coppermack Posted January 10, 2015 Share Posted January 10, 2015 I've got a 94 ch613 with a mack 350. Truck ran hot on last trip (hauling grain 25 miles) and then all of the sudden ran cool and wouldn't even get above 120 or so. I assumed it was a sticky thermostat replaced thermostat. Next trip out this afternoon loaded truck (ran app. 1 hr before I hit the road) temp was around 130-150. Made it less than 5 miles and gauge was about to bump into the red. Pulled over, cooled off and came back to shop. Now I'm guessing water pump or maybe an air lock? Pretty terrible as a mechanic so any help appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
1958 F.W.D. Posted January 10, 2015 Share Posted January 10, 2015 I'm guessing you got some air in there when you changed out the thermostat, but then again I like engines with dual spark plugs so take what I say with a grain of salt........ 1 Quote TWO STROKES ARE FOR GARDEN TOOLS Link to comment Share on other sites More sharing options...
coppermack Posted January 10, 2015 Author Share Posted January 10, 2015 I'm guessing you got some air in there when you changed out the thermostat, but then again I like engines with dual spark plugs so take what I say with a grain of salt........Had a neighbor suggest that as well. What's the best way to "burp" it and check. Lol. Quote Link to comment Share on other sites More sharing options...
gearhead204 Posted January 10, 2015 Share Posted January 10, 2015 without being there to look at it I would say find the highest point on the water manifold or the temp. sender and remove the sender or a plug from the manifold and burp it. you may want to drain about 3 gallons first then with plug or sender removed slowly fill the rad. until coolant comes out sender or plug hole then reinstall sender or plug and then finish filling rad. ( make sure the front of the eng. is slightly higher than the rear of the eng. this should remove all trapped air) 1 Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted January 10, 2015 Share Posted January 10, 2015 And then do the bottle test. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
carlotpilot Posted January 10, 2015 Share Posted January 10, 2015 you may also be looking at a blown head gasket 1 Quote Link to comment Share on other sites More sharing options...
coppermack Posted January 10, 2015 Author Share Posted January 10, 2015 Thanks. sure hoping for air in my system and not a blown gasket Quote Link to comment Share on other sites More sharing options...
carlotpilot Posted January 10, 2015 Share Posted January 10, 2015 hope the solution is simple downtime is a bummer 1 Quote Link to comment Share on other sites More sharing options...
Glensts Posted January 10, 2015 Share Posted January 10, 2015 When I fill with antifreeze I always remove the heater hose that goes into the shutoff valve at the manifold. When a/f comes out of there I close the valve and put heater hose back on. Then open valve and refill. Been working good since I did it that way and haven't airlocked since. 2 guys works better for this if you got because usually I'm on top of the tire 1 Quote Link to comment Share on other sites More sharing options...
6368 Posted January 10, 2015 Share Posted January 10, 2015 And then do the bottle test.care to elaborate for the uninitiated. such as myself 1 Quote Link to comment Share on other sites More sharing options...
Popular Post theakerstwo Posted January 10, 2015 Popular Post Share Posted January 10, 2015 Yes that would be a test to see if you are getting compression in the coolant.It could be a haedgasket leaking as well as a liner cracked or head cracked.But to do the test just get a plactic pop bottle and fill with water.Take the end of the over flow hose just under the rad cap on the rad or coolant tank and put it down in the bottle of water.This needs to be done when the engine is as hot as you can get it.With it running at half speed watch for air bobbles in the water.There should be no bubbles.A air compressor can do this so if you find the air in the bottle you need to disconnect the compressor.Also remember that a new engine will pass air into the coolant when the engine is cold.So keep it hot for the test.This will not be as good of a test as if you was performing this test under load but it has served me well for years plus its sure cheaper than the rip and replace method so many guys use. Also I may add that this is more effective than these chemical test the gas engines use.I have never had any use for the chemical test. 5 Quote glenn akers Link to comment Share on other sites More sharing options...
bts-4120 Posted January 12, 2015 Share Posted January 12, 2015 is the truck actually boiling over I have seen faulty temp. sensors do this to Quote Link to comment Share on other sites More sharing options...
coppermack Posted January 12, 2015 Author Share Posted January 12, 2015 It was steaming pretty good when I pulled over. Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted January 12, 2015 Share Posted January 12, 2015 Also with a heat problem that has had most of the major parts checked or replaced and still heats the water pump pressure needs checked.You may have a new pump on it and with out rereading to check a water pump the water pump pressure should be checked before replacing it thinking its bad.To do so use a 50 psi gauge and connct into the coolant system anywere before or below the thermostat.With full engine speed the pressure should be around 18psi and I am guessing with out looking in the manual.I know on one of my engines it was about that.If its lower than that look for a belt slipping due to bad pulleys or belt or a bad pump.The engine does not have to be cold or hot and the thermostat be closed or open changes things very little.The rad cap can be on or off also. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
coppermack Posted February 5, 2015 Author Share Posted February 5, 2015 Just thought I'd update. Ended up being air in the system. Burped it and has been running fine Quote Link to comment Share on other sites More sharing options...
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