replacing thermostats

[rmaciver]

Where are the thermostats on 99' suburban 4x4 6.5L. I've read that there are 2 on this engine. Can anybody help?

[john8662]

First off, why are you wanting to change them?

To answer your question, the thermostats will be located just underneath a 4 bolt outlet housing connected to the upper radiator hose. The aluminum crossover holds the thermostats themselves.

When considering thermostats, I'd only recommend Robertshaw stats or the factory AC Delco stats. The AC stats are only available in 195 temp, and the Robertshaw you can get in 180, etc.

I don't know of a distributor that I'd buy from for Robershaw stats currently, but perhaps a search here on the forum will reveal a few locations.

The manufacture of these stats is

Robertshaw homepage (http://www.cooperstandard.com/us/en/Aftermarket/Aftermarket_Products_Thermostat.asp)

You're after the "Extra Performance" line for the 6.5.

But, you are correct in that a '99 will have two (and thats a good thing).

P.S.

Welcome to The Diesel Page Forums!

[MTTwister]

I stumbled across them at Checker Auto - in a yellow Prestone box, with a small RobertShaw printed on the side. There was a good variety of temp ranges available. A little pricier than Kennedy, but had 'em when I was ready for them, in 180

[rmaciver]

thanks John8662 and MTTwister for your responses.
I had a scan done and the code came up bad thermostat. I figured that might be it because my gauge never came off 160degrees. I would have ordered them through Robert Shaw cause I've heard good things but I wanted to do it this weekend so couldn't wait for shipping. I found them @ NAPA for 10.99 ea. all the other places had them for $35ea.
What a nightmare getting that last lower bolt off the housing. thanks again

[reitmanr]

Not being real handy myself, my mechanic replaced my old stat ( 180 I think) with a nice new 195.
Should I insist he get a 180 to enhance cooling, as we often are towing a horse trailer?
I notice that the temp really is pretty constant at 195 without a trailer.
DO DIESELS RUN BETTER AT 195 OR 180?
And how tough is it to upgrade to the two stat 97 style cooling system?

[MTTwister]

"mit..." Minor PITA! I did mine earlier this summer '96). I would recommend doing the '97 HO waterpump at the same time. It seems like a lot of junk to pull, but its not THAT bad. I took a week, but there were some week nights I didn't futz with it. Pulled the radiator, then wound up pulling the brush bar to get at the front grill in order to clean all the coolers while I was in there. The vacuuum pump has access holes in the pulley (didn't know that on disassembly whichmade breaking some bolst loose 'interesting). Also, you can unbolt the A/C compressor from the mount and move it around without disconnecting any plumbing.
The Thermo Cross over bolts are a little tough to get to, but cleaning the gasket surfaces is the real pain- You can see 'em, but ya can't get to 'em.
Also - Get a Heater Hose barb type fitting for the housing, and use a small section of heater hose to the tube, versus reusing the flunky GM adapter. ( NAPA had a nice short adapter that would hold a clamp). Also NAPA guys ordered in a gasket for the water pump plate (it's a wierd setup). With the gasket, and a thin coating of RTV there-on, and a thin coating of RTV on the threads of the bolts that go into the water jacket, mine went back together with no leaks.
Search on the '97 cooling upgrade, etc and you'll get a eye full of reading first. It's in the upper right corner of the page. Good Luck

edit - oh by the way - I used 1 180

[flintspear]

Thanks for this discussion. I'm going to do a cooling rehab on my cc, with 195 t'stats, hoping to keep the temps more constant. Cooling and heating cycles have got to work the heads/block more, which might encourage cracking? I'm hauling a 3 horse trailer over Wolf Creek Pass, not much cooling problem there, just a long hill at 11,500.

I love my truck.

Flintspear. 98 cc K3500. KE filter, bone stock from there.

[reitmanr]

Wolfcreek Pass! That is the one pass ( 8%) that nearly done us in on a 103 degree day a few summers ago. I had to pull over, cool down the engine and then proceed in a lower gear. That actually started me thinking there had to be something to do to keep the poor old engine from cooking. Since then many truckers have told us how they avoid that pass. Oh well, I know better and would only try it in a lower gear to start with, and maybe travel early or late- not in the hottest part of the day.

And--- I am still not clear if the engine runs better at 180 degrees or at 195 degrees. Seems like I would want to keep it as cool as possible. Please- some one who understands diesels better than me, let me know hich way to go and why.

Thanks to all- the page sure gets me thinking and planning the future for my old '95.

[flintspear]

WEll, I do go over in 3rd gear, which helps cool things down some in my truck. And I don't usually do it in the summer, more in the fall, etc. Hunting camp!

I love my truck.

98 cc k3500. KE filter, bone stock from there.