Skip to main content ↑ ↓
Topic: Cat 3208 thermostat replacement (Read 2920 times) previous topic - next topic

Cat 3208 thermostat replacement

Looked like a 2 hour job with my side radiator, haha. First order of business was to unscrew the sheared off petcock on the bottom of radiator. Had a new one ready to screw back in, but got a bath during the process. I had three 2.5 gallon buckets for the partial drain, 6 gallons + the few quarts that missed the bucket was sufficient to lower the level below the tsat housing. On to loosen the 4 bolts securing the housing that contains the two tstats. BTW 2 thermostats and gasket were about $39 at local cat dealer. Put the socket on the upper port side and applied about 15 ft/lbs on the bolt and it went PING and starts spinning. Exempletive muttered. Upper starboard bolt, no ping but spinning and feels weird.  Exempletive muttered. Neither bolt is backing out. Two lower bolts come right out. Loosen both hose clamps on rubber elbow. Pick up smart phone and search for to see if you can helicoil cast iron, and found out there are some newer threadserts. Ok back to trying to get the upper bolts to back out, get a pry bar hopping to get the bolts to catch a thread. No luck. They did not feel quite like other broken or stripped threads i have experienced but went into this 3-4" thick cast iron housing. THEY ARE THRU BOLTS!  with nuts on the backside, and very hard to access with an open endwrench. Once off I spent an 1.5 hours scraping the large gasket surfaces on each side. I feel sorry for you rear radiator coaches. Seat the new tstats in high tack gasket sealer on the engine side to avoid them slipping out  while trying to wedge the housing into place. I ended up hot glueing the new nuts and washers to an 6" open end wrench to get the upper backside nuts started. Job took 8 hours, to figure out, run to store to get replacement nuts, etc.

Hopefully this will help out others.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Cat 3208 thermostat replacement

Reply #1 –
I need mine done also, could you come over and demonstrate with your glue gun so I can learn the proper methods :))? 

I'm waiting for winter to do the T-stats plus, flush & clean, replace water pump, replace temperature sender a/o switch, replace main hoses with Gates Green Stripes, refill with new ELC coolant.  Have no idea what's in Her or how long it's been since last change.  Had coolant tested and it is fine, although low on SCA's  and only 30% coolant.  Installed new filter with SCA's.  No long trip planned, just gonna park Her at camp for next three months during deer season.  Might and I mean "Might" dip below freezing during that time.

If you know how much total coolant is needed it would be helpful also. 

Thanks for write up, very helpful,
Dan

'87 40' Grand Villa 4000 SBID ORED
CAT 3208TA 300Hp driving MT647, PacBrake
Unkown watts Solar
'17 Conti's HSR2 10-22.5
Cove, Texas
Previous: '76 to '16,  5' 10", 0.1Hp, hauling 85lb BackPack shod on Keen Boots

Re: Cat 3208 thermostat replacement

Reply #2 –
Use a box wrench with duct tape on one side to hold a nut and the high tack to hold washers to the nut.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Cat 3208 thermostat replacement

Reply #3 –
Could not use the  box end, and tape works well on 90% of the time. I just had to get a little more radical and hot glue was great.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Cat 3208 thermostat replacement

Reply #4 –
Bought drill powered self priming Chinese pump to transfer antifreeze back in. Cheap yes, self priming no. Sacrificed the old yellowing fresh water hose that the dw declared a be no go, for a hoses. After about 5.8 gallons transferred the pump shaft seal started leaking. O Reilly's will get the pump back. Fired her up, drove some and waited for the motor to heat up and cycle the new thermostats. Only sepage was from the new petcock. May take a 2 hour road trip to get most of air worked out. This was a southern California coach so antifreeze looks diluted, but will have to get tested. I no longer believe in flushing with water and refill. Corrosion occurs mostly when you introduce new oxygen into a mostly oxygen depleted  hot water system. a fresh water flush is chock full of oxygen, minerals and chloramine. Most cities use chloramine now because it cheaper and much safer than pure chlorine to treat water. Bad news is, it appears to be very detrimental to rubber parts, seals and antifreeze. Plumbing industry has been fighting this for several years to develop long term seals.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Cat 3208 thermostat replacement

Reply #5 –
Understand everything except the California part,do they tend to use less coolant there?
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Cat 3208 thermostat replacement

Reply #6 –
I am guessing the concentration is less than what is required for -20 f. That is common in KS.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake
 

Re: Cat 3208 thermostat replacement

Reply #7 –
Agree on the cold part but with 50/50 you get maximun boiling point.
96 U270 BUILD 4810
85 380SL
Drummonds TN.