is pitted below the surface that sandpaper couldn't get to. I did use RTV between the housing and new gasket and torqued each bolt to 13 ft-lbs.

Bobbie · Feb 13, 2017

Ok, get a new one and try again with a new dry gasket.Be sure the thermostat will not fit upside down.Also be sure water is not coming from the top water hose itself.

desertred · Feb 13, 2017

So, which housing would be the better to use - aluminum or cast iron? Would one be more prone to warp or rust/corrode over the other?

Johnnie Walker · Feb 13, 2017

I have the dorman late model replacement on both XJ and MJ. I have a plug in the one in my XJ and adapter + cooling sender in my MJ. Inexpensive and does the job. zero issues. I believe I have the OE one from my XJ I could sell for cheap if that's what you want..

trippled · Feb 13, 2017

Aluminum is fine. A lot of these t stat gaskets have a side that is sticky to aid install. There is a very difficult to see clear liner you must peel off, or it will leak past it.

Hypoid · Feb 13, 2017

Gee, I thought they were all pot metal! :gee:

Cheap is good enough. One problem I have noticed is aftermarket thermostats with an excessively tall bead worked into the sheet metal flange.

The Stant replacement does not seem to present this problem.

JeepNoob · Feb 13, 2017

I'd go with aluminum, cast iron will rust. (If you don't believe this, look at the coolant in a cast iron block and engine, like, mmmm, I dunno a 4.0 that hasn't had the coolant changed regularly...) In fact, I'm pretty sure that factory T-stat housing on my '96 is aluminum. I like to remove the T-stat when flushing the engine to make things easier. Every time I've re-installed the T-stat and housing, I clean up the surfaces (wire brush works good) and install a Fel-Pro gasket. Think I generally use a light coating of water pump sealant on the gasket surfaces to keep everything in place too. Never had a leak.

Jeep Driver · Feb 13, 2017

I have yet to see a CI housing on a 2.5 or 4.0

lazyxj · Feb 14, 2017

Never seen a cast iron housing on an XJ.
If you are changing the thermostat housing, spend a little time with a dremmel or die grinder and, using a carbide burr, round and clean up the inside passages, to improve flow.
If this sounds too complicated, Hesco sell a ported, high flow housing for $33, plus shipping.
http://www.hesco.us/products/7969/t...rmostat-housing-for-the-aluminum-head-hesalth

md21722 · Feb 14, 2017

I have used both the dealer replacement and one from NAPA. Of course the dealer one looks nicer, but both work. They are both aluminum if I remember correctly. The dealer one is definitely aluminum. Aluminum can corrode, and cast iron can rust.

alexgalexg · Feb 15, 2017

Did you use the gasket or the sealant. I have an aluminum housing on mine and is not warped. But it may be worth your time to ensure that you dont have any stripped threads and that sealant wont do the trick. If its bad just get aluminum

Bobbie · Feb 15, 2017

Forgot in my reply before that it very important to chase the threads for they will get trash in them and the bolt will bottom out.Silicone in the threads will do the same thing.Get a new gasket and start over very clean and dry.

96Sportxj · Feb 15, 2017

When I did mine I had to make a few passes with a file before she stopped leaking.

Waynerd · Feb 17, 2017

Pick one up at NAPA. Aluminum, cheap. Just don't use the gasket that comes with it. I usually spread a thin layer of sealant on the gasket. Not enough for it to squeeze out around the edges when tightened but just a very thin layer.

desertred · Feb 17, 2017

I picked up a new aluminum housing and FelPro gasket from Oreilly's. I will install this weekend and see how it goes.

desertred · Feb 17, 2017

Johnnie Walker said:
I have the dorman late model replacement on both XJ and MJ. I have a plug in the one in my XJ and adapter + cooling sender in my MJ. Inexpensive and does the job. zero issues. I believe I have the OE one from my XJ I could sell for cheap if that's what you want..

The one I got from O'Reilly's has a plug that goes into a port next to the heater hose. Is that the plug you were referring to? If so, did you use RTV in the threads to prevent leaks? The threads appear to be tapered. I'm not fond that the manufacturer (Murray) put an indented stamp in the middle of the mating surface about the thickness of the gasket. Just seems like more points of failure.

Johnnie Walker · Feb 18, 2017

If you mean a threaded hole on the driver side, yes that is a late model style. 3/8 npt IIRC. I have not used teflon, loctite or RTv

desertred · Feb 19, 2017

Well, I got the new housing on with a FelPro gasket and the T-stat is leaking worse than the original leak. No problem with the plug, the leak is coming from near the bottom housing bolt. So tomorrow, I get to do it all over again!

T-Stat Hosing - Aluminium or Cast Iron?

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