kracer58 Posted March 29, 2011 Share Posted March 29, 2011 Evertime I let it idle more than 5 minutes or so it starts to shoot anti freeze out the over flow. Then if I start to drive it it quits. Or if I just drive it and shut it off evertime i stop for awhile (stop lights or signs are fine) nothing happens. Please help. Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/ Share on other sites More sharing options...
Deere Mack Posted March 29, 2011 Share Posted March 29, 2011 Is the temp normal and holding steady? Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75106 Share on other sites More sharing options...
Mackpro Posted March 29, 2011 Share Posted March 29, 2011 Evertime I let it idle more than 5 minutes or so it starts to shoot anti freeze out the over flow. Then if I start to drive it it quits. Or if I just drive it and shut it off evertime i stop for awhile (stop lights or signs are fine) nothing happens. Please help. Thanks.Is your over flow jug ( the jug with the plsatic cap, not metal radiator cap) mounted on the passenger side frame rail by the radiator or is it on the driver side fire wall? Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75108 Share on other sites More sharing options...
Dlock13 Posted March 29, 2011 Share Posted March 29, 2011 (edited) We just went through this with our 454 a little while back. There is some service bulletins from Mack that discuss this. Here are some pointers to start with. The screen at the back of the oil cooler can be clogged up with debris, the water pump seal goes bad and can suck air and cause a coolant pushing condition. The radiator cap can be bad. The air compressor head could be cracked and putting air into the coolant system. Then finally the more expensive problem...cracked heads or blown gaskets. I would first try a new radiator cap if that stops it you got off very cheap. To check if the compressor is putting air into the coolant you can bypass the cooling lines at the compressor and see if it still pushes coolant. CAUTION do not let your engine run too long or the compressor can overheat. The water pump test is just as easy to replace the water pump in my opinion and while you are at it pull the oil cooler, the back end has a screen which might need to be cleaned out. Also a thermostat would be a good thing to do as well. Not a very difficult job. Now if none of these fix your problem you want to check for exhaust gases in the coolant. First remove the fan belts so the water pump can't rotate, remove the thermostat and re-install the housing minus the thermostat, fill the coolant until it is almost to the top of the thermostat housing with the hose removed. Start the engine and look for bubbles or puffing similar to a model train. If there is any evidence of this you will need to start pulling heads. Either a gasket problem or a head cracked between the valves. Hope this helpsWe weren't so lucky it was a cracked head at #2 cylinder Edited March 29, 2011 by Dlock13 Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75109 Share on other sites More sharing options...
kracer58 Posted March 30, 2011 Author Share Posted March 30, 2011 Is your over flow jug ( the jug with the plsatic cap, not metal radiator cap) mounted on the passenger side frame rail by the radiator or is it on the driver side fire wall?It's mounted on the driver side fire wall Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75169 Share on other sites More sharing options...
kracer58 Posted March 30, 2011 Author Share Posted March 30, 2011 Is the temp normal and holding steady?Yes the temp never goes up it holds steady. Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75170 Share on other sites More sharing options...
Mackpro Posted March 30, 2011 Share Posted March 30, 2011 It's mounted on the driver side fire wallWith the engine cold replace the metal radiator cap with a new one ( make sure its a 10 pound and not a 16 pound) and make sure its seats and seals good in the top "surge tank". The top half ( where the metal radiator cap is) is called the surge tank which you could say is actually part of the radiator as it is directly connected to the radiator and is under the same pressure as the radiator. The bottom half is the overflow tank/jug. When the pressure build up in the surge tank and excess 10 psi the cap opens and vents coolant into the bottom half/ overflow. With the engine cold I would fill the top surge tank to the top and completely empty the bottom tank. Then go for a test drive. Many times we see drivers add coolant just to the overflow /bottom then when the top/surge tank does its normal vent into the lower/overflow jug its alread full then it has nowhere to go but out the small hole in the cap which gives the impression that it has a blown headgasket or other problem. Also check the small line between the top surge tank and the top of the upper radiator hose. This hose can get brittle and come apart inside and cause all kinds of weird problems (air trapped in cooling system). Take it off and see if you can blow through it both ways and make sure its still flexable and not hard and brittle. Quote Link to comment https://www.bigmacktrucks.com/topic/18501-98-mack-e7-427-problem/#findComment-75181 Share on other sites More sharing options...
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