| thermostat question [message #269384] |
Sat, 10 January 2015 15:55  |
paulb
Messages: 24
Registered: June 2013
Location: Lansdale PA
Karma: 1
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Towards the end of the summer, and now when I run the engine once a month, my water temp doesn't stay on 180 degrees when cruising at 55 or when I warm up the engine. It stays close to 160 or even lower and when I warm up only hits maybe 140 to 160 during idle. Could this merely be a bad 180 stat stuck open or a symptom another problem? This was happening before the temps got below freezing, I last ran the engine in late November.
Paul Bauerlein
'75 ex-Glenbrook
Lansdale, PA
[Updated on: Sat, 10 January 2015 15:55] Report message to a moderator |
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| Re: thermostat question [message #269388 is a reply to message #269384] |
Sat, 10 January 2015 16:50  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
Karma: 0
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Sounds like either your thermostat is stuck open or your fan clutch is stuck engaged. When this happens do you still have dash heat? If yes, thermostat is likely stuck open. If no, maybe fan clutch is stuck engaged.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: thermostat question [message #269391 is a reply to message #269384] |
Sat, 10 January 2015 17:54 |
Gadabout
Messages: 124
Registered: March 2013
Location: Edmonton
Karma: 2
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Check the temperature sender and wire, make sure the contact is clean, if it is lose or dirty you may be simply be getting a false reading. You might also want to remove the sender and make sure the probe is clean. Also inspect the sensor wire (running over the engine) for any damage - No cost to do these quick checks.
If the thermostat is old then consider replacing it, compared to other things it is a relatively low cost. Most thermostats use wax and a spring to control coolant, with each heat cycle the wax and spring give up some of there initial design specifications, in time the thermostat needs replacement. The Robert Shaw thermostat seems to be the recommended one for our needs , from reading the forum, I understand that some other designs have caused problems.
Hers is some more info: http://www.gmcmotorhome.info/engine.html#stat
Good luck with the troubleshooting and let us know whey you find the problem to be...
Carl Harr : Driver NASCAR Pro Series #2
1978 Gadabout-Restoring
1978 Palm Beach
1976 Glenbrook
Prevost Featherlite H3-45
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| Re: thermostat question [message #269401 is a reply to message #269384] |
Sun, 11 January 2015 02:00 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Paul,
One of the things I have done on my old school engines is to use a "perminant" or "reusable" thermostat housing gasket. This allows you to take the T stat housing off anytime for testing without the need for a new gasket or gasket sealer. If on the road you only need a wrench to remove the bolts. I don't know if others have used them or know of good or bad experience with them? I have found them to be very convenient for around $10.
I hope you get it figured out. Let me know if you ever want a second set of eyes on something, I am just up the PA Turnpike one exit and drive by your town every day.
Looking forward to warmer temps. 14 degrees now. I just put another shovel of coal on the fire.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: thermostat question [message #269403 is a reply to message #269384] |
Sun, 11 January 2015 07:28 |
paulb
Messages: 24
Registered: June 2013
Location: Lansdale PA
Karma: 1
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Thanks for all the responses, gentlemen. It is a Robert Shaw Thermostat. Its not the fan clutch. I'll check the coolant today, and run the engine. I have been having issues with the heater being slow to get hot. I'll get back to you later if thats it. Everything else is going to have to wait until the temps get over (way over) 16º !
Paul Bauerlein
'75 ex-Glenbrook
Lansdale, PA
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| Re: thermostat question [message #269405 is a reply to message #269384] |
Sun, 11 January 2015 08:56 |
paulb
Messages: 24
Registered: June 2013
Location: Lansdale PA
Karma: 1
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Junior Member |
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Well, the engine has been running at high idle for an hour. Given ambient of 17º the gauge reads barely 100º. Heater is luke warm. Has to be the thermostat. Again, thanks for the responses. I have a spare Robert Shaw 190º stat I bought way back in 2007. Once it warms up to an acceptable level I'll change it out. Enjoy your Sunday, sun's out here in force, will be a nice day today.
Paul Bauerlein
'75 ex-Glenbrook
Lansdale, PA
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| Re: thermostat question [message #269411 is a reply to message #269384] |
Sun, 11 January 2015 10:30 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Replace the radiator cap with a new 9# unit. They have a service life of 5 years due to rubber having a service life. The coolant recovery system won't work if the cap gasket is bad or the one way check valve in the cap is bad. Most caps are way old as time marches on.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: thermostat question [message #269430 is a reply to message #269429] |
Sun, 11 January 2015 20:32 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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OEM system is low pressure. You do not want to over-pressure your OEM radiator. OEM is 8 lbs. 9 lbs is closest easily available. Suggest getting one with a handle or relief valve so that it is easier to remove. I find the OEM style hard to remove because of the awkward placement.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: thermostat question [message #269431 is a reply to message #269429] |
Sun, 11 January 2015 20:32 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Broham wrote on Sun, 11 January 2015 20:19JohnL455 wrote on Sun, 11 January 2015 11:30Replace the radiator cap with a new 9# unit.
Why a 9lbs cap? what was the factory cap?
thanks
9lb was the factory or OEM radiator cap rating. Greater may result in failure of your radiator or heater core.
The new aluminum radiator allows use of 15/16 lb cap -- but old heater cores may still may be subject to failure.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Sun, 11 January 2015 20:33] Report message to a moderator |
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| Re: thermostat question [message #269467 is a reply to message #269384] |
Mon, 12 January 2015 11:43 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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some Robert shaw type thermostats have a small bypass hole drilled in them so a small amount of coolent will flow thru them even when they are closed. this isn't necessarily a bad thing unless the coolent stays too cool.
Roy Keen
Minden,NV
76 X Glenbrook
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